Crown CT-400 Service manual

Com-Tech 400 Amplifier Service Manual

POWER AMPLIFIER

SERVICE MANUAL

COM-TECH® 400

Model CT400B

©1995 by 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

Com-Tech®, ODEP® and Crown® are registered trademarks of Crown International, Inc.

K-SVCCT400

12-95

1

Com-Tech 400 Amplifier Service Manual

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]

CAUTION

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.

WARNING

AVIS

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 REDUCE THE RISK OF ELECTRIC

SHOCK, DO NOT EXPOSE THIS

EQUIPMENT TO RAIN OR MOISTURE!

2

Com-Tech 400 Amplifier Service Manual

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

Q43214-8 Control Module Parts List .................... 21

Q43242-9 Control Module Parts List .................... 22

Q42706-4 Display Module Parts List.................... 23

Q42716-3 Output Module Parts List .................... 24

Q42888-0 Output Module Parts List .................... 25

Q42969-8 Output Module Parts List .................... 26

Q43188-4 Output Module Parts List .................... 27

Q43012-6 Main Module Parts List........................ 28

Q43043-1 Main Module Parts List........................ 31

Q43129-8 Main Module Parts List........................ 34

Q43238-7 Main Module Parts List........................ 37

3

Com-Tech 400 Amplifier Service Manual

Introduction

This manual contains service information on Crown
power amplifiers. It is designed to be used in conjunc­tion with the applicable Owner's Manual. However,
some important information is duplicated in this Ser­vice Manual in case the Owner's Manual is not readily
available.

NOTE: THE INFORMATION IN THIS MANUAL IS INTENDED
FOR USE BY AN EXPERIENCED TECHNICIAN ONLY!

Scope

This Service Manual in intended to apply to all versions
of the CT-400B amplifier including the Amcron ver­sion. The Parts Listings include parts specific for the
US version and the European version (CT-400BE13).
For parts specific only to other versions contact the
Crown Technical Support Group for help in finding
part numbers.

This Service Manual includes several sections. These
sections include Parts Information, Specifications,
Voltage Conversion, Circuit Theory, Electrical Test
Procedures, Non-Module Parts Lists, and Module
Parts Lists. Schematics are attached. Note that com­ponent parts with circuit board comprise a complete
module. Module part numbers are always associated
with a specific circuit board, although an unpopulated

circuit board may be built up with different parts to
create different modules. Note that Crown does not
sell blank (unpopulated) circuit boards.

Each of the compact audio power amplifiers are
designed for professional or commercial use. Provid­ing high power amplification from 20Hz to 20KHz with
minimum distortion, they feature balanced inputs with
bridged and parallel monophonic capability. Specific
features vary depending on model family.

Warranty

Each Owner's Manual contains basic policies as re­lated 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
(including round trip shipping within the United States),
all warranty service should be referred to the Crown
Factory or Authorized Warranty Service Center. See
the applicable Owner’s Manual for warranty details. To
find the location of the nearest Authorized Service
Center or obtain instructions for receiving Crown Fac­tory Service please contact the Crown Technical Sup­port Group (within North America) or your Crown/
Amcron Importer (outside North America).

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]

4

Com-Tech 400 Amplifier Service Manual

Parts Information

General Information

Later sections include both mechanical 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. Com­mon letters used are C, D, H, M, P, and Q. The second
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
number after the prefix letter; the space is considered
a character.) The seventh character is usually a hy­phen, though it may be a letter to indicate a revision or
special note. The last character is called a check-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
numbers. These five numbers identify a type of part.
The seventh character is a hyphen. Remaining char­acters 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 re­placement. Structural items such as modules and
panels are available from Crown only.

shipment on a C.O.D. or pre-payment (check or credit
card) basis.

Terms

Normal terms are pre-paid. Net-30 Days applies to
only those firms having pre-established accounts with
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 re­turned 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.

Crown is not a general parts warehouse. Parts sold by
the Crown Parts Department are solely for servicing
Crown/Amcron products. Part prices and availabil-

ity are subject to change without notice.

Crown

Parts Department

Mailing Address:

PO Box 1000

Elkhart, IN USA 46515-1000

Shipping Address:

57620 C.R. 105

Elkhart, IN USA 46517

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. Estab­lished accounts with Crown will receive shipment
freight prepaid and will be billed. All others will receive

Phone: [phone]

or: [phone]

Toll Free: [phone]

FAX: [phone]

5

Com-Tech 400 Amplifier Service Manual

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
are guaranteed through the warranty period (normally
3 years). Because our testing methods are more strin­gent than our published specifications, every Crown
amplifier will exceed its published specifications.

Power

Power

8 Ohm Stereo—230W/Ch
4 Ohm Stereo—255W/Ch
70-V Line Stereo—225W/Ch
8 Ohm Bridge Mono—470W
4 Ohm Parallel Mono—445W
2 Ohm Parallel Mono—450W
Bridge Mono, 140-V Line—450W
Parallel Mono, 70-V Line—455W

Load Impedances: Rated for 16, 8, 4, 2, Ohm, and 70­V use. Safe with all types of loads, even totally reactive
loads.

AC Mains: 120VAC at 60 Hz with standard three-wire
grounded connector for North American units; 100VAC,
120VAC, 220VAC, and 240VAC at 50 or 60 Hz units
are available when ordered country specific. Com­Tech 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 milliwatts to
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
dynamic thermal conditions without interrupting power.
Current limiting for shorted load protection. DC/LF and
common mode output current Fault circuitry to mute
audio. Delay of 4 seconds from turn on mutes amplifier
to prevent dangerous turn-on transients.

Mechanical

Input Connectors: Balanced three-terminal barrier block

for each channel on standard P.I.P.-BB module (in­cluded)

Output Connectors: Four-terminal barrier block.
Front Panel Controls: A front panel rocker switch used

to power the amplifier on and off.
Back Panel Controls: A three-position switch which

selects 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.

Internal Controls: A three-position switch selects 0.775V,

1.4V, or 26 dB voltage gain input sensitivity.
Indicators: Amber Enable indicator shows on/off status

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
proportion to ODEP limiting. A yellow indicator for
each 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: 19 inches wide, 3.5 inches high, 16 inches
deep behind front mounting surface.

Weight: 31 lbs, 12.5 oz. (14.4 kg)

6

Com-Tech 400 Amplifier Service Manual

Theory

Overview

It should be noted that over time Crown makes im­provements and changes to their products for various
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.

This section of the manual explains the general opera­tion of a typical Crown power amplifier. Topics cov­ered include Front End, Grounded Bridge, and ODEP.
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 innova­tions including grounded bridge and ODEP technolo­gies. Cooling techniques make use of the what is
essentially air conditioner technology. Air flows bot­tom to top, and front to side. Air flows a short distance
across a wide heatsink. This type of air flow provides
significantly better cooling than the “wind tunnel”
technology used by many other manufacturers. Out­put transistors are of the metal can type rather than
plastic 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 maximum reliability. Another electronic tech­nique used is negative feedback. Almost all power
amplifiers utilize negative feedback to control gain
and provide stability, but Crown uses multiple nested
feedback loops for 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.

For additional details refer to the specification section,
or to the applicable Owner’s Manual.

Front End Operation

The front end is comprised of three stages: Balanced
Gain Stage (BGS), Variable Gain Stage (VGS), and
the 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) side of the balanced input is fed
to the inverting input of the first op-amp stage. A
potentiometer is provided for common mode rejection
adjustment. Electrically, the BGS is at unity gain.
(From an audio perspective, however, this stage
actually provides +6dB gain if a fully balanced signal
is placed on its input.) The BGS is a non-inverting
stage. It’s output is delivered to the Variable Gain
Stage.

Variable Gain Stage (VGS)

From the output of the BGS, the signal goes to the VGS
where gain is determined by the position of the Sen­sitivity Switch, and level is determined by the level
control. VGS is an inverting stage with the input being
fed to its op-amp stage. Because gain after this stage
is fixed at 26dB (factor of 20), greater amplifier sensi­tivity is achieved by controlling the ratio of feedback to
input resistance. The Sensitivity Switch sets the input
impedance to 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.

Features specific to the Com-Tech Series’ include
slew rate limiting, and audio muting for delay or
protective action. This amplifier can operate in either
a Bridged or Parallel Mono mode as well as dual
(stereo). A sensitivity switch allows selection of input
voltage required for rated output. Level controls are
mounted on the rear panel and are of the rotary type.
Front panel indicators 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 reserve energy status. In
general, the packaging of this model is designed for
maximum watt/price/weight/size value with user friendly
features.

Error Amp

The inverted output from the VGS is fed to the non­inverting input of the Error Amp op-amp stage through
an AC coupling capacitor and input resistor. 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
produce a near open loop gain condition which in turn
results in high peak output voltage. The output of the

7

Com-Tech 400 Amplifier Service Manual

Theory

Error Amp, called the Error Signal (ES) drives the
Voltage Translators.

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),
translating the signal from ground referenced ±15V to
±Vcc reference. LVAs provide the main voltage ampli­fication 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 bal­anced voltage translator stage. These offset reference
voltages drive the input to the Voltage Translator
transistors. A nested NFb loop from the output of the
amplifier mixes with the inverted signal riding on the
offset references. This negative feedback fixes gain at
the offset reference points (and the output 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
gain with equal gain. They shift the audio from the
±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/protec­tion transistors act as switches to totally shunt audio to
ground during the turn-on delay, or during a DC/LF or

Fault protective action.

Last Voltage Amplifiers (LVAs)

The Voltage Translator stage channels the signal to
the Last Voltage Amplifiers (LVA's) in a balanced
configuration. The +LVA and -LVA, with their push-pull
effect through the Bias Servo, drive the fully comple­mentary output stage. The LVAs are configured as
common emitter amplifiers. This configuration pro­vides sufficient voltage gain and inverts the audio. The
polarity inversion is necessary to avoid an overall
polarity inversion from input jack to output jack, and it
allows the NFb loop to control Error Amp gain by
feeding back to 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

Figure 2 is a simplified example of the grounded
bridge 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 of the bridge (driving the load), and one
NPN and one PNP on the Low Side of the bridge
(controlling the ground reference for the rails). The
output stages are biased to operate class AB+B for
ultra low distortion in the signal zero-crossing region
and high efficiency.

High Side (HS)

The High Side (HS) of the bridge operates much like
a conventional bipolar push-pull output configuration.

Audio

Inputs

8

BGS VGS Error

Amp

+

-

+

-

+

-

Figure 1. Typical Amplifier Front End and Voltage Amplification Stages.

+15V

Voltage Divider

+

-15V

-

ODEP

Q100

Q103

Mute

Q121

Q122

NFb Loop

Voltage

Translators

Q101

Q102

+VCC

Q105

NPN Outputs (+HS)
PNP Outputs (-HS)

Q110

-VCC

LVA's

Com-Tech 400 Amplifier Service Manual

Theory

As the input drive voltage becomes more positive, the
HS NPN conducts and delivers positive voltage to the
load. Eventually the NPN devices reach full conduc­tion and +Vcc is across the load. At this time the HS
PNP is biased off. When the drive signal is negative
going, the HS PNP conducts to deliver -Vcc to the load
and the HS NPN stage is off.

The output of the +LVA drives the base of predriver
device. Together, the predriver and driver form the
first two parts of the three-deep Darlington and are
biased class AB. They provide output drive through
the bias resistor, bypassing the output devices, at
levels below about 100mW. An RLC network between
the predriver and driver provide phase shift compen­sation and limit 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
greater in value so that PNP output 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
Vce under static conditions. The positive and negative
halves of the HS output are in parallel with this 3.3V.
With a full base-emitter on voltage drop across
predrivers and drivers, the balance of voltage results
in approximately .35V drop across the bias resistors in
the positive half, and about .5V across the bias resistor
in the negative half. Q18 conduction (and thus bias) 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
power supply bridge rectifier is not ground refer­enced, nor is the secondary of the main transformer.
In other words, the high voltage power supply floats
with respect to ground, but ±Vcc remain constant with
respect to each other. This allows the power supply to
deliver +Vcc and -Vcc from the same bridge rectifier
and filter as a total difference in potential, regardless
of their voltages with respect to ground. The LS uses

+

+Vcc (Positive Rail)

Input
signal

HIGH SIDE LOW SIDE

Load

(speaker)

-Vcc (Negative Rail)

Inverting Op-amp

-

Figure 2. Crown Patented Grounded Bridge Topology

9

Com-Tech 400 Amplifier Service Manual

Theory

inverted feedback from the HS output to control the
ground reference for the rails (±Vcc). Both LS quad­rants are arranged in a three-deep Darlington and are
biased AB+B in the same manner as the HS.

When the amplifier output swings positive, the audio is
fed to an op-amp stage where it is inverted. This
inverted signal is delivered directly to the bases of the
positive (NPN) and negative (PNP) LS predrivers. The
negative drive forces the LS PNP devices on (NPN
off). As the PNP devices conduct, Vce of the PNP
Darlington drops. With LS device emitters tied to
ground, -Vcc is pulled toward ground reference.
Since the power supply is not ground referenced (and
the total voltage 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, for example, the power
supply produced a 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 poten­tial. At the negative amplifier output peak, +Vcc = 0V
and -Vcc equals the total power supply potential with
a negative polarity. Using the same example as above,
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
capable of producing 140V peak-to-peak at the ampli­fier output when the grounded bridge topology is
used. The voltage used in this example are relatively
close to the voltages of the PB-1/460CSL.

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)

To further protect the output stages, a specially devel­oped 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 Volt­age Translator stage by removing drive that may
exceed the safe-operating-area of the output stage.

ODEP senses output current by measuring the volt­age dropped across LS emitter resistors. LS NPN
current (negative amplifier output) and +Vcc are
sensed, then multiplied to obtain a signal proportional
to output power. Positive and negative ODEP voltages
are adjustable via two potentiometers. Across ±ODEP
are a PTC and a thermal sense (current source). The
PTC is essentially a cutoff switch that causes hard
ODEP limiting if heatsink temperature exceeds a safe
maximum, regardless of signal level. The thermal
sense causes the differential between +ODEP and –
ODEP to decrease as heatsink temperature increases.
An increase in positive output signal output into a load
will result in –ODEP voltage dropping; an increase in
negative output voltage and current will cause +ODEP
voltage to drop. A complex RC network between the
±ODEP circuitry is used to simulate the thermal barri­ers between the interior of the output device die
(immeasurable by normal means) and the time delay
from heat generation at the die until heat dissipates to
the thermal sensor. The combined effects of thermal
history and instantaneous dynamic power level result
in an accurate simulation of the actual thermal condi­tion of the output transistors.

The total effect is to deliver a peak to peak voltage to
the speaker load which is twice the voltage produced
by the power supply. Benefits include full utilization of
the power supply (it conducts current during both
halves of the output signal; conventional designs
require 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

10

Com-Tech 400 Amplifier Service Manual

Theory

BALANCED

INPUTS

+VOLTAGE

TRANSLATOR

VGSBGS

-1

ERROR

AMP

OUTPUT

DEVICE

EMULATION

PROTECTION

-VOLTAGE

TRANSLATOR

+LVA

-1

HIGH SIDE

BIAS

SERVO

-LVA

-1

MAIN NEGATIVE FEEDBACK (NFb) LOOP

LOW SIDE

-1

INVERTING

BRIDGE

BALANCE

BIAS

DIODE

STRING

POSITIVE

HIGH SIDE

OUTPUT

NPN STAGE

NEGATIVE
HIGH SIDE

OUTPUT

PNP STAGE

POSITIVE

LOW SIDE

OUTPUT

NPN STAGE

NEGATIVE
LOW SIDE

OUTPUT

PNP STAGE

Figure 3. Typical Crown Amplifier Basic Block Diagram (One Channel Shown)

11

Com-Tech 400 Amplifier Service Manual

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 proce­dure. These tests, though meant for verification and
alignment of the amplifier, may also be very helpful in
troubleshooting. For best results, tests should be
performed in order.

All tests assume that AC power is from a regulated 120
VAC source. Test equipment includes an oscillo­scope, 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 other­wise specified.

Test 1: DC Offset

Spec: 0 VDC, ±10 mV.
Initial Conditions: Controls per standard, inputs shorted.
Procedure: Measure DC voltage at the output connec-

tors (rear panel). There is no adjustment for output
offset. If spec is not met, there is an electrical malfunc­tion. Slightly out of spec measurement is usually due
to U104/U204 out of tolorance.

Test 2: Output Bias Adjustment

Spec: 300 to 320 mVDC.
Initial Conditions: Controls per standard, heatsink tem-

perature less than 40°C.
Procedure: Measure DC voltages on the output module
across R31 (15 ohm), adjust R26 if necessary. Mea­sure DC voltages on the output module across R32 (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 mea­sure ambient room temperature. Use this information
when referencing the following chart.

The following list of ODEP bias voltages VS. tempera­ture is based on the use of Main Modules built on any
circuit board up to and including the D 7993-5 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. tempera­ture 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
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

–ODEP Procedure: Measure pin 3 of J500 and, if neces­sary, adjust R121 to obtain V

as specified above.

–ODEP

Measure pin 3 of J500 and, if necessary, adjust R221
to obtain V

as specified above.

–ODEP

+ODEP Procedure: Measure pin 4 of J500 and, if neces­sary, adjust R132 to obtain V

as specified above.

+ODEP

Measure pin 4 of J500 and, if necessary, adjust R232
to obtain V

as specified above.

+ODEP

12

Com-Tech 400 Amplifier Service Manual

Electrical Checkout Procedures

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: No load. Inject a 0 dBu (.775VRMS) 100 Hz

sine wave into each channel, one channel at a time,
with inverting and non-inverting inputs shorted to­gether. At the output measure less than –44 dBu
(4.9mVRMS). Inject a 0 dBu 20 kHz sine wave into
each channel, one channel at a time, with inverting and
non-inverting inputs shorted together. At the output
measure less than –24 dBu (49mVRMS). For Main
Modules 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 8: Level Controls

Spec: Level controlled by level controls.
Initial Conditions: Controls per standard.
Procedure: No load. Inject a 1 kHz sine wave. With level

controls fully clockwise you should see full gain. As
controls are rotated counterclockwise, observe simi­lar gain reduction in each channel. When complete,
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: Load each channel to 1 ohm. Inject a 1 kHz

differentiated (or 10% duty cycle) square wave. See
figure 4. Increase output level until current limit oc­curs. Current limit should occur at 13 ±2 Amps (13
Vpk). Observe clean (no oscillations) current clipping.

In

.047 uF

Out

1K Ohm

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
output. Inject a 0.775 VAC 1 kHz sine wave with the
Sensitivity Switch in the 0.775V 8/4 ohm position.
Measure 42.4 VAC ±2.5 VAC at the amplifier output.
Inject a 0.775 VAC 1 kHz sine wave with the Sensitivity
Switch in the 0.775 VAC 70-V position and the Output
Mode Switch in the 70-V position. Measure 70.7 VAC
±4.2 VAC at the amplifier output. Return the Sensitivity
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.
Initial Conditions: Controls per standard, 8 ohm load on

each channel.
Procedure: Inject a 1 kHz sine wave and adjust for 1
watt output (2.8 VAC). Check input and output signals
against each other, input and output signals must be
within 10° of each other.

Figure 4. Differentiator Circuit

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
each output. Observe the slope of the square wave. It
should typically measure 17-25 V/µS. Also, the square
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: 8 ohm load on each channel. Inject a 20 kHz
sine wave into the channel 1 input and increase output
level to 42 VAC. Measure less than 42 mVAC at the
output of channel 2. Inject a 20 kHz sine wave into the
channel 2 input and increase output level to 42 VAC.
Measure less than 42 mVAC at the output of Ch 1.

13

Com-Tech 400 Amplifier Service Manual

Electrical Checkout Procedures

Test 12: Output Power

Spec at 8 Ohm Stereo: ≥ 215 Watts/Ch at 0.1% THD
Spec at 4 Ohm Stereo: ≥ 230 Watts/Ch at 0.1% THD
Spec at 70-V Mode, Stereo: ≥ 210 Watts/Ch at 0.1% THD
Initial Conditions: Controls per standard
Procedure: Load each channel to 8 ohms. Inject a 1 kHz

sine wave and measure at least 41.47 VAC at the
output of each channel. Load each channel to 4 ohms.
Inject a 1 kHz sine wave and measure at least 30.33
VAC at the output of each channel. Switch each
channel to the 70-V mode. Load each channel to 25
ohms. Inject a 1 kHz sine wave and measure at least

70.7 VAC at the output of each channel. All power
measurements 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

parallel with 2µF. Inject a 20 kHz sine wave with 30
VAC 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: Load each channel with the primary
(red and black leads) of a PS-U transformer (CPN D
7040-5). Each channel in the 70-V mode. Inject a 10 Hz
sine wave with an output level sufficient enough to
cause 3 to 5 flyback pulses for 10 seconds.
Procedure Short: Inject a 60 Hz sine wave into the input
and adjust for 5 VAC at the output. Short each chanel,
one at a time, for 10 seconds.

Test 14: ODEP Limiting

Spec: No oscillation on ODEP limiting wave form; 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.
Procedure: Load the amplifier to 4 ohms per channel.
Inject a 60 Hz sine wave into each channel and adjust
the output to 15 VAC. Allow the amplifier to heat up
until you observe a wave form similar to figure 5. Allow
the amplifier to cool for a few miniutes. Switch the
amplifier to Parallel Mono mode and remove the load
from channel 2. Inject a 60 Hz sine wave into each
channel and adjust the output to 15 VAC. Allow the
amplifier to heat up and observe limiting on both
channels.

Figure 5. ODEP Limiting Wave Form

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

VAC sine wave into each channel and verify that each
channel cycles into mute.

Test 16: Signal to Noise Ratio

Spec: ≥ 100 dB below 8 ohm rated continuous average

20-20kHz power.

Initial Conditions: Controls per standard. Short inputs.
Procedure: Load each channel to 8 ohms. Measure

less than 415µV at the output of each channel (20 Hz­20 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.

From an on condition, turn off the amplifier and monitor
the output noise at the time of turn off.
Note: Turn off noise may increase significantly if the
amplifier is cycled off and on.

14

Com-Tech 400 Amplifier Service Manual

Electrical Checkout Procedures

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

SMPTE standard IM signal (60 Hz and 7 kHz sine wave
mixed at 4:1 ratio). Set the 60 Hz portion of the sine
wave to 32 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 32 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: Load each channel to 8 ohms. Inject a 1 kHz

sine wave into each input and drive the output 6 dB
into clip for 10 seconds. The amplifier should not
activate any protective circuits (ODEP, Fault, or LF
Protection).

Post Testing

After completion of testing, if all tests are satisfactory,
the amplifier controls should be returned to the posi­tions required by customer. If conditions are unknown
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

15

Com-Tech 400 Amplifier Service Manual

Parts List (Non-Module)

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
C10169-8 Breaker, 15 Amp VDE 1
C10171-4 Breaker, 8 Amp VDE (200V-240V Models) 1
D 7604-8 Power Transformer (120V 60 Hz) 1
D 9010-6 Power Transformer (220V/240V) 1
D 8036-2 Power Transformer (100V/120V) 1
A10094-8 Washer, #10 Internal Tooth 4
A10099-7 Nylon Shoulder Washer, #10 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

16

Com-Tech 400 Amplifier Service Manual

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
F11449J9 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

17

Com-Tech 400 Amplifier Service Manual

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

Fan Assembly

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

18

Com-Tech 400 Amplifier Service Manual

Module and Schematic Information

Module History

The Com Tech 400B amplifier was introduced in 1990.
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 avail­able. Use Q43188-4 as service replacement.
Q43188-4
Output Module on P10396-3 board.

Main Modules:

Q42781-7
Original B Version Main Module. This Module's parts
list is not documented. No longer available. Use
Q43129-8 as a service replacement.
Q42921-9
Main Module on D 7605-5 board. This Module's parts
list is not documented. No longer available. Use
Q23129-8 as a service replacement.
Q43012-6
Main Module on D 7911-7 board. Use Q43129-8 as a
service replacement.
Q43043-1
Main Module on D 7993-5 board. No longer available.
Use Q43129-8 as service replacement.
Q43129-8
Main Module on D 8283-0 board.
Q43238-7
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.
Q43214-8
CT-400/800 fan control on P10404-5 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:

The schematics provided are representative only.
There may be slight variations between amplifier to
amplifier. These schematics are intended to be used
for troubleshooting purposes only.

For amplifiers with main boards D 7605-5, D 7911-7,
D 7993-5, and D 8283-0 or earlier, refer to schematic
number J0523-1.

For amplifiers with main board D 8369-7 refer to
schematic number J0631-2.

19

Com-Tech 400 Amplifier Service Manual

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

20

Com-Tech 400 Amplifier Service Manual

Q43214-8 Control Module (P10404-5 board) Parts List

Capacitors

C700 C800 C 8426-6 .1µF 200V
C701 C801 C 8426-6 .1µF 200V
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

Misc.

Board P10404-5
J900 C 7672-6 8 Pin MTA Header
J901 C 7873-0 2 Pin MTA Header
Tab Terminal C 7817-7 W1-W3,

W100-W102,
W200-W202

21

Com-Tech 400 Amplifier Service Manual

Q43242-9 Control Module (P10405-2 board) Parts List

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 A10266-3622 3.6K .5W
R701 R801 A10266-1812 180 .5W
R702 R802 A10266-3622 3.6K .5W
R703 R803 A10266-3622 3.6K .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 P10405-2
J900 C 7672-6 8 Pin MTA Header
J901 C 7873-0 2 Pin MTA Header
Tab Terminal C 7817-7 W1-W3, W100-W102

W200-W202

0 Ohm Jmp C 5868-2

22

Com-Tech 400 Amplifier Service Manual

Q42706-4 Display Module (D 7083-5 board) Parts List

Capacitors

C500 C600 C 6802-0 .47µF 50V
C901 C 6804-6 .1µF 50V

Diodes

D500 D600 C 3181-2 1N4148
D501 D601 C 3181-2 1N4148
D900 C 3533-4 1N966B 16V Zener
D901 C 3533-4 1N966B 16V Zener

LED's

E500 E600 C 7863-1 Green
E501 E601 C 4431-0 Yellow
E502 E602 C 7863-1 Green
E900 C 4342-9 Amber

Transistors

Q500 Q600 C 3625-8 2N4125
Q501 Q601 C 3625-8 2N4125
Q502 Q602 C 7458-0 2N4123
Q503 Q603 C 3625-8 2N4125

Resistors

R500 R600 A10266-1031 10K
R501 R601 A10266-2221 2.2K
R502 R602 A10266-1051 1M
R503 R603 A102662751 2.7M
R504 R604 A10266-2032 20K .5W
R505 R605 A10266-2221 2.2K
R506 R606 A10266-4751 4.7M
R507 R607 A10266-2221 2.2K
R508 R608 A10266-1021 1K
R905 A10266-5141 510K
R906 A10266-2721 2.7K
R907 A10266-5141 510K
R908 A10266-3931 39K
R909 A10266-3931 39K
R910 A10266-4741 470K
R911 A10266-3931 39K
R912 A10266-1041 100K
R913 A10266-1031 10K
R914 A10266-8211 820
R915 A10266-3931 39K
R916 A10266-3631 36K
R917 A10266-8211 820
R918 A10266-3931 39K

Integrated Circuits

U903 C 4345-2 LMT339
U904 C 7661-9 LM358N
U905 C 4345-2 LMT339

Misc.

Board D 7083-5
IC Socket C 4508-5 16 Pin
LED Spacer C 7712-0
Cable H42913-6 8 Cond 24AWG

Ribbon Cable
with Connector

23

Com-Tech 400 Amplifier Service Manual

Q42716-3 Output Module (P10233-8 or P10263-5 board) Parts List

Capacitors

C01 C 3978-1 .047µF
C02 C 2938-6 .1µF
C03 C 2938-6 .1µF
C04 C 6806-1 .01µF
C05 C 6806-1 .01µF
C06 C 6806-1 .01µF
C07 C 6807-9 .001µF
C08 C 6809-5 220pF
C09 C 6850-7 180pF

Diodes

D01 C 2851-1 1N4004
D02 C 2851-1 1N4004
D03 C 2851-1 1N4004
D04 C 2851-1 1N4004
D05 C 2851-1 1N4004
D06 C 2851-1 1N4004
D07 C 2851-1 1N4004
D08 C 2851-1 1N4004
D09 C 2851-1 1N4004
D10 C 2851-1 1N4004
D11 C 2851-1 1N4004
D12 C 2851-1 1N4004

Inductors

L00 C 6592-6 1.3µH Output Coil
L01 C 3510-2 470µH
L02 C 3510-2 470µH

Transistors

Q17 C 7271-7 NPN MPSU10
Q19 C 7318-6 PNP MPSU60

Note: Q18, S100, Driver Transistors, and Output Tran­sistors are not included with Output Module. See
Output Assembly parts list for these part numbers.

Resistors

R00 C 2626-7 470
R01 C 2872-7 100
R02 C 3299-2 5.6 .5W
R04 C 6486-2 .2 5W
R07 C 6486-2 .2 5W
R09 C 4479-9 22
R10 C 2872-7 100
R11 C 7317-8 2.7 5W
R12 C 1001-4 2.7 1W
R13 C 2626-7 470
R16 C 6486-2 .2 5W
R19 C 6486-2 .2 5W
R21 C 3299-2 5.6 .5W
R22 C 4479-9 22
R23 C 6844-2 250 Pot LS Bias
R24 C 4300-7 13K
R25 C 2628-3 2.2K
R26 C 6844-2 250 Pot HS Bias
R27 C 6495-3 390
R28 C 4300-7 13K
R30* C 6626-3* 102*

Misc.

Board P10233-8 or P10263-5
Jumpers C 5868-2 0 Ohm .25W
J500 J600 C 7057-0 10 Pin Header

*Note: R30 is 102 Ohms in most units, though in some
cases a different value may be used to match the
installed S100/S200 LM334 (C5826-0) device grade.
This is the standard value and is used with the most
common LM334 grade, green. If the LM334 is marked
with a blue dot, R30 should be a 107 Ohm resistor
(A10265-10701); if it is marked with a yellow dot then
R30 should be a 100 Ohm resistor (A10265-10001).

24

Com-Tech 400 Amplifier Service Manual

Q42888-0 Output Module (P10315-3 board) Parts List

Capacitors

C01 C 8511-5 .047µF 250V Ax
C02 C 8426-6 .1µF
C03 C 8426-6 .1µF
C04 C 6805-3 .022µF
C05 C 6805-3 .022µF
C06 C 6806-1 .01µF 100V Ax
C07 C 6807-9 .001µF 100V Ax
C08 C 6809-5 220pF
C09 C 6810-3 180pF

Diodes

D01 C 2851-1 1N4004
D02 C 2851-1 1N4004
D03 C 2851-1 1N4004
D04 C 2851-1 1N4004
D05 C 2851-1 1N4004
D06 C 2851-1 1N4004
D07 C 2851-1 1N4004
D08 C 2851-1 1N4004
D09 C 2851-1 1N4004
D10 C 2851-1 1N4004
D11 C 2851-1 1N4004
D12 C 2851-1 1N4004

Inductors

L00 C 6592-6 1.3µH Output Coil
L01 C 3510-2 470µH
L02 C 3510-2 470µH

Transistors

Q17 C 8508-1 NPN 2SC3298B
Q19 C 8509-9 PNP 2SA1306B

Note: Q18, S100, Driver Transistors, and Output Tran­sistors are not included with Output Module. See
Output Assembly parts list for part numbers.

Resistors

R00 C 2626-7 470
R01 C 2872-7 100
R02 C 7778-1 5.6 .5W Flame Proof
R04 C 6486-2 .2 5W
R07 C 6486-2 .2 5W
R09 C 7779-9 22 Flame Proof
R10 C 2872-7 100
R11 C 7317-8 2.7 5W
R12 C 1001-4 2.7 1W
R13 C 2626-7 470
R16 C 6486-2 .2 5W
R19 C 6486-2 .2 5W
R21 C 7778-1 5.6 .5W Flame Proof
R22 C 7779-9 22 Flame Proof
R23 C 6844-2 250 Pot LS Bias
R24 C 4300-7 13K
R25 C 2628-3 2.2K
R26 C 6844-2 250 Pot HS Bias
R27 C 6495-3 390
R28 C 4300-7 13K
R30* C 6626-3* 102*

Misc.

Board P10315-3
Jumpers C 5868-2 0 Ohm .25W
Clips D 6414-3 Q17/Q19 Hold Down
J500 J600 C 7057-0 10 Pin Header

*Note: R30 is 102 Ohms in most units, though in some
cases a different value may be used to match the
installed S100/S200 LM334 (C5826-0) device grade.
This is the standard value and is used with the most
common LM334 grade, green. If the LM334 is marked
with a blue dot, R30 should be a 107 Ohm resistor
(A10265-10701); if it is marked with a yellow dot then
R30 should be a 100 Ohm resistor (A10265-10001).

25

Com-Tech 400 Amplifier Service Manual

Q42969-8 Output Module (P10337-7 board) Parts List

Capacitors

C01 C 8511-5 .047µF 250V Ax
C02 C 8426-6 .1µF
C03 C 8426-6 .1µF
C04 C 6805-3 .022µF
C05 C 6805-3 .022µF
C06 C 6806-1 .01µF 100V Ax
C07 C 6807-9 .001µF 100V Ax
C08 C 6810-3 180pF
C09 C 6809-5 220pF
C10 C 7697-3 .01µF
C11 C 7697-3 .01µF
C43 C 7697-3 .01µF

Diodes

D01 C 2851-1 1N4004
D02 C 2851-1 1N4004
D03 C 2851-1 1N4004
D04 C 2851-1 1N4004
D05 C 2851-1 1N4004
D06 C 2851-1 1N4004
D07 C 2851-1 1N4004
D08 C 2851-1 1N4004
D09 C 2851-1 1N4004
D10 C 2851-1 1N4004
D11 C 2851-1 1N4004
D12 C 2851-1 1N4004

Inductors

L00 C 6592-6 1.3µH Output Coil
L01 C 3510-2 470µH
L02 C 3510-2 470µH

Transistors

Q17 C 8508-1 NPN 2SC3298B
Q19 C 8509-9 PNP 2SA1306B

Note: Q18, S100, Driver Transistors, and Output Tran­sistors are not included with the Output Module. See
Output Assembly parts list for part numbers.

Resistors

R00 A10266-4711 470
R01 A10266-1011 100
R04 C 6486-2 .2 5W
R07 C 6486-2 .2 5W
R10 A10266-1011 100
R11 A10266-2R73 2.7 1W
R12 A10266-2R73 2.7 1W
R13 A10266-4711 470
R14 A10266-2R73 2.7 1W
R16 C 6486-2 .2 5W
R19 C 6486-2 .2 5W
R23 C 6844-2 250 Pot LS Bias
R24 A10266-1331 13K
R25 A10266-2221 2.2K
R26 C 6844-2 250 Pot HS Bias
R27 A10266-3911 390
R28 A10266-1331 13K
R29 A10266-5101 51
R30* A10265-10201* 102*
R31 C 3614-2 15 .5W Flame Proof
R32 C 3614-2 15 .5W Flame Proof
R33 C 7779-9 22 .5W Flame Proof
R34 C 7779-9 22 .5W Flame Proof

Misc.

Board P10337-7
Jumpers C 5868-2 0 Ohm .25W
Clips D 6414-3 Q17/Q19 Hold Down
J500 J600 C 7057-0 10 Pin Header

*Note: R30 is 102 Ohms in most units, though in some
cases a different value may be used to match the
installed S100/S200 LM334 (C5826-0) device grade.
This is the standard value and is used with the most
common LM334 grade, green. If the LM334 is marked
with a blue dot, R30 should be a 107 Ohm resistor
(A10265-10701); if it is marked with a yellow dot then
R30 should be a 100 Ohm resistor (A10265-10001).

26

Com-Tech 400 Amplifier Service Manual

Q43188-4 Output Module (P10396-3 board) Parts List Cont.

Capacitors

C01 C 8511-5 .047µF 250V Ax
C02 C 8426-6 .1µF
C03 C 8426-6 .1µF
C04 C 6805-3 .022µF
C05 C 6805-3 .022µF
C06 C 6806-1 .01µF 100V Ax
C07 C 6807-9 .001µF 100V Ax
C08 C 6810-3 180pF
C09 C 6809-5 220pF
C43 C 7697-3 .01µF Disc

Diodes

D01 C 2851-1 1N4004
D02 C 2851-1 1N4004
D03 C 2851-1 1N4004
D04 C 2851-1 1N4004
D05 C 2851-1 1N4004
D06 C 2851-1 1N4004
D07 C 2851-1 1N4004
D08 C 2851-1 1N4004
D09 C 2851-1 1N4004
D10 C 2851-1 1N4004
D11 C 2851-1 1N4004
D12 C 2851-1 1N4004

Inductors

L00 C 6592-6 1.3µH Output Coil
L01 C 3510-2 470µH
L02 C 3510-2 470µH

Resistors

R00 A10266-4711 470
R01 A10266-1011 100
R04 C 6486-2 .2 5W
R07 C 6486-2 .2 5W
R10 A10266-1011 100
R11 A10266-2R73 2.7 1W
R12 A10266-2R73 2.7 1W
R13 A10266-4711 470
R14 A10266-2R73 2.7 1W
R16 C 6486-2 .2 5W
R19 C 6486-2 .2 5W
R23 C 6844-2 250 Pot LS Bias
R24 A10266-1331 13K
R25 A10266-2221 2.2K
R26 C 6844-2 250 Pot HS Bias
R27 A10266-3911 390
R28 A10266-1331 13K
R29 A10266-5101 51
R30* A10265-10201* 102* 1%
R31 C 3614-2 15 .5W
R32 C 3614-2 15 .5W
R33 C 7779-9 22 .5W Flame Proof
R34 C 7779-9 22 .5W Flame Proof

Misc.

Board P10396-3
Z1-Z7, Z9 C 5868-2 0 Ohm Jumper
Z8 A10124-24 Solid Wire
Clips D 6414-3 Q17/Q19 Hold Down
J500 J600 C 7057-0 10 Pin Header

Transistors

Q17 C10155-7 NPN 2SC4793
Q19 C10156-5 PNP 2SA1837

Note: Q18, S100, Driver Transistors, and Output Tran­sistors are not included with Output Module. See
Output Assembly parts list for part numbers.

*Note: R30 is 102 Ohms in most units, though in some
cases a different value may be used to match the
installed S100/S200 LM334 (C5826-0) device grade.
This is the standard value and is used with the most
common LM334 grade, green. If the LM334 is marked
with a blue dot, R30 should be a 107 Ohm resistor
(A10265-10701); if it is marked with a yellow dot then
R30 should be a 100 Ohm resistor (A10265-10001).

27

Com-Tech 400 Amplifier Service Manual

Q43012-6 Main Module (D 7911-7 board) Parts List

Capacitors

C 1 C 4303-1 1000µF
C 2 C 3913-8 470µF
C 4 C 6802-0 .47µF
C5 A10124-24 Jumper Wire
C6 A10124-24 Jumper Wire
C 7 C 6804-6 .1µF
C100 C200 C 5311-3 22µF
C101 C201 C 2821-4 10pF
C103 C203 C 6805-3 .022µF
C104 C204 C 6805-3 .022µF
C105 C205 C 6812-9 47pF
C106 C206 C 6812-9 47pF
C107 C207 C 6804-6 .1µF
C108 C208 C 6814-5 12pF
C109 C209 C 7417-6 .0033µF
C110 C210 C 5362-6 2.2µF
C111 C211 C 6804-6 .1µF
C112 C212 C 6803-8 .12µF
C113 C213 C 6802-0 .47µF
C114 C214 C 8854-9 100µF
C115 C215 C 8854-9 100µF
C116 C216 C 6802-0 .47µF
C117 C217 C 6803-8 .12µF
C118 C218 C 6814-5 12pF
C119 C219 C 6802-0 .47µF
C120 C220 C 6804-6 .1µF
C122 C222 C 6811-1 100pF
C123 C223 C 6812-9 47pF
C124 C224 C 6812-9 47pF
C129 C229 C 6814-5 12pF
C130 C230 C 6812-9 47pF
C133 C233 C 6813-7 27pF
C134 C234 C 6805-3 .022µF
C135 C235 C 6805-3 .022µF
C136 C236 C 6808-7 470pF
C137 C237 C 6808-7 470pF
C138 C238 C 6813-7 27pF
C139 C239 C 6813-7 27pF
C140 C240 C 6812-9 47pF
C141 C241 C 6812-9 47pF
C144 C244 C 8576-8 100µF
C145 C245 C 6812-9 47pF
C146 C246 C 6812-9 47pF
C147 C247 C 6806-1 .01µF
C148 C248 C 6810-3 180pF
C149 C249 C 6808-7 470pF
C150 C250 C 6806-1 .01µF
C151 C251 C 6806-1 .01µF
C152 C252 C 6950-7 82pF 5%
C153 C253 C 6804-6 .1µF
C154 C254 C 8426-6 .1µF 250V

C155 C255 C 6804-6 .1µF
C156 C256 C 6804-6 .1µF
C157 C257 C 6806-1 .01µF

Diodes

D1 C 2851-1 1N4004
D2 C 2851-1 1N4004
D3 C 2851-1 1N4004
D4 C 2851-1 1N4004
D5 C 2851-1 1N4004
D6 C 2851-1 1N4004
D7 C 2851-1 1N4004
D108 D208 C 3181-2 1N4148
D109 D209 C 3181-2 1N4148
D110 D210 C 3181-2 1N4148
D111 D211 C 5061-4 1N3070
D112 D212 C 3181-2 1N4148
D113 D213 C 3181-2 1N4148
D114 D214 OPEN
D115 D215 OPEN
D120 D220 C 3181-2 1N4148
D121 D221 C 3181-2 1N4148
D122 D222 C 3181-2 1N4148
D123 D223 C 5061-4 1N3070
D124 D224 C 3181-2 1N4148
D125 D225 C 3181-2 1N4148
D126 D226 C 5061-4 1N3070
D127 D227 C 5061-4 1N3070
D128 D228 C 5061-4 1N3070
D129 D229 C 3181-2 1N4148
D130 D230 C 3181-2 1N4148
D131 D231 C 3181-2 1N4148
D132 D232 C 3181-2 1N4148

Transistors

Q100 Q200 D 2961-7 NPN 2N3859A
Q101 Q201 C 3578-9 PNP MPSA93
Q102 Q202 C 3810-6 NPN MPSA43
Q103 Q203 C 3786-8 PNP PN4250
Q105 Q205 C 3578-9 PNP MPSA93
Q106 Q206 C 3625-8 NPN 2N4125
Q107 Q207 C 3786-8 PNP PN4250
Q108 Q208 C 5891-4 NPN MTS105
Q109 Q209 D 2961-7 NPN 2N3859A
Q110 Q210 C 3810-6 NPN MPSA43
Q112 Q212 C 3625-8 NPN 2N4125
Q113 Q213 C 3625-8 NPN 2N4125
Q115 Q215 D 2962-5 NPN MPS8097
Q116 Q216 C 3786-8 PNP PN4250
Q117 Q217 D 2961-7 NPN 2N3859A
Q118 Q218 D 2961-7 NPN 2N3859A
Q119 Q219 C 3625-8 NPN 2N4125

28

Com-Tech 400 Amplifier Service Manual

Q43012-6 Main Module (D 7911-7 board) Parts List

Q120 Q220 C 3625-8 NPN 2N4125
Q121 Q221 C 7458-0 NPN 2N4123
Q122 Q222 C 7458-0 NPN 2N4123
Q123 Q223 C 7458-0 NPN 2N4123
Q124 Q224 C 3625-8 NPN 2N4125

Resistors (.25W 5% unless noted otherwise)

N100 N200 D 4669-4 Resistor Network
N101 N201 D 6081-0 Resistor Network
N102 N202 D 6082-8 Resistor Network
R1 A10265-53621 53.6K 1%
R2 OPEN
R3 OPEN
R4 A10265-46421 46.4K 1%
R7 A10266-1041 100K
R8 A10266-2031 20K
R9 A10266-5121 5.1K
R10 OPEN
R16 A10266-5121 5.1K
R17 A10266-2031 20K
R18 A10266-1041 100K
R100 R200 C 7409-3 5K Linear Pot
R101 R201 A10265-49911 4.99K 1%
R102 R202 A10266-5111 510
R103 R203 A10265-10031 100K 1%
R104 R204 A10266-2721 2.7K
R105 R205 A10266-2721 2.7K
R106 R206 A10266-1231 12K
R107 R207 A10266-6831 68K
R108 R208 A10266-8211 820
R109 R209 A10266-6801 68
R110 R210 A10266-6831 68K
R111 R211 A10266-1231 12K
R112 R212 A10266-5131 51K
R113 R213 A10266-4721 4.7K
R114 R214 A10266-4721 4.7K
R115 R215 A10266-5141 510K
R116 R216 A10266-2751 2.7M
R117 R217 A10266-4731 47K
R118 R218 A10266-2711 270
R119 R219 A10266-5111 510
R120 R220 A10266-2711 270
R121 R221 C 5062-2 100K Pot (-ODEP)
R122 R222 A10266-2741 270K
R123 R223 A10266-2032 20K .5W
R124 R224 A10266-6821 6.8K
R125 R225 C 7782-3 100 Flame Proof
R126 R226 C 7782-3 100 Flame Proof
R127 R227 A10266-6821 6.8K
R128 R228 A10266-1031 10K
R129 R229 A10266-1041 100K
R130 R230 A10266-1041 100K

R131 R231 A10266-1031 10K
R132 R232 C 5062-2 100K Pot (+ODEP)
R133 R233 A10266-2741 270K
R134 R234 A10266-2032 20K .5W
R135 R235 C 7782-3 100 Flame Proof
R136 R236 A10266-6821 6.8K
R137 R237 C 7782-3 100 Flame Proof
R138 R238 A10266-6821 6.8K
R139 R239 A10266-8211 820
R140 R240 A10266-6801 68
R141 R241 A10266-1541 150K
R142 R242 A10266-1541 150K
R143 R243 A10266-1041 100K
R144 R244 A10266-1041 100K
R145 R245 A10266-1851 1.8M
R146 R246 A10266-1031 10K
R147 R247 C 7781-5 200 .5W FP
R148 R248 A10266-2721 2.7K
R149 R249 C 7781-5 200 .5W FP
R150 R250 A10266-2721 2.7K
R151 R251 A10266-1031 10K
R152 R252 A10266-1231 12K
R153 R253 JUMPER A10124-24
R154 R254 A10265-12131 121K 1%
R155 R255 A10266-1321 1.3K
R156 R256 A10266-1321 1.3K
R157 R257 A10266-1321 1.3K
R158 R258 A10266-9121 9.1K
R159 R259 A10266-1021 1K
R160 R260 A10266-10021 10K 1%
R161 R261 A10266-4701 47
R162 R262 A10266-4701 47
R163 R263 A10265-12131 121K 1%
R164 R264 A10265-10021 10K 1%
R165 R265 A10265-12131 121K 1%
R166 R266 A10266-1851 1.8M
R167 R267 A10265-10011 1K 1%
R168 R268 A10265-95301 953 1%
R170 R270 A10265-10011 1K 1%
R171 R271 A10265-95301 953 1%
R173 R273 A10265-10021 10K 1%
R174 R274 A10265-24921 24.9K 1%
R175 R275 A10265-15821 15.8K 1%
R176 R276 A10265-24921 24.9K 1%
R177 R277 A10265-69811 6.98K 1%
R179 R279 A10266-1321 1.3K
R180 R280 A10266-4711 470
R181 R281 A10266-4721 4.7K
R182 R282 A10266-2201 22
R183 R283 A10266-2421 2.4K
R184 R284 A10266-4741 470K
R185 R285 A10266-2421 2.4K

29

Com-Tech 400 Amplifier Service Manual

Q43012-6 Main Module (D 7911-7 board) Parts List

R186 R286 A10266-2751 2.7M
R187 R287 A10266-3631 36K
R188 R288 A10266-3631 36K
R189 R289 A10266-2731 27K
R190 R290 A10266-2051 2M
R191 R291 A10266-3331 33K
R192 R292 A10266-1031 10K
R193 R293 A10266-1031 10K
R194 R294 A10266-1041 100K
R195 R295 A10266-3021 3K
R196 R296 A10266-4721 4.7K
R197 R297 A10266-1031 10K
R198 R298 A10266-4721 4.7K
R199 R299 A10266-1031 10K
R906 R1006 OPEN
R907 R1007 OPEN
R908 R1008 OPEN
R909 R1009 A10266-4741 470K
R910 R1010 A10266-4741 470K
R911 R1011 A10266-1521 1.5K
R912 R1012 A10266-4711 470
R913 R1013 A10266-1051 1M
R914 R1014 A10266-1051 1M
R915 R1015 A10266-2201 22
R916 R1016 A10266-2201 22

IC’s

U1 C 5095-2 UA7815
U2 C 5096-0 UA7915
U100 U200 C 6911-9 UPA75
U101 U201 C 4345-2 LM339
U102 U202 C 4345-2 LM339
U103 U203 C 6910-1 UPA76
U104 U204 C 7558-7 MC33079P

Misc.

Board D 7993-5
Socket C 3450-1 14 Pin (Qty 6)
N ut A10102-5 Hex 6-32 (Qty 2)
Heatsink C 5341-0 TO-220 (Qty 2)
Torq Spreader C 6541-4 (Qty 2)
Washer A10096-5 #6, Split (Qty 2)
Screw A10240-0608 Stainless (Qty 2)
J1 C 7593-4 5 Pin Header
J2 C 4508-5 16 Pin Socket
J3 C 7526-4 3 Pin Header
J100 J200 OPEN
J500 J800 D 6619-7 10 Inch Ribbon
J600 J700 D 6620-5 6 Inch Ribbon
Cable Tie C 1811-6 (Qty 4)

Switches

S2 OPEN
S3 C 7960-5 Sensitivity
S4 C 6781-6 Switch, St/Mono

30

Com-Tech 400 Amplifier Service Manual

Q43043-1 Main Module (D 7993-5 board) Parts List

Capacitors

C 1 C 4303-1 1000µF
C 2 C 3913-8 470µF
C 4 C 6802-0 .47µF
C5 A10124-24 Jumper Wire
C6 A10124-24 Jumper Wire
C 7 C 8897-8 .1µF
C100 C200 C 5311-3 22µF
C101 C201 C 2821-4 10pF
C103 C203 C 6805-3 .022µF
C104 C204 C 6805-3 .022µF
C105 C205 C 6812-9 47pF
C106 C206 C 6812-9 47pF
C107 C207 C 8897-8 .1µF
C108 C208 C 6814-5 12pF
C109 C209 C 7417-6 .0033µF
C110 C210 C 5362-6 2.2µF
C111 C211 C 8897-8 .1µF
C112 C212 C 8991-9 .47µF
C113 C213 C 8987-7 22µF
C114 C214 C 8854-9 100µF
C115 C215 C 8854-9 100µF
C116 C216 C 8987-7 22µF
C117 C217 C 8991-9 .47µF
C118 C218 C 6814-5 12pF
C119 C219 C 6802-0 .47µF
C120 C220 C 8897-8 .1µF
C122 C222 C 6811-1 100pF
C123 C223 C 6812-9 47pF
C124 C224 C 6812-9 47pF
C129 C229 C 6814-5 12pF
C130 C230 C 6812-9 47pF
C133 C233 C 6813-7 27pF
C134 C234 C 6805-3 .022µF
C135 C235 C 6805-3 .022µF
C136 C236 C 6808-7 470pF
C137 C237 C 6808-7 470pF
C138 C238 C 6813-7 27pF
C139 C239 C 6813-7 27pF
C140 C240 C 6812-9 47pF
C141 C241 C 6812-9 47pF
C144 C244 C 8576-8 100µF
C145 C245 C 6812-9 47pF
C146 C246 C 6812-9 47pF
C147 C247 C 6806-1 .01µF
C148 C248 C 6810-3 180pF
C149 C249 C 6808-7 470pF
C150 C250 C 6806-1 .01µF
C151 C251 C 6806-1 .01µF
C152 C252 C 6950-7 82pF 5%
C153 C253 C 8897-8 .1µF
C154 C254 C 8426-6 .1µF 250V

C155 C255 C 8897-8 .1µF
C156 C256 C 8897-8 .1µF
C157 C257 C 6806-1 .01µF

Diodes

D1 C 2851-1 1N4004
D2 C 2851-1 1N4004
D3 C 2851-1 1N4004
D4 C 2851-1 1N4004
D5 C 2851-1 1N4004
D6 C 2851-1 1N4004
D7 C 2851-1 1N4004
D108 D208 C 3181-2 1N4148
D109 D209 C 3181-2 1N4148
D110 D210 C 3181-2 1N4148
D111 D211 C 5061-4 1N3070
D112 D212 C 3181-2 1N4148
D113 D213 C 3181-2 1N4148
D114 D214 OPEN
D115 D215 OPEN
D120 D220 C 3181-2 1N4148
D121 D221 C 3181-2 1N4148
D122 D222 C 3181-2 1N4148
D123 D223 C 5061-4 1N3070
D124 D224 C 3181-2 1N4148
D125 D225 C 3181-2 1N4148
D126 D226 C 5061-4 1N3070
D127 D227 C 5061-4 1N3070
D128 D228 C 5061-4 1N3070
D129 D229 C 3181-2 1N4148
D130 D230 C 3181-2 1N4148
D131 D231 C 3181-2 1N4148
D132 D232 C 3181-2 1N4148

Transistors

Q100 Q200 D 2961-7 NPN 2N3859A
Q101 Q201 C 3578-9 PNP MPSA93
Q102 Q202 C 3810-6 NPN MPSA43
Q103 Q203 C 3786-8 PNP PN4250
Q105 Q205 C 3578-9 PNP MPSA93
Q106 Q206 C 3625-8 NPN 2N4125
Q107 Q207 C 3786-8 PNP PN4250
Q108 Q208 C 5891-4 NPN MTS105
Q109 Q209 D 2961-7 NPN 2N3859A
Q110 Q210 C 3810-6 NPN MPSA43
Q112 Q212 C 3625-8 NPN 2N4125
Q113 Q213 C 3625-8 NPN 2N4125
Q115 Q215 D 2962-5 NPN MPS8097
Q116 Q216 C 3786-8 PNP PN4250
Q117 Q217 D 2961-7 NPN 2N3859A
Q118 Q218 D 2961-7 NPN 2N3859A
Q119 Q219 C 3625-8 NPN 2N4125

31

Com-Tech 400 Amplifier Service Manual

Q43043-1 Main Module (D 7993-5 board) Parts List

Q120 Q220 C 3625-8 NPN 2N4125
Q121 Q221 C 7458-0 NPN 2N4123
Q122 Q222 C 7458-0 NPN 2N4123
Q123 Q223 C 7458-0 NPN 2N4123
Q124 Q224 C 3625-8 NPN 2N4125

Resistors (.25W 5% unless noted otherwise)

N101 N201 D 7945-5 Resistor Network
N102 N202 D 6082-8 Resistor Network
R1 A10265-53621 53.6K 1%
R2 OPEN
R3 OPEN
R4 A10265-46421 46.4K 1%
R7 A10266-1041 100K
R8 A10266-2031 20K
R9 A10266-5121 5.1K
R10 OPEN
R16 A10266-5121 5.1K
R17 A10266-2031 20K
R18 A10266-1041 100K
R100 R200 C 7409-3 5K Linear Pot
R101 R201 A10265-49911 4.99K 1%
R102 R202 A10266-5111 510
R103 R203 A10265-10031 100K 1%
R104 R204 A10266-2721 2.7K
R105 R205 A10266-2721 2.7K
R106 R206 A10266-1231 12K
R107 R207 A10266-6831 68K
R108 R208 A10266-8211 820
R109 R209 A10266-6801 68
R110 R210 A10266-6831 68K
R111 R211 A10266-1231 12K
R112 R212 A10266-5131 51K
R113 R213 A10266-4721 4.7K
R114 R214 A10266-4721 4.7K
R115 R215 A10266-5141 510K
R116 R216 A10266-2751 2.7M
R117 R217 A10266-4731 47K
R118 R218 A10266-2711 270
R119 R219 A10266-5111 510
R120 R220 A10266-2711 270
R121 R221 C 5062-2 100K Pot (-ODEP)
R122 R222 A10266-2741 270K
R123 R223 A10266-2032 20K .5W
R124 R224 A10266-6821 6.8K
R125 R225 C 7782-3 100 Flame Proof
R126 R226 C 7782-3 100 Flame Proof
R127 R227 A10266-6821 6.8K
R128 R228 A10266-1031 10K
R129 R229 A10266-1041 100K
R130 R230 A10266-1041 100K
R131 R231 A10266-1031 10K

R132 R232 C 5062-2 100K Pot (+ODEP)
R133 R233 A10266-2741 270K
R134 R234 A10266-2032 20K .5W
R135 R235 C 7782-3 100 Flame Proof
R136 R236 A10266-6821 6.8K
R137 R237 C 7782-3 100 Flame Proof
R138 R238 A10266-6821 6.8K
R139 R239 A10266-8211 820
R140 R240 A10266-6801 68
R141 R241 A10266-1541 150K
R142 R242 A10266-1541 150K
R143 R243 A10266-1041 100K
R144 R244 A10266-1041 100K
R145 R245 A10266-1851 1.8M
R146 R246 A10266-1031 10K
R147 R247 C 7781-5 200 .5W FP
R148 R248 A10266-2721 2.7K
R149 R249 C 7781-5 200 .5W FP
R150 R250 A10266-2721 2.7K
R151 R251 A10266-1031 10K
R152 R252 A10265-11821 11.8K 1%
R153 R253 JUMPER A10124-24
R154 R254 C 8261-7 121K 0.1%
R155 R255 A10266-1321 1.3K
R156 R256 A10266-1321 1.3K
R157 R257 A10266-1321 1.3K
R158 R258 A10265-11321 11.3K 1%
R159 R259 A10266-1021 1K
R160 R260 C 8260-9 10K 0.1%
R161 R261 A10266-4701 47
R162 R262 A10266-4701 47
R163 R263 C 8261-7 121K 0.1%
R164 R264 C 8260-9 10K 0.1%
R165 R265 C 8261-7 121K 0.1%
R166 R266 A10266-1851 1.8M
R167 R267 A10265-10011 1K 1%
R168 R268 A10265-97601 976 1%
R170 R270 A10265-10011 1K 1%
R171 R271 A10265-95301 953 1%
R173 R273 C 8260-9 10K 0.1%
R174 R274 A10265-24921 24.9K 1%
R175 R275 A10265-15821 15.8K 1%
R176 R276 A10265-24921 24.9K 1%
R177 R277 A10265-69811 6.98K 1%
R179 R279 A10266-1321 1.3K
R180 R280 A10266-4711 470
R181 R281 A10266-4721 4.7K
R182 R282 A10266-2201 22
R183 R283 A10266-2421 2.4K
R184 R284 A10266-4741 470K
R185 R285 A10266-2421 2.4K
R186 R286 A10266-2751 2.7M

32

Com-Tech 400 Amplifier Service Manual

Q43043-1 Main Module (D 7993-5 board) Parts List

R187 R287 A10266-3631 36K
R188 R288 A10266-3631 36K
R189 R289 A10266-2731 27K
R190 R290 A10266-2051 2M
R191 R291 A10266-3331 33K
R192 R292 A10266-1031 10K
R193 R293 A10266-1031 10K
R194 R294 A10266-1041 100K
R195 R295 A10266-3021 3K
R196 R296 A10266-4721 4.7K
R197 R297 A10266-1031 10K
R198 R298 A10266-4721 4.7K
R199 R299 A10266-1031 10K
R906 R1006 OPEN
R907 R1007 OPEN
R908 R1008 OPEN
R909 R1009 A10266-4741 470K
R910 R1010 A10266-4741 470K
R911 R1011 A10266-1521 1.5K
R912 R1012 A10266-4711 470
R913 R1013 A10266-1051 1M
R914 R1014 A10266-1051 1M
R915 R1015 A10266-2201 22
R916 R1016 A10266-2201 22
R917 R1017 A10265-10021 10K 1%
R918 R1018 A10265-10021 10K 1%
R919 R1019 A10265-10021 10K 1%
R920 R1020 A10265-10021 10K 1%
R921 R1021 C 9079-2 200 Pot (CMR Null)

IC’s

U1 C 5095-2 UA7815
U2 C 5096-0 UA7915
U100 U200 C 6911-9 UPA75
U101 U201 C 4345-2 LM339
U102 U202 C 4345-2 LM339
U103 U203 C 6910-1 UPA76
U104 U204 C 7558-7 MC33079P

Misc.

Board D 7993-5
Socket C 3450-1 14 Pin (Qty 6)
N ut A10102-5 Hex 6-32 (Qty 2)
Heatsink C 5341-0 TO-220 (Qty 2)
Torq Spreader C 6541-4 (Qty 2)
Washer A10096-5 #6, Split (Qty 2)
Screw A10240-0608 Stainless (Qty 2)
J1 C 7593-4 5 Pin Header
J2 C 4508-5 16 Pin Socket
J11 C 7526-4 3 Pin Header
J100 J200 OPEN
J500 J800 D 6619-7 10 Inch Ribbon
J600 J700 D 6620-5 6 Inch Ribbon
Cable Tie C 1811-6 (Qty 4)

Switches

S2 OPEN
S3 C 7960-5 Sensitivity
S4 C 6781-6 Switch, St/Mono

33

Com-Tech 400 Amplifier Service Manual

Q43129-8 Main Module (D8283-0 board) Parts List

Capacitors

C 1 C 4303-1 1000µF
C 2 C 3913-8 470µF
C 4 C 6802-0 .47µF
C5 A10124-24 Jumper Wire
C6 A10124-24 Jumper Wire
C 7 C 8897-8 .1µF
C100 C200 C 5311-3 22µF
C101 C201 C 9464-6 10pF
C103 C203 C 6805-3 .022µF
C104 C204 C 6805-3 .022µF
C105 C205 C 6812-9 47pF
C106 C206 C 6812-9 47pF
C107 C207 C 8897-8 .1µF
C108 C208 C 6814-5 12pF
C109 C209 C 7417-6 .0033µF
C110 C210 C 5362-6 2.2µF
C111 C211 C 8897-8 .1µF
C112 C212 C 8991-9 .47µF
C113 C213 C 8987-7 22µF
C114 C214 C 8854-9 100µF
C115 C215 C 8854-9 100µF
C116 C216 C 8987-7 22µF
C117 C217 C 8991-9 .47µF
C118 C218 C 6814-5 12pF
C119 C219 C 6802-0 .47µF
C120 C220 C 8897-8 .1µF
C122 C222 C 6811-1 100pF
C123 C223 C 6812-9 47pF
C124 C224 C 6812-9 47pF
C129 C229 C 6814-5 12pF
C130 C230 C 6812-9 47pF
C133 C233 C 6813-7 27pF
C134 C234 C 6805-3 .022µF
C135 C235 C 6805-3 .022µF
C136 C236 C 6808-7 470pF
C137 C237 C 6808-7 470pF
C138 C238 C 6813-7 27pF
C139 C239 C 6813-7 27pF
C140 C240 C 6812-9 47pF
C141 C241 C 6812-9 47pF
C144 C244 C 8576-8 100µF
C145 C245 C 6812-9 47pF
C146 C246 C 6812-9 47pF
C147 C247 C 6806-1 .01µF
C148 C248 C 6810-3 180pF
C149 C249 C 6808-7 470pF
C150 C250 C 6806-1 .01µF
C151 C251 C 6806-1 .01µF
C152 C252 C 6950-7 82pF 5%
C153 C253 C 8897-8 .1µF
C154 C254 C 8426-6 .1µF 250V

C155 C255 C 8897-8 .1µF
C156 C256 C 8897-8 .1µF
C157 C257 C 6806-1 .01µF
C158 C258 C 6805-3 .022µF
C159 C259 C 6805-3 .022µF
C160 C260 C 6811-1 100pF
C161 C261 C 6811-1 100pF

Diodes

D1 C 2851-1 1N4004
D2 C 2851-1 1N4004
D3 C 2851-1 1N4004
D4 C 2851-1 1N4004
D5 C 2851-1 1N4004
D6 C 2851-1 1N4004
D7 C 2851-1 1N4004
D108 D208 C 3181-2 1N4148
D109 D209 C 3181-2 1N4148
D110 D210 C 3181-2 1N4148
D111 D211 C 5061-4 1N3070
D112 D212 C 3181-2 1N4148
D113 D213 C 3181-2 1N4148
D114 D214 C 3181-2 1N4148
D115 D215 C 3181-2 1N4148
D120 D220 C 3181-2 1N4148
D121 D221 C 3181-2 1N4148
D122 D222 C 3181-2 1N4148
D123 D223 C 5061-4 1N3070
D124 D224 C 3181-2 1N4148
D125 D225 C 3181-2 1N4148
D126 D226 C 5061-4 1N3070
D127 D227 C 5061-4 1N3070
D128 D228 C 5061-4 1N3070
D129 D229 C 3181-2 1N4148
D130 D230 C 3181-2 1N4148
D131 D231 C 3181-2 1N4148
D132 D232 C 3181-2 1N4148
D133 D233 C 3181-2 1N4148
D134 D234 C 3181-2 1N4148

Transistors

Q100 Q200 D 2961-7 NPN 2N3859A
Q101 Q201 C 3578-9 PNP MPSA93
Q102 Q202 C 3810-6 NPN MPSA43
Q103 Q203 C 3786-8 PNP PN4250
Q105 Q205 C 3578-9 PNP MPSA93
Q106 Q206 C 3625-8 NPN 2N4125
Q107 Q207 C 3786-8 PNP PN4250
Q108 Q208 C 5891-4 NPN MTS105
Q109 Q209 D 2961-7 NPN 2N3859A
Q110 Q210 C 3810-6 NPN MPSA43
Q112 Q212 C 3625-8 NPN 2N4125

34

Com-Tech 400 Amplifier Service Manual

Q43129-8 Main Module (D8283-0 board) Parts List

Q113 Q213 C 3625-8 NPN 2N4125
Q115 Q215 D 2962-5 NPN MPS8097
Q116 Q216 C 3786-8 PNP PN4250
Q117 Q217 D 2961-7 NPN 2N3859A
Q118 Q218 D 2961-7 NPN 2N3859A
Q119 Q219 C 3625-8 NPN 2N4125
Q120 Q220 C 3625-8 NPN 2N4125
Q121 Q221 C 7458-0 NPN 2N4123
Q122 Q222 C 7458-0 NPN 2N4123
Q123 Q223 C 7458-0 NPN 2N4123
Q124 Q224 C 3625-8 NPN 2N4125
Q125 Q225 C 3786-8 PNP PN4250A
Q126 Q226 C 5891-4 NPN MTS105

Resistors

R1 A10265-53621 53.6K 1%
R2 OPEN
R3 OPEN
R4 A10265-46421 46.4K 1%
R7 A10266-1041 100K
R8 A10266-2031 20K
R9 A10266-5121 5.1K
R10 OPEN
R16 A10266-5121 5.1K
R17 A10266-2031 20K
R18 A10266-1041 100K
R100 R200 C 7409-3 5K Linear Pot
R101 R201 A10265-49911 4.99K 1%
R102 R202 A10266-5111 510
R103 R203 A10265-10031 100K 1%
R104 R204 A10266-2721 2.7K
R105 R205 A10266-2721 2.7K
R106 R206 A10266-1231 12K
R107 R207 A10266-6831 68K
R108 R208 A10266-8211 820
R109 R209 A10266-5601 56
R110 R210 A10266-6831 68K
R111 R211 A10266-1231 12K
R112 R212 A10266-5131 51K
R113 R213 A10266-4721 4.7K
R114 R214 A10266-4721 4.7K
R115 R215 A10266-5141 510K
R116 R216 A10266-2751 2.7M
R117 R217 A10266-4731 47K
R118 R218 A10265-27401 274 1%
R119 R219 A10265-66501 665 1%
R120 R220 A10265-28701 287 1%
R121 R221 C 5062-2 100K Pot (-ODEP)
R122 R222 A10266-2741 270K
R123 R223 A10266-2032 20K .5W
R124 R224 A10266-6821 6.8K
R125 R225 C 7782-3 100 Flame Proof

R126 R226 C 7782-3 100 Flame Proof
R127 R227 A10266-6821 6.8K
R128 R228 A10266-1331 13K
R129 R229 A10266-1041 100K
R130 R230 A10266-1041 100K
R131 R231 A10266-1331 13K
R132 R232 C 5062-2 100K Pot (+ODEP)
R133 R233 A10266-2741 270K
R134 R234 A10266-2032 20K .5W
R135 R235 C 7782-3 100 Flame Proof
R136 R236 A10266-6821 6.8K
R137 R237 C 7782-3 100 Flame Proof
R138 R238 A10266-6821 6.8K
R139 R239 A10266-8211 820
R140 R240 A10266-5601 56
R141 R241 A10266-1541 150K
R142 R242 A10266-1541 150K
R143 R243 A10266-1041 100K
R144 R244 A10266-1041 100K
R145 R245 A10266-2251 2.2M
R146 R246 A10266-1031 10K
R147 R247 C 7781-5 200 .5W FP
R148 R248 A10266-2721 2.7K
R149 R249 C 7781-5 200 .5W FP
R150 R250 A10266-2721 2.7K
R151 R251 A10266-1031 10K
R152 R252 A10265-11821 11.8K 1%
R153 R253 JUMPER A10124-24
R154 R254 C 8261-7 121K 0.1%
R155 R255 A10266-1321 1.3K
R156 R256 A10266-1321 1.3K
R157 R257 A10266-1321 1.3K
R158 R258 A10265-11521 11.5K 1%
R159 R259 A10266-1021 1K
R160 R260 C 8260-9 10K 0.1%
R161 R261 A10266-4701 47
R162 R262 A10266-4701 47
R163 R263 C 8261-7 121K 0.1%
R164 R264 C 8260-9 10K 0.1%
R165 R265 C 8261-7 121K 0.1%
R166 R266 A10266-2251 2.2M
R167 R267 A10265-10011 1K 1%
R168 R268 A10265-10011 1K 1%
R170 R270 A10265-10011 1K 1%
R171 R271 A10265-10011 1K 1%
R173 R273 C 8260-9 10K 0.1%
R174 R274 A10265-24921 24.9K 1%
R175 R275 A10265-15821 15.8K 1%
R176 R276 A10265-24921 24.9K 1%
R177 R277 A10265-69811 6.98K 1%
R179 R279 A10266-1321 1.3K
R180 R280 A10266-4711 470

35

Com-Tech 400 Amplifier Service Manual

Q43129-8 Main Module (D8283-0 board) Parts List

R181 R281 A10266-4721 4.7K
R182 R282 A10266-2201 22
R183 R283 A10266-2421 2.4K
R184 R284 A10266-4741 470K
R185 R285 A10266-2421 2.4K
R186 R286 A10266-2751 2.7M
R187 R287 A10266-3631 36K
R188 R288 A10266-3631 36K
R189 R289 A10266-2731 27K
R190 R290 A10266-2051 2M
R191 R291 A10266-3331 33K
R192 R292 A10266-1031 10K
R193 R293 A10266-1031 10K
R194 R294 A10266-1041 100K
R195 R295 A10266-3021 3K
R196 R296 A10266-4721 4.7K
R197 R297 A10266-1031 10K
R198 R298 A10266-4721 4.7K
R199 R299 A10266-1031 10K
R906 R1006 OPEN
R907 R1007 OPEN
R908 R1008 OPEN
R909 R1009 A10266-4741 470K
R910 R1010 A10266-4741 470K
R911 R1011 A10266-1521 1.5K
R912 R1012 A10266-4711 470
R913 R1013 A10266-1051 1M
R914 R1014 A10266-1051 1M
R915 R1015 A10266-2201 22
R916 R1016 A10266-2201 22
R917 R1017 A10265-10021 10K 1%
R918 R1018 A10265-10021 10K 1%
R919 R1019 A10265-10021 10K 1%
R920 R1020 A10265-10021 10K 1%
R921 R1021 C 9079-2 200 Pot (CMR Null)
R922 R1022 A10265-66501 665 1%
R923 R1023 A10265-35711 3.57K 1%
R924 R1024 A10265-66501 665 1%
R925 R1025 A10265-10031 100K 1%
R926 R1026 A10265-66501 665 1%
R927 R1027 A10265-10031 100K 1%
R928 R1028 A10265-35711 3.57K 1%
R929 R1029 A10266-7531 75K
R930 R1030 A10266-7531 75K

Resistor Networks

N101 N201 D 7945-5 Resistor Network
N102 N202 D 6082-8 Resistor Network

Switches

S2 OPEN
S3 C 7960-5 Sensitivity
S4 C 6781-6 Switch, St/Mono

Integrated Circuits

U1 C 5095-2 UA7815
U2 C 5096-0 UA7915
U100 U200 C 6911-9 UPA75
U101 U201 C 4345-2 LM339
U102 U202 C 4345-2 LM339
U103 U203 C 6910-1 UPA76
U104 U204 C 7558-7 MC33079P

Miscellaneous

Board D 8283-0
Socket C 3450-1 14 Pin (Qty 6)
N ut A10102-5 Hex 6-32 (Qty 2)
Heatsink C 5341-0 TO-220 (Qty 2)
Torque Spdr C 6541-4 (Qty 2)
Washer A10096-5 #6, Split (Qty 2)
Screw A10240-0608 Stainless (Qty 2)
J1 C 7593-4 5 Pin Header
J2 C 4508-5 16 Pin Socket
J11 C 7526-4 3 Pin Header
J100 J200 OPEN
J500 J800 D 6619-7 10 Inch Ribbon
J600 J700 D 6620-5 6 Inch Ribbon
Cable Tie C 1811-6 (Qty 4)
TP 1 C 9450-5 Hdr, 6 pin RT Angle
Spacer C 9225-1 Plastic Spcr (Qty 5)

36

Com-Tech 400 Amplifier Service Manual

Q43238-7 Main Module (D 8369-7 board) Parts List

Capacitors

C1 C 9859-7 1000µF
C2 C 9859-7 1000µF
C4 C 6802-0 .47µF
C5 A10124-24 Jumper Wire
C6 A10124-24 Jumper Wire
C7 C 8897-8 .1µF
C100 C200 C 5311-3 22µF
C101 C201 C 9464-6 10pF
C103 C203 C 6805-3 .022µF
C104 C204 C 6805-3 .022µF
C105 C205 C 6812-9 47pF
C106 C206 C 6812-9 47pF
C107 C207 C 8897-8 .1µF
C108 C208 C 6814-5 12pF
C109 C209 C 7417-6 .0033µF
C110 C210 C 5362-6 2.2µF
C111 C211 C 8897-8 .1µF
C112 C212 C 8991-9 .47µF
C113 C213 C 8987-7 22µF
C114 C214 C 8854-9 100µF
C115 C215 C 8854-9 100µF
C116 C216 C 8987-7 22µF
C117 C217 C 8991-9 .47µF
C118 C218 C 6814-5 12pF
C119 C219 C 6802-0 .47µF
C120 C220 C 8897-8 .1µF
C122 C222 C 6811-1 100pF
C123 C223 C 6812-9 47pF
C124 C224 C 6812-9 47pF
C129 C229 C 6814-5 12pF
C130 C230 C 6812-9 47pF
C133 C233 C 6813-7 27pF
C134 C234 C 6805-3 .022µF
C135 C235 C 6805-3 .022µF
C136 C236 C 6808-7 470pF
C137 C237 C 6808-7 470pF
C138 C238 C 6813-7 27pF
C139 C239 C 6813-7 27pF
C140 C240 C 6812-9 47pF
C141 C241 C 6812-9 47pF
C144 C244 C 8576-8 100µF
C145 C245 C 6812-9 47pF
C146 C246 C 6812-9 47pF
C147 C247 C 6806-1 .01µF
C148 C248 C 6810-3 180pF
C149 C249 C 6808-7 470pF
C150 C250 C 6806-1 .01µF
C151 C251 C 6806-1 .01µF
C152 C252 C 6950-7 82pF 5%
C153 C253 C 8897-8 .1µF
C154 C254 A10434-104JD .1µF 250V

C155 C255 C 8897-8 .1µF
C156 C256 C 8897-8 .1µF
C157 C257 C 6806-1 .01µF
C158 C258 C 6805-3 .022µF
C159 C259 C 6805-3 .022µF
C160 C260 C 6811-1 100pF
C161 C261 C 6811-1 100pF

Diodes

D1 C 2851-1 1N4004
D2 C 2851-1 1N4004
D3 C 2851-1 1N4004
D4 C 2851-1 1N4004
D5 C 2851-1 1N4004
D6 C 2851-1 1N4004
D7 C 2851-1 1N4004
D108 D208 C 3181-2 1N4148
D109 D209 C 3181-2 1N4148
D110 D210 C 3181-2 1N4148
D111 D211 C 5061-4 1N3070
D112 D212 C 3181-2 1N4148
D113 D213 C 3181-2 1N4148
D114 D214 C 3181-2 1N4148
D115 D215 C 3181-2 1N4148
D120 D220 C 3181-2 1N4148
D121 D221 C 3181-2 1N4148
D122 D222 C 3181-2 1N4148
D123 D223 C 5061-4 1N3070
D124 D224 C 3181-2 1N4148
D125 D225 C 3181-2 1N4148
D126 D226 C 5061-4 1N3070
D127 D227 C 5061-4 1N3070
D128 D228 C 5061-4 1N3070
D129 D229 C 3181-2 1N4148
D130 D230 C 3181-2 1N4148
D131 D231 C 3181-2 1N4148
D132 D232 C 3181-2 1N4148
D133 D233 C 3181-2 1N4148
D134 D234 C 3181-2 1N4148

Transistors

Q100 Q200 D 2961-7 NPN 2N3859A
Q101 Q201 C 3578-9 PNP MPSA93
Q102 Q202 C 3810-6 NPN MPSA43
Q103 Q203 C 3786-8 PNP PN4250
Q105 Q205 C 3578-9 PNP MPSA93
Q106 Q206 C 3625-8 NPN 2N4125
Q107 Q207 C 3786-8 PNP PN4250
Q108 Q208 C 5891-4 NPN MTS105
Q109 Q209 D 2961-7 NPN 2N3859A
Q110 Q210 C 3810-6 NPN MPSA43
Q112 Q212 C 3625-8 NPN 2N4125

37

Com-Tech 400 Amplifier Service Manual

Q43238-7 Main Module (D 8369-7 board) Parts List

Q113 Q213 C 3625-8 NPN 2N4125
Q115 Q215 D 2962-5 NPN MPS8097
Q116 Q216 C 3786-8 PNP PN4250
Q117 Q217 D 2961-7 NPN 2N3859A
Q118 Q218 D 2961-7 NPN 2N3859A
Q119 Q219 C 3625-8 NPN 2N4125
Q120 Q220 C 3625-8 NPN 2N4125
Q121 Q221 C 7458-0 NPN 2N4123
Q122 Q222 C 7458-0 NPN 2N4123
Q123 Q223 C 7458-0 NPN 2N4123
Q124 Q224 C 3625-8 NPN 2N4125
Q125 Q225 C 3786-8 PNP PN4250A
Q126 Q226 C 5891-4 NPN MTS105

Resistors

R1 A10265-53621 53.6K 1%
R2 OPEN
R3 OPEN
R4 A10265-46421 46.4K 1%
R7 A10266-1041 100K
R8 A10266-2031 20K
R9 A10266-5121 5.1K
R10 OPEN
R16 A10266-5121 5.1K
R17 A10266-2031 20K
R18 A10266-1041 100K
R100 R200 C 9785-4 5K Linear W/21 Det.
R101 R201 A10265-49911 4.99K 1%
R102 R202 A10266-5111 510
R103 R203 A10265-10031 100K 1%
R104 R204 A10266-2721 2.7K
R105 R205 A10266-2721 2.7K
R106 R206 A10266-1231 12K
R107 R207 A10266-6831 68K
R108 R208 A10266-8211 820
R109 R209 A10266-5601 56
R110 R210 A10266-6831 68K
R111 R211 A10266-1231 12K
R112 R212 A10266-5131 51K
R113 R213 A10266-4721 4.7K
R114 R214 A10266-4721 4.7K
R115 R215 A10266-3641 360K
R116 R216 A10266-2751 2.7M
R117 R217 A10266-4731 47K
R118 R218 A10265-27401 274 1%
R119 R219 A10265-66501 665 1%
R120 R220 A10265-28701 287 1%
R121 R221 C 5062-2 100K Pot (-ODEP)
R122 R222 A10266-2741 270K
R123 R223 A10266-2032 20K .5W
R124 R224 A10266-6821 6.8K
R125 R225 C 8836-6 100 .5W Flame Proof

R126 R226 C 8836-6 100 .5W Flame Proof
R127 R227 A10266-6821 6.8K
R128 R228 A10266-1331 13K
R129 R229 A10266-1041 100K
R130 R230 A10266-1041 100K
R131 R231 A10266-1331 13K
R132 R232 C 5062-2 100K Pot (+ODEP)
R133 R233 A10266-2741 270K
R134 R234 A10266-2032 20K .5W
R135 R235 C 8836-6 100 .5W Flame Proof
R136 R236 A10266-6821 6.8K
R137 R237 C 8836-6 100 .5W Flame Proof
R138 R238 A10266-6821 6.8K
R139 R239 A10266-8211 820
R140 R240 A10266-5601 56
R141 R241 A10266-1541 150K
R142 R242 A10266-1541 150K
R143 R243 A10266-1041 100K
R144 R244 A10266-1041 100K
R145 R245 A10266-2251 2.2M
R146 R246 A10266-1031 10K
R147 R247 C 7781-5 200 .5W Flame Proof
R148 R248 A10266-2721 2.7K
R149 R249 C 7781-5 200 .5W Flame Proof
R150 R250 A10266-2721 2.7K
R151 R251 A10266-1031 10K
R152 R252 A10265-11821 11.8K 1%
R153 R253 JUMPER A10124-24
R154 R254 C 8261-7 121K 0.1%
R155 R255 A10266-1321 1.3K
R156 R256 A10266-1321 1.3K
R157 R257 A10266-1321 1.3K
R158 R258 A10265-11521 11.5K 1%
R159 R259 A10266-1021 1K
R160 R260 C 8260-9 10K 0.1%
R161 R261 A10266-4701 47
R162 R262 A10266-4701 47
R163 R263 C 8261-7 121K 0.1%
R164 R264 C 8260-9 10K 0.1%
R165 R265 C 8261-7 121K 0.1%
R166 R266 A10266-2251 2.2M
R167 R267 A10265-10011 1K 1%
R168 R268 A10265-10011 1K 1%
R170 R270 A10265-10011 1K 1%
R171 R271 A10265-10011 1K 1%
R173 R273 C 8260-9 10K 0.1%
R174 R274 A10265-24921 24.9K 1%
R175 R275 A10265-15821 15.8K 1%
R176 R276 A10265-24921 24.9K 1%
R177 R277 A10265-69811 6.98K 1%
R178 R278 A10266-2021 2K
R179 R279 A10266-1321 1.3K

38

Com-Tech 400 Amplifier Service Manual

Q43238-7 Main Module (D 8369-7 board) Parts List

R180 R280 A10266-4711 470
R181 R281 A10266-4721 4.7K
R182 R282 A10266-2201 22
R183 R283 A10266-2421 2.4K
R184 R284 A10266-4741 470K
R185 R285 A10266-2421 2.4K
R186 R286 A10266-2751 2.7M
R187 R287 A10266-3631 36K
R188 R288 A10266-3631 36K
R189 R289 A10266-2731 27K
R190 R290 A10266-2051 2M
R191 R291 A10266-3331 33K
R192 R292 A10266-6221 6.2K
R193 R293 A10266-6221 6.2K
R194 R294 A10266-1041 100K
R195 R295 A10266-3021 3K
R196 R296 A10266-4721 4.7K
R197 R297 A10266-1031 10K
R198 R298 A10266-4721 4.7K
R199 R299 A10266-1031 10K
R300 R400 A10266-1041 100K
R301 R401 A10266-1041 100K
R906 R1006 OPEN
R907 R1007 OPEN
R908 R1008 OPEN
R909 R1009 A10266-4741 470K
R910 R1010 A10266-4741 470K
R911 R1011 A10266-1521 1.5K
R912 R1012 A10266-4711 470
R913 R1013 A10266-1051 1M
R914 R1014 A10266-1051 1M
R915 R1015 A10266-2201 22
R916 R1016 A10266-2201 22
R917 R1017 A10265-10021 10K 1%
R918 R1018 A10265-10021 10K 1%
R919 R1019 A10265-10021 10K 1%
R920 R1020 A10265-10021 10K 1%
R921 R1021 C 9079-2 200 Pot (CMR Null)
R922 R1022 A10265-66501 665 1%
R923 R1023 A10265-35711 3.57K 1%
R924 R1024 A10265-66501 665 1%
R925 R1025 A10265-10031 100K 1%
R926 R1026 A10265-66501 665 1%
R927 R1027 A10265-10031 100K 1%
R928 R1028 A10265-35711 3.57K 1%
R929 R1029 A10266-7531 75K
R930 R1030 A10266-7531 75K

Resistor Networks

N101 N201 D 7945-5 Resistor Network
N102 N202 D 6082-8 Resistor Network

Switches

S3 C 7960-5 Sensitivity
S4 C 6781-6 Switch, Stereo/Mono

Integrated Circuits

U1 C 5095-2 UA7815
U2 C 5096-0 UA7915
U100 U200 C 6911-9 UPA75
U101 U201 C 4345-2 LM339
U102 U202 C 4345-2 LM339
U103 U203 C 6910-1 UPA76
U104 U204 C 7558-7 MC33079P

Misc.

Board D 8369-7
Socket C 3450-1 14 Pin (Qty 6)
Nut A10102-5 Hex 6-32 (Qty 2)
Heatsink C 5341-0 TO-220 (Qty 2)
Tq Spreader C 6541-4 (Qty 2)
Washer A10096-5 #6, Split (Qty 2)
Screw A10240-0608 Stainless (Qty 2)
J1 C 7593-4 5 Pin Header
J2 C 4508-5 16 Pin Socket
J11 C 7526-4 3 Pin Header
J100 J200 OPEN
J500 J800 D 6619-7 10 Inch Ribbon
J600 J700 D 6620-5 6 Inch Ribbon
Cable Tie C 1811-6 (Qty 4)
TP 1 C 9450-5 Header, 6 pin RT Ang
Spacer C 9225-1 Plastic Spcr (Qty 5)

39