Crown Com-Tech CT-200 User manual

Com-Tech 200 Amplifier Service Manual
1
COM-TECH®200
POWER AMPLIFIER
SERVICE MANUAL
K-SVCCT200
12-95
Com-Tech®,ODEP® and Crown®are registered trademarks of Crown International, Inc.
Mailing Address:
P.O. Box 1000
Elkhart, IN U.S.A. 46515-
1000
Shipping Address:
57620 C.R. 105
Elkhart, IN U.S.A. 46517
©1995 by CROWN INTERNATIONAL, INC.
Model CT200B

Com-Tech 200 Amplifier Service Manual
2
À PRÉVENIR LE CHOC
ÉLECTRIQUE N’ENLEVEZ
PAS LES COUVERTURES.
RIEN DES PARTIES
UTILES À L’INTÉRIEUR.
DÉBRANCHER LA BORNE
AVANT D’OUVRIR LA
MODULE EN ARRIÈRE.
TO PREVENT ELECTRIC SHOCK DO
NOT REMOVE TOP OR BOTTOM
COVERS. NO USER SERVICEABLE
PARTS INSIDE. REFER SERVICING
TO QUALIFIED SERVICE
PERSONNEL. DISCONNECT
POWER CORD BEFORE REMOVING
REAR INPUT MODULE TO ACCESS
GAIN SWITCH.
CAUTION AVIS
WARNING
TO REDUCE THE RISK OF ELECTRIC
SHOCK, DO NOT EXPOSE THIS
EQUIPMENT TO RAIN OR MOISTURE!
The information furnished in this manual does not include all of the details of design, production, or variations of
the equipment. Nor does it cover every possible situation which may arise during installation, operation or
maintenance. If you need special assistance beyond the scope of this manual, please contact the Crown
Technical Support Group.
Mail: P.O. Box 1000 Elkhart IN 46515-1000
Shipping: 57620 C.R. 105 Elkhart IN 46517
Phone: [phone]
FAX: [phone]

Com-Tech 200 Amplifier Service Manual
3
Table of Contents
Introduction ............................................................ 4
Parts Information .................................................... 5
Specifications ......................................................... 6
Theory .................................................................... 7
Electrical Checkout Procedures ........................... 12
Parts List (Non Module)........................................ 16
Module and Schematic Information...................... 19
Q42762-7 Control Module Parts List..................... 20
Q43215-5 Control Module Parts List..................... 21
Q43244-5 Control Module Parts List..................... 22
Q43242-9 Control Module Parts List..................... 23
Q42706-4 Display Module Parts List .................... 24
Q42716-3 Output Module Parts List ..................... 25
Q42888-0 Output Module Parts List ..................... 26
Q42969-8 Output Module Parts List ..................... 27
Q43188-4 Output Module Parts List ..................... 28
Q43013-4 Main Module Parts List ........................ 29
Q43044-9 Main Module Parts List ........................ 32
Q43128-0 Main Module Parts List ........................ 35
Q43237-9 Main Module Parts List ........................ 38

Com-Tech 200 Amplifier Service Manual
4
Crown
Technical Support Group
Factory Service
Parts Department
Mailing Address:
PO Box 1000
Elkhart, IN USA 46515-1000
Shipping Address:
57620 C.R. 105
Elkhart, IN USA 46517
Phone: [phone]
Toll Free: [phone]
FAX: [phone]
This manual contains service information on Crown
poweramplifiers. Itisdesignedtobeusedinconjunc-
tion with the applicable Owner's Manual. However,
some important information is duplicated in this Ser-
viceManual in casethe Owner's Manualis not readily
available.
NOTE: THE INFORMATION IN THIS MANUAL IS INTENDED
FOR USE BY AN EXPERIENCED TECHNICIAN ONLY!
Scope
ThisServiceManualinintendedtoapplytoallversions
oftheCT-200BamplifierincludingtheAmcronversion.
The Parts Listings include parts specific for the US
version and the European version (CT-200BE13). For
partsspecificonlytootherversionscontacttheCrown
TechnicalSupport Group for helpin finding part num-
bers.
ThisServiceManual includes several sections. These
sectionsincludePartsInformation,Specifications,Volt-
ageConversion,CircuitTheory, ElectricalTestProce-
dures, Non-Module Parts Lists, and Module Parts
Lists. Schematics are attached. Note that component
partswith circuit board comprise a completemodule.
Module part numbers are always associated with a
specificcircuitboard,althoughanunpopulatedcircuit
board may be built up with different parts to create
differentmodules.NotethatCrowndoesnotsellblank
(unpopulated) circuit boards.
Each of the compact audio power amplifiers are de-
signed for professional or commercial use. Providing
high power amplification from 20Hz to 20KHz with
minimumdistortion,theyfeaturebalanced inputs with
bridged and parallel monophonic capability. Specific
features vary depending on model family.
Warranty
Each Owner's Manual contains basic policies as re-
lated to the customer. In addition it should be stated
that this service documentation is meant to be used
only by properly trained service personnel. Because
most Crown products carry a 3 Year Full Warranty
(includingroundtripshippingwithintheUnitedStates),
all warranty service should be referred to the Crown
Factory or Authorized Warranty Service Center. See
theapplicableOwner’sManualforwarrantydetails.To
find the location of the nearest Authorized Service
Centerorobtain instructions for receiving CrownFac-
toryServicepleasecontacttheCrownTechnicalSup-
port Group (within North America) or your Crown/
Amcron Importer (outside North America).
Introduction

Com-Tech 200 Amplifier Service Manual
5
Parts Information
ment on a C.O.D. or pre-payment (check or credit
card) basis.
Terms
Normal terms are pre-paid. Net-30 Days applies to
onlythosefirmshavingpre-establishedaccountswith
Crown. If pre-paying, the order must be packed and
weighed before a total bill can be established, after
which an amount due will be issued and shipment
made upon receipt of pre-payment. New parts re-
turned for credit are subject to a 10% re-stocking fee,
and authorization from the Crown Parts Department
must be obtained before returning parts for credit.
Crownisnotageneralpartswarehouse.Partssoldby
the Crown Parts Department are solely for servicing
Crown/Amcronproducts.Partpricesandavailability
are subject to change without notice.
General Information
Latersectionsincludebothmechanical and electrical
parts lists for this product. The parts listed are current
as of the date printed. Crown reserves the right to
modify and improve its products for the benefit of its
customers.
Part Numbering System
As of the printing of this manual, Crown is using two
numbering systems. The elder system always uses
eight characters. The first character is a letter. Com-
monlettersusedareC,D,H,M, P,andQ. Thesecond
through sixth characters are numbers. The numbers
build sequentially (for each prefix letter) as new parts
are added to our parts inventory system. (In some
cases there will be a space then a four character
numberaftertheprefixletter;thespaceisconsidered
a character.) The seventh character is usually a hy-
phen,thoughitmaybealettertoindicatea revisionor
specialnote.Thelastcharacteriscalledacheck-digit,
and is useful to Crown for internal tracking.
Crown is in the process of converting to a new part
number system. Length may vary from eight to twelve
characters. There is still a letter prefix, then five num-
bers. These five numbers identify a type of part. The
seventhcharacterisa hyphen.Remainingcharacters
identify the details of the type of part identified by the
first part of the number.
Standard and Special Parts
Many smaller electrical and electronic parts used by
Crown are stocked by and available from electronic
supply houses. However, some electronic parts that
appear to be standard are actually special. A part
ordered from Crown will assure an acceptable re-
placement. Structural items such as modules and
panels are available from Crown only.
Ordering Parts
When ordering parts, be sure to give the product
model, and include a description and part number
(CPN/DPN) from the parts listing. Price quotes are
available on request.
Shipment
Shipment will be normally made by UPS or best other
method unless you specify otherwise. Shipments are
made to and from Elkhart, Indiana USA, only. Estab-
lishedaccountswithCrownwillreceiveshipmentfreight
prepaid and will be billed. All others will receive ship-
Crown
Parts Department
Mailing Address:
PO Box 1000
Elkhart, IN USA 46515-1000
Shipping Address:
57620 C.R. 105
Elkhart, IN USA 46517
Phone: [phone]
or: [phone]
Toll Free: [phone]
FAX: [phone]

Com-Tech 200 Amplifier Service Manual
6
Specifications
Unless noted otherwise, all specifications are based
on driving an 8 ohm load per channel, both channels
driven, the sensitivity switch in the 26dB position, the
AC supply is 120VAC at 60Hz. Crown specifications
areguaranteed throughthewarrantyperiod(normally
3years).Because our testing methods are morestrin-
gent than our published specifications, every Crown
amplifier will exceed its published specifications.
Power
Power
8 Ohm Stereo—110W/Ch
4 Ohm Stereo—150W/Ch
70-V Line Stereo—105W/Ch
8 Ohm Bridge Mono—295W
4 Ohm Parallel Mono—225W
2 Ohm Parallel Mono—300W
Bridge Mono, 140-V Line—210W
Parallel Mono, 70-V Line—210W
Load Impedances: Rated for 16, 8, 4, 2, Ohm, and 70-V
use. Safe with all types of loads, even totally reactive
loads.
AC Mains: 120VAC at 60 Hz with standard three-wire
groundedconnectorforNorthAmericanunits;100VAC,
120VAC,220VAC,and240VACat50or60Hzunitsare
available when ordered country specific. Com-Tech
amplifiers are not voltage convertable.
Performance
Frequency Response: ±0.1dB from 20 Hz to 20 kHz at 1
Watt.
Phase Response: ±10° from 10 Hz to 20 kHz at 1 Watt.
Signal to Noise Ratio: A-weighted, better than 105 dB
below full rated output. Better than 100 dB below full
rated output from 20 Hz to 20 kHz.
Total Harmonic Distortion (THD): <0.05% from 20 Hz to
1 kHz, increasing linearly to 0.1% at 20 kHz at 500W.
I.M.Distortion: <0.05% from less than 164 milliwattsto
520 W at 26 dB gain.
Slew Rate: >13V per microsecond. (Slew rates are
limited to useful levels for ultrasonic/RF protection.)
Damping Factor: >1000 from 10 Hz to 400 Hz.
DC Offset: <10 millivolts.
Input Impedance: Nominally 20K ohms balanced; 10K
ohms unbalanced.
Output Impedance: <10 milliohms in series with <2
microhenries.
Protection Systems: Output Device Emulation Protec-
tion (ODEP) limits drive in the event of dangerous
dynamicthermalconditionswithoutinterruptingpower.
Currentlimitingforshortedloadprotection.DC/LFand
common mode output current Fault circuitry to mute
audio.Delayof4secondsfromturnonmutesamplifier
to prevent dangerous turn-on transients.
Mechanical
InputConnectors:Balancedthree-terminalbarrierblock
for each channel on standard P.I.P.-BB module (in-
cluded)
Output Connectors: Four-terminal barrier block.
FrontPanelControls:Afrontpanelrockerswitchusedto
power the amplifier on and off.
Back Panel Controls: A three-position switch which se-
lects Stereo, Bridge-Mono, or Parallel-Mono mode. A
rotary potentiometer for each channel used to control
output level. A two position recessed switch for each
channel selects between 8/4 ohm and 70-V modes. A
push button circuit breaker used to protect the power
supply.
InternalControls:Athree-positionswitchselects0.775V,
1.4V, or 26 dB voltage gain input sensitivity.
Indicators:AmberEnableindicatorshowson/offstatus
of low-voltage power supply. A green indicator for
each channel shows the reserve energy status. If no
reserve energy is available the indicator will dim in
proportiontoODEPlimiting.Ayellowindicatorforeach
channel flashes in the event of distortion. And green
SPI (signal presence indicator) indicators show the
presence of output signal.
Construction: Black splatter-coat steel chassis with
specially designed flow-through ventilation system.
Mounting: Standard EIA 310 front-panel rack mount
with supports for supplemental rear corner mounting.
Dimensions:19incheswide,3.5incheshigh,16inches
deep behind front mounting surface.
Weight: 29 lbs, 6.5 oz.

Com-Tech 200 Amplifier Service Manual
7
Theory
Overview
It should be noted that over time Crown makes im-
provementsandchangestotheirproductsforvarious
reasons. This manual is up to date as of the time of
writing. For additional information regarding these
amplifiers, refer to the applicable Technical Notes
provided by Crown for this product.
Thissectionofthemanualexplainsthegeneralopera-
tionofatypicalCrownpoweramplifier.Topicscovered
includeFrontEnd,GroundedBridge,andODEP.Due
to variations in design from vintage to vintage (and
similarities with other Crown products) the theory of
operation remains simplified.
Features
Com-Tech amplifiers utilize numerous Crown innova-
tionsincluding grounded bridge and ODEPtechnolo-
gies. Cooling techniques make use of the what is
essentiallyairconditionertechnology.Airflowsbottom
to top, and front to side. Air flows a short distance
across a wide heatsink. This type of air flow provides
significantlybettercoolingthanthe“windtunnel”tech-
nology used by many other manufacturers. Output
transistorsareofthemetalcantyperatherthanplastic
case. This allows for a significantly higher thermal
margin for the given voltage and current ratings. All
devices used are tested and graded to ensure maxi-
mum reliability. Another electronic technique used is
negative feedback. Almost all power amplifiers utilize
negative feedback to control gain and provide stabil-
ity,butCrownusesmultiplenestedfeedbackloopsfor
maximum stability and greatly improved damping.
Most Crown amplifiers have damping in excess of
1000 in the bass frequency range. This feedback,
along with our compensation and ultra-low distortion
output topology, make Crown amplifiers superior.
FeaturesspecifictotheCom-TechSeries’includeslew
rate limiting, and audio muting for delay or protective
action.ThisamplifiercanoperateineitheraBridgedor
Parallel Mono mode as well as dual (stereo). A sensi-
tivity switch allows selection of input voltage required
forratedoutput.Levelcontrolsaremountedontherear
panelandareoftherotarytype.Frontpanelindicators
let the user know the status of the low voltage power
supply (enable), signal presence, distortion, and an
ODEP indicator for each channel which shows the
reserveenergystatus.Ingeneral,thepackagingofthis
model is designed for maximum watt/price/weight/
size value with user friendly features.
Foradditionaldetailsrefertothespecificationsection,
or to the applicable Owner’s Manual.
Front End Operation
Thefrontendiscomprisedofthreestages: Balanced
GainStage(BGS),VariableGainStage(VGS),andthe
Error Amp. Figure 1 shows a simplified diagram of a
typical front end with voltage amplification stages.
Balanced Gain Stage (BGS)
Input to the amplifier is balanced. The shield may be
isolated from chassis ground by an RC network to
interrupt ground loops via the Ground Lift Switch. The
non-inverting (hot) side of the balanced input is fed to
the non-inverting input of the first op-amp stage. The
inverting(negative)sideofthebalancedinputisfedto
the inverting input of the first op-amp stage. A poten-
tiometer is provided for common mode rejection ad-
justment.Electrically,theBGSisatunitygain.(Froman
audio perspective, however, this stage actually pro-
vides+6dBgainifafullybalancedsignalisplacedon
itsinput.)TheBGSisanon-invertingstage.It’soutput
is delivered to the Variable Gain Stage.
Variable Gain Stage (VGS)
FromtheoutputoftheBGS,thesignalgoestotheVGS
wheregain is determined by the position of the Sensi-
tivity Switch, and level is determined by the level
control. VGS is an inverting stage with the input being
fedto its op-amp stage.Because gain after thisstage
is fixed at 26dB (factor of 20), greater amplifier sensi-
tivityisachievedbycontrollingtheratiooffeedbackto
input resistance. The Sensitivity Switch sets the input
impedanceto this stage and varies the gain such that
the overall amplifier gain is 26 dB, or is adjusted
appropriately for 0.775V or 1.4V input to attain rated
output.
Error Amp
The inverted output from the VGS is fed to the non-
invertinginputoftheErrorAmpop-ampstagethrough
anACcoupling capacitorandinputresistor. Amplifier
output is fed back via the negative feedback (NFb)
loop resistor. The ratio of feedback resistor to input
resistor fixes gain from the Error Amp input to the
output of the amplifier at 26 dB. Diodes prevent
overdriving the Error Amp. Because the Error Amp
amplifies the difference between input and output
signals, any difference in the two waveforms will pro-
duce a near open loop gain condition which in turn
results in high peak output voltage. The output of the
Error Amp, called the Error Signal (ES) drives the
Voltage Translators.

Com-Tech 200 Amplifier Service Manual
8
Theory
Voltage Amplification
The Voltage Translator stage separates the output of
the Error Amp into balanced positive and negative
drive voltages for the Last Voltage Amplifiers (LVAs),
translatingthesignalfromgroundreferenced±15Vto
±Vccreference.LVAsprovidethemainvoltageampli-
fication and drive the High Side output stages. Gain
from Voltage Translator input to amplifier output is a
factor of 25.2.
Voltage Translators
A voltage divider network splits the Error Signal (ES)
into positive and negative drive signals for the bal-
ancedvoltagetranslatorstage.Theseoffsetreference
voltagesdrive the input to theVoltage Translator tran-
sistors. A nested NFb loop from the output of the
amplifier mixes with the inverted signal riding on the
offsetreferences.Thisnegativefeedbackfixesgainat
theoffset reference points (and theoutput of the Error
Amp) at a factor of -25.2 with respect to the amplifier
output. The Voltage Translators are arranged in a
common base configuration for non-inverting voltage
gainwithequalgain.Theyshifttheaudiofromthe±15V
reference to VCC reference. Their outputs drive their
respective LVA.
Also tied into the Voltage Translator inputs are ODEP
limiting transistors and control/protection transistors.
The ODEP transistors steal drive as dictated by the
ODEP circuitry (discussed later). The control/protec-
tiontransistorsactasswitchestototallyshuntaudioto
ground during the turn-on delay, or during a DC/LF or
Fault protective action.
Last Voltage Amplifiers (LVAs)
TheVoltageTranslatorstagechannelsthesignaltothe
LastVoltageAmplifiers(LVA's)inabalancedconfigu-
ration. The +LVA and -LVA, with their push-pull effect
throughtheBias Servo, drive the fully complementary
output stage. The LVAs are configured as common
emitter amplifiers. This configuration provides suffi-
cient voltage gain and inverts the audio. The polarity
inversion is necessary to avoid an overall polarity
inversionfrominputjacktooutputjack,anditallowsthe
NFblooptocontrolErrorAmpgainbyfeedingbackto
its non-inverting input (with its polarity opposite to the
output of the VGS). With the added voltage swing
provided by the LVAs, the signal then gains current
amplification through the Darlington emitter-follower
output stage.
Grounded Bridge Topology
Figure2isasimplifiedexampleofthegroundedbridge
output topology. It consists of four quadrants of three
deep Darlington (composite) emitter-follower stages
per channel: one NPN and one PNP on the High Side
ofthebridge (driving the load), and oneNPNand one
PNP on the Low Side of the bridge (controlling the
ground reference for the rails). The output stages are
biasedtooperateclassAB+Bforultralowdistortionin
the signal zero-crossing region and high efficiency.
High Side (HS)
TheHighSide(HS) ofthebridgeoperatesmuch like a
conventional bipolar push-pull output configuration.
Astheinputdrive voltagebecomesmorepositive,the
HSNPN conducts and delivers positive voltage to the
load.EventuallytheNPNdevicesreachfullconduction
and+Vccisacrosstheload.AtthistimetheHSPNPis
+
-+ -+ -
BGS VGS Error
Amp
Audio
Inputs
Voltage Divider
NFb Loop
+
-
ODEP Mute
+15V
-15V
+VCC
-VCC
NPN Outputs (+HS)
PNP Outputs (-HS)
Q100
Q103
Q121
Q122
Q101
Q102
Q105
Q110
Voltage
Translators
LVA's
Figure 1. Typical Amplifier Front End and Voltage Amplification Stages.

Com-Tech 200 Amplifier Service Manual
9
biasedoff.Whenthedrivesignalisnegativegoing,the
HSPNPconductstodeliver-VcctotheloadandtheHS
NPN stage is off.
The output of the +LVA drives the base of predriver
device.Together,thepredriveranddriverformthefirst
twopartsofthe three-deepDarlingtonandarebiased
class AB. They provide output drive through the bias
resistor,bypassingtheoutputdevices,atlevelsbelow
about100mW.AnRLCnetworkbetweenthepredriver
anddriverprovidephaseshiftcompensationandlimit
driver base current to safe levels. Output devices are
biased class B, just below cutoff. At about 100mW
output they switch on to conduct high current to the
load. Together with predriver and driver, the output
device provide an overall class AB+B output.
The negative half of the HS is almost identical to the
positive half, except that the devices are PNP. One
difference is that the PNP bias resistor is slightly
greaterinvaluesothatPNPoutput devices run closer
to the cutoff level under static (no signal) conditions.
This is because PNP devices require greater drive
current.
HS bias is regulated by Q18, the Bias Servo. Q18 is a
Vbe multiplier which maintains approximately 3.3V
Vceunderstaticconditions.Thepositiveandnegative
halves of the HS output are in parallel with this 3.3V.
With a full base-emitter on voltage drop across
Theory
+
-
+Vcc (Positive Rail)
-Vcc (Negative Rail)
Load
(speaker)
Input
signal
HIGH SIDE LOW SIDE
Inverting Op-amp
Figure 2. Crown Patented Grounded Bridge Topology
predrivers and drivers, the balance of voltage results
inapproximately.35Vdropacrossthebiasresistorsin
thepositivehalf,andabout.5Vacrossthebiasresistor
inthenegativehalf.Q18conduction(andthusbias)is
adjustable.
A diode string prevents excessive charge build up
within the high conduction output devices when off.
Flyback diodes shunt back-EMF pulses from reactive
loads to the power supply to protect output devices
from dangerous reverse voltage levels. An output
terminating circuit blocks RF on output lines from
entering the amplifier through its output connectors.
Low Side (LS)
The Low Side (LS) operates quite differently. The
powersupplybridgerectifierisnotgroundreferenced,
nor is the secondary of the main transformer. In other
words, the high voltage power supply floats with re-
spect to ground, but ±Vcc remain constant with re-
spect to each other. This allows the power supply to
deliver +Vcc and -Vcc from the same bridge rectifier
andfilterasatotaldifferenceinpotential,regardlessof
their voltages with respect to ground. The LS uses
inverted feedback from the HS output to control the
ground reference for the rails (±Vcc). Both LS quad-
rantsarearrangedin athree-deepDarlingtonandare
biased AB+B in the same manner as the HS.

Com-Tech 200 Amplifier Service Manual
10
Whentheamplifieroutputswingspositive,theaudiois
fed to an op-amp stage where it is inverted. This
invertedsignalisdelivereddirectly to the basesofthe
positive(NPN)andnegative(PNP)LSpredrivers.The
negativedriveforcestheLSPNPdeviceson(NPNoff).
AsthePNPdevicesconduct,VceofthePNPDarlington
drops. With LS device emitters tied to ground, -Vcc is
pulled toward ground reference. Since the power
supplyisnotground referenced(andthetotalvoltage
from +Vcc to -Vcc is constant) +Vcc is forced higher
above ground potential. This continues until, at the
positive amplifier output peak, -Vcc = 0V and +Vcc
equals the total power supply potential with a positive
polarity.If,forexample,thepowersupplyproduceda
total of 70V from rail to rail (±35VDC measured from
ground with no signal), the amplifier output would
reach a positive peak of +70V.
Conversely, during a negative swing of the HS output
where HS PNP devices conduct, the op-amp would
output a positive voltage forcing LS NPN devices to
conduct. This would result in +Vcc swinging toward
ground potential and -Vcc further from ground poten-
tial. At the negative amplifier output peak, +Vcc = 0V
and -Vcc equals the total power supply potential with
anegativepolarity.Usingthesameexampleasabove,
a 70V supply would allow a negative output peak of -
70V. In summary, a power supply which produces a
total of 70VDC rail to rail (or ±35VDC statically) is
capableofproducing140Vpeak-to-peakattheampli-
fieroutputwhenthegroundedbridgetopologyisused.
Thevoltageusedinthisexamplearerelativelycloseto
the voltages of the PB-1/460CSL.
The total effect is to deliver a peak to peak voltage to
the speaker load which is twice the voltage produced
bythe power supply. Benefits include full utilization of
the power supply (it conducts current during both
halves of the output signal; conventional designs re-
quire two power supplies per channel, one positive
and one negative), and never exposing any output
device to more than half of the peak to peak output
voltage (which does occur in conventional designs).
Low side bias is established by a diode string which
also shunts built up charges on the output devices.
Bias is adjustable via potentiometer. Flyback diodes
perform the same function as the HS flybacks. The
output of the LS is tied directly to chassis ground via
ground strap.
Output Device Emulation Protection (ODEP)
Theory
Tofurtherprotecttheoutputstages,aspeciallydevel-
oped ODEP circuit is used. It produces a complex
analog output signal. This signal is proportional to the
always changing safe-operating-area margin of the
output transistors. The ODEP signal controls the Volt-
age Translator stage by removing drive that may
exceed the safe-operating-area of the output stage.
ODEPsensesoutputcurrentbymeasuringthevoltage
dropped across LS emitter resistors. LS NPN current
(negativeamplifieroutput)and+Vccaresensed,then
multiplied to obtain a signal proportional to output
power. Positive and negative ODEP voltages are ad-
justable via two potentiometers. Across ±ODEP are a
PTCandathermalsense (current source).ThePTCis
essentially a cutoff switch that causes hard ODEP
limiting if heatsink temperature exceeds a safe maxi-
mum, regardless of signal level. The thermal sense
causesthedifferentialbetween+ODEPand–ODEPto
decrease as heatsink temperature increases. An in-
crease in positive output signal output into a load will
result in –ODEP voltage dropping; an increase in
negativeoutputvoltageandcurrentwillcause+ODEP
voltage to drop. A complex RC network between the
±ODEP circuitry is used to simulate the thermal barri-
ers between the interior of the output device die (im-
measurablebynormalmeans)andthetimedelayfrom
heat generation at the die until heat dissipates to the
thermal sensor. The combined effects of thermal his-
tory and instantaneous dynamic power level result in
anaccuratesimulation of the actual thermalcondition
of the output transistors.

Com-Tech 200 Amplifier Service Manual
11
Theory
NEGATIVE
LOW SIDE
OUTPUT
PNP STAGE
POSITIVE
LOW SIDE
OUTPUT
NPN STAGE
NEGATIVE
HIGH SIDE
OUTPUT
PNP STAGE
POSITIVE
HIGH SIDE
OUTPUT
NPN STAGE
HIGH SIDE
BIAS
SERVO
+LVA
-1
-LVA
-1
+VOLTAGE
TRANSLATOR
-VOLTAGE
TRANSLATOR
OUTPUT
DEVICE
EMULATION
PROTECTION
ERROR
AMP
VGSBGS
BALANCED
INPUTS
INVERTING
BRIDGE
BALANCE
LOW SIDE
BIAS
DIODE
STRING
-1
-1
MAIN NEGATIVE FEEDBACK (NFb) LOOP
Figure 3. Typical Crown Amplifier Basic Block Diagram (One Channel Shown)

Com-Tech 200 Amplifier Service Manual
12
Electrical Checkout Procedures
General Information
The following test procedures are to be used to verify
operation of this amplifier. DO NOT connect a load or
inject a signal unless directed to do so by the proce-
dure. These tests, though meant for verification and
alignment of the amplifier, may also be very helpful in
troubleshooting.Forbest results, tests should be per-
formed in order.
AlltestsassumethatACpowerisfromaregulated120
VACsource.Testequipmentincludesanoscilloscope,
a DMM, a signal generator, loads, and I.M.D. and
T.H.D. noise test equipment.
Standard Initial Conditions
Level controls fully clockwise.
Stereo/Mono switch in Stereo.
Sensitivity switch in 26 dB fixed gain position.
70-V mode switches in the 8/4 ohm position.
It is assumed, in each step, that conditions of the
amplifier are per these initial conditions unless other-
wise specified.
Test 1: DC Offset
Spec: 0 VDC, ±10 mV.
InitialConditions:Controlsperstandard,inputsshorted.
Procedure: Measure DC voltage at the output connec-
tors (rear panel). There is no adjustment for output
offset.Ifspecisnotmet,thereisanelectricalmalfunc-
tion.Slightlyoutofspecmeasurementisusuallydueto
U104/U204 out of tolorance.
Test 2: Output Bias Adjustment
Spec: 300 to 320 mVDC.
InitialConditions: Controlsperstandard,heatsinktem-
perature less than 40°C.
Procedure:MeasureDCvoltagesontheoutputmodule
across R31 (15 ohm), adjust R26 if necessary. Mea-
sureDCvoltagesontheoutputmoduleacrossR32(15
ohm), adjust R23 if necessary. Repeat for second
channel.
Test 3: ODEP Voltage Adjustment
Spec: Bias Per Chart, ±0.1V DC.
Initial Conditions: Controls per standard, heatsink at
room temperature 20 to 30°C (68 to 86°F). Note: This
adjustment should normally be performed within 2
minutes of turn on from ambient (cold) conditions. If
possible measure heatsink temperature, if not mea-
sure ambient room temperature. Use this information
when referencing the following chart.
The following list of ODEP bias voltages VS. tempera-
ture is based on the use of Main Modules built on any
circuit board up to and including the D 7911-7 board.
°F °C V–ODEP V+ODEP
66 18.9 –10.31 11.41
68 20.0 –10.26 11.36
70 21.1 –10.20 11.30
72 22.2 –10.14 11.24
74 23.3 –10.09 11.19
76 24.4 –10.03 11.13
77 25.0 –10.00 11.10
78 25.6 –9.97 11.07
80 26.7 –9.91 11.01
82 27.8 –9.86 10.96
84 28.9 –9.80 10.90
86 30.0 –9.74 10.84
88 31.1 –9.69 10.79
90 32.2 –9.63 10.73
92 33.3 –9.57 10.67
94 34.4 –9.51 10.61
The following list of ODEP bias voltages VS. tempera-
ture is based on the use of Main Modules built on the
D 7993-5 board.
°F °C V-ODEP V+ODEP
66 18.9 -9.31 10.31
68 20.0 -9.26 10.26
70 21.1 -9.20 10.20
72 22.2 -9.14 10.14
74 23.3 -9.09 10.09
76 24.4 -9.03 10.03
77 25.0 -9.00 10.00
78 25.6 -8.97 9.97
80 26.7 -8.91 9.91
82 27.8 -8.86 9.86
84 28.9 -8.80 9.80
86 30.0 -8.74 9.74
88 31.1 -8.69 9.69
90 32.2 -8.63 9.63
92 33.3 -8.57 9.57
94 34.4 -8.51 9.51
The following list of ODEP bias voltages VS. tempera-
ture is based on the use of Main Modules built on any
circuit board after the D 7993-5 board.
°F °C V–ODEP V+ODEP
66 18.9 –10.31 10.31
68 20.0 –10.26 10.26
70 21.1 –10.20 10.20
72 22.2 –10.14 10.14
74 23.3 –10.09 10.09
76 24.4 –10.03 10.03

Com-Tech 200 Amplifier Service Manual
13
77 25.0 –10.00 10.00
78 25.6 –9.97 9.97
80 26.7 –9.91 9.91
82 27.8 –9.86 9.86
84 28.9 –9.80 9.80
86 30.0 –9.74 9.74
88 31.1 –9.69 9.69
90 32.2 –9.63 9.63
92 33.3 –9.57 9.57
94 34.4 –9.51 9.51
–ODEPProcedure: Measure pin3ofJ500and,ifneces-
sary, adjust R121 to obtain V–ODEP as specified above.
Measure pin 3 of J500 and, if necessary, adjust R221
to obtain V–ODEP as specified above.
+ODEPProcedure: Measure pin4ofJ500and,ifneces-
sary, adjust R132 to obtain V+ODEP as specified above.
Measure pin 4 of J500 and, if necessary, adjust R232
to obtain V+ODEP as specified above.
Test 4: AC Power Draw
Spec: 60 Watts maximum quiescent.
Initial Conditions: Controls per standard.
Procedure: With no input signal and no load, measure
AC line wattage draw. If current draw is excessive,
check for high AC line voltage or high bias voltage.
Test 5: Common Mode Rejection
Spec at 100 Hz: –70 dB.
Spec at 20 kHz: –50 dB.
Initial Conditions: Controls per standard.
Procedure: Noload.Injecta0dBu(.775VRMS)100Hz
sine wave into each channel, one channel at a time,
with inverting and non-inverting inputs shorted to-
gether. At the output measure less than –44 dBu
(4.9mVRMS).Injecta0dBu20kHzsinewaveintoeach
channel,onechannelatatime,withinvertingandnon-
inverting inputs shorted together. At the output mea-
surelessthan–24dBu(49mVRMS).ForMainModules
with board numbers lower than D 7993-5 adjust N100
and N200 to calibrate CMR. For Main Modules with
board number D 7993-5 or greater adjust R921 and
R1021.
Test 6: Voltage Gain
Spec 26dB Gain: Gain of 20.0 ±3%.
Spec 0.775V 8/4 ohm Sensitivity: ±6%.
Spec 0.775V 70-V Sensitivity: ±6%.
Initial Conditions: Controls per standard.
Procedure: No load connected. Inject a 0.775 VAC 1
kHz sine wave with the Sensitivity Switch in the 26 dB
position.Measure 15.5 VAC ±0.5 VAC at the amplifier
Electrical Checkout Procedures
output. Inject a 0.775 VAC 1 kHz sine wave with the
Sensitivity Switch in the 0.775V 8/4 ohm position.
Measure 28.9 VAC ±1.7 VAC at the amplifier output.
Injecta0.775VAC1kHzsinewavewiththeSensitivity
Switch in the 0.775 VAC 70-V position and the Output
Mode Switch in the 70-V position. Measure 70.7 VAC
±4.2VACattheamplifieroutput.ReturntheSensitivity
Switch to the 26 dB position. Return the Output Mode
Switches to the 8/4 ohm position.
Test 7: Phase Response
Spec: ±10° from 10 Hz to 20 kHz at 1 Watt.
InitialConditions:Controlsperstandard,8ohmloadon
each channel.
Procedure:Injecta1kHzsinewaveandadjustfor1watt
output (2.8 VAC). Check input and output signals
against each other, input and output signals must be
within 10° of each other.
Test 8: Level Controls
Spec: Level controlled by level controls.
Initial Conditions: Controls per standard.
Procedure:Noload.Injecta1kHzsinewave.Withlevel
controls fully clockwise you should see full gain. As
controlsarerotatedcounterclockwise,observesimilar
gainreductionineachchannel.Whencomplete,return
level controls to fully clockwise position.
Test 9: Current Limit
Spec: Current Limit at 13 Amps, ±2 Amps.
Initial Conditions: Controls per standard.
Procedure:Loadeachchannelto1 ohm. Inject a 1kHz
differentiated (or 10% duty cycle) square wave. See
figure4.Increaseoutputleveluntilcurrentlimitoccurs.
Current limit should occur at 13 ±2 Amps (13 Vpk).
Observe clean (no oscillations) current clipping.
Figure 4. Differentiator Circuit
In Out
.047 uF
1K Ohm

Com-Tech 200 Amplifier Service Manual
14
Electrical Checkout Procedures
Test 10: Slew Rate & 10 KHz Square Wave
Spec: 17 - 25 V/µS, 8 ohm load.
Initial Conditions: Controls per standard.
Procedure: Load each channel to 8 ohms. Inject a 10
kHz square wave to obtain 35 Volts zero-to-peak at
eachoutput. Observe the slope of the square wave. It
shouldtypicallymeasure17-25V/µS.Also,thesquare
wave must not include overshoot, ringing, or any type
of oscillation.
Test 11: Crosstalk
Spec: -60 dB at 20 kHz.
Initial Conditions: Controls per standard. Terminate
input of channel not driven with 600 ohms.
Procedure:8ohmloadoneachchannel.Injecta20kHz
sinewaveintothechannel1inputandincreaseoutput
level to 29 VAC. Measure less than 29 mVAC at the
output of channel 2. Inject a 20 kHz sine wave into the
channel 2 input and increase output level to 29 VAC.
Measure less than 29 mVAC at the output of Ch 1.
Test 12: Output Power
Spec at 8 Ohm Stereo: ≥105 Watts/Ch at 0.1% THD
Spec at 4 Ohm Stereo: ≥140 Watts/Ch at 0.1% THD
Specat70-VMode,Stereo:≥100Watts/Chat0.1%THD,
50 Ohm load.
Initial Conditions: Controls per standard
Procedure:Loadeachchannelto8ohms.Injecta1kHz
sine wave and measure at least 28.98 VAC at the
outputofeachchannel.Loadeachchannelto4ohms.
Inject a 1 kHz sine wave and measure at least 23.66
VACattheoutputofeachchannel.Switcheachchan-
nel to the 70-V mode. Load each channel to 50 ohms.
Injecta1kHzsinewaveandmeasureatleast70.7VAC
attheoutputofeachchannel.Allpowermeasurements
must be at less than 0.1% THD.
Test 13: Reactive Loads
Spec: No oscillations. Safe with all types of loads.
Initial Conditions: Controls per standard.
Procedure Capacitive: Load each channel to 8 ohms in
parallelwith2µF.Injecta20kHzsinewavewith22VAC
output for 10 seconds.
Procedure Inductive: Load each channel to 8 ohms in
parallel with 159µH. Inject a 1 kHz sine wave with 15
VAC output for 10 seconds.
Procedure Torture: Loadeachchannel with the primary
(red and black leads) of a PS-U transformer (CPN D
7040-5).Eachchannelinthe70-Vmode.Injecta10Hz
sine wave with an output level sufficient enough to
cause 3 to 5 flyback pulses for 10 seconds.
ProcedureShort: Injecta60Hzsinewave into the input
andadjustfor5 VAC at the output. Short each chanel,
one at a time, for 10 seconds.
Test 14: ODEP Limiting
Spec:NooscillationonODEPlimitingwaveform;either
channel controls limiting in Parallel Mono mode.
Initial Conditions: Controls per standard; rag or other
obstruction blocking fan blade so it does not turn (if
FAN is installed).
Procedure: Load the amplifier to 2 ohms per channel.
Injecta60 Hz sine wave into eachchannel and adjust
theoutputto10VAC.Allowtheamplifiertoheatupuntil
you observe a wave form similar to figure 5. Allow the
amplifiertocoolforafewminiutes.Switchtheamplifier
to Parallel Mono mode and remove the load from
channel 2. Inject a 60 Hz sine wave into each channel
andadjustthe output to 10 VAC. Allow theamplifierto
heat up and observe limiting on both channels.
Test 15: LF Protection
Spec: Amplifier mutes for dangerous subsonic fre-
quencies.
Initial Conditions: Controls per standard.
Procedure: No load. Inject a .5 Hz 6 Vp-p, or a 2 Hz 6
VACsinewaveintoeach channel and verify that each
channel cycles into mute.
Figure 5. ODEP Limiting Wave Form

Com-Tech 200 Amplifier Service Manual
15
Electrical Checkout Procedures
Test 16: Signal to Noise Ratio
Spec:≥100dBbelow8ohmratedcontinuousaverage
20-20kHz power.
Initial Conditions: Controls per standard. Short inputs.
Procedure:Loadeachchannelto8ohms.Measureless
than 290µV at the output of each channel (20 Hz-20
kHz bandpass filter).
Test 17: Turn off Transients
Spec: < 80mV across an 8 ohm speaker load
Initial Conditions: Controls per standard.
Procedure: Load the output with an 8 ohm speaker.
Fromanoncondition,turnofftheamplifierandmonitor
the output noise at the time of turn off.
Note: Turn off noise may increase significantly if the
amplifier is cycled off and on.
Test 18: Intermodulation Distortion
Spec at 0 dB output: ≤0.01%.
Spec at -35 dB output: ≤0.05%.
Initial Conditions: Controls per standard.
Procedure: Load each channel to 8 ohms. Inject a
SMPTEstandardIMsignal(60Hzand7kHzsinewave
mixed at 4:1 ratio). Set the 60 Hz portion of the sine
wave to 23 volts RMS. Set the 7 kHz portion to 25%.
With an IM analyzer measure less than 0.01% IMD.
Repeat test at -35 dB (reference 23 volts RMS, 60 Hz
portion) and measure less than 0.05% IMD.
Test 19: Clipping
Spec: No protective action during test.
Initial Conditions: Controls per standard.
Procedure:Loadeachchannelto8ohms.Injecta1kHz
sinewaveintoeachinputanddrivetheoutput6dBinto
clip for 10 seconds. The amplifier should not activate
anyprotectivecircuits(ODEP,Fault,orLFProtection).
Post Testing
After completion of testing, if all tests are satisfactory,
the amplifier controls should be returned to the posi-
tionsrequiredbycustomer.Ifconditions areunknown
or unspecified, factory settings are as follows:
Level Controls: 9 to 11 O'Clock.
Sensitivity Switch: 0.775V 8/4 Ohm.
Stereo/Mono Switch: Stereo.
70-V Mode Switches: 8/4 Ohm position.
Power: Off

Com-Tech 200 Amplifier Service Manual
16
Supplimental Items
CPN Item Quantity
A10087-71012 Rack Screw, 10-32 x .75 8
C 3342-0 Feet, Selfstick Black 4
D 4137-2 Nylon Washer 4
A10086-70808 Screw, 8-32 x .5 (For volume cover) 2
A10101-12 Spacer, #8 x 5/16OD x 1/4L (For volume cover) 2
F11489-6 Plexiglass Plate (Volume cover) 1
K80636-2 CT Series Reference Manual 1
Power Supply
CPN Item Quantity
A10087-11028 Screw, 10-32 x 1.75 (For transformer) 4
C 10171-4 Breaker, 8 Amp VDE 1
C10168-0 Breaker, 4 Amp VDE (200V-240V Models) 1
D 7212-0 Power Transformer (120V 60 Hz) 1
D 7224-5 Power Transformer (220V/240V) 1
D 8022-2 Power Transformer (100V/120V) 1
A10099-7 Nylon Shoulder Washer, #10 4
A10095-4 Lockwasher, #10 External Star 4
A10098-5 Washer, 1/4" Belleville Spring 4
C 8752-5 Bridge Rectifier, 35A 400V 2
C 9852-2 Capacitor, 6300µF 200V Electrolytic 2
C 9870-4 Screw, 10-32 x .38 4
D 2934-4 Solder Lug, .218 Hole 4
D 6764-1 Washer, Shoulder 4
D 8438-0 Bracket, Capacitor 2
Output Assembly (One Per Channel)
CPN Item Quantity (Per Channel)
A10315-1 Screw, 6-32 x .56 Hex Washer Head 12
C 8188-2 Output Power Transistor, PNP 2
D 6729-4 Output Power Transistor, NPN 2
C 7065-3 Output Power Transistor, PNP (early units) 2
C 8573-5 Driver Transistor, 2SA1186 PNP 2
C 8574-3 Driver Transistor, 2SC2837 NPN 2
M20591-0 Old Style Driver Transistor Assm. NPN, 2SC2527 2
M20590-2 Old Style Driver Transistor Assm. PNP, 2SA1077 2
D 7665-9 Mounting Clip, TO3P (For Drivers) 2
D 7666-7 Mounting Bracket, TO3P (For Drivers) 2
D 7796-2 Sil Pad, 2.87 x 14.57 (Between Heatsink & Chassis) 1
D 6280-8 Sil Pad for use with Output Board P10315-3 1
D 6104-0 Sil Pad for use with Output Board P10233-8 1
D 7797-0 Output Pad (Between Module and Chassis) 1
C 7597-4 Output Pad for use with Output Board P10315-3 1
D 7026-4 Output Pad for use with Output Board P10233-8 1
D 8774-8 PTC, 95DegC Cast Alum. 1
F12019-0 Heatsink (Under Diode String) 1
C 8813-5 Bias Transistor MPS8097/MPSA18 NPN (Q18) 1
B 5842-8 Tubing, #24 Thin Wall Red (For Q18) Order in Inches
C 5826-0 LM234Z-6 Thermal Sense (S100/200) 1
B 5464-1 Tubing, #24 Teflon Thin Wall Order in Inches
M21324-5 Aluminum Heat Sink, 3/4" With Fins 2
Parts List (Non-Module)

Com-Tech 200 Amplifier Service Manual
17
Parts List (Non-Module)
Back Panel Assembly
CPN Item Quantity
D 8367-1 Knob, .5 Dia. Level Control 2
A10086-10410 Screw, 4-40 x .62 2
A10086-70808 Screw, 8-32 x .5 4
A10094-2 Lockwasher, #4 Internal Star 2
A10100-7 Aluminum Spacer, .250OD x .140ID x .312L 2
A10109-70808 Screw, 8-18 x .5 4
A10214-4 Strain Relief 1
C10187-0 Strain Relief (For European Power Cord) 1
A11793-0105D Power Cord, 16-3 SJT Neon UL/CSA 1
A10793-0503D Power Cord, European Plug (E-13 Amplifiers) 1
C 4508-5 IC Socket, 16 Pin 1
C 5990-4 Barrier Block, 4 Term. 1
C 6821-0 Edge Card Connector, 22 Contact 1
C 7957-1 Slide Switch, DPDT 15A (70-V Mode) 2
C 8812-7 Cable Tie, 5.5" 2
C10060-9 Header, 5 Pin R Angle Locking 1
D 6899-5 Ribbon Connector, PIP Daisy 1
D 7623-8 Cable, 10" 22AWG With Terminals 1
F12690-8 Back Panel 1
P10286-6 PIP Interconnect Board 1
Chassis Front Assembly
CPN Item Quantity
A10031-1 Captive Nut, 8-32 x .060 Flush (For rack ears) 4
A10090-70808 Screw, 8-32 x .5 Oval Head (For Grille) 3
A10101-5 Nylon Washer, .5 x .136 x .02 (For Grille) 3
A10173-1 Clip, Filter Grille 3
C 5297-4 Screw, 8-32 x .37 (For rack ears) 4
C 6487-0 Power Switch, 2 Pole 22 Amp Rocker 1
D 6944-9 Air Filter, 1.45 x 16.23 1
F11439J0 Front Panel Overlay 1
F12706-2 End Cap (For Rack ears) 2
F12710-4 Grille, Filter 1
Main Chassis Assembly
CPN Item Quantity
A10094-3 Washer, #6 Internal Star, Black 8
A10110-70605 Screw, 6-32 x .312 Taptite (For covers) 7
D 7249-2 Label, 3 Position Voltage Gain 1
D 8501-5 Top Cover 1
D 8548-6 Bottom Cover 1
A10086-10606 Screw, 6-32 x .375 4
A10086-70806 Screw, 8-32 x .37 1
A10094-3 Washer, #6 Internal Star, Black 3
A10094-6 Washer, #8 Internal Star 2
A10109-10822 Screw, 8-18 x 1.375 2
A10110-70812 8-32 x .750 Taptite 2
A10192-1 Snap Bushing, OCB .500 3
C 1811-6 4" Cable Tie 8
C 3163-0 Solder Lug, #6 2

Com-Tech 200 Amplifier Service Manual
18
Parts List (Non-Module)
Main Chassis Assembly Cont.
CPN Item Quantity
C 6457-3 Screw, #8 x 3/8 2
C 6912-7 Tension Retaining Board Supports 2
C 6913-5 1" Spacer Toggle Nut, Plastic 2
C 6914-3 .75" Spacer Toggle Nut, Plastic 2
C 7705-4 Flat Cable Clamp 2
C 9491-9 Screw, 6-32 x .312 3
C 9953-8 Screw, 6-20 x .312 6
C10111-0 Button, Mtg. 2
D 7060-3 Sil Pad, 7 Mil 2.05 x .775 1
F11632-1 Bracket, Transformer Mtg. 1
F12642-9 Chassis, 3.5" 1
PIP-BB
CPN Item Quantity
M46011-9 PIP-BB Assembly 1
A10086-70806 Screw, 8-32 x .37 2
A10094-5 Lockwasher, #8 Internal Star Black 2
A10110-10608 Screw, 6-32 x .5 4
A10266-2202 Resistor, 22 Ohm .5W 2
C 3842-9 Barrier Block, 3 Position 2
C 6806-1 Capacitor, .01µF 100V 2
C 7161-0 Screw, #8 x 1/4 #6 PNHD 2
F12553J7 Panel 1
P10343-5 PC Board 1
CT-200 Fan Assembly (Optional on Domestic Units)
CPN Item Quantity
M44084-8 CT Fan Assembly 1
A10110-70605 Screw, 6-32 x .312 Taptite 2
C 7062-0 Screw, 6-32 x 5/16 2
C 9939-7 Fan Blade 1
D 8439-8 Fan Bracket 1
H43495-3 Fan Motor with Faston Connectors 1

Com-Tech 200 Amplifier Service Manual
19
Module and Schematic Information
Module History
TheComTech200Bamplifierwasintroducedin1990.
Since then there have been several updates and
revisions, some of which called for new modules. The
following is a list of all modules used up to this date,
December 1995.
Output Modules: (left and right are identical)
Q42716-3
Original Output Module on P10233-8 or P10263-5
board.
Q42888-0
Output Module on P10315-3 board.
Q42969-8
Output Module on P10337-7 board. No longer avail-
able. Use Q43188-4 as service replacement.
Q43188-4
Output Module on P10396-3 board.
Main Modules:
Q42774-2
Original B Version Main Module. This Module's parts
list is not documented. No longer available. Use
Q43128-0 as a service replacement.
Q42922-7
Main Module on D 7605-5 board. This Module's parts
list is not documented. No longer available. Use
Q23128-0 as a service replacement.
Q43013-4
Main Module on D 7911-7 board. This module is still
available at this time. If not, then use Q43128-0 as a
service replacement.
Q43044-9
MainModuleonD7993-5board.Nolongeravailable.
Use Q43128-0 as service replacement.
Q43128-0
Main Module on D 8283-0 board.
Q43237-9
Main Module on D 8369-7 board. Detent Pots. Not
reverse compatible.
Control Module:
Q42762-7
CT-200/400 fan control on P10317-9 board.
Q43215-5
CT-200 fan control on P10404-5 board.
Q43244-5
CT control module for 120V, 60 Hz only. On P10405-2
board.
Q43242-9
CT control module for Export models. On P10405-2
board.
Display Module:
Q42706-4
CT display on D 7083-5 board.
Schematic Information:
Theschematicsprovidedarerepresentativeonly.There
maybeslightvariationsbetweenamplifiertoamplifier.
Theseschematicsareintendedtobeusedfortrouble-
shooting purposes only.
ForamplifierswithmainboardsD7605-5,D7911-7,D
7993-5, and D 8283-0 or earlier, refer to schematic
number J0552-3.
Foramplifierswithmainboard D 8369-7refertosche-
matic number J0630-4.

Com-Tech 200 Amplifier Service Manual
20
Q42762-7 Control Module (P10317-9 board) Parts Lists
Capacitors
C700 C800 C 8426-6 .1µF 250V
C701 C801 C 8426-6 .1µF 250V
C900 C 8963-8 .47µF 250V
C901 C 8963-8 .47µF 250V
Diodes
D700 D800 C 3181-2 1N4148
D900 C 2851-1 1N4004
Relays
K1 C 7860-7 SPST
Transistors
Q700 Q800 C 3625-8 PNP 2N4125
Q701 Q801 C 7663-5 Triac MAC224A4
Q900 C 3625-8 PNP 2N4125
Q901 C 3625-8 PNP 2N4125
Q902 C 3625-8 PNP 2N4125
Resistors
R700 R800 A10266-1222 1.2K .5W
R701 R801 A10266-1812 180 .5W
R900 A10266-2722 2.7K .5W
R901 A10266-1021 1.5K .5W
R902 C 7669-2 300 10W
R903 C 7669-2 300 10W
R904 A10266-3902 39 .5W
R905 A10266-3602 36 .5W
ICs
U700 U800 C 7664-3 MOC3031 Optotriac
U901 C 7665-0 MOC3011 Optotriac
U902 C 7665-0 MOC3011 Optotriac
Misc.
Board P10317-9
J900 C 7672-6 8 Pin MTA Header
Tab Terminal C 7817-7 W1-W3,W100-W102
W200-W202
0 Ohm Jmp C 5868-2