Teac 80-8 User manual

TABLE OF CONTENTS PAG E
INTRODUCTION ....................... 1
CONTROL IDENTIFICATION .............. 2- 4
THEORY OF OPERATION - MAINTENANCE ... 5-18
.........................
DAILY SETUP 19
GENERAL ADVICE ON MAINTENANCE ...... 19-20
......................
SERVICE CHART 20-21
CONNECTIONAND OPERATION OF THE DX-8 . . 22-23
HOW THE DX-8 WORKS - THEORY ........ 23-24
ENTERING "RECORD" .................. 24-25
SPECIFICATIONS ...................... 25
rhe guarantee of performance that we provide for the
80-8 must have severa1 restrictions. We say that the
recorder will perform properly only if
it is adjustedpre
perly and the guarantee is that such adjustment will be
possible. However, we cannot guarantee your skill in
adjustment or your technical comprehension of this
manual. Therefore, Basic Daily Setup
is not covered by
the Warranty. If your attemps at such things as rebias
and record EQ trim are unsuccessful, we must make a
service charge to correct your mistakes.
Recording
is an art as well as a science. A successful
recording is often judged primarily on the quality of
sound as art. and we obviouslycannot guarantee that A
company that makes paintand brushes for artistscannot
say that the paintings made with their products will
be
well received critically. The art is the province of the
artist TEAC/TASCAM can make no guarantee that the
80-8 in itself will aswre the quality of the recordings
ywmake.
Your skill as a technician and your abilities as an artist
will be significant factors inthe results you achieve.
This tape deck has
a Serial Nurnber
locatedon the rear panel. Please record
the Model Nurnber and Serial Nurnber
and retainthern for your records.
Model Nurnber
Serial Nurnber
INTRODUCTION
Introduction to the 80-8 and
Its Design Philosophy
No matter how elaborate a multichannel tape recorder is,
it doesn't do the job without help. A lot of equiprnent is
involved, andalotof talent as well. The recorderbecomes
the keystone in a systern that involves rnicrophones,
mixers, loudspeakers, amplifiers and many sophisticated
electronic devices. Everything contributes
a part to the
system of multichannel recording.
Because of what we have learned about multichannel
recording systems in the past
8 years, TEAC decided to
concentrate on improving functions in the
80-8 that are
strictly the province of the tape recorder and to remove
features that we felt were best placed elsewhere in the
system. The cost saved by eliminating features that are
usuallyduplicated by our mixers, such as headphone amps
and microphone inputs has been used to improve the
overall quality of the recorder. The result,
a better and
more flexible recorderfreproducer for the system of
multitrack recording. This logica1 growth now reflects the
needs of the studio style or, if you will, the professional
recordist.
It has long been our contention that professionalism is
defined by people and what results they achieve. It's not
something that automatically happens when you buy
a
tape machine with alot of tracks, or avery high price. It's
what you do with the equipment and how well you do it
that makes the point.
In designing the
80-8, we believe we have been guided by
the multi-channel system as
it truly is. We are sure our
recorder/reproducer can deliver the performance neces-
sary to achieve solid results.
If you would Iike to comrnent on our design philosophy,
please feel free to contact us. Criticism .and comrnent
from our owners has helped us improveour productsand
our business. We welcorneal1 feedback.
Please send in the warranty card. Although
it is not
absolutely necessary to insure warranty protection, it will
allow us to learn some things about who you are and what
you do with tape. From time to time we mail out
literature and information of interest tothe multichannel
recordist. Let us know where you are and we'll keep in
touch.
dbx noise reduction systern rnade under licensefrorn dbx, Incorporated. The word dbx
and the Syrnbol are tradernarks of dbx, Incorporated.
TWARNING: T0 PREVENT FIRE OR SHOCK HAZARD. DO NOT
EXPOSE THIS APPLIANCE T0 RAIN OR MOISTURE. I

CONTRO1 IDENTIFICATON
Front Panel Controlsand Indicators
@ NAB Hub Adapters
Permanently mounted. Use 10-112' ree1 only. Rotate
Adapter ring CW to tighten.
@ Index Counter
4-digit counter indicates relative Iocation of selections on
tape. Used in ~onjunctionwith memory button for
memory stop operation.
@ lndex Counter Reset Button
Push toset counter tozero.
@ POWER Switch
Controls AC power
t0 transP0rt and electronics. Push
again toshut off power.
OMEMORY
When depressed, transport will enter stop mode when
counter reads
9999 during rewlnd operation. Actual
stopping point of tape will depend on transport speed
when counter triggers the stop operation.
@ LED RecordStatus Indicators (FUNCTION SELECT)
These lights show three states.
Light off
- Safe, playback or input
Light blinks
- Recordready, but not in progress
Light stays lit - Recording in progress (or RECORD/
PAUSE Mode)
a FUNCTION SELECT Buttons (8)
Determinerecordand play status.
Up
- Safe, playback or source determined by OUT-
PUT SELECT buttons.
Down - Ready t0 record. If transport controls have
Selected "Record" depressing button will be-
gin recording immediately Output 0f recorder
switchestosource.
@ OUTPUT SELECT Buttons
Selects which of 3 possible sources will feed the output
jacks and the meter circuits. LED's above buttons show

b;
l,*
k A selection.
rz
5'.
lis INPUT - Meter reads line input to recorder, input
%;
signal appears at output jacks.
B;
Tape signal will not be heard.
se NORM - Used for al1 norma1 operations, recording,
E?
syncfreproduce and playback. Meter reads
k
input or head #2 play output depending
f'
on settingof function select buttons.
MONITOR
- Selects head #3. Meter now reads tape
playback. Does not prevent recording on
head
#2. Used in set-up to check perform-
ance and recordfplay monitoring of tape.
@CUE Lever
This control will defeat the fast motion tape lifters. The
more pressure you apply, the closer the tape will come to
the heads. This will allow playback signal to be heard in
fast motion for cueing. Use only enough pressure to hear
the signal. Too muchsignal will damage the electronics,so
be sure the cue lever is nOt engaged (locked)when in fast
motion. The latch position is provided only for hand
winding the tape to find an edit point. Push the lever al1
the way up a second time to release.
@ input LevelControl (8)
For adjusting the source of line level signal. Settinghas no
effect on playback.
+.
@ VU Type Averaging Meter
For visual reference of input signal levels.
@ LED Peak OVERLOAD Indicator
.I
*
. -
Complements VU meter by monitoring transient peaks.
The trigger is factory calibrated at +l0 VU, adjustable.
Transport Motion Controls
6 microswitches - Fast forward, rewind, stop, pause, play
and record. The use of a remote control RC-170 will not
disable the front pane1controls.
t? Master Record Status LED
Shows record state.
Off
- safe
Blinking
- Record ready
On - Recordingin progress (or

Reel Installation
s Fig. 1 Reel lnstallation
@PAUSE LED
This LED will blink for the first 10-15 seconds after the
power is switched on. Transport will not operate until this
LED goes out. Lightsup in PAUSE.
@ Tape Path
Thread the tape
as indicated on the diagram. Over the
tape tension arm
@ (on ree1 side) under the impedance
roller @ (away from reel)across heads, betweencapstan
@ and pinch roller @l and behind shut off arm @
(awayfrom ree1 side).
The shut off arm will drop power to the transport if the
tape breaks.
It's a good idea toallow itto drop when you
take a break in the middle of a session. Doing this will
stop the constant rotation of the capstan, and will
lengthen the life of the capstan motor bearings.
It is not
necessary to unthread the tape. Just allow
it to become
slack so that shut off arm can drop.
Head Location and Adjustment
Head Block illustrations showing al1 parts, tape path, and
al1 adjustments. Screw for guides and head adjustments.
Hex ~ockettvpe screws 0, harefor azimuthadjustment.
Fig. 2 Head Locationand Adjustment
@ ERASE HEAD
@ NORM (RECORDIREPRODUCE) HEAD
@ MONITOR (REPRODUCE) HEAD
@ TAPE GUIDESAND HEIGHT ADJUSTMENT HEX SOCKET
SCREWS
@ TAPE LIFTERS
@ SCRAPE FLUTTER ROLLER
@ NORM HEAD AZIMUTH ADJUSTMENT HEX SOCKET
SCREWS
@ MONITOR HEAD AZIMUTH ADJUSTMENT HEX SOCKET
SCREWS
@ NORM HEAD SHIELD COVER
@ HEAD HOUSING
6ack Panel Plugs and Jacks
@ AC POWER Cord.
@$ AC Switched. AC power supplied when 80-8 is ON.
Use no more than 300
W.
@ FUSE Holder. Contains 3 amp fuse for overload pro-
tection.
@ GND Connection. For connecting a grounding wire
between components, or to earth ground
as necessary.
@ REMOTE Control Socket. For optional RC-170remote
contro1 unit. Needs no dummy plug when not in use.
@ INPUT Jacks. Line inputs for recording are connected
to these eight pin cord jacks.
@ OUTPUT Jacks. Line outputs.
@ DBX Interface Section. Removal panel for direct in-
tegral DBX interface (see DBX Interface section).
NOTE: For use with the DX-8 unit only.

THEORY OF OPERAT ION-MAINTENANCE
If you are new to high quality sound recording equip-
ment, you should become aware of the fact that high
quality sound requires high quality maintenance.
Recording studios that rent time by the hour are very
fussy about maintaining their equipment. Tape recorders
and other electronic gear in the studio are checked out
before every session. And, if necessary, adjusted to "spec"
by an "in house" service technician. He is usually
prepared to correct any problem from a minor shift in
circuit performance to
a major breakdown n amotor. He
has a full stock of spare parts and al1 the est equipment
he needs.
Now that you are running your own "studio" you will
have to make some decisions about maintaining it, and
your 80-8. You will have to become your own "in house"
service technician. Well, what about the test gear and the
spare parts? A stock of spare parts and a super deluxe
electronic test bench can easily cost many times the price
of the recorder. Fortunately. the most frequently needed
adjustments use the least expensive equipment, and the
very costly devices are only needed for major parts
replacements such as drive and rewind motors or head
assemblies. Replacing parts cannot be considered "daily
maintenance" by any means, so we suggest that you leave
the major mechanical and electrical repair to the Dealer
Service Center. That's what it's for
Adjustments to the motors
- back tension and brake
torque are not required often and can safely be left to
dealer service. The adjustments for wow and flutter
require severa1 thousands of dollars of testgear toperform.
It's not practical to consider doing these adjustments
yourself unless you have fifty machinesto service. Then it
might pay to buy the test gear.
In order to help you make plans about the more routine
adjustments to your 80-8, we have made this maintenance
section of the owners manual as easy to understand as
technology will allow. It's a short course in tape recorder
theory as well as a list of adjustmentsand will help you to
understand what
is going on inside when you record. Read
the manual, decide what test equipment you can afford
(although it
is not violently expensive, it is not free) and
determine what service you can do yourself.
Cleaning
The first thing-youwill need for service is definitely the
least expensive
- Cleaning fluids and swabs. The whole
outfit,
2 fluids and al1 the cotton swabs you'll need for
months cost less than one roll of high quality tape. We
can't stress the importance of cleaning too much. Clean
up before every session. Clean up after every session.
Clean up every time you take a break in the middle of a
session (we're serious). How come? Well there are two
good reasons we can think of right off the top:
1. Any dirt or oxide buildup on the heads will force the
tape away from the gaps that record and playback.
This will drastically affect the response. Even so small a
layer of dirt as one thousandth of an inch will cause big
troubles. All the money you have paid for high
performance will be wiped out by abit of oxide. Wipe
itoff with headcleaner and get back to normal.
2. Tape and tape oxide act very much the same as fine
sandpaper. The combination will grind down the tape
path in time. If you don't clean off this abrasive on a
regular basis, the wear will be much more rapid and,
what's worse, it will become irregular. Even wear on
8
E'
A= IOMILS
i
O O. 2 0.4 0.6 O. 8 1.0
SPACING - MILS
W
>
0.05
u
J W
a
0.02
O O 1
Fig. 3 Curves showing fall-off of reproduced signals versus spacing
from reproducer head.
(Courtesy, Minnesota Mining and Manufacturing Co.)
A- I MIL
SPACING - MILS
Fig.
4 Curves showing the fall-off of recorded signals versus
spacing from recording head.
(Courtesy, Minnesota Mining and Manufacturing Co.
heads can be compensated for by electronic adjust-
ments for atime, but uneven wear can produce notches
on heads and guides that will cause the tape to "skew"
and skip around from one path to another, making
adjustment impossible. This ragged pathway chews up
the tape, thus dropping more abrasive, thus causing
more uneven wear and so
- a vicious spira1 that can't
be stopped once it gets agood start. The only solution
will then be to replace not only the heads, but al1 the
tape guides as well. Beingconscienciousabout cleaning
the tape path on the 80-8 will more than double the
service life of the headassembly.

Degaussing (Demagneti~in~)
A little stray magnetism goes a long way. A long way
towards making trouble for your tapes. It only takes a
small amount
(.2 gauss) to cause trouble on the record
head and playing 10 rolls of tape will put about that much
charge on the heads and other ferrous parts of the tape
path.
A little more than that (.7 gauss) will start to erase
high frequency signal on previously recorded tapes.
Demagnetize the whole tape path, including the tips of
the tension arms every six fully played 10%" reels. This is
a fair "rule of thumb" even though it may be a bit hard to
keep track of. Fast motion isn't as significant to the
heads, so we don't give an hourly reference. It's the
recordlplay time that counts.
Degaussing is always done with the recorder turned off. If
you try it with the electronics on, the 60 cycle current
pulses produced by the degausser will look just like 60 Hz
audio to the heads, at about 10,000 VU and will seriously
damage the electronics andlor .the meters. Turn off the
machine, turn on the degausser at least 3 feet away from
the recorder. Move slowly in to the tape path. Move the
degausser slowly up and down in close proximity to al1
ferrous parts and, slowly move away to at least 3 feet
before turning off.
It's a good idea to concentrate when you are degaussing.
Don't try to hold aconversation or think of anything else
but the job you are doing. If the degausser is turned off or
on by accident while it is near the heads, you may put a
permanent charge on them that no amount of careful
degaussing will remove
- head replacement time again,
we're sorry to say. Make sure you are wide awake for this
procedure.
A clean and properly demagnetized tape recorder will
maintain its performance without any other attention for
quite some time. Even if it does drift as a recorder, it
won't ruin previously recorded material, and getting
it
back in good shape will not be too difficult. To make
electronic adjustments, you need test gear, so let's go over
what's necessary.
1) Alignment Tapes
You need one for each speed that the recorder operates
at. For the 80-8the specs are:
Referencefluxivity: 250 nWb/m
Equalizationstandard: IEC
15ips m & 35ps
(See page 10; Test Tapes)
These test tapes are made by severa1 companies, but
there are many different tape specs. Be sure you have
the right one.
Lets's talk about each sDec separately.
Reference Fluxivity
- How much magnetic energy is
necessary on the tape to make the meter read "O VU"
in playback?This
is the "benchmark" or standardyou
tune your playback electronics to. 250 nano Webers
per meter
is the correct value for the 80-8. If alower or
higher "Reference Fluxivity"
is used to set up the
playback, al1 your other measurements will be off.
IEC Equalization
- Here we have a lot to talk about.
The process of magnetic recording is far from "flat."
Every circuit in a tape recorder will alter the leve1 of
signal with respect to
its frequency - some deliber-
ately, some unavoidably. The deliberate errors are used
to overcome the unavoidable problems. Here
is a
selection of frequency response graphs at various
points inthe recording process:
1. Ifthe input signal starts this way
Beginning, okay
20Hz 20kHz
Fig. 5
2. EQ to overcome head loss at high frequency and
bass anomalies
Deliberate error
l I
Fig. 6
3. Record Head Response
(6 dB per octave rise until gap in head approaches
wavelength)
Unavoidableerror
Small wavelengths (high frequencies) are partially
erased as fast as they are recorded.
Fig. 7
We will assume something recorded, but it's not flat on
the tape either. Now we'll play
it back.
4. Playback Head Response
(6 dB per octaverise again, same as recordhead)
Unavoidableerror
Small wavelengths are not picked up
by gap.
1
I I
Fig. 8

THEORY OF OPERATION-MAINTENANCE(C~~~~~~~~)
5. Playback EQ
Now we must overcome the characteristic response
of heads in magnetic work.
Bigdeliberate error
Helps lower tape hiss
as well as restoring proper
levels to high frequencies.
Fig. 9
6. The result of al1 this equalization is this (hopefully)
Fig. 10
The idea is to use the electronicsthat are adjustable to
cope with the problems that are caused by the nature
of the magnetic recordingprocess. We can't change the
basic laws of magnetic physics, so we change the record
and playback equalization. Now comes the sticky part.
How much EQ do we use in each stage? If every
manufacturer of tape recorders used their own stan-
dard, their idea of what was best, there would be no
playback compatibility. Tapes made on one recorder
would not play back properly on another of different
make. The standards for record and playback equaliz-
ation are established by societies of scientists, engineers
and users inthe profession.They are:
NAB National Association of Broadcasters
IEC International ElectrotechnicalCommission
CCIR International Radio ConsultiveCommission
DIN Deutsche Industrie Normen
Unfortunately, they don't
al1 agree. Each organization
has
a slightly different approach to solving the prob-
lems of tape recording. Scientists and engineers are
human,
as well, and have been known to disagree,
sometimes violently about what ways are best. Ad-
vances in the manufacture of tape, improvements in
head design, and the lowering of electronic circuit costs
have made bizarre solutions quickly change into
practical realities. The optimums have shifted and will
probably continue to do so. Standards are set by man,
not cast instone.
But while the scientists are boxing in the conference
room, we would like to be recording, so TEAC has
selected the IEC standard for recordlreproduce EQ
as
the recommendationfor the 80-8.
+ 1s
+ 10
V)
i +s
I,
- s
20 40 100 Zoo 400 Ih 2h 4h Oh 2-
FRfOUENCY IN HERTZ
Fig. 11 Typical recording (pre-equalization) for %-inchtape
recorders using NAB characteristics.
FREOVENCY IN HERTZ
Fig. 12 Typical post-equalization for %-inch tape recorden using
NAB characteristics.
100 200 400 Ih 2h 4k
FREOUEWCY IN HERTZ
Fig. 13 Typical pre-equalizationcharacteristia for %-inch tape
recordersrunning 7.5 and 15 ips using the CCIR (DIN)
!tandard.
Fig. 14 Typical post-equalization curves for %-inch recorders
using CC1
R characteristia, at 7.5 and 15 ips.
Since these Reference Standard tapes cost about 3
times the price of a big roll of the best blank tape, plan
on storing them carefully in
a place that will not
encounter any magnetic fields that might damage them
- away from loudspeakers, guitar pickup, tape record-
er and record player motors, power amplifiers (magnet-
ic field surges in big transformers when amps are
turned on and off can be very powerful) or anything
magnetic that might alter the quality of the reference
standard. If you don't damage them physically or
magnetically (don't play them on dirty or magnetized
recorders, or loan them out to the carelessl they will
last for severa1 years.

If it is not possible to obtain a tape that has both the IEC Correction Chart (illus.)
IEC EQ and afluxivity of 250 nWb/m, select the IEC
EQ as the preferred single standard. A different
reference fluxivity requires only that you make alevel
correction once. Just use adifferent mark on the meter
instead of "zero." A different EQ curve requires a
different amount of correction for each frequency and
is much harder to use
- especially for abeginner.
Level corrections for different reference fluxivity:
Use this
instead of
"O" VU
15ips 185 nWb/m
- (Ampex operating level) -3 VU
200 nWb/m -- (STL, MRL) -2 VU
Below are tabulated some commonly encountered flux
levels along with their dB differences, and their differences
in dB from 185nwb/m.
Ampex operating level
3 dB above
Ampex operating level
DIN Standard
6 dB above
Ampex operating level
+a
+ 7
+e
+l
+ 4
+ 3
t2
+I
0 o
5-,
-2
- 3
- 4
-5
O m
FROXmCI IN URIZ
Fig. 15
If you must use NAB EQtapes, these amounts of read-
ing are correct. NAB has more boost in playback, the
tape will read progressively higher as frequencies rise
whenplayedonan IEC adjustedrecorder. At 250 nWb/m
reference read these numbers to set IEC EQ.
Since the low frequency EQ on the 80-8 is fixed, the
differences are academic. On to the next piece of test
equipment.
2) VTVM or FET Multimeter
Fig. 16 Head Alignment Fine Adjustment Set-up and Test
Connections (PLAYBACK)
DECK
under TEST
With an input impedanceof at least 1 megohm that can
read levels down to -80 (full scale) you can think of
this as a very accurate VU rneter of very wide range.
Meters with lower input impedances will draw power
from the circuits to be measured and will affect the
readings. Meters that have adequate input impedance
but do not read below -40 (.O1 V) can
be used for
reference levels and frequency responsemeasurements,
but will not be capableof makingsignal-to-noise,erase
efficiency or bias circuit measurements where the
output of the circuit being adjusted is expected to
be
very low.
,I
J
WTIUT
((i: ,o 1
NORM MONITOR
o o

This tool is not cheap and is just as important as the
test tapes. Without agood reference meter, you can do
very little in the way of accurate adjustment. Spend as
much as you can here. It's worth it. Next. ...
3) Signal Generator or Oscillator.
Here you get a break. A simple oscillator will do al1 the
work and won't send you to the poor house. There are
severa1 on the market for less than $100. lfyou get one
with a meter on it, you won't have
19 calibrate its
output with the big meter as often. TI , device is very
useful in a studio for troubleshooting a good invest-
ment. It should have at least the following frequencies.
Sine wave is al1 that is required, at a distortion of no
more than .5%. Most modern units do better than this
easily. This unit is the workhorse on the equipment
list. Whether you are reading the big meter (FETI or
the meters on the recorder. you will need a signal to
read, this instrument or the test tapes will provide you
with signals.
Test tapes, tone generator, VTVM or FET meter .
. .
This is the basic package and will do almost every
adjustment in the sequence
- except the first one . . .
4) The Oscilloscope.
Even a simple one
is not cheap. Fortunately, a simple
one is al1 you need. You can spend $6,000 and more
for the big ones, but for this purpose $100
- $200 will
be more than enough. It must have a "vertical" and a
"horizontal" amplifier and an X-Y mode. That's al1
you use to do the one adjustment you need it for.
Tilt, height and tangency adjustments on the 80-8 are
virtually unnecessary. The precision head block mount-
ing plate practically guarantees long term accuracy in
these areas. Only major physical force will disturb the
relationship of the head block tothe tape path. As long
as you don't drop the recorder"facedown"or strikethe
head assembly with a hammer al1 should be well. A
small azimuth adjustment (I0.5degrees) is provided for
fine tuning. This adjustment
is accomplishedby apply-
ing screw thread pressure to a slot in the base of the
head itself. (See Fig. 21, pg 10.)
Assuming that the motors are not in need of attention
(that's for Dealer Service), Azimuth, or headalignment
is the number one step in maintenance. . .. so let's
begin.
Fig. 17 Haad Adjurtment (Azimuth)
The gaps in the heads that do the erasing, recording,
and playing back must be precisely perpendicular to
the tape. PRECISELY. Even a tiny error in alignment
will rnake problems for the recorder. If the heads are
not in alignment, both with the tape, and with respect
to each other, tones recorded on one head will not play
properly on the other. In the table below, the error
is
shown with the loss in dB for 1K and 10K. The
amount of tilt
is given in the fractions of a single
degree called minutes, 60 minutes to a degree. As you
can see, it only takes '/4 degree to cause bigtrouble.
Fig. 18 Loss due to azimuth misalignment for 43-mi1quarter-
track. (Courtesy,Ampex Corp. Test Tape Laboratory)
Since the 80-8can use a single head (head #2 in the
stack) to perform al1 functions (recording, sync play
and playback)
it won't hurt the recorder to use the
"whiibang studio alignment" procedure, which is todo
nothing about alignment at all. You won't notice
anything wrong with the sound you make, but there
are drawbacks.
1. Your tapes won't play properly on any other
recorder (whizbangstandards are unique).
2. Noaccurate tune-up of the recorder will be possible,
as most test procedures use one head as a reference
for the other. To do this, they must be aligned
perfectly.
Thread the 15 ips test tape on the recorder and find
the operating level section of the tape. Connect the
outputs for tracks 2 and
7 of the recorder to the 2
inputs of an oscilloscope, track 2 to the vertical input
that makes the beam draw lines up and down and
7 to
the horizontal input (draws lines left to right). Set the
'scope to the "Vector" or XY mode. You will have to
consult the instrumentation book for the scope to
determine how to do this. We don't know what brand
of test gear you have. Play the tone, and this is what
you should see:
%-Mi1Wavelength
LOSS Azimuth
Error in
in dB Minutes
0.5 dB 3.71
1
.O dB 5.22
2.0 dB 7.30
3.0 dB 8.83
4.0 dB 10.08
5.0dB 11.13
6.0 dB 12.04
7.0 dB 12.84
8.0 dB 13.54
9.0 dB 14.18
10.0 dB 14.75
l-MilWavelength
Loss Azimuth
Error in
in dB Minutes
0.5 dB 14.86
1.0 dB 20.90
2.0 dB 29.21
3.0 dB
4.0 dB
5.0 dB
6.0 dB
7.0 dB
8.0 dB
9.0 dB
10.0 dB
2 alone
%-Mi1Wavelength
Loss Azimuth
Error in
in dB Minutes
0.5 dB 7.43
1.0 dB 10.45
2.0 dB 14.60
3.0 dB 17.67
4.0 dB 20.16
5.0 dB 22.16
6.0 dB 24.08
7.0 dB 25.68
8.0 dB 27.09
9.0 dB 28.36
10.0 dB 29.50
Track 7 levels.
alone One track
or the other
is dominant.

If the lines are not the same length for each track
alone,
it indicates that the 2tracks are not puttingout
the same level. Adjust with the 'scope controls.
If the playback head is not straight up and down, you
will see this kindof picture:
(Asrnall misalignment (Alarger error (Abig one,
30" out of phasel
90" outof phasel 180" out of phasel
(Perfectazirnuth
O", inphasel
Fig. 19 Phase Shift
How much distance error is involved depends on the
frequency or pitch of the tone and the speed of the
tape. One "cycle" per second at 15 ips would be hard
to misalign. To get Scope picture No.
6, you would
have t0 separate the gaps in the playback head by 7%
inches, but one cycle per second
is not audio. How
about 1,000 cycles per second of tape travel? At 15
pis, the separation or tilt in the head for scope picture
No.
6 becomes .O075 inch. And at 15,000 Hz at 15ips
it's .O005 inch. Not much tilt will produce a bigerror.
Slower tape speeds mean even smaller spacings and
good azimuth becomes even more important. The
proper method of adjustment is to look first at along
wave, say 1000 cycles, and make a coarse adjustment.
Then work up in frequency, adjusting shorter and
shorter wavelengths smaller and smaller amounts. If
you start adjusting with 10kHz or 15kHz, you can
make a big mistake. Here's why. .. . Since the very
short wavelengths are very close together on the tape,
it is possible to get a good "picture" on the scope by
adjusting one full cycle off. If you work up to 15K.
checking and adjusting as you go, you will avoid this
mistake.
0.OWi
y 0.001
I O
z
z
x
s
W
r 001
1
o lIO
20 50 100 200 500 li 21 5k Ok 20k
FREQUENCY IN HERTZ
Fig. 20 Velocity of recording media versus recorded wavelength
in inchesfor e given frequency.
Once you have everything set up - the reference tape
is playing, the scope is running and showing the X-y
display, you need a Hex Wrench and this diagram to
find the right adjustment point. Adjusting the screw
will rotate the head very slightly.
AZIMUTH ADJ.
Fig. 21 Head Adjustment Screws and Alignment
Test Tapes for 80-8
TEAC YTT-1104SP(for reproducealignment)
Tape speed: 15ips; referencefluxivity: 250 nWb/m;
equalization: IEC; time constant:
& 35 psec.
- or -
MRL31J-129 (Magnetic Reference Lab.)
All specs are identica1with YTT-1104SPexcept for
the reference fluxivity which
is 200nWb/m and thus
its reproduce output level will be 2dB lower.
The next step is to play al1 the signals from the lowest
frequency to the highest on the 15 ips alignmenttape
- one play for each head position (2-3). and DO
NOTHING. Just have alook.
It's not a good idea to turn knobs just to "see what
happens." Just because an adjustment can
be made
doesn't mean
it's necessary. The recorder is very solid
and
is well adjusted at the factory, so in al1 test and
maintenance procedures, check first, then ifsomething
is not right, adjust. Taking your time will save endless
grief. A new machine
is very likely to be "on the
money" when you get
it and if you keep it clean and
degaussed will drift away from top shape very slowly.
It's not necessary to plan on a major overhaul when it
comes out of the box.

THEORY OF OPERATION-MAINTENANCE(C0ntinued)
Locations of Electrical Adjustments
The electronics for the record, reproduce, and
bias amplifiers are on one PC card per channel.
1 TRIM POT NUMBER 1 REFERENCE NUMBER I FUNCTION I
13104 10kOhms I MONIT LEVEL
1 2 1 R103 10k I NORM LEVEL 1
l 3 l
R105 22k
l
METER CAL
l
1 R102 6.8k 1 MONIT EQ 1
5
6
7
8
9
10
I p 12 I R106 22k I PEAK LED 1
R101 6.8k
R107 22k
R111 l k
R112 50k
l l
NORM EQ
INPUT MONIT LEVEL
ERASE & BIAS LEVEL
BIAS LEVEL
R110 10k
R108 3.3k
REC LEVEL
REC EQ
PEAK ADJ
11
-
R109 470
- REPRO BIAS TRAP
L I
-
-
REPRO BIAS TRAP
L 3
T 2
RECORD BIAS TRAP
INTER STAGE TRANSFORMER

Note: Value of "dB"in the Data refers to OdB = lV, ex- For example, -10 dB (0.3V)
is applied to the line in
cept where specified. If
a Test Set or VTVM calibrated jacks, the VTVM which
is connected at the line out
to
O dB = 0.775V is to be used, appropriatecompensa- put jacks reads -7.8dB (0.3V) instead of -10dB
tion should be made. (0.3V).
I I
I
Electrical Adjustment Procedure
I
REPRODUCE CALIBRATION:
When we're sure the playback and record heads are
properly aligned, we can move on to the electronic
adjustments.
The first step here
is to actually check your merer caii-
bration. To open the service door loosen the 2 captive
screws, one in each upper corner. The panel hinge re-
quires
a clearance of about 318" before it can tilt
forward, so a sliding mount on the bottomedge of the
service door has been provided. Draw the entire panel
straight out slightly before attempting to tilt the top
edge forward.
Connect the VTVM to the output termina1 of track 1.
Turn the machine ON, and thread the 15 ips alignment
tape. Play the "operating level" portion (a voice on the
tape identifies eachsection
at the beginning).
Switch the OUTPUT SELECT on the 80-8to MONI-
TOR. Adjust the playback or "reproduce" level with
trim pot
#l R104, 10k Ohms MONIT LEVEL, until
the VTVM reads - 10dB (0.3 V).
Switch the OUTPUT SELECT to NORMAL. Adjust
the playback level with trim pot#2 R103, 10K Ohms
NORM LEVEL, until the meter reads -1 0 dB (0.3 V).
Now read the meter on the front panel of the80-8. It
should read "O VU."
If it does not, then you must use the extender card
to gain access to the proper contro1 pot. Carefully re-
move channel 1 electronics from the machine. But
don't unplug the cables that are attached to it. There
is just enough wire on them to allow you to attachthe
card extender (see ill.) to the electronic card, and re-
place the whole works in their proper receptacle. The
card will now operate, but will
sit upso you can see al1
the components on the board. Find trim pot R105,
22k Ohms. This pot is mountedon the topof the card
on the component side of the board.
Adjusting R105 will allow you to set the meter on the
80-8. You adjust the 80-8meter to read
"O VU," not
-10, the reading on the VTVM. The VU meter will
read O at any voltage you set it for - the correct one
is O VU. This is the right setting for the 80-8. You read
-10 dB (0.3 V) on the VTVM and adjust the 80-8
meters to read
O VU at this level.
Thus, the card extender is necessary only if the 80-8
meters do not read
O when the VTVM reads -10 dB.
Remove the test tape from the 80-8, turn off the
power, and disconnect the card extender. Return the
channel 1 electronics to
its proper place in the rack.
Rethread the tape, and turn the power on. Plug the
VTVM into channel 2 output. Play the "operating
level" section of the
test tape. Switch the OUTPUT
SELECT to MONITOR, adjust trim pot
#l on track 2
electronics so the VTVM reads -10 dB (0.3 V).
Switch the OUTPUT SELECT to NORMAL, adjust
trim pot #2 on track 2 electronics so the VTVM reads
- 10dB (0.3 V). Now read track 2 meter. It should
read O VU. If not, you must repeat the previous pro-
cedure for adjusting the meter circuit (card extender,
etc.)

THEORY OF OPERATION-MAINTENANCE(continued)
1
Electrical Adjustment Procedure
I
Six tracks still remain to be checkedand adjusted, but
as you can see, the adjustments are the same as for
track 1. Inbrief:
1. play the tape "operating level"
2. readthe VTVM for head 3, MONITOR
3. adjust for -10 dB (0.3 V) reading with trim pot
#l
4. switch to NORMALon OUTPUT SELECT
5. read the VTVl\rl. Adjust trim pot
#2
6. read the meter on the80-8 - it must read O VU
7. adjust th-e meter trim pot #3 R105, 22 k Ohms
METER CAL
You do this for al1 8 tracks: 16 level sets and, if
necessary, 8 meter trims. Don't get discouraged. When
you are unfamiliar with anything,
it takes more time.
Practice will speed things up. The entire adjustment
procedure involves reading and setting (if necessary)
about 128 controls. When you are used to doing it, it
should only take about an hour and
a half. Have
patience, you'll learn soon enough. It is absolutely
worth it.
One more word of encouragement. The circuits in the
80-8are very stable. Most of the time you will make
a
reading and not have to adjust anything. When some-
thing does go wrong, you will be able to fix it very
quickly, and get back torecording.
In summary, with the VTVM and test tape, you have
adjusted the playback level on the 80-8 to the test
tape. But your playback reference is not yet complete.
You have only "zeroed" one point on a line of
frequency response. To establish the rest of the line,
you must measure and adjust one more frequency.
Advance the alignment tape for 15ips to'the section
that
is recorded at 16kHz and adjust the trim pot
marked MONIT
EQ #4 R102,6.8 k Ohms - switch to
NORMAL on the OUTPUT SELECT, and adjust trim
pot #5, R101, 6.8 kOhms NORM
EQ. The reading for
both positions should be -10 VU on the 80-8meters.
Since you have checked and adjusted the playback
meter circuit, you now can use the meters on the80-8
for the test readings.
By adjusting al1 of the preceding trimmers, you have
established two things: an operating playback level or
"zero", and
a playback frequency response reference.
You know that both heads on the 80-8arereproducing
the test tape in an identica1manner.
RECORD CALIBRATION:
VTVY 1
Fig. 22 Test Connection for RecordingCheck

Now you can use the MONITOR head as a test
instrument to check and adjust the record circuits.
Almost al1 of the following steps involve recording
a
tone on a tape and reading the playback output of the
recorder. YOU WON'T ALTER THE PLAYBACK
CONTROLS. They are now
al1 set. You will make al1
necessary adjustments by trimming the record electron-
ICS.
This way, you can be sure that the recordings you
make, no matter what brand of tape you use (the
brand of tape becomes part of the test procedure when
you record your test tones on
it), will playback
properly on any 80-8.
The alignment tape can be put away. Before storing,
the tape should be played al1 the way from front to
back (not fast wound), and stored tails out, so it will
last longer. Even if you decide not to attempt any
major maintenance yourself, we strongly suggest you
purchase an alignment tape. An occasiona1playingwill
tell you when you need to call the"doctor".
It's good
insurance to know the truth.
The record adjustments begin with the INPUT MONIT
LEVEL trim of the 80-8. The INPUTMONIT LEVEL
controls the meter reading of the signal
as it arrives at
the electronics (before it is recorded). You must be
sure you are sending the right amount of signal in
before you can adjust record levels
ad equalization
controls.
Connect the referencelevel, or signal generator to track
1 input on the 80-8. The correct level
is -10 dB
(0.3 V).
The frequency to use
is 1 kHz. Rotate the front panel
knob to the
"2 o'clock" position. It's a good idea to
mark
it. Check the OUTPUT SELECT. Make sure you
have the button marked INPUTdepressed. If you get a
reading, use trim pot
#6 R107, 22 kOhms, INPUT
MONIT LEVEL, and adjust the meter to read
O VU.
As always, repeat this check on al1 8 tracks of the 80-8.
Pluggingand unpluggingtest equipmentcan be tedious.
You can save some time by doing
a referencecheck on
your mixer. Ifyou know that your console meter reads
O VU accurately (check it with the VTVM), you can
assign the reference oscillator signals to the 80-8
through the mixer connections to the inputs. Assign,
read, adjust: next track, assign, read adjust. . . no need
t0 pull plugs.
ABOUT THE BIAS:
At this point in the adjustment procedure we'll stop
for
a time and talk about a major section of the
recorder electronics. The Bias Oscillator and
its related
circuitry. The Bias Oscillator produces
a very high
frequency signal that does two big jobs in the80-8.
It
supplies the 100 kHz (one hundredthousandcycles per
second) frequency to the Bias Amplifiers in the 80-8.
There is a Bias Amplifier on every card, one for each
track. The Bias Amplifier provides power for the erase
head and bias signal for the recordhead. Erasure is easy
to explain, so we'll tackle that subject first. A lot of
power
is used to remove al1 signal from the tape just
prior to
its being recorded. The erase head has a rather
large gap and completely cleans off any magnetic field
on the tape
by brute force. No new signal is recorded
by this head. The gap is much too large to be effective
as a recordingdevice.
From the same amplifier, current is added to the
record head circuit lead. This high frequency signal
overcomes magnetic inertia intape, and gets everything
moving. If there were no "starter current" to help the
record signal, we would see this kind of trouble on a
scope.
WITHOUT BIAS D~rrorted
If we pul rh~s in. - .
Fig. 23
We would get ihir oui
The beginning and ending points of the wave would be
distorted by the reluctance of the iron bits to change
their magnetic state from one polarity to the other.
Crossing that zero Iine takes extra energy. The Bias
Signal provides
it. We put in this:
- - . and gei back thir - .
Audio and Bis rnixed - - -
Fig. 24
Where did the 100 kHz go? It disappears from the
output because the head gap
is too large to play it
back. The individua1changes of magnetic energy on the
tape are smaller than the gap size so aplus and aminus
wave are both within the gap
at the same time. They
cancel out. Mawelous! On with the problems of
alignment.
Well, maybe not so marvelous. Because of the fact that
there
is one amplifier doing 2 separate jobs. The
adjustments we make on one circuit wili affect the
other. In fact, there are 3 interacting circuits and life
can get pretty tricky right here. The 3 adjustables are
(insequence):
1. The erase current adjustment trim pot #7 R111,
1k0hms ERASE & BIAS LEVEL.
2. The bias current (for the record head) trim pot #8
R112, 50 kOhms BIAS LEVELthe large blue one.
3. The biastraps. Since there
is a lotof power involved
here, you have
2 problems. The record bias signal
must not go to the record electronics, only to the
head so there
is a big high frequency filter (very
high, just to keep the bias out) on the wire to the
record head.
I BIAS I I
7 REC HEAO I
REC AMP
l
Fig. 25 t

THEORY OF OPERATION-MAINTENANCE(contlnued)
Electrical Adjustrnent Procedure
These adjustable circuits are on the card inside, and the ERASE.ADJUST:
extender must be used if adjustments are necessary.
We've given you the bad news (they interact). Now Let's get back in sequence again. First
- the erase
we'll give you the good news. Unless you adjust the adjust. The idea here is to make sure al1 signals come
erase current or the bias current by a very large off the tape when you want them to, so you record a
amount, you won't need to check these circuits more 1 kHz tone on the brand of tape you wish to use at
than once every six months or so. The traps seldom
O dB level, that's +l0VU, full saturation and then,
need adjustment .unless something is wrong with the erase
it (record no input signal over the tone). While
master oscillator. The "traps" are expected totune out erasing, you read the output with the VTVM and a
the 100 kHi frequency that the bias oscillator is 1 kHz filter. Since the filter will "pass" only 1 kHz,
producing, and the range of adjustment that they have you should get a reading of -65dB. If the reading is
is not very good at filtering a much different frequen- higher than that, you need more erase current. Adjust
cy. If the master bias oscillator drifts, it must be trim pot #7 R111, 1 kOhms to correct the readingto
re-adjusted to produce 100kHz. Since this bias oscilla- -65 dB. This circuit does not require daily or weekly
tor master circuit adjustment requires something ex- adjustment. Once every 6 months should do, unless
pensive (very) called a frequency counter, it's wise to you hear signal left on the tape when you are working.
assume
it's a dealer problem. Cart it in for this kind of The filter is TEAC part No. M-206. You connect it
service. There are also bias traps in the playback circuit between the recorder output and the meter (vTvM).
to keep any stray leaks out of them as well, but they
are not as touchy as the record-related circuit traps,
and won't affect the load on the bias amplifier. They
are tricky to adjust, but very stable.
In sequence, you
OSCI~~OSCOPE
adjust them (if necessary) at the very end of the entire
A~~ SMR
alignment procedure so we'll mention them again.
OX~LLP~W
O
DECK
under TEST
..-.m
Fig. 26 Test Connectionsfor Erese Measurament
VTW
,,, imi FLTER
a
.--o
a-
0 0

BIAS LEVEL ADJUST: This adjustment is made
while you are recording
a tone on the type of tape
you'll be using for the session. It will be different for
each brand of tape.
Set up the signal generator (oscillator). The frequency
is 10kHz. The level should be O VU on the meters of
the 80-8 on INPUT. Start the machine. record the
signal, and switch to MONITOR on the OUTPUT
SELECT.
Begin the adjustment by making sure trim pot
#8
R112, 50 kOhms BIAS LEVEL is inthe fully counter-
clockwise position (off, no bias at all). Now, as you
rotate the trim pot
#8 clockwise, the VU meter will
rise tosome peak reading. Continuethe clockwise rota-
tion slowly until the reading on the meter drops back
3dB from the peak. If, at peak the meter goes off
scale, adjust the front panel input level contro1to keep
the reading on scale.
What
is important here is not the zero. It is the reduc-
tion of the peak by precisely 3 dB. Ifyou have moved
the input level pot on the front panel of the 80-8to
keep your reading on scale, the next adjustment will
correct your input reference.
Fig. 27 Bias LevelAdjustment Squencr
I
BIAS
(Pot rotated clockwise)
1.307
Fig. 28 Bias Limits Chart
If there is insufficient CW rotation of trim pot #8 to
achieve
a peak, dealer service of the Bias amplifieri
oscillator system will be required. Many voltages inthe
circuit must be adjusted accurately and this type of
problem is not considered to be "Daily Maintenance".
Bring it in.
When doing bias adjustments, al1
8 channels should be
recording at once, even though you are adjusting only
one at
a time.
With the oscillator running at 1 kHz, switch back to
INPUT. Adjust the front panel input knob to
2 o'clock
position and adjust trim pot #6 R107 INPUTMONIT
LEVEL for
O VU indication on meters.
BIAS TRAP ADJUST:
Now
is the time to do the bias trap in the record
circuit: the card extender
is used. With no inputsignal,
test point
is located on the card. Positive side of
VTVM
is connected to test point, negative side to
ground. Tune inductor L3for minimum.
Fig. 29
16

THEORY OF OPERATION-MAINTENANCE(continued)
Insert
Electrical Adjustment Procedure
RECORD LEVEL ADJUST: 4. Recordthe tone at 15 ips.
5. Switch to "MONITOR" read 80-8 meter
We give these adjustments just to be accurate and
6. With trim pot #9 R110, 10 kOhms REC LEVEL,
thorough, and remind you again that they are seldom adjust to "O VU".
needed. Unless you have made some really drastic With only afew adjustments remaining in the complete
change in your recorder, you should not worry about procedure, let's review al1 you have done up to this
this adjustment for at least
6 months. point. Step by step, you have:
Again, to be thorough, at this point it would be wise to
1. Cleaned and degaussed the tape path.
check erase and bias again before proceeding. On a
2. Adjusted the head azimuth of both heads to 90° by
major overhaul
it might be necessary to go through checking and adjusting progressively higher and
these
3 steps 3 or. 4 times before finally moving on to higher frequencies.
the record equalization and then, once more from erase
3. Checked the 80-8 meters against a precision meter
through to the end. Describingthis procedurethis way and set
.316 volt output as "O VU" playback.
is probably giving the manufacturing setup, or a head
4. Adjusted playback from both playhead positions to
replacement sequence when al1 values of the record be
"O VU" at 1 kHz and at 15 kHz, using the test
circuit must be re-qualified. If noise is heard, signals tapes
as an absolute reference of magnetic level.
don't erase completely even after adjustment, or there
5. Applied a reference level to the input of the 80-8
is not enough rotation of the bias trim pot left to get a and adjusted the
"O VU" point tobe ,316 volt, both
"drop" in bias, the whole adjustment should be inthe circuit and on the meter.
considered, but only under these unusual circum-
6. Set the erase level, using blank tape of your selected
stances. brand and type.
However, we do recommend that you select a brand of
7. Set bias level for the tape of choice.
high quality tape and stick to it. Changing bias every
8. If you have the equipment, make sure no bias is
day for different tapes will make the recorder cranky goingto the record amplifiers.
and a little harder toadjust. Constant messing with the
9. If you have the equipment, set (after bias) the
controls
is unwise. It is a much better idea to do as record
"O VU" and read it off playback. You now
little as possible and let the recorder "settle in" to one know that the tape you are making has the same
kind. level of magnetic flux recorded on it as the
We are now ready to adjust the record circuitry. We reference alignment tape, but only at
1 kHz, the
first check the low frequency input level at
1 kHz to basic adjustment frequency - you now select
get a reference. The steps are as follows:
18 kHz and adjust trim pot #l0 R108, 3.3 kOhms
1. Adjust oscillator to 1 kHz REC EQ, and read playback from the MONITOR
2. Select "INPUT" on OUTPUT SELECT buttons position. Adjust to "O VU". One setting remains.
3. Send in .316 volt, set "O VU" on 80-8 meter

The Peak Adjust Circuit
The trim pot in this circuit oniy has a very small range,
% dB. It is for final high end adjustment. The frequency
to send in
is 18 kHz, recordthe tone at "O VU" in, switch
to MONITOR and read the result. Adjust trim pot
#l 1
R109, to read "O VU" in playback.
Both of the record equalization circuits have rather
a
small range of adjustment. The high frequency adjust is
3 dB, the peak adjust is % dB. If you can't seem to get a
"good" reading because you run out of adjustmentrange,
check these
3 points.
The "Record adjust" (point #9 in this review). Re-do,
send in
"O VU" at 1 kHz. Record the tone and read
playback. If it is low, it will be impossible to get
15 kHz or 18 kHz up to "O VU." Reset and try again.
Still no good? Re-check the bias. If the bias current is
too high, the high frequency sensitivity is reduced in
relation to the 1 kHz point. Check itout.
Switch the 80-8to INPUT and send in
a signal of 1 kHz at
a level of 1volt (O dB, +l 0 VU). Adjust the trim pot # 12
R106. 22 k0hms until the LED goes on.
We suggest that you do this LED adjustment
as rapidly as
possible. +l0VU is not good for the meter movement.
More than one minute of operation
at +l0 may damage
the armature, so set everything up before applying the
signal and be brief.
With the 80-8 al1 buttoned upand the service door closed
you can now check the Signal to Noise of the whole
system. You use the big test meter. Recordwith no input
signal and read the result. The reading should be -60 dB
or better (un-weighted).
That's it. The whole procedure for an electronic overhaul
of the 80-8. Mechanical adjustments such
as brake and
holdback torque, ree1 height adjust and wow and flutter
measurements must be done first, but they are major
service and should not be necessary "out of the box." The
transport logic contro1and switching system are described
inthe service manual.
We'll sell you a copy if you want one, but digital i.c.
theory is very complex and the necessary test equipment
for repairs costs more than the recorder. The service
manual is not written as a guide to the beginner, so be
advised,
it may not help your understandingof the 80-8.
It is usefulonly tothe experiencedmaintenancetechnician.
Fig. 30 Frequency Response-OVERALL
If al1 this fails to produce a readingthat lies within the
tolerances for frequency response on this graph,
it is
time to replace the heads. If more equlization were
added to the record circuit to overcome wear, the
boost needed would be large enough to make the
Signal to Noise ratio specification impossible to
achieve.
Let's assume everything
is OK so far. You have sent in
and read back good numbers for 15 ips, everything in
spec
at both frequencies. Now, as a check, record
everything you have on your tone generator (if
it is
variable be reasonable, say 10 frequencies) 40 Hz,
100Hz, 400 Hz, 1kHz, 4 kHz, 10kHz, 15kHz, 18kHz
- compare with the graph above.
Fine tuning the bias against the frequency trim pots
will allow you to get a littlecloser to perfectly flat. It's
time consumingbut worthwhile. Suit yourself.
Remember the tjias traps?We've discussed the adjustment
of the bias traps in the record circuit and what they do
and now that we're done with the final changes to the
record equalization, we can measure the Signal to Noise
performance and tune the playback bias traps. Connect
the VTVM to the output of the recorder. Use the card
extender (Part 60853030). Locate the play bias traps L,,
Li on the card. With the unit in RECORD but no signal
other than the bias being recorded, adjust for
a minimum
reading on the TEST meter (VTVM).
While you have the extender card on the electronics we
should describe the LED or peak reading adjustment.
Examine the diagramlillustration to find the trim pot.

DAILY SETUP
It's obvious that this entire procedure is not something
that can be completed quickly. You don't begin a
"major" ten minutes before the musicians arrive. Itis not
likely to be necessary every day, but what is reasonable?
Most good engineers make two quick tests. If nothing is
amiss, they start setting up the rest of the session with
confidence. If there is a problem, they go further. Here is
what they do.
1. Clean and degauss. 0bvi.ous first step.
2. After the recorder has been on for 10 minutes and is
nicely warmed up, they check the playback response
with the test tape. A little trim?OK, no problem.
3. They then set up the signal generator and record
severa1 frequencies, say 100 Hz, 4 k, 10 k. Looks good?
Then we can begin.
4. A very fussy engineer will take a look at the bias adjust
to make sure everything is OK there as well, before he
looks at the record EQ.
These three quick checks will usually uncover any serious
troubles, and the idea
is to work backwards up the chain
of adjustments if anything shows an error. "Playback" is
the first step in a major overhaul, and Record EQ
is the
last.
If everything works OK, you can assume al1 is well. If you
get something funny as a reading, you will have to track it
down, but these three tests will usually give you some idea
of where the problem lies. Work backwards through the
recorder (that's forward through the adjustments, by the
way, they run from back to front inthe procedure,don't
get confused) until you uncover the problem. You always
clean and degauss, and you should always check the
playback response with the test tape. Again, playback,
bias, record check, no problems, OK, go, and good luck
with your tapes.
Speaking of tape, we strongly suggest that you buy good
quality tape and stick to one kind. White box tape is
cheap for a reason.
It doesn't perform as well as the "good
stuff," and will be hard to tune up to, and may even
damage your recorder. Excessive shedding of oxide,
uneven slitting and other defects too numerous to
mention will make al1 your efforts go for very little. Tape
is important, use the best.
It's awkward to flip pages in doing the tesi procedures,so
we are including a chart of al1 the adjustments in their
proper sequence on one page. Once you have the idea, al1
you need are the trimmer numbers and such. Here they
are.
GENERA1 ADVICE ON MAINTENANCE
Don't attempt to adjust a stone cold machine. Turn iton
and let itwarm up for 10 minutes.
Don't adjust the "traps" with ametal screw driver or tool.
The meta1tip will affect the value of the part and will give
false readings. Use a plastic T.V. adjustment tool, or cut a
strip of rigid plastic tosize. (Creditcards will work, if you
have an old one you don't need.)
Suspect any large change inadjustment that happens al1 at
once.
Stop and think, if you turn a pot and get no change in
reading, have you adjusted the wrong control?
Always turn the machine "off" when installing the
extender card.
Remove the alignment tape from the heads when switch-
ing power "on" or "off." A switching transient on a badly
adjusted recorder can "print" on the tape.
Tape and electronic "hiss" should be smooth sounding. If,
when recording, you detect popping, or sputtering noises,
degauss the heads. If this doesn't change the sound, plan
on a record bias trap adjustment.
If the oscilloscope picture is not stable when using the
alignment tape (the trace opens and shuts like a mouth)
suspect the holdback torque adjustment. When recording
and playing test tones, suspect the tape slitting as well as
the motor adjusts. If the reference tape doesn't do this,
but the recording tape does,
it's definitely not the
recorder.
It is the tape that is at fault.
At the end of a session, take the time toslow wind (play)
the roll off the machine and store it "tails out." This is
the best way.
Don't plan on recording over a splice. Any steady tone
such as singing, or violins that you attempt to printover a
cut in the tape may show a dropout, or momentary
interruption. Even the best splice in the world
is thicker
than normal. The splicingtape adds quite alot, and makes
the tape "bump" when it goes by the head. This is
especially important if you are using DBX. The dropout
will be pade much more noticeable by the action of the
DBX.
It is a good idea to pad your master tapes by winding
some blank tape on both ends, and adding leader tape.
Put a test tone (1 kHz) on each tape for reference level
checks. Then it's easier to set up machines and mixers
when recording sessions occur on different dates or
different machines.
Keep a TRACK SHEET. Write down what happened
during the session and what went on to the tape. You
might list such things as mic placement;complete/incom-
plete takes; brand of tape used; speeds; noise reduction;
comments (for example: a producer might have liked a
particular bass part more than others, so you can save it
and use itduring overdubbing and mix-down).
Have the tools-of-the-trade handy - leader tape, razor
blades, splicing tape, maskingtape, grease pencils, etc.
There's another oldsayingaround studio circles: if
it's not
labeled, use it. So it's a very good idea to label al1 tape
boxes and reels. And pack atrack sheet in every box.
When you're not working on atape, it's safest to put itin
its box; don't leave it on the machine where an accident
could wipe out weeks of work.
Regardless of how well you maintain your 80-8, break-
down can occur at an unfortunate times. We strongly re-
commend that you purchase a spare electronics "card"
for your 80-8. If one channel "goes down" a spare card
will prove invaluable.