DYNACO Stereo 80 User manual

Stereo 80
Vacuum Tube Amplifier
Owner's Manual
Stereo 80 Vacuum Tube Power Amplifier
OFF
ON
BIAS DISPLAY
TRIODE
ULTRALINEAR
POWER ON
POWER OFF
R
STEREO 80
Vacuum Tube Power Amplifier
V3 V4 V7 V8
LEFT CHANNEL RIGHT CHANNEL
OUTPUT TUBE BIAS ADJUSTMENT

Contents
Introduction ........................................................................ 3
Vacuum Tube Warm Up .................................................... 4
Rear Panel Inputs and Outputs ........................................... 4
Input Sensitivity Setting ..................................................... 5
Power On/Off Indicators and Fuses .................................... 6
Triode/Ultralinear Modes ................................................... 7
Bias Adjustments - general ................................................. 8
Output Tube Bias Adjustment Procedure ........................... 9
Burn-In Procedure for New Output Tubes ......................... 10
Tube Replacement .............................................................. 11
Alternate Tube Types ......................................................... 13
Minimizing Noise in the System ........................................ 14
Warranty ............................................................................. 15
Stereo 80 Specifications ..................................................... 16
Schematics .......................................................................... 17
Stereo 80 PC Board Parts List ............................................ 20
Please read this manual thoroughly before operating your new Stereo 80.

Introduction
Congratulations on your purchase of the Dynaco Stereo 80 Amplifier. This product was
designed to provide the highest combination of quality and value available, which is the
Dynaco tradition.
The Dynaco Stereo 80 amplifier uses special power supply buffering circuitry - found
in no other brand of amplifiers in this class. We have included a separate buffer circuit
for each of the input and driver tubes in the Stereo 80, allowing each amplification stage
to function more independently, (as if each one had its own separate power supply).
This method contributes significantly to the sonic clarity of the Stereo 80.
The Stereo 80 can be operated in either Triode or Ultralinear mode. Switching between
the two is easily done via a front panel switch.
State-of-the-art biasing circuitry allows you to easily attain precision bias settings for
each of the output tubes through front panel adjustments and indicators.
Another special feature of the Stereo 80 is its adjustable Input Sensitivity. This allows
the Stereo 80 to be connected directly to components having vastly different output
signal levels. The user can, for example, connect a CD player directly to the Stereo 80
without using a preamplifier.
You will find the Stereo 80 sounds better than the large majority of other amplifiers -
both solid state and vacuum tube designs - regardless of price. Your Stereo 80 was
designed and built entirely in the USA. We are proud to offer this outstanding amplifier
to discerning audiophiles the world over.
Dynaco Engineering Group

Vacuum Tube Warm-Up
Although a vacuum tube power amplifier begins to work in as little as 15 seconds after being switched on,
it is important to allow a 3 minute warm-up period before using the amplifier.
Output tubes can be slightly damaged each time they are forced into use before being warmed-up,
resulting in non-optimum sound and shorter tube life. If one listens to music during the warm-up period,
one may notice that the output volume of the amplifier changes as the tubes warm up.
We recommend that you wait at least 3 minutes after switching the amplifier on before using it. On the
Stereo 80, waiting about one minute after the four bias lamps turn from “green” to “off” is a proper
(minimum) warm-up period. (See section entitled Bias Adjustments - general)
Rear Panel Inputs and Outputs
Inputs
There are two input jacks located on the rear panel of the amplifier - labeled Left and Right. These
connect to your preamplifier Line Outputs.
Never plug in, or disconnect, interconnect cables from other components to the
amplifier when it is turned on. To do so could cause a fuse to blow or even damage the
speakers.
Outputs
Match the impedance of your speakers to the amplifier by connecting the positive (+) speaker wire of
each channel to its corresponding 2 ohm, 4 ohm, or 8 ohm red binding post. Connect the negative (-)
speaker wire from each channel to its corresponding black binding post.
You can safely connect or disconnect speaker cables to/from the amplifier while it is turned on. It is best
at those times to turn down volume control(s) on any equipment connected to the amplifier inputs.
(Nevertheless, care should be taken to not touch bare speaker wires together if one end of the speaker
cable is connected to the amplifier.)
4

Input Sensitivity Setting
The Input Sensitivity adjustment is located on the rear panel, to the right of the input RCA jacks. This
feature allows you to select how large of an input signal will result in full power output of the amplifier.
The Input Sensitivity adjustment can be used to “match” the Stereo 80 inputs to your preamplifier
outputs. You can set it so that the preamplifier volume control can be turned all the way up before
clipping occurs in the Stereo 80. This also allows you to connect audio components, such as CD players,
directly to the Stereo 80 without using a preamplifier, if desired.
Most power amplifiers have input sensitivities in the range of 1 to 1.5 volts. If an amplifier has an input
sensitivity of 1 volt, this means that an input signal level of 1 volt will produce the full rated output power
of the amplifier.
The Input Sensitivity on the Stereo 80 can be adjusted as follows:
Set at Normal (12 o’clock) the input sensitivity is approximately 1.5V.
Set at Low (9 o’clock) the input sensitivity is approximately 5.5V.
Set at High (3 o’clock) the input sensitivity is approximately .5V.
Set fully clockwise, the input sensitivity is under .3V.
5

Power On/Off Indicators and Fuse
The Stereo 80 Power On/Off indicator is either the Ultralinear (red) lamp or the Triode (amber) lamp.
The lamp which is lit when the Power On/Off switch is turned on will depend upon the Triode/Ultralinear
switch position.
During the first minute or so after the Stereo 80 is first switched on, all four output tube bias indicator
lamps glow green. As the unit warms up, these lamps should go off, indicating the unit is ready for use.
If the bias indicator lamps remain green (or turn red) after the initial warm-up period, a low or high AC
line voltage condition may be indicated. The AC line voltage varies from country to country, city to city,
house to house, and even the time of day in many locations. It can also be affected by common
appliances such as electric heaters, microwave ovens, clothes dryers, etc. Therefore, you may need to set
the output tube bias adjustments to suit your own location. (See section entitled Bias Adjustments -
general.)
Fuses
AC Line Fuse (F1):
7 Amp Fast-Blow - 100 or 120VAC
3.5 Amp Fast-Blow - 220 or 240VAC
To remove the AC line fuse, use a small screwdriver to
push forward the tab near the center of the Power
Entry Module.
Always remove the power cord when accessing the AC line fuse.
6
PUSH TAB TO RELEASE FUSE HOLDER
120
120120
120

Triode/Ultralinear Modes
The Ultralinear mode is usually considered to be the “normal” mode of operation. The overall power
rating of the amplifier is specified for Ultralinear mode.
In Ultralinear mode, the screen grid of each output tube is connected to a tap on its associated output
transformer. When Triode mode is selected, the screen grids are (instead) connected to the plates of their
respective output tubes.
Operating the amplifier in Triode mode reduces the amplifier output power to about 1/2 of that in
Ultralinear mode. Triode mode also softens the clipping characteristics of the amplifier so it seems to
need less output power. Triode mode produces more lower-even order harmonics, whereas Ultralinear
mode produces higher-odd order harmonics.
Some people prefer Triode mode; some people prefer Ultralinear mode. The choice of which mode to use
is also often influenced by the sonic characteristics of the speakers being used.
You can listen and compare to determine which mode sounds best to you for your chosen music material
and speakers.
7

Bias Adjustments - general
The Stereo 80 incorporates integrated circuits that monitor the actual quiescent (idle) current of each
output tube. For each output tube there is a separate bias adjustment potentiometer accessible from the
front panel of the amplifier. Directly above each adjustment potentiometer is the indicator lamp for the
tube which it adjusts.
The front panel switch labeled Bias Display On/Off must be ON for bias adjustments. The Bias Display
On/Off switch (optionally) can be left on while listening to music. If it is left on there will be a “light-
show” display effect which varies with the music material.
During bias adjustments each indicator lamp shows three different conditions. When it glows green it
means that the bias is set too low for the output tube. When it glows red it means that the bias is set too
high. When the lamp is not lit (neither green nor red) it means that the bias setting is correct and is in the
range of 74 to 87 millivolts, (measured across each 2 ohm output tube current sensing resistor - R20, 21,
120, or 121). The correct bias current setting for the EL34 output tubes used with the Stereo 80 is:
40ma +/- 5ma
Before bias adjustments are made, the amplifier must be fully warmed up. As a minimum requirement,
the amplifier should be turned on for 15 minutes prior to bias adjustments. Letting it idle for a full hour
so that all components come up to full thermal equalization is also a good idea, but not usually required.
Notes: For newly installed output tubes, the first three hours is the “burn-in” period. During this time
bias settings need to be closely monitored because they go higher (by themselves) while the tubes
burn-in. If a tube is operated with its bias setting a lot higher than it should be, the tube could
actually burn out or cause other amplifier components to fail.
The output tubes in your new Stereo 80 have already been burned-in and properly biased at the
factory. Nevertheless, when you first start using your amplifier you should check the bias
settings using the Output Tube Bias Adjustment Procedure on the following page.
As mentioned earlier, AC line voltage levels can vary greatly. Even after proper output tube bias
adjustments are completed on your amplifier, temporary changes in the AC line voltage can make it seem
that the bias settings are not correct. If the AC line voltage is low, one or more of the bias indicator lamps
may continue to glow green after the initial one-minute warm-up period. Likewise, if one or more of the
bias indicator lamps glows red after the initial warm-up period, a high AC line voltage condition may be
indicated. If a low or high AC line voltage condition is only temporary, you do not need to re-adjust the
bias settings..
8

Output Tube Bias Adjustment Procedure
1) Warm up amplifier for 15 minutes (or more).
2) Turn off any equipment connected to the amplifier inputs and ensure that the Bias Display On/Off
switch is ON.
3) Using the adjustment tool provided with the amplifier, adjust each 25-turn trimmer potentiometer
to a point where its lamp does not glow. (This point should be midway between red and green.)
Counter-clockwise rotation turns the bias down, “towards green”.
Clockwise rotation turns the bias up, “towards red”.
Notes: If the lamp is glowing red it means that the bias is set too high. Do not turn the adjustment
potentiometer further clockwise as this makes the bias setting even higher.
If an output tube bias indicator lamp cannot be adjusted for both green and red, the associated
output tube is probably faulty.
Adjusting the potentiometer for one lamp can seem to affect the lamps of the other tubes as well.
This is normal. Allow each change to settle for a second or two before going on to the next
trimmer potentiometer. Repeat the adjustments as necessary.
Bias adjustments will be needed less often as the output tubes age.
Bias adjustments can be made at any time while using the amplifier - as long as the amplifier is
warmed up.
If the Bias Display On/Off switch is left on, one can easily check the bias settings at a glance.
This could be whenever the amp is not receiving input signals (such as during the blank time between
tracks on a CD or record).
9

Burn-In Procedure for New Output Tubes
Note: This procedure applies only when you have installed new output tubes which have not yet been
burned-in. (The tubes installed on your new Stereo 80 have already been burned-in at the
factory.) Also see section entitled: Tube Replacement.
1) Turn off any equipment connected to the amplifier inputs.
2) Turn the bias adjust potentiometer for each newly installed tube fully counter-clockwise. This can
take as many as 30 turns. A faint “clicking” sound, which is not harmful, may be heard if you
continue to turn the potentiometer beyond its fully counter-clockwise position. (Use the
adjustment tool provided with the amplifier.)
3) Switch the amplifier on and allow it to warm up 5 to 10 minutes. Ensure that the Bias Display
On/Off switch is set to ON. Note that all bias indicator lamps adjusted in 2) glow green. If any
bias adjustment lamp is not glowing green, ensure that its bias adjustment potentiometer is turned
fully counter-clockwise.
Note: If an output tube indicator lamp cannot be adjusted for both green and red, the associated output
tube is probably faulty.
4) Adjust the bias potentiometer for each newly installed tube as follows:
a) Turn the potentiometer clockwise to a point where its lamp goes off (glows neither red
nor green.)
b) Slowly turn the potentiometer counter-clockwise, again, to the point where its lamp just
begins to glow fully green again. Repeat this step for each lamp as necessary until all
four are glowing green.
5) After 10 minutes check the indicator lamps to see that they are still glowing green. For any lamp
not glowing green, slowly turn its potentiometer counter-clockwise only until it glows green
again.
6) Check every 30-45 minutes to ensure that the indicator lamps are still glowing green and adjust
them if necessary.
7) After three hours, adjust each bias potentiometer to a position where its lamp does not glow
(midway between red and green).
This completes the burn-in procedure for new output tubes. As future bias adjustments become
necessary, use the Output Tube Bias Adjustment Procedure on page 9.
10

Tube Replacement
CAUTION: Before replacing tubes on your Stereo 80 ensure the AC power cord is un- plugged from
its AC (wall) outlet (or that the AC power cord is unplugged from the back of the unit) and
wait for three minutes to allow the high voltage power supply to discharge. Gloves may be
worn when changing tubes. Never touch live circuit elements in vacuum tube equipment
because lethal voltages are present when these are turned on.
Note: There are no user serviceable parts inside the Stereo 80 chassis. If a problem arises other than
normal periodic tube replacement, refer to your dealer or a qualified technician.
The most common type of problem in tube equipment is excessive noise caused by a worn or faulty tube.
The characteristics of this noise can vary a great deal, such as: “excessive hiss,” “sputtering,” “rustling
noises,” etc. If a noise problem occurs with your Stereo 80, 99% of the time it will be due to a faulty
tube. Vacuum tube equipment owners become familiar with tube noises and usually become less alarmed
by them as time goes on.
Microphonics (various "pinging" or "howling" sounds) is due to a tube being overly sensitive to physical
vibrations. To avoid this, do not operate vacuum tube equipment on top of vibrating surfaces (such as
loudspeakers). But, if a tube is so sensitive that just having the amplifier turned on causes the
microphonic sounds, the tube will have to be replaced. It can happen that a tube becomes microphonic
with age or that it is only microphonic before it warms up (or only after it warms up).
Because it is possible for oxidation to build up on vacuum tube pins, it is a good idea to remove and clean
them with a small (brass bristle) wire brush once a year. At this time it is also recommended to clean the
tube pins with contact cleaner. Contact cleaner leaves a thin coating on the pins which helps prevent
oxidation. The contact cleaner can either be sprayed directly onto the tube pins (don’t get any on the
glass part of the tube) or can be sprayed on a clean cloth which is then used to wipe the tube pins.
Notes: When removing a tube, grasp the tube socket with one hand and the tube with the other hand.
Move the tube (slightly) from side to side while pulling upward.
An easy way to determine if a tube in any position is causing undesirable
noise is to swap the suspected tube with its counterpart in the opposite channel.
If the noise jumps to the other channel, the tube you suspected is indeed faulty.
The most certain method for confirming a faulty tube is by substitution of a known
good tube.
11

Tube Replacement (cont.)
Input and Driver Tubes
The input and driver tubes in your Stereo 80 could provide 5,000 to 10,000 hours of use. They will
probably outlast the output tubes by a factor of 2:1. We recommend that the input and driver tubes be
replaced after no more than 3,000 to 4,000 hours of use to avoid the slightly "muffled" sound or slight
bass "roll-off" which can begin to occur with old tubes. This replacement interval is equivalent to about 2
1/2 years when the amplifier is used 4 hours per day (or 5 years when used 2 hours per day).
The most likely source of tube noise in the Stereo 80 is the 12AT7 input tube - V1 (left channel) or V5
(right channel).
Output Tubes
You should expect the EL34s in the Stereo 80 to provide 3,000 to 4,000 hours of use before they have to
be replaced. Some audiophiles replace them after as little as 1000 hours of use to keep the amplifier in
top form. It is not uncommon, however, for an output tube to become faulty during its normal lifetime.
The following conditions indicate possible output tube failure:
➣An output tube will not bias properly - or refuses to hold its setting.
➣The amplifier produces a somewhat “muffled” sound during use.
➣The line fuse blows (other than from normal fuse fatigue).
➣An output tube glows red during operation.
➣Arcing is noticed inside the tube, upon close inspection.
➣A tube filament will not light up.
Maximum performance of the Stereo 80 is achieved by using matched pairs of output tubes. The
amplifier will work without matched output tube pairs, but may not fully meet all of the performance
specifications. Matched pairs of output tubes are available from Dynaco or through your dealer.
12

Alternate Tube Types
It is true that vacuum tubes made by different manufactures can actually sound different. The amount and
type of sonic differences can be subtle or fairly obvious to a discerning listener. Also, tube reliability and
longevity often varies according to manufacturer.
Vacuum tube manufacturers are still introducing new versions of older tube designs. These new designs
are commonly labeled with partly or wholly new part numbers. Furthermore, different vacuum tube
manufacturers often use different part numbers for their own versions of “equivalent” tubes. Distributors
sometimes substitute tubes from different manufacturers and/or substitute tubes with alternate part
numbers without informing their customers first.
Some audiophiles feel strongly about which manufacturer and/or particular version of vacuum tube to use
for specific applications. The tubes installed on your new Stereo 80 have been selected to provide the
best sound and long life.
As of this writing, vacuum tubes are still produced by manufacturers in Germany (Siemens), Russia
(Sovtek), Czechoslovakia (Telsa), China (Sino), Yugoslavia (EI), and in England. Your dealer can
recommend U.S. tube distributors, if needed.
Alternate tube part numbers which can be used on the Stereo 80:
Designator Common Part Numbers Alternate Part Numbers
V1, V5 12AT7 ECC81
V2, V6 6DJ8 6922, ECC88, 7308
V3, V4, V7, V8 EL34 EL34G, 6CA7
If tube replacement becomes necessary, Dynaco can supply you with new tubes
and/or a list of specifically recommended vacuum tubes for the Stereo 80.
13

Minimizing Noise in the System
Hum is caused by amplification of the 50 or 60 Hz AC power line signal that is transmitted via the
magnetic fields around power transformers and power cables. RF interference usually comes from
inadequate shielding of cables or components. If any of these types of noises are encountered, one or
more of the following pointers concerning proper component positioning and grounding may be of use:
➣Ensure that each system component, especially the preamplifier, is located far enough away from the
other components so that they will not pick up hum from them, and that the AC power cables are not
in close proximity to audio cables.
➣Ensure that all audio cables are securely pushed into their respective jacks. A faulty audio cable,
although rare, can be a source of hum if its outer shield is broken or disconnected from an RCA plug
at one end of the cable.
➣The best system grounding scheme is to have your preamplifier well grounded to an earth ground
point and function as the system's main ground reference. Other system components are then quite
adequately grounded via their audio cables to the preamplifier’s ground. Using this grounding
scheme can be as simple as just plugging the preamplifier’s power cable into a three prong AC outlet.
However, if the AC outlet itself does not provide a really "good" ground, the power cable can be
plugged into a three-to-two prong adapter and a wire can be run from the tab on the adapter to the
nearest cold water pipe.
➣Another solution to AC power cable "ground loop" hum problems is to plug the AC power cables
from all of the system components into a common "socket strip" (available from most hardware
stores).
➣If RF noise (usually an AM radio station or CB transmission) is a problem in your area, an AC power
filter can be purchased into which some or all of your system power cords can be plugged. This is
done if the RF is coming in through the building's AC wiring. However, if RF gets into the system
via your turntable, you may have to use tonearm cables with better shielding. (This is tested by
unplugging the turntable from the system and putting "shorting plugs" in the preamplifier’s phono
inputs before listening again.) RF noise is sometimes eliminated by simply moving the turntable or
other components to another location in the room.
➣ Hum from a turntable is usually traced to an adjacent power transformer or a missing
or improper ground. Check to see that the turntable motor is grounded via a wire to
the preamplifier’s grounding post - (or try removing this wire from the ground post if it
is already connected there).
14

Warranty
For three years from the date of purchase (one year for tubes) Dynaco will repair, for the original owner,
any defect in materials or workmanship that occurs in normal use, without charge for parts or labor.
It is the owner's responsibility to provide transportation to the authorized Dynaco service representative
who will perform warranty service, and to present proof of purchase in the form of a dated sales slip when
requesting service.
Excluded from this warranty is damage that results from abuse, misuse, accidents, shipping, or repairs or
modification by anyone other than an authorized Dynaco service representative. This warranty is void if
the serial number has been removed or defaced. This warranty gives you specific legal rights, and you
may also have other rights - which vary from state to state.
If service is required, contact the dealer from whom you purchased the amplifier. If that is not possible,
write Dynaco, giving us:
✓Your name and address
✓Make and model of your amplifier
✓The amplifier’s serial number
✓When and where you purchased it (copy of sales slip)
✓Description of the problem
✓ Whether you have the original carton and fillers or need new ones
DYNACO strongly recommends using only its performance checked pre-
tested vacuum tubes. For best amplifier performance, matched pairs of
power output tubes are available. Each tube is guaranteed to perform
properly in its intended application for ONE YEAR. Orders for tubes
may be paid for by personal check or money order. Please also include
$4.00 for shipping and handling.
15

Stereo 80 Specifications
POWER OUTPUT 40W per channel into 2, 4, or 8 ohms
POWER BANDWIDTH: 40W from 17Hz to 75kHz (-3dB points)
THD < 1% @ full power @ 1kHz<.05% @ 1W @ 1kHz, matched output tubes
FREQUENCY RESPONSE 2Hz to 60kHz (-3dB points)
INPUT SENSITIVITY .3V for full power output (Input Sensitivity Control set to maximum)
INPUT IMPEDANCE 50k
SLEW RATE 30V/µS
SIGNAL-TO-NOISE RATIO 90db below full output
TUBE COMPLEMENT two 12AT7, two 6DJ8, four EL34
POWER CONSUMPTION: 210 Watts
AC LINE VOLTAGE 100V, 120V, 220V, or 240V @ 50/60 Hz
DIMENSIONS 17” Wide, 7.75” High, 15” Deep
SHIPPING WEIGHT 42 lbs
WARRANTY Three years - parts and labor. (one year on tubes)
16

C3
C5B
C2
R19
R9
R4
R1
2M
.47uF
.22uF
2.0K
100pF/400v
1/2 12AT7
49
8
7
6
3
2
1
1M
V1
630V
R10
1
2
3
9
301
LEFT
INPUT
R2
301
00601P 1 3
STEREO 80 AUDIO SECTION
3 MAR 95 OFREV PAGE DWG#
R3
301
R5
301
R12 27K
3
301
R11
6
7
8
C4
.22uF
630V
11K R13
3
R15
R18
1K 1K
3
4
8
FB-2
EL34
V3
6DJ8
V2
EL34
V4
5
3
8
1
4FB-3
+480V
8 ohm 4 ohm 2 ohm
C
R14 30K
5
400V
R16
270K
R17
270K
LEFT
OUTPUTS
TRIODE ULTRALINEAR
FB-1
K1-A
FB-4 TRIODE ULTRALINEAR
K1-B
5
1
R20
2
R21
T2
3 AND 5 RESISTORS ARE METAL OXIDE
1/2 AND 1 RESISTORS ARE METAL FILM
YEL
ORN
BRN
BLK
BLU
GRN
RED
GRN/ HT
BLU/ HT
R6 2K
C1
220pF
400V
R8
6.04K
R7
12.7K
5
2
5
C103
C105B
C102
R119
R109
R104
R101
2M
.47uF
.22uF
2.0K
100pF/400v
1/2 12AT7
49
8
7
6
3
2
1
1M
V5
630V
R110
1
2
3
9
301
R102
301
R103
301
R105
301
R112
27K
3
301
R111
6
7
8
C104
.22uF
630V
11K
R113
3
R115 R118
1K 1K
3
4
8
FB-6
EL34
V7
6DJ8
V6
EL34
V8
5
3
8
1
4FB-7
8 ohm 4 ohm 2 ohm
C
R114
30K
5
400V
R116 270K R117 270K
RIGHT
OUTPUTS
TRIODE ULTRALINEAR
FB-5
K2-A
FB-8 TRIODE ULTRALINEAR
K2-B
5
1
R120
2
R121
T3
YEL
ORN
BRN
BLK
RED
R106
2K
C101
220pF
400V
R108
6.04K
R107
12.7K
5
2
5
Y3 Y4 Y7 Y8
P3 P7 P8
R22
300, 3
R23
300, 3
R122
300, 3
R123
300, 3
P4
T2F
T2G
T3G
T3F
BLU
GRN
GRN/ HT
BLU/ HT
C5A 330pF/400v
C105A 330pF/400v
P1A
50K
L IN
RIGHT
INPUT
P1B
50K
R IN
SENSITIVITY
INPUT
SENSITIVITY
INPUT
+475V
A
+475V
B
+475V
B
+475V
C
+475V
D
+475V
D
+480V
1/2 12AT7
V1
1/2 12AT7
V5

00601P 2 3
STEREO 80 POWER SUPPLY SECTION
3 MAR 95 OFREV PAGE DWG#
270uF
7A / 100V
T1
S 1
100
F1
120 VAC X 2
50/60 Hz
(100V TAP)
BRN
BRN/ HT
HT
BLK
BLK/ HT
3.5A / 220V
BLK RED
C251
R201A
ON
C253 C254
PO ER
ENTRY
MODULE
OFF
AC PO ER
300V
C204
L1 = .32h @ 360mA
680uF
300V
C206
.68uF
630V
C210
R213
470
ZD1
Q1 Q2
C220
.047uF
630V
R214
470
ZD4
C221
.047uF
630V
12V 12V
ZD2
200V
5
ZD5
200V
5
G
D
S
G
D
S
1M
1
R211
4.7M
R215
470
ZD7
Q3 Q4
C222
.047uF
630V
R216
470
ZD10
C223
.047uF
630V
12V 12V
ZD8
200V
5
ZD11
200V
5
G
D
S
G
D
S
R209 264K R210
RED
ORN
F B1
YEL
V1
4 5
C224
4200uF
4
4 4
5
5 5
V5
V6 V2
100uF
C214 C215
100uF
R208
2.4K, 3
U2
7815
I
G
O
35V
C225
470uF
35V
R219
5.2 ohms, 3
56uF
C216
400V
56uF
C217
400V
100V 100V
VIO VIO
D7
D8
C226
470uF
35V
1M, 1
R217
264K R218
10uF
C227
250V
U1
7812
O
G
I
D2
D4
D1
D6
470uF
C211
35V
.022F
C212 C213
10uF
9 9
ZD3
200V
5
ZD6
200V
5
ZD12
200V
5
ZD9
200V
5
D3 D5
BLU
K1 K2
SHIELDS
XMR
D9
YEL
(GRN/YEL)
680uF
300V
C207
.68uF
630V
C218
M1
K1 K2
M2
+12V
GND
- 60V
4.7M
R212
C219
.68uF
630V
250V 35V
C208 C209
680uF 680uF
300V 300V
C205
270uF
300V
47K
5w
R202
47K
5w
R203
47K
5w
R204
47K
5w
R205
47K
5w
R206
47K
5w
R207
HV OUT - TO T2 / T3
C252
R201B
100
120V 100V 0.0V 120V 0.0V
L
N
(FAST BLO )
7A / 120V
3.5A / 240V
C251 THROUGH C254
ARE .01uF, 1.4kV
G
4 3 6
10
8 9 5 7
GRN
2 7V3 V4 V7 V8
2 2 2 7 7 7
I G O G D S
7812, 7815 IRF 830
D1 - D11 = 2.5A, 1KV ZD2, 3, 5, 6, 8, 9, 11, 12 = 1N5388B
Q1 - Q4 = IRF830
ZD1, 4, 7, 10 = 1N5242B
C228
.022uF
GRN
250V
GRN GRN
C229
100uF
35V
D11 R220
39 ohm
+475V
A
+475V
B
+475V
C
+475V
D
+480V

00601P 3 3
STEREO 80 BIAS ADJUST & INDICATORS
3 MAR 95 OFREV PAGE DWG#
S 2
ULTRALINEARTRIODE
D10
LED5
R75
1K 1K
R76
LED6
P3
25K 25K
P4
R71 R72 39K 39K
V3 BIAS ADJUST V4 BIAS ADJUST
C
C52 C51
160V
.1uF
14
7
.047uF .047uF
11
13
12
8 9
10
1/4
1/4 1/4 1/4
4
1
6 5
2
3
LM339
U3
160V 160V
C55
GREEN
RED
(V3 BIAS)
C54
C53
14
7
.047uF
.047F
11
13
12
8 9
10
1/4
1/4 1/4 1/4
4
1
6 5
2
3
LM339
U4
160V 160V
Y3
+12V
Y4 Y7 Y8
GND
R63
20.5K
127
R64
127
R65
17.4K
R66
(74mV)
(87mV)
R55
1.1K
R56 R57
R58
1.1K 1.1K 1.1K
BIAS ADJUST PC BOARD
(MOUNTED TO FRONT PANEL)
BIAS INDICATORS
OFF ON
S 3
P3 P4 P7 P8
- 60V
P7 P8
25K 25K
R73 R74 39K 39K
V7 BIAS ADJUST V8 BIAS ADJUST
M1
K1 K2
M2
(TRIODE) (ULTRALINEAR)
R51 10K R52
10K
R53 10K R54 10K
C C C
+12V
2 1 3
1 32
GREEN
RED
(V4 BIAS)
LED1 LED2
GREEN
RED
(V7 BIAS)
R59
1.1K
R60 R61
R62
1.1K
1.1K 1.1K
GREEN
RED
(V8 BIAS)
LED3 LED4
REDAMBER

Stereo 80 PC Board Parts List
Resistors
39 ohm, 1/2W, metal film R220
49 ohm, 1/2W, metal film R4, 104
100 ohm, 1/2W, metal film R201A, 201B
127 ohm, 1/2W, metal film R64, 66
301 ohm, 1/2W, metal film R2, 3, 5, 10, 11, 102, 103, 105, 110, 111
470 ohm, 1/2W, metal film R213, 214, 215, 216
1K, 1/2W, metal film R15, 18, 75, 76, 115, 118
1.1K, 1/2W, metal film R55, 56, 57, 58, 59, 60, 61, 62
2K, 1/2W, metal film R6, R19, 106, 119
6.04K, 1/2W, metal film R8, 108
10K, 1/2W, metal film R51, 52, 53, 54
12.7K, 1/2W, metal film R7, 107
17.4K, 1/2W, metal film R63
20.5K, 1/2W, metal film R65
39K, 1/2W, metal film R71, 72, 73, 74
264K, 1/2W, metal film R209, 218
270K, 1/2W, metal film R16, 17, 116, 117
1Meg, 1/2W, metal film R1, 101
2 Meg, 1/2W, metal film R9, 109
4.7Meg, 1/2W, metal film R211, 212
1 Meg, 1W, metal film R210, 217
5.2 ohm, 3W, metal oxide R219
300 ohm, 3W, metal oxide R22, 23, 122, 123
2.4K, 3W, metal oxide R208
11K, 3W, metal oxide R13, 113
27K, 3W, metal oxide R12, 112
30K, 3W, metal oxide R14, 114
2 ohm, 5W, metal oxide R20, 21, 120, 121
47K, 5W, metal oxide R202, 203, 204, 205, 206, 207
Dual Potentiometer - 50K audio taper P1
Trimmer Potentiometer - 25K P3, 4, 7, 8
Capacitors
.01uF, 1.4kV, ceramic disk C251, 252, 253, 254
100pF, 400V, polypropylene, 5% C5B, C105B
220pF, 400V, polypropylene, 5% C1, 101
330pF, 400V, polypropylene, 5% C5A, 105A
.022uF, 250V, polypropylene, 10% C212, 228
.047uF, 160V, polypropylene, 10% C51, 52, 53, 54
.047uF, 630V, polypropylene, 10% C220, 221, 222, 223
.1uF, 160V, polypropylene, 10% C55
.22uF, 630V, polypropylene, 10% C3, 4, 103, 104
.47uF, 400V, polypropylene, 10% C2, 102
.68uF, 630V, polypropylene, 10% C210, 218, 219
10uF, 35V, alum electrolytic C213
10uF, 250V, alum electrolytic C227
56uF, 400V, aluminum electrolytic C216, 217
100uF, 35V, alum electrolytic C229
100uF, 100V, alum electrolytic C214, 215
270uF, 300V, alum electrolytic C204, 205
470uF, 35V, alum electrolytic C211, 225, 226
680uF, 300V, alum electrolytic C206, 207, 208, 209
4200uF, 35V, alum electrolytic C224
20