Logitek ULTRA-VU Installation and operating instructions

ULTRA-VU
LED BARGRAPH
AUDIO METER
Operation & Service Manual
Logitek

Logitek Software License Agreement
The Ultra-VU unit you have purchased contains embedded software.
The software is owned by Logitek Electronic Systems, Inc. and is pro-
tected by United States copyright laws and international treaty provi-
sions.
Logitek grants to you the right to use one copy of the embedded soft-
wareineach Ultra-VUmeter you purchase.Youmaynot rent or lease the
software.Youmaynotreverseengineer,decompile,disassemble,orcre-
ate derivative works from the software.You may not create copies of the
software.
This statement will be governed by the laws of the State of Texas,
U.S.A. Logitek reserves all rights not specifically granted in this state-
ment.
All information contained herein is confidential.No portions of this man-
ual may be reproduced by any means without written permission from
Logitek Electronic Systems, Inc.
COPYRIGHT 1995, LOGITEK ELECTRONIC SYSTEMS, INC.
5622 Edgemoor DRIVE ¤ HOUSTON, TX 77081 USA ¤ 800-231-5870 (OUTSIDE USA & CANADA 713-664-4470) ¤ FAX [phone]
Electronic Systems, Inc.
Logitek

TABLE OF CONTENTS
SECTION 1— GENERAL INFORMATION
1-1 General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1-2 Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1-3 Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1-4 Instrument Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1-5 Where to Find Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
SECTION 2 — PREPARATION FOR USE
2-1 Initial Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2-2 Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2-3 Repacking for Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2-4 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2-5 Connecting Mains Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2-6 Input Selection on Dual Input Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2-7 Connecting Digital Input Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2-8 Connecting Analog Input Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2-9 Rear Panel Programming Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
SECTION 3 — OPERATING INSTRUCTIONS
3-1 Bargraph Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3-2 VU Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3-3 PPM Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3-4 Peak Hold Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3-5 LOUD — Loudness Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3-6 I-S — Image/Sum Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3-7 FINE — High Resolution Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3-8 Auxiliary Data Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3-9 Changing Display Brightness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3-10 CLIP indicator set point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3-11 Resetting the Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
SECTION 4 — MAINTENANCE
4-1 General Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4-2 Fuse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4-3 Handling of CMOS Integrated Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4-4 Access to Circuit Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4-5 Power Supply LG-253. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4-6 Analog Input Control Card LG-266 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4-7 Digital/Dual Input Control Card LG-265 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4-8 Display Assembly LG-267 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4-9 ADC Input Card LG-264 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
SECTION 5 — REPLACEMENT PARTS LIST
5-1 Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5-2 Analog Input Control Card. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5-3 Digital/Dual Input Control Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5-4 Display Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5-5 ADC Input Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
SECTION 6 — MANUFACTURERS LIST
SECTION 7 — DIAGRAMS
7-1 Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7-2 Analog Input Control Card. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7-3 Dual Input Control Card. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7-4 Display Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7-5 ADC Input Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
SECTION 8 — QUICK REFERENCE GUIDE
Ultra-VU LED Meter
OPERATION & SERVICE MANUAL

SECTION 1— GENERAL INFORMATION
1-1 General Description
TheLogitek Ultra-VUis abargraphtypeaudiome-
terfeaturingtwotricolorLEDbargraphswith clipindi-
cators. Two function buttons and several auxiliary
data indicators are also included on the front panel.
1-2 Electrical Specifications
Bargraphs per meter: Two
Indicators per bargraph: 63
Normal Range: -70 dB to 0 dB plus clip - digital
-50 dB to + 20 dB plus clip - analog
Fine Range: .2 dB per segment around ref pt.
Reference Point: -10,-12,-14,-16,-18 or -20 dB
Peak Markers:8,9,10,12,14,16,18 dB above ref pt
Ballistics:
VU Mode 300 mS/20dB attack & release
PPM Mode 0 mS attack, 2.8S/24dB release
Peak Hold 0 mS attack, 2 or 5 Second hold
Max Hold 0 mS attack, pushbutton release
Image/Phase 4 Sec hold on max image
Clip Indicator: trigger on 1 or 4 consecutive
clipped samples
Frequency Response:
Normal +/-.1 dB 20 Hz - 20 KHz
Loudness Filter 58 dBSPL auditory curve
-40 dB 20 Hz, 0 dB 1250 Hz, -50 dB 20 KHz
Brightness control: 8 levels
Analog Input:
Sensitivity -10 to +20 dBu for full scale
rear panel adjustable
Overload Level +24 dBu
Impedance 40 Kohm balanced
Connector 3-pin XLR
Digital Input:
Formats AES/EBU or S/PDIF
Impedance 110 Ohm (XLR)
75 Ohm (coax adapter)
Pass-through 2200 Ohm (XLR)
Termination transformer balanced
AC Line Input Voltage:
50-60 Hz 105-129 VAC or
(switch settable) 220-240 VAC
Power Requirement:
UV1-(all), UDT-(all) 10 Watts
UV2-(all) 20 Watts
Dimensions:
1RU enclosure 19"Wx7"Dx1
34’H
Desk top enclosure 814“Wx9"Dx2
14”H
1-3 Standards
The Ultra-VU meters are designed to conform to
the ballistic standards described in IEEE document
G.2.1.2/13, IEC document 268 and EBU document
3205-E. This ensures that the bargraph motion will
closely track other standard mechanical and elec-
tronic meters.
The one exception to these standards is the PPM
attack time.The Ultra-VU uses a true peak measure-
ment scheme that always displays the highest peak
of the input signal. The PPM standard specifies a
short averaging period for peak signals that keeps
soundswith durations too short tobeheard wellfrom
beingdisplayed,nomatterhowloudtheyare.Thede-
lay also allows mechanical meters to keep up with
fast changing inputs. Under most circumstances
there is no noticeable difference between true peak
and PPM peak readings.However, if you do need the
Ultra-VU to conform to the PPM peak standard then
pleasecontacttheLogitekfactoryforfurtherinforma-
tion.
1-4 Instrument Identification
The Ultra-VU is identified by a model number and
athreeorfourdigitserial number.Themodelnumber
and serial number appear on a label on the back of
the unit near the power cord. All correspondence to
your Logitek dealer or to the Logitek factory should
refer to the model number and serial number.
1-5 Where to Find Help
Logitek customer service personnel are available
to help with any questions, comments or problems
you might have with the Ultra-VU meter, both during
and after the warranty period.Our hours of operation
are8AMto5PMcentraltime.Wemaybecontactedin
one of the following ways.
By Phone: [phone] (USA & Canada)
or 713-664-4470
By Fax: [phone]
By Email: [email protected]
By Mail: Logitek Electronic Systems, Inc.
5622 Edgemoor Drive
Houston, Texas 77081
USA
** Ultra-VU Operation & Service Manual ** Page 4

SECTION 2 — PREPARATION FOR USE
2-1 Initial Inspection
Check the shipping carton carefully for external
damage.If the carton shows evidence of abuse, ask
the carrier’s agent to be present when the unit is un-
packed.Carefully unpack the unit to avoid damaging
the equipment through the use of careless proce-
dures.Inspectallequipmentfordamagesimmediate-
ly after unpacking.Bent and broken parts, dents and
scratches should be noted.If damage is found, refer
to paragraph 2-2 for recommended claim proce-
dures. Keep all packing material for possible future
use.
2-2 Claims
Iftheunithas been damaged,notifythecarrierim-
mediately.Fileaclaim withthe carrier and adviseLo-
gitek of such action to arrange for repair or
replacement without waiting for a claim to be settled
with the carrier.
2-3 Repacking for Shipment
Ifthe unit mustbereturnedto Logitek,attacha let-
tertoitshowingtheowner’snameandaddress.Ade-
scription of necessary service should be included in
theletter.Theoriginalshippingcartonandpackaging
materials should be used for reshipment if possible.
UseFRAGILElabelsoneachsurface.Returntheunit
freight prepaid. Be sure to insure the unit for its full
value.Theunitwillberepairedpromptlyandreturned
freight prepaid.
2-4 Installation
Rackmount Enclosure
The Ultra-VU rackmount models are designed to
be mounted in a standard 19" equipment rack by us-
ingthe fourmounting holes in the corners of the front
panel. Plastic washers should be used to keep the
mounting screw for marring the front panel finish.
Desktop Enclosure
The Ultra-VU desktop enclosure is designed to sit
on any flat surface.The front of the meter may be an-
gled up for easier viewing by raising the bale located
on the bottom of the box.
While flow through ventilation is not necessary,
the units should not be mounted directly above
equipment which produces significant heat, such as
equipment using vacuum tubes. The unit should
never be operated if the ambient temperature is
above 55 degrees C (131 degrees F).
2-5 Connecting Mains Power
Connectthe meterto thepowermainswith the en-
closed power cord.The unit is factory set for 115VAC
operation unless specifically labeled otherwise, but
230VAC operation can be selected via a slide switch
located next to the power transformer inside the unit.
To gain access to the voltage select switch, remove
the enclosure top cover. The switch is located adja-
cent to the large power transformer.
2-6 Input Selection on Dual Input Models
If the digital receiver can lock onto an input signal
then the meter will display that signal whether it con-
tains errors or not. If no signal is connected to the
digital input or the data rate is out of the receiver’s
capture range, then the meter will display the analog
signal. This happens even if nothing is connected to
the analog inputs.The Ultra-VU can be forced to dis-
play only one input by connecting a remote switch to
the unit. Consult the factory for details.
2-7 Connecting Digital Input Models
The Ultra-VU accepts AES/EBU or S/PDIF serial
dataatsampleratesof30,000to50,000samplesper
secondviaafemaleXLRconnectorontherearpanel.
The input is also wired directly to the male XLR con-
nector on the back panel for use in loop-through
mode. The loop-through connector provides a con-
venient way to daisy-chain several pieces of equip-
ment off of one digital output. Loop-through works
wellwithAES/EBUsignalsbutshouldbelimitedto10
feet with S/PDIF signals and cables.
S/PDIF signals using RCA type plugs may be con-
nected to the input using an RCA to XLR adapter.
Coax cables using BNC connectors can be con-
nectedtothe inputusinga BNC toXLRadapter.Both
adapters are available from Logitek.
AES/EBU Connection
Pin 1 Shield
Pin 2 Signal +
Pin 3 Signal -
It is also important to set the two input load
switches located between the two XLR connectors.
Input Load Switch Settings
Sw1 Sw2 Ohms Use
Up Up 2200 Loop-through mode
Up Dn 110 balanced twisted pair (XLR)
Dn Up 75 unbalanced coax (RCA & BNC)
Dn Dn 44 do NOT use this combination
Page 5 ** Ultra-VU Operation & Service Manual **

2-8 Connecting Analog Input Models
The Ultra-VU accepts balanced or unbalanced in-
puts via rear panel XLR connectors on analog input
only models or 3-circuit 1/4" phone plugs on dual in-
put models.The connectors are wired as follows:
Balanced Connection
Pin 1 or Sleeve Shield
Pin 2 or Tip Signal +
Pin 3 or Ring Signal -
Unbalanced Connection
Pin 1 or Sleeve Shield
Pin 2 or Tip Center Hot
Pin 3 or Ring Connect to pin 1
TheUltra-VUshieldpinsarebondeddirectlytothe
chassisattheconnectoranddonotshareanyground
paths with the internal circuitry. This allows cable
shieldstobeconnectedat both endswithoutcausing
hum problems.
The zero reference level for each input can be set
anywherebetween-10dBuand+20dBubyadjusting
themultiturngaincontrollocatedadjacenttoeachin-
put connector. A small flat blade screwdriver is
needed to adjust the gain.
2-9 Rear Panel Programming Switches
A block of eight mode setting switches is located
on the rear panel of the meter to the right of the input
XLR connectors. The switches are numbered 1
through 8 and are set by pushing the white levers up
or down with a small screwdriver or pen point.
Thebargraphzeroreferencemarkerand therefer-
ence level of the zoom display is set via switches 6, 7
and 8 as shown.
Zero Reference Setting
Sw6 Sw7 Sw8 dBs below full scale
Up Up Up -10 dB
Up Up Dn -12 dB
Up Dn Up -14 dB
Up Dn Dn -16 dB
Dn Up Up -18 dB
Dn Up Dn -20 dB
Dn Dn Up -20 dB
Dn Dn Dn -20 dB
A second set of orange markers indicate the de-
sired peak operating level. Switches 3, 4 and 5 set
these markers a fixed number of dBs above the zero
reference level.
Peak Marker Setting
Sw3 Sw4 Sw5 Function
Up Up Up +18 dB above reference
Up Up Dn +16 dB above reference
Up Dn Up +14 dB above reference
Up Dn Dn +12 dB above reference
Dn Up Up +10 dB above reference
Dn Up Dn +913dB above reference
Dn Dn Up +8 dB above reference
Dn Dn Dn Off
Switch1turnsthepeakdisplayonandoff.Thisisa
single red dot with a fast attack time and a slow re-
lease time. Peak hold is controlled from the front
panelandisunaffectedbyswitch1. Switch2setsthe
dynamics of the peak display. True peak shows the
largest single peak.This mode is useful for avoiding
digital clipping. PPM mode averages the peak read-
ingoverashortperiodandiscomparabletoPPMme-
chanical meters. The green average display is
unaffected by switch 2 and is always VU response.
Bargraph Settings
Sw1 Sw2 Function
Up Peak display OFF
Dn Peak display ON
Up True peak dynamics
Dn PPM dynamics
The programming switches are only checked oc-
casionally,soitmaytakeuptotwosecondsforswitch
changes to be reflected in the meter’s operation.
** Ultra-VU Operation & Service Manual ** Page 6

SECTION 3 — OPERATING INSTRUCTIONS
3-1 Bargraph Description
The Ultra-VU display contains two multi-LED bar-
graphdisplaysmountedoneabovetheother.Thetop
bar shows either left channel (L) or image/phase(φ)
information.The bottom bar shows either right chan-
nel (R) or mono sum (S) information. The bars are
marked at the left end to indicate their function. The
tricolor LEDs can be green, red or orange depending
on their function and cover the range from -70 dBFS
to 0 dBFS.
Thetop LED ofeach baris larger and red only.It is
used as a clipping indicator and can be set to illumi-
nateon anyclipped signal or onlyafter fourconsecu-
tive clipped samples.
The zero reference point of the meter is indicated
by a dim orange marker in the bargraph. The refer-
ence mark can be varied between -10 and -20 dBFS
via switches on the back panel. An optional peak
marker can be set from +8 to +18 dB above the zero
referenceand is usedas areferenceindicator forthe
PPM display.
3-2 VU Display
VUisindicatedbyasolidgreenbar.VUrepresents
the perceived loudness of the input signal. The mo-
tionofthebarsconformstotheindustrystandard300
mSec per 20 dB rise and fall times. Note that the
speed of the bar will appear faster near the top of the
meter display because each segment there repre-
sents fewer dBs than at the bottom of the meter.The
VU display can be turned off by pressing the MODE
button at the bottom left corner of the front panel re-
peatedly until the VU bars disappear.
3-3 PPM Display
Peak program meter (PPM) information is shown
byasinglered segment.PPM representsthehighest
point of the input signal. The display has a zero rise
time and an industry standard 2.8 Sec per 24 dB fall
time.The dot will appear to fall faster near the top of
the meter range because each segment there repre-
sents fewer dBs than at the bottom of the meter.The
PPMdisplayis alwaysactiveunless itis turned offby
the programming switches on the back panel.
The VU and PPM displays are calibrated so that
theywillreadthe samewhenconnected to sinewave
signals.The red PPM dot will be on top of the highest
green segment of the VU bar resulting in a bright or-
ange dot. For dynamic signals the difference be-
tween the top of the VU bar the PPM dot is
approximately the crest factor.
3-4 Peak Hold Display
The peak hold display is a single red segment that
maintains the highest PPM reading for a user se-
lectable amount of time.If the holding period expires
before the PPM dot equals or exceeds the peak hold
dot, then the peak hold dot will turn off.It will turn on
again when the PPM dot reaches a peak and starts
falling again.
Two holding modes are available. Release (Rel)
modeholdsthepeakreadingforeither2or5seconds
depending on the position of the rear panel program
switches. Maximum (Max) mode holds the highest
peak reading until it is manually reset by turning the
peak hold off and then on again.
Peak hold can be cycled through Off, Rel and Max
modes by repeatedly pressing the HOLD button at
the lower right corner of the meter front panel.
3-5 LOUD — Loudness Filter
The VU display can be compensated to match the
frequencyresponseofthehumanearbyenablingthe
loudness filter. This will cause the VU bars to more
closely represent the actual loudness perceived by
the listener and allow better level matching between
different kinds of program material.
Theloudnessfilteriscalibratedforalisteninglevel
of58dBSPL.Thefilterwillbelessaccurateforlisten-
ing levels above and below this point.
To activatethe filter, pressthe MODEbuttonin the
lower left corner of the meter front panel until the
“Loud” indicator is lit.
Users of the digital input meters should note that
filtering is a function of sample rate.The meter has a
separate filter for each of the five sample rates listed
on the front panel.If a non listed sample rate is used
the loudness filter will be deactivated.
3-6 I-S — Image/Sum Display
The image and sum displays are activated by
pressing the MODE button in the lower left corner of
the meter front panel until the “φ” indicator if lit.
In this mode, the lower bargraph displays the
mono sum of the left and right input channels. The
display operates identically to the left and right bar-
graphsexceptthattheloudnessfilterisnotavailable.
The upper bargraph shows the stereo image and
relative phase information. Three orange markers
are located at 90 degrees left, 0 degrees center and
90 degrees right. The scale covers 180 degrees
whichis thelargestrelativephasedifferencetwosig-
nal can have.
Thereddotindicatesthecurrentlocationoftheleft
channelinthestereosoundfieldandthegreendotin-
dicatesthecurrentlocationoftherightchannelinthe
stereo sound field. The overall width and location of
thestereoimageisshownbyasecondpairofredand
Page 7 ** Ultra-VU Operation & Service Manual **

green segments that hold the furthest left and right
readings for about four seconds.
If a mono signal is being displayed, then the red
and green segments will be at the same location re-
sulting inadotthatlooksorange.Ifthemonosignalis
offcenter(suchasleftchannelonly),theresultingor-
ange dot will be off to one side of the display.
3-7 FINE — High Resolution Mode
Fine is a high resolution mode that expands the
meter scale to .2 dB per segment around the 0 VU
point.This mode is useful when doing precise align-
mentsusingsteadystatesignals.Fineisactivatedby
pressing the MODE button at the bottom left of the
meter front panel until the FINE indicator lights..
3-8 Auxiliary Data Display
Ultra-VU models with serial digital inputs provide
information about the input data format via indicator
lights along the bottom of the meter front panel.
EMPH indicates pre-emphasis has been applied
to the audio and is recovered from the embedded
channel status data. The circle is lit only when em-
phasis is detected. The indicator is accurate with
both AES/EBU and S/PDIF input formats.
PRO indicates whether the data stream is in the
professional or consumer format and is recovered
fromtheembeddedchannel status data.Thecircleis
lit only when the AES/EBU professional format is de-
tected.
SAMPLE RATE is the actual data sample fre-
quency measured by the meter in one second inter-
vals. This function is active even when the received
data is invalid.
Sample Rate Data Display
Label Meaning
32.0 32,000 Hz, +/- .1%
44.0 44,056 Hz, +/- .1%
44.1 44,100 Hz, +/- .1%
47.9 47,952 Hz, +/- .1%
48.0 48,000 Hz, +/- .1%
-none- no data or non standard rate
3-9 Changing Display Brightness
The overall illumination level of the meter can be
set to one of eight levels. To change the brightness
level, press the MODE button until the BRT indicator
lights.Then press the HOLD button until the desired
illumination level is achieved.
3-10 CLIP indicator set point
The large red clip segment at the top of each bar-
graphcanbesettolightonthereceptionofeitherone
or four clipped samples in a row. To change the set-
ting press the MODE button until the CLIP indicator
alongthebottomofthemeterlights.Asegmentinthe
lower bargraph will start to blink alternately red and
greentoindicatethecurrentsetting.Press the HOLD
button until the desired setting is shown on the bar-
graph.
3-11 Resetting the Program
TheUltra-VUcontainssoftwarethatexecutesona
programmable DSP chip. If the processor memory
becomescorrupted,themeterwillprobablyfailto op-
erate. In most cases, an independent watchdog cir-
cuit will notice that the meter is working incorrectly
and restart the system.
The processor can be reset manually by turning
the power off and then back on again.
***********NOTICE * **********
Once a day the display will freeze for a second
while the meter goes through a reset and the analog
to digital converter recalibrates itself.
****************************
** Ultra-VU Operation & Service Manual ** Page 8

SECTION 4 — MAINTENANCE
4-1 General Information
The Ultra-VU is designed to need a minimum of
maintenance for long trouble-free operation. Should
repair be necessary, the technician should first read
the information in the manual concerning the circuits
in question and should follow proper procedures for
testing and replacing semiconductors. Logitek engi-
neers are readily available at the factory to provide
technical assistance both during and after the war-
ranty period.
**********WARNING***********
The inside of the Ultra-VU contains no controls or
user serviceable parts.The cover should only be re-
moved by competent technical personnel capable of
servicingthistypeofequipment.Hazardousvoltages
exist on the underside of some circuit cards.
*****************************
4-2 Fuse
The primary winding of the power transformer is
fusedwitha1/2ampslow-blow20mmfusehousedin
a fuse holder in a slide-out drawer under the power
cordonthe rearpanelofthe unit.It should onlybere-
placedwithfusesofthesametypeandcurrentrating.
The power cord must be unplugged from the rear
panel to gain access to the fuse holder.
**********WARNING***********
Do NOT replace the fuse without first disconnect-
ing the meter’s power cord from the wall socket, as
dangerous voltages are present which may cause
electrical shock.Always use fuses of the same value
and type as specified in this manual. Do
NOT use
fusesofahighervaluethanthosespecified,asshock
hazard and fire hazard may result.
*****************************
A blown fuse is most often, although not always, a
symptom of another failure.Related circuitry should
always be carefully examined after any fuse failure,
especially if a replacement fuse also blows.
4-3 Handling of CMOS Integrated Circuits
All logic components in the Ultra-VU meter are
CMOS type integrated circuits. Even though all cir-
cuitshavebuiltinstatic dischargeprotection,special
care must be taken in the handling of these devices,
particularly in dry environments.
*********IMPORTANT**********
Do NOT remove or handle CMOS integrated cir-
cuits except in a grounded environment which is free
of the risk of static electricity. Store such circuits on
conductive foam or in anti-static controllers.Do
NOT
store on styrofoam or other plastic sheets.Improper
handling may damage these devices.
*****************************
4-4 Access to Circuit Cards
Access to the circuitry of the rackmount and half-
rack meters is accomplished by removing the six
screws that attach the top cover. The inside of the
desktopunitisaccessedbyremovingthefourscrews
alongtheedgesofthebottompanelandpullingapart
the two halves of the plastic case.
4-5 Power Supply LG-253
Each Ultra-VU contains a ground isolated and fil-
tered step-down power supply to create the neces-
sary operating voltages. This supply is located on a
PCB on the right side of the meter enclosure.
Mains AC from the power entry module J2 is fed
throughfuse F1, located in a drawerunder thepower
cordinJ2,toJ1onsupplycardLG-253.J1feedsvolt-
age selection switch S1 which connects the dual pri-
maries of transformer T1 in series for 230VAC
operation or parallel for 115VAC operation.The dual
secondaries of T1 are wired in parallel and loaded
withafull-wavebridgerectifierRT1.TheDCoutputof
RT1isfilteredbycapacitorsC1 and C2andfedto the
redandgreenoutputpads.Thevoltageshouldbebe-
tween 8 to 10 VDC with less than .5 volt of ripple.
Analog input models will also have a charge pump
consisting of IC1 and C3 that feeds filter C4 and the
black output pads. The voltage should be -8 to -10
VDC with less than .1 volt of ripple.
Jumperssolderedtotheoutputpadsfeedpowerto
one or two meter control cards.
**********WARNING***********
Dangerous voltages are present on the bottom of
the power supply card. Always disconnect the AC
power cord when servicing this circuit board.
*****************************
4-6 Analog Input Control Card LG-266
+7 VDC from input connector P4 is connected to
voltage regulators IC12 and IC5 as well as display
board connector P6.IC12 feeds the digital section of
thePCBwhileIC5feedstheanalogfrontend.-7 VDC
from input connector is connected to voltage regula-
tor IC6 which feeds the analog front end.
On power up, the DSP is kept in reset by IC8 until
the power has stabilized, ensuring a good power on
reset.IC8also containsa watchdogtimer that will re-
set the DSP if its ST pin is not taken low at least once
every 150 mSec. This pin is normally pulsed low
every 5 mSec by the left bargraph load signal.
The DSP (IC11) is clocked by a 12.288 MHz crys-
tal oscillator consisting of Y1, C26, C25 and an inter-
nal driver. IC11, Pin 43 is a buffered output of the
oscillator.
Page 9 ** Ultra-VU Operation & Service Manual **

The first thing the DSP (IC11) does after reset is
copy its program from EPROM IC10 to internal RAM
memory. The program executes continuously. Note
thatthe8 bitdatabusisconnected tothemiddle byte
of the DSP’s 24 bit data port.
Address decoder IC9 is used to reset the watch-
dog timer (IC8) and to connect the rear panel pro-
gramming switches (S1-S8) to the data bus via
resistor pack R20.
Front panel pushbutton switches S11 and S12 are
connected to the DSP data port via resistor pack
R19.
Serial data is sent synchronously (data, clock,
load)tothe displaydriverchipsvia displayconnector
P6in32bitstrings.Dataisplacedonthetopbitofthe
DSPdataportandclockedintothedisplaydriversvia
a write to address decoder IC9. Other writes to IC9
will load the 32 bit data string into the display drivers
via P6. A write to the left bargraph will also be de-
coded by IC8 and used to rest the watchdog timer.
The audio from the left input XLR connector J1 is
connectedtoaRFlowpassfilterformedbyR10,R11,
C1 and C2. The resistors also form a -9 dB pad with
the input impedance of the balanced receiver IC3.
IC3 provides an additional -6 dB pad between its in-
put and output.These pads allow +20 dBu input sig-
nals to be handled by the +/- 5 volt supply rails. The
output of IC3 is unity gain inverted by op-amp IC2a
and fed back to the reference input of IC3. This en-
ables IC3 to present an identical resistive load on its
two input pins. Input gain is adjusted via trimpot R1
which is the feedback resistor around gain stage
IC1a.
*********IMPORTANT**********
Only replace IC2 with an op-amp which is slower
than the SSM2143 such as the TL072 used here. A
faster op-amp like the NE5532 will cause the output
of IC3 to oscillate.
*****************************
Signal from IC1a is fed through antialias filter R15
C4 and DC isolated by C3 before connecting to the
leftinputofthesigmadeltaanalogtodigitalconverter
IC7.The right channel connects to the converter via
similar circuitry.
The 12.288 MHz master clock input to the ADC is
generated by a crystal oscillator located on the DSP
chip.Combined left and right audio data is sent syn-
chronously (data, clock, frame sync) to the DSP in
64-bit strings.The DSP reset signal from IC8 is also
connected to the ADC. The DSP activates the reset
once a day which causes the ADC to perform a self
calibration routine for about half a second. If the me-
ter has undergone a substantial temperature
change, such as when it is first powered up, it may
generate noise up to -70 dBFS until it undergoes a
calibration cycle
4-7 Digital/Dual Input Control Card LG-265
Power from input connector P4 is connected to
voltage regulators IC2 and IC3 as well as display
board connector P6. IC2 is a +5VDC regulator that
feeds power to the analog front end of data receiver
IC1. The voltage is filtered by C2, C6 and clamped
against over voltage and voltage reversal by D1.IC3
is a +5VDC regulator that feeds the digital portion of
IC1 and all other circuits on the control board. The
output voltage is filtered by C3 and clamped by D2.
Distributed power filtering is supplied by C4,7,8,9 &
10.
On power up, the DSP is kept in reset by IC4 until
the power has stabilized, ensuring a good power on
reset.IC4also containsa watchdogtimer that will re-
setthe DSP if its STpin innot takenlowat leastonce
every 150 mSec. This pin is normally pulsed low
every 5 mSec by the left bargraph load signal.
The DSP (IC6) is clocked by a 12.288 MHz crystal
oscillator consisting of Y1,C11,C12 and an internal
driver.IC6,pin43isabufferedoutputoftheoscillator.
The first thing the DSP (IC6) does after reset is
copyitsstartupprogramfromEPROMIC5tointernal
RAM memory.That program executes once and then
loads the main program from EEPROM which exe-
cutescontinuously.Notethatthe8bitdatabusiscon-
nected to the middle byte of the DSP’s 24 bit data
port.
The rear panel programming DIP switches S1-S8
are also connected to the DSP’s middle data byte via
isolation resistors R10 and control that portion of the
databuswhenneithertheDSPnortheEEPROMout-
put is active.The DSP inputs the switch positions via
a read to address zero.
FrontpanelpushbuttonsS11,12,13areconnected
to the high byte of the DSP 24-bit data port via con-
nector P3 and isolation resistors R9.
Serial data is sent synchronously (data, clock,
load) to the display driver chips via the display con-
nector P6 in 32 bit strings. Data is placed on the top
bit (bit 23) of the DSP data port and clocked into the
display drivers via a write to address decoder IC7.
Other writes to IC7 will load the 32 bit data string into
the left bargraph, right bargraph or scale/indicator
driver groups via P6.A write to the left bargraph will
also reset the watchdog timer.
Two channel audio data is fed synchronously
(data, clock, frame sync) from digital data receiver
IC1 to DSP (IC6) serial port 1.
EncodedaudiodataentersthemeterviaXLRcon-
nectorJ1 andisdirectly connectedto theoutputcon-
nectorP2.Notethatnobufferingisappliedtotheloop
through output.
** Ultra-VU Operation & Service Manual ** Page 10