Infinity BU120revD, HTS20revD SERVICE MANUAL

BU-120/HTS-20

Powered Subwoofer

SERVICE MANUAL

Infinity Systems Inc.

250 Crossways Park Drive

Woodbury, N.Y. 11797

1-800-553-3332

A Harman International Company

Rev D 11/2000

Amplifier/Subwoofer BU-120/HTS-20

SAFETY INFORMATION

Warning

Any person performing service of this unit will be exposed to
hazardous voltages and the risk of electric shock. It is
assumed that any person who removes the amplifier from this
cabinet has been properly trained in protecting against
avoidable injury and shock. Therefore, any service
procedures are to be performed by qualified service personal
ONLY!

Caution

This unit does not have a power switch. Hazardous voltages
are present within the unit whenever it is plugged in.

Before the amplifier is plugged in, be sure its rated voltage
corresponds to the voltage of the AC power source to be
used. Incorrect voltage could cause damage to the amplifier
when the AC power cord is plugged in. Do not exceed rated
voltage by more than 10%: operation below 90% of rated
voltage will cause poor performance or may shut the unit off.

List of SafetyComponentsRequiring
ExactReplacements

F1 Fuse SLO BLO 1.0A 250V 20mm.

UL approved

Leakage/Resistance Check

Before returning the unit to the customer, perform a leakage
or resistance test as follows:

Leakage Current. Note there is no power switch on this unit.
When the power plug is plugged in, the unit is live. Connect
the unit to its rated power source. Using an ammeter,
measure the current between the neutral side of the AC
supply and chassis ground of the unit under test. if leakage
current exceeds 0.5mA, the unit is defective. Reverse the
polarity of the AC supply and repeat.

Resistance. Measure the resistance from either side of the
line cord to chassis ground. If it is less than 500k ohms, the
unit is defective.

WARNING! DO NOT return the unit to the customer if it fails
one of these tests until the problem is located and corrected.

PWRCORD SPT-2 or better with polarized plug, UL

approved wired with the hot side to fused side.
Use with factory replacement panel strain relief
only.

T1 Transformer. Use only factory replacement.

DBR or D1 Bridge diode. Use only factory replacement.

C1, 2 4700uF, 50V electrolytic filter caps. Be sure

replacement part is at least the same working
voltage and capacitance rating. Also the lead
spacing is important. Incorrect spacing may
cause premature failure due to internal cabinet
pressure and vibration.

C6 10uF 50V electrolytic radial* BU120 and HTS-20 rev. A only.

S53AMI or CN1 Power output module. Use only factory

replacement

Faceplate Faceplate. Use only factory replacement

Air leak cover Use only factory replacement

CMC1 Use only factory replacement

L1 Use only factory replacement

Fuse PCB Use only factory replacement

Main PCB Use only factory replacement
R29 470Ω .25W METAL OXIDE, non flammable

* See Service Bulletin (INF2000-01) page 15.

2

Amplifier/Subwoofer BU-120/HTS-20

TABLE OF CONTENTS

SAFETY INFORMATION..................................................2

GENERAL SPECIFICATIONS..........................................3

DETAILED SPECIFICATIONS .........................................4

CONTROLS AND THEIR FUNCTION .............................6

BU-120/HTS-20 CONNECTIONS.....................................7

OPERATION ...................................................................11

BU-120/HTS-20 TEST SET UP AND PROCEDURE ....12

BU-120/HTS-20 POWER AMP MODULE

TESTING FLOW CHART ...............................................13

SERVICE BULLETIN INF9902 - APRIL 1999 ...............14

SERVICE BULLETIN INF2000-01 - JANUARY 2000....15

TECH TIPS .....................................................................16

BU-120/HTS-20 PACKING & CABINET ASSEMBLY....17

BU-120/HTS-20 AMPLIFIER ASSEMBLY

EXPLODED VIEW ..........................................................18

BU-120/HTS-20 rev. A PCB (revision 3.52)

Component Side Trace...................................................20

BU-120/HTS-20 rev. A PCB (revision 3.52)

Solder Side Trace...........................................................21

BU-120/HTS-20 rev. A PCB (revision 3.53)

Component Side Trace...................................................22

BU-120/HTS-20 rev. A PCB (revision 3.53)

Solder Side Trace...........................................................23

BU-120/HTS-20 ELECTRICAL PARTS LIST.................24

BU-120/HTS-20 IC DIAGRAMS .....................................25

BU-120/HTS-20 SCHEMATIC 1 of 2 .............................26

BU-120/HTS-20

HTS-20 REV B ELECTRICAL PARTS LIST

SCHEMATIC 2 of 2 .............................27

....................28

HTS-20 REV B CIRCUIT BOARDS.................................31

HTS-20 REV B SCHEMATIC...........................................33

GENERAL SPECIFICATIONS

Frequency Response (± 3dB) .................30Hz – 150Hz

Output (RMS).............................150W

Driver ..................................12"Woofer

Crossover Frequency .......................50Hz ~ 150Hz (continuously variable)

Dimensions (HxWxD).....................14½"(36.8cm) x 14 ½" (36.8cm) x14 ½ " (36.8cm)

Add 1 ¾" (4.5cm) for feet.

Weight..................................43lbs/19.5 kg,

Refinements may be made on occasion to existing products without notice,
but will always meet or exceed original specifications unless otherwise stated.

REGARDING SERVICE FOR THE INFINITY HTS-20 SUBWOOFER

There are two versions, an "A" and "B", with minor internal differences.
Data for both versions is included, and differences noted in the following pages.
Units can be identified for service as follows:
 Amplifier faceplate says "Made in Canada" on the "A" version.

 Amplifier faceplate says "Made in China" on the "B" version.

3

Amplifier/Subwoofer BU-120/HTS-20

DETAILED SPECIFICATIONS

LINE VOLTAGE Yes/No Hi/Lo

Line

US 120vac/60Hz Yes 108-132 120 Vrms Normal Operation
EU 230vac/50-60Hz Yes 207-264 230 Vrms Normal operation, MOMS

Asia 100vac/50Hz No 90-110 100 Vrms Normal Operation

Parameter Specific

ation

Amp Section

Type (Class AB, D,
other)

Load Impedance
(speaker)

Rated Output Power 150 Watts 150 1 input driven
THD 0.3 % 1 22k filter 75w (Power Bandwidth

THD @ 1 Watt 0.5 % 0.8 22k filter
DC Offset 10 mV-DC 20 @ Speaker Outputs
Damping factor 100 DF 50

Input Sensitivity

Input Frequency 40 Hz Nominal Freq. 1 input driven
Line Input 63 mVrms ±2dB To Rated Power/ Vol @

Speaker/Hi Level Input 4.8 Vrms ±2dB To Rated Power/ Vol @

D n/a n/a Class D Preferred...Sink

4 Ohms n/a Nominal Z-curve required

Unit QA Test

Nom. Unit Notes

required

Conditions Notes

Limits

required for Class AB

30-100Hz)

1 input driven: AP source

Max

Max

Z = 600 ohms
1 input driven: AP source

Z = 25 ohms

Signal to Noise

SNR-A-Weighted 100 dBA 90 Relative to rated output A-Weighting filter
SNR-unweighted 75 dBr 70 Relative to rated output 22k filter
SNR rel. 1W-unweighted 65 dBr 55 relative to 1W Output 22k filter
Residual Noise Floor 3 mVrms 4 Volume @max, using

RMS reading on A/P

Input Impedance

Line Input 10k ohms n/a Nominal
Speaker/Hi Level Input 200 ohms n/a Nominal

Filters 0dBr = 1w @ 50Hz
Low Pass (fixed or

variable)
Low Pass filter (point or

range)
Slope 18-24 dB/Octaven/a

Subsonic filter (HPF) 34 Hz ±2dB -3dB Point
Slope 24 dB/Octaven/a

Variable

50-150 Hz ±2dB -3dB Point

22k filter required due to
100kHz switching noise
present at speaker output

4

Amplifier/Subwoofer BU-120/HTS-20

Limiter (yes/no) yes

Max. Output
Power/THD=10%

150w/10%P

-max/TH

D

Features

Phase Switch (yes/no) yes — functional
Volume pot Taper

linear — functional

(lin/log)

Input Configuration —
Line In

L,R — functional

(L,C,R,AC3,Mono)
Line Outputs (L,C,R) L,R — functional Buffered Output /

Spkr/Hi Level In

(L,C,R,mono)

L,R — functional

Spkr Out: Hi Pass Filter 100 Hz functional

functional Maximum Output Power Maximum THD as a result

of limiting.

Enabled w/Line/Spkr Input Select Switch

Pre-Volume control

Enabled w/Line/Spkr Input Select Switch

8 ohm Satellite: 6dB/oct
passive xover

Driven from zero ohms
source impedance

Signal-Present LED Yes — — — Bi-Color LED

(green=signal/ red=no
signal)

Signal-Present Input
Freq.

100 Hz functional Nominal 200uF Series Cap on

PCB

Signal-Present Level 35 mV functional 100Hz into Line Input w/

1 ch. driven

Power on Delay time <2 sec. AC Power Applied

Transients/Pops

Turn-on/off Transient 500 mV-peak 2v-pp @ Speaker Outputs AC Line cycled from OFF

to ON or ON to Off

Efficiency

Stand-by Input Power 14 Watts @ nom. line voltage
Power Cons.@rated

110 Watts @ nom. line voltage

power
Efficiency 136% % Relative to rated output

Protection

Short Circuit Protection yes functional Direct short at output
BU120

Line

Fuse Rating 1.0 Amps Type-T or Slo Blo

HTS-20
Line Fuse Rating 2.0 Amps Type-T or Slo Blo

5

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 CONNECTIONS

When connecting your subwoofer make sure you turn
all the power off.

There are several ways to connect your subwoofer.
Read this section carefully to determine which method
is best suited for your installation.

The subwoofer may be fed directly with a low-level
signal taken from a preamplifier's output by using the
second set of output jacks on the rear of the
preamplifier (See Figure 1). If a preamplifier has only
one set of outputs, you may use two (2) “Y” connectors
(See Figure 2) to connect the subwoofer. Use
standard shielded leads terminated at each end with
male RCA connectors. Connect one end of each
stereo pair of leads to the preamplifier's left and right
outputs and connect the other end to the
corresponding left and right LOW-LEVEL INPUTS (1)
on the subwoofer.

If you are using a tube preamplifier and the connecting
leads will be longer than 10 feet (3 meters), we
recommend not using the above connection method. A
tube preamplifier may not be able to handle the
capacitance introduced by leads more than 10 feet in
length. Instead, try using the high-level connection
methods listed on pages 5-7.

Figure 1.

preamp's output by connecting second set of
output jacks to the rear of your amplifier.

Figure 2.

connectors) if your preamp has only one set
of outputs.

- A low-level signal can be used from a

- You can use this method (2“Y”

7

Amplifier/Subwoofer BU-120/HTS-20

When using a single subwoofer, you MUST use a pair of stereo low-level leads from your preamplifier's outputs. When using
two subwoofers, one for the left and another for the right channels, connect the left preamplifier output to BOTH the left and
right LOW-LEVEL INPUTS of the subwoofer used for the left channel by using a Female-to-Male “Y” connector at the
subwoofer's output. Connect the right-channel preamplifier output to both jacks of the right-channel subwoofer in the same
manner (See Figure 3). If the preamplifier has a mono subwoofer output, you'll also need a Male-to-Female “Y” connector to
split the mono signal to the subwoofer pair (See Figure 3).

Figure 3.

The subwoofer may be connected to your system using the
HIGH-LEVEL INPUTS (4) on the plate located on the rear
panel of the subwoofer. Use speaker wire, maintaining
proper polarity (+ to + and - to -). Attach the speaker wire to
the left and right HIGH-LEVEL INPUTS on the subwoofer
and the other ends to the proper left and right OUTPUTS on
your amplifier or receiver (See Figure 4).

If you plan to use two subwoofers (one for the left and the
other for the right channel), connect wires from the left and
right OUTPUT on your power amplifier or receiver and
attach the other ends to the corresponding HIGH-LEVEL
INPUTS on each subwoofer. Observe polarity (See Figure

4).

Figure 4.

subwoofer.

- Use this method when using a single subwoofer output or two subwoofers.

- Use this method when using a single

8

Amplifier/Subwoofer BU-120/HTS-20

Figure 5.

subwoofers.

- Use this method when using two

Figure 6.

one subwoofer to satellites.

Depending on whether you are using one or two
subwoofers, connecting your satellites can be
accomplished in one of two ways. If you are using a
single subwoofer with a pair of satellites, connect
them as shown in Figure 6.

- Use this method when connecting

9

Amplifier/Subwoofer BU-120/HTS-20

Figure 7.

connecting two subwoofers to
satellites.

If you are using two subwoofers as a
stereo pair with a pair of satellites, connect
them as shown in Figure 7.

BU-120
The subwoofer has a variable frequency
control that can be used to block unwanted
frequencies (between 50 - 150Hz) from
being reproduced by the subwoofer.
When you set this control depends on the
low-frequency capabilities of your satellite
speakers. Adjust this knob to the lowest
frequency that you satellite speakers were
designed to reproduce (refer to Operation,
step 7).

HTS-20 - Has no external control. If you are
using a receiver or surround processor
containing a Dolby Digital and/or DTS
decoder, set the crossover bypass switch
to "On". If you are using a stereo or Dolby
Pro Logic receiver, set this switch to "Off";
this places the preset roll-off crossover
frequency point at 100Hz.

- Use this method when

10

Amplifier/Subwoofer BU-120/HTS-20

OPERATION

Setting the Controls

1. Initially set the subwoofer's Volume control to the minimum
position.

2. BU120 - Initially set the subwoofer's Crossover Frequency
control to 12 o'clock.
HTS-20 - If you are using a receiver or surround processor
containing a Dolby Digital and/or DTS decoder, set the
crossover bypass switch to "On". If you are using a stereo
or Dolby Pro logic receiver, set this switch to "Off"; this places
the preset roll-off crossover frequency point at 100Hz.

3. Set the subwoofer's Phase switch to the "0" position.

Turn the Power On

4. Turn on the entire audio system and play any music
source.

5. Turn the Volume control to its mid position. If no sound
emanates from the subwoofer, check the AC line cord and
input cables. Are the connectors on the cables making proper
contact? Is the AC plug connected to a “live” receptacle?

Adjusting the Volume

6. Set the overall volume control of the preamplifier or stereo
to a comfortable level. Adjust the subwoofer's Volume control
until you obtain a pleasing blend of bass. Bass response
should not overpower the room but rather be adjusted so
there is a harmonious blend across the entire musical range.
Many users have a tendency to set the subwoofer volume too
loud following the belief that a subwoofer is there to produce
lots of bass. This is not entirely true. A subwoofer it there to
enhance bass, extending the response of the entire system
so the bass can be felt as well as heard. However, overall
balance must be maintained; otherwise, the music will not
sound natural. An experienced listener will set the volume of
the subwoofer so its impact on bass response is always there
but is never obtrusive.

Room Placement

8. The room placement of the subwoofer is the most critical
aspect of its installation. It will be necessary for you to try
various locations in your listening room before you choose
the final location. Some possible starting points include:
behind the right channel satellite speaker, along the back
wall between the satellites, along a side wall (but not too
close to a corner), or behind a couch or a chair.

In general, the closer the subwoofer is to wall and corners,
the greater the effect of low-frequency enhancement.
Experiment with the Crossover Frequency and Volume
controls in different locations until you are pleased with the
result you obtain from your particular application.

A Word of Advice

The Low-Frequency Roll-off and Volume controls may be
set anywhere within their rotation. However, it will be a most
unusual circumstance if you have to set the Volume control
completely clockwise. This may indicate an unbalanced
condition in your system (too much bass) or an especially
large room, or room placement may not be correct. Try
several other locations before concluding that the Volume
control must be set at maximum.

A Word About Tone Controls

The tone controls on your electronic components
(preamplifier, receiver, etc.) should be used with the utmost
discretion. Excessive boost can create severe power
demands on your power amplifier. Maximum bass boost
can create a demand for literally hundreds of watts in the
bass region, whereas in the “flat” position, or with the tone
controls switched out of the system, your average listening
level may be impressively and realistically loud at less than
10 watts. The remaining power capacity required is on
reserve for power peaks on sharp transients and powerful
crescendos.

The Crossover Frequency Controls (BU120
only)

7. The Crossover Frequency control sets the high-frequency
roll-off, adjustable from 50 to 150Hz. Where you set this
control depends on the low-frequency capabilities of your
satellite speakers, system placement, and other factors
affecting the mid-bass region. Turn the control UP
(clockwise) until you feel there is too much mid-bass
information (around 100Hz), then back the control down a bit
until that area sounds more natural. To hear more low bass,
turn the Crossover Frequency control DOWN a bit and the
Volume control UP by about the same amount. This will
increase low bass while leaving the mid-bass sounding the
same as it did before the adjustment. To reduce low bass
without changing midbass, turn the Crossover Frequency
control UP and the Volume control DOWN. Switch the Phase
switch between “NOM” and “REV” positions while listening to
music. The selection that sounds the best is the correct
adjustment for your system.

11

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 POWER AMP MODULE TESTING FLOW CHART (HTS-20 rev. " A" only)

13

Amplifier/Subwoofer BU-120/HTS-20

SERVICE BULLETIN INF9902 - APRIL 1999

This is considered a Minor repair
To: All Infinity Service Centers
Models: BU-120/HTS-20 (rev. "A" only)

Subject: Check Solder Joints in Event of Failure

Some performance related complaints in the BU-120/HTS-20 powered Subwoofers may be caused by cold solder
connections between the 28 pins of the Power Amp Module and the main circuit board. When troubleshooting,
failure to check these joints can result in erroneous conclusions or wasted time.

In the event you receive a Subwoofer with the complaints “Dead, or No Output, or Motorboating (Oscillation)”,
perform the steps listed below first before any further troubleshooting takes place:

1) Unplug all cables, lay the subwoofer on a padded surface.

2) Remove all Philips screws around the outer perimeter of the amplifier faceplate.

3) Remove amplifier assembly; you should be able to remove the amplifier far enough out of the cabinet to

service it without removing the woofer wires.

4) Locate the Power Amp Module; it is the large gray component with a metal case. On the solder side of the
circuit board are the 28 soldered connections to the Module.

5) Regardless of whether you can visibly see breaks in any of the connections or not, carefully re-solder all 28 pin
connections, adding 60/40 rosin core solder. Take care not “bridge” any connections on the board with
solder.

6) Inspect the solder joints to the main filter capacitors C1 and C2 on the main PCB and re-solder if needed.

7) Replace the amplifier assembly back into the cabinet; replace the screws.

8) Test the unit by applying a signal from a music source, adjust the volume to a moderate level and confirm the

original problem has been corrected.

14

Amplifier/Subwoofer BU-120/HTS-20

SERVICE BULLETIN INF2000-01 - JANUARY 2000

Warranty labor rate: MINOR repair
To: All Infinity Service Centers
Models: BU-120/HTS-20 (rev. "A" only)

Subject: Failure of C6

In the event you receive a BU-120 subwoofer with the complaint “no output” and capacitor C6 (10uf 50v NPE) is damaged in
the amplifier, replace with the following part: Infinity part# 30712 (10uf 100v NPE)

LED2

C2

+

C1

+

AC

C11

C7A

AC

+ DIODE BRIDGE

C7B

14

CMC

C24

Q4

L1

L3

L4

GND

R4A

R4B

R4C
R5
R6

CW

SPK­SPK+

C7

2

3

R16

Q5

R17

C6

General reference for location only; not all parts or designators may conform to this drawing.

It is also recommended following the repair that the instructions included in bulletin #INF9902 are folllowed.

Models Serial number 120/230V Status Action

BU-120/HTS-20 All serial numbers affected Replace if damaged Replace C6 with Infinity part# 30712

15

Amplifier/Subwoofer BU-120/HTS-20

TECH TIPS

Troubleshooting tips and solutions to common service problems

For models: BU-120/HTS-20

TIP# INFTT2000-01

Complaint:

How do you replace or service any of the front panel components on the Subwoofer faceplate for model
BU-120/HTS-20.

Probable Cause:

The High level Input terminals, potentiometers, RCA jack, and switch(es) are behind a sealed cover to protect the
air-tight integrity of the cabinet enclosure.

Solution:

1) Unplug all external cables from the subwoofer; place the cabinet on a padded surface.

2) Remove any subwoofer grille; remove the woofer from the cabinet. Detach the two connections from the

woofer terminals.

3) Remove all Phillips screws holding the amplifier to the cabinet; remove the amplifier.

4) Remove all knobs, nuts, and Philips screws from the outer control section of the amplifier faceplate.

5) Locate the sealed cover on the inside of the amplifier faceplate (see illustration); the bead of adherent must be

broken to remove the main PCB with front panel components from the plastic faceplate. This is most easily
accomplished by CAREFULLY using a box cutter, exacto knife, or similar sharp instrument. First scrape all
excess material from the three surfaces; then force the blade into the groove between the rear cover and the
faceplate. DO NOT attempt to remove the rear cover from the main PCB.

6) When enough material is removed, the main PCB with cover should pull away from the faceplate, exposing
the components.

7) After servicing a bead of “silicon seal” or similar adherent must be applied to all surfaces where it was
removed. Reassemble the rest of the components in reverse order.

16

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 PACKING & CABINET ASSEMBLY

SCREWS (4)

FEET
(SET OF 4)
#200310

SCREWS (8)

BU-120/HTS-20
CABINET ASSEMBLY

12" WOOFER
BU-120/HTS-10 (rev. "A" 200300
HTS-20 (rev. "B") 090-312000-000

CABINET
NOT FOR SALE

AMPLIFIER
ASSEMBLY

SCREWS (8)

WARRANTY
CARD
#333715-001

FEET PAD (4)
STICKERS
#200252

TOP STYROFOAM
RAIL PADS
(2 per carton)
#200360

BU-120 or HTS-20
SUBWOOFER

PLASTIC BAG

BOTTOM
STYROFOAM
RAIL PADS
(2 per carton)
#200360B

OWNER'S MANUAL
BU-120 - #200230
HTS-20 - #HTS20GUIDE

CARTON
BU-120 - #200320
HTS-20 - #HTS20CTN

BU-120/HTS-20 PACKING

NOTE: The HTS-20 subwoofer is part of the HTS-20 system and

packaged with 5 satellite speakers; the master carton is not shown.

00369

17

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 AMPLIFIER ASSEMBLY EXPLODED VIEW

A

B

C

D

E

BU-120/HTS-20

1

Amplifier Assembly

1

Exploded View

2

3

2

3

4

5

6

7

HTS-20

201819 20 6

BU-120

62018 6119

4

5

6

7

A

B

C

D

E

18

1 70170 #4x0.5" screws to secure input jacks 3
2 70171 #10 x 1" machine screw bolts for 4transformer 4 per unit 4
3 70172 #10 keps nuts for transformer 4
4 70173 #6 x 0.5" screws for fuse PCB 2
5 70301 Hum Shield Metal bracket mounted on transformer 1

BU-120 and HTS-20 rev "A" ONLY

5 073-014023-900 Hum Shield Metal bracket mounted on transformer 1

HTS-20 rev "B" ONLY

6 A70302 Volume Control/Crossover Knob 2/1

BU-120 and HTS-20 rev "A" ONLY

6 061-2-020000-000 Volume Control Knob 1

HTS-20 rev "B" ONLY

10 80110 T1 Transformer #4340 SAFETY PART 1

BU-120 and HTS-20 rev "A" ONLY

10 042-010028-001 T1 Transformer SAFETY PART 1

HTS-20 rev "B" ONLY

11 80111 F1 Fuse 250V, 1.0A, T type slo blo fuse SAFETY PART 1

BU-120 and HTS-20 rev "A" ONLY

11 091-000096-000 F1 Fuse 250V, 2.0A, T type slo blo fuse SAFETY PART 1

HTS-20 rev "B" ONLY

12 80105 Power cord, 2 conductor SAFETY PART 1

BU-120 and HTS-20 rev "A" ONLY

12 083-041802-017 Power cord, 2 conductor SAFETY PART 1

HTS-20 rev "B" ONLY

13 80106 Fuse PCB complete with connectors SAFETY PART 1

BU-120 and HTS-20 rev "A" ONLY

13 011-080203-000 Fuse PCB complete with connectors SAFETY PART 1

HTS-20 rev "B" ONLY

14 80112 Main PCB SAFETY PART 1

BU-120 and HTS-20 rev "A" ONLY

14 015-131700-101 Main PCB SAFETY PART 1

HTS-20 rev "B" ONLY
15 70303 Faceplate with labels SAFETY PART 1
16 A70304 Air leak cover SAFETY PART 1
17 70305 Pwr cord strain relief SAFETY PART 1

BU-120 and HTS-20 rev "A" ONLY
17 061-314002-000 Pwr cord strain relief SAFETY PART 1

HTS-20 rev "B" ONLY
18 108320 Dual RCA input jacks 1

BU-120 and HTS-20 rev "A" ONLY
18 072-010058-000 Dual RCA input jacks 1

HTS-20 rev "B" ONLY
19 108115 High level Input and Output terminals 1

BU-120 and HTS-20 rev "A" ONLY
19 062-050800-000 High level Input and Output terminals 1

HTS-20 rev "B" ONLY
20 70150 Phase Switch/Crossover bypass 1/2

BU-120 and HTS-20 rev "A" ONLY
20 074-030002-000 Phase Switch/Crossover bypass 2

HTS-20 rev "B" ONLY

Ref#

Part#

Description Qty

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 rev. A PCB (Component Side Trace)

G

F

E

1

Layer

race
T

Side

2

3

4

5

G

F

E

D

C

B

A

D

Component

-

3.52

C

Revision

B

A

1

2

3

4

5

20

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 rev. A PCB (Solder Side Trace)

G

F

E

1

board
the

through

viewed

2

3

4

5

G

F

E

D

C

B

Layer as

D

race
T

Side

C

Solder

-

3.52

B

Revision

A

A

1

2

3

4

5

21

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 rev. A PCB (Component Side Trace)

G

F

E

1

Layer

race
T

Side

2

3

4

5

G

F

E

D

C

B

A

Component

-

3.53

Revision

D

C

B

A

1

2

3

4

5

22

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 rev. A PCB (Solder Side Trace)

G

F

E

1

board
the

through

viewed

2

3

4

5

G

F

E

D

C

B

A

Layer as

race
T

Side

Solder

-

3.53

ANCY

F

D

C

B

A

1

2

3

4

5

23

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 rev. A ELECTRICAL PARTS LIST

REF# PART# DESCRIPTION QTY REF# PART# DESCRIPTION QTY

Resistors

R1 40705 4.7M 1/4W 5% carbon film 1
R2 40426 24k 1/4W 5% carbon film 1
R3 40412 33.2k 1/4W 1% metal film 1
R4 40406 100k 1/4W 5% carbon film 1
R4a/b/c 40105 0.1 1/2W 5% 3pcs. 3
R5, 6 40420 1k 1/4W 5% carbon film 2
R7 40409 10k 1/4W 5% carbon film 1
R8 40406 100k 1/4W 5% carbon film 1
R9 40421 3.9k 5W 5%, 3W can be used 1
R14 40409 10k 1/4W 5% carbon film 1
R15 40406 100k 1/4W 5% carbon film 1
R16, 17 40101 820 2W 5% carbon film 2
R18 40407 220k 1/4W 5% carbon film (LED sens) 1
R19 40422 1k 1/2W 5% carbon film 1
R20 40405 4.7k 1/4W 5% carbon film 1
R21 40409 10k 1/4W 5% carbon film 1
R22 40410 2.2k 1/2W 5% carbon film 1
R24 40417 47k 1/4W 5% carbon film 1
R25 40406 100k 1/4W 5% carbon film 1
R26 40701 1.0M 1/4W 5% carbon film 1
R27 40428 8.2k 1/4W 1% metal film 1
R29 40103 470 1/4W 5% METAL FILM 1

Safety part

R30, 31 40429 16.4k 1/4W 1% metal film 2
R32 40415 470k 1/4W 5% carbon film 1
R33 40100 332 1/2W 5% carbon film 1
R35 40422 301k 1/4W 1% metal film 1
R36 40427 23.7k 1/4W 1% metal film 1
R37, 38 40417 47k 1/4W 5% carbon film 2
R39 40430 36.5k 1/4W 1% metal film 1
R40 40431 68k 1/4W 5% metal film 1
R42, 43 40406 100k 1/4W 5% carbon film 2
R44 40409 10k 1/4W 5% carbon film 1
R45 40409 10k 1/4W 5% carbon film 1
R46 40104 4.7 1/4W 5% carbon film 1
R48 40432 6.98k 1/4W 1% metal film 1
R49 40415 470k 1/4W 5% carbon film 1
R50 40100 332 1/4W 5% carbon film 1
R51 40417 47k 1/4W 5% carbon film 1
R52 40404 1k 2W 5% carbon film 1
R53, 54, 55, 56 40106 100 2W 5% carbon film 4
R57 40404 1k 2W 5% carbon film 1
R58 40435 8.06k 1/4W 1% metal film 1
R59 40405 4.7k 1/4W 5% carbon film 1
R60 40701 1.0M 1/4W 5% carbon film 1
Crossover 40425 50k 1/4W 10% Double Log Pot 1
Level 40402 5k 1/4W 10% Single Linear Pot 1

C4 30504 100nF 50V -4% Mono-cer rad 1

C5 30504 100nF 50V -4% Mono-cer rad 1

C6 30705 10uF 50V -4% Electrolytic Radial NP 1

C7 30510 33nF 50V 10% Mono-ceramic axial 1
C7a/b 30505 100nF 100V 20% Metal Polyester Rad 1
C8, 9 30504 100nF 50V +80/-20% Mono-ceramic axial 2
C11 30702 100uF 35V -4% Electrolytic Radial 1
C13 30507 10nF 50V 20% Mono-ceramic axial 1
C14 30511 330nF 50V 10% Mono-ceramic axial 1
C15, 16 30707 220uF 50V 20% Electrolytic Radial 2
C17 30502 100nF 50V -4% Mono-ceramic radial 1
C18, 19, 20 30504 100nF 50V 10% Mono-ceramic axial 3
C24 30502 100nF 50V -4% Mono-ceramic axial 1
C26 30512 22nF 50V 10% Mono-ceramic axial 1
C27 30513 3.3nF 50V 10% Mono-ceramic axial 1
C28 30507 10nF 50V 20% Mono-ceramic axial 1
C29 30703 4.7uF 50V -4% Electrolytic Radial 1
C31 30514 47nF 50V 10% Mono-ceramic axial 1

0.2"/ax 0.3"

0.2"/ax 0.3"

Safety part (See Service Bulletin
INF2000-01 page 15)

temp stable

Diodes

D1 50101 ZENER 1N5256B 30V 5% 0.5W 1
LED 1 or 2 50106 Dual Cir LED (2 legged) 2
D2, 4 50104 1N4148 100V 0.1A 4
D3 50102 ZENER 1N4749A 24V 5% 1W 1
D6 50103 ZENER 1N5234B 6.2V 5% 0.5W 1
D9, 10 50105 ZENER 1N4744A 15V 5% 1W 2
DBR 50100 Bridge Rect 200V 4A Safety part

Transistors

Q1 60151 MPS A13 30V NPN (Darl) 1
Q2 60152 2N3906 40V PNP, 2N4402 alternate 1
Q3 60153 2N3904 40V NPN, 2N4401 alternate 1
Q4, 5 60154 MPS A56 80V PNP 2

IntegratedCircuits

U1 60100 LM324 Quad OpAmp +/-15 1
U2 60101 TLO 82 Dual OpAmp +/-15 1

60301 S53AMI Power Amp module 1

SAFETY PART

Inductors

CMC1 80100 mc4438 Safety part 1
L1 80101 mc4436 Safety part 1
L2 80102 BL02RN2-R62 Ferrite Bead 1

Capacitors

C1, 2 30706 4700uF 50V -4% Electrolytic Radial 2

Safety part

C3 30514 47nF 50V -4% Mono-ceramic axial 1

24

+6V 15

16
17

V+

1+6V
2

V+

3

18

4

O/P

19

5

O/P

20

6

V- V-

21

7

22

8

SD 24

+15V 23 9 +15V

10 SD

FR 25 11 FR

I/P 26 12 I/P

GND 27 13 GND

-15V 28 14 -15V

00228

NOTE: THE FOLLOWING PROCEDURES MUST BE FOLLOWED WHEN
INSTALLING NEW AMP MODULES:
FAILURE TO FOLLOW ONE OR MORE OF THESE STEPS MAY
RESULT IN THE INSTANT DESTRUCTION OF THE MODULE WHEN
POWERED UP.

1) Align white indent marker on Amp Module with indent marker on main
PCB; alternately position of label on the top of the module; incorrectly
replacing the Module 180

0

in the PCB slot will result in its destruction.

2) All AC powered test instruments (meters, oscilloscopes, etc.) must
have a floating ground, i.e. be connected to an isolation transformer.

3) Align and position the Amp Module before soldering.

4) Attach the amp Module with the mounting screws before soldering or
powering up.

5) Use only rosin-core or non-acid core solder; thoroughly de-flux the
surfaces after soldering.

If the new Amp Module has larger mounting hole(s) in the case, and
the stock screws no longer will fit, and screws of the proper type can­not be obtained locally order:

(2) part# 60301S (screws)
(2) part# 60301N (nuts)

S53AM/S64AMI - Power Amp module SAFETY PART

BU-120 and HTS-20 rev “A” ONLY

4IN3

GND2-15V

5

S/D

6

+15V

7

V-

8

V-

9

V-

10

O/P

11

V+

12

V+

146V13

V+

1

FB

15

LIMIT

PWR MODULE

CN1

00370

HTS-20 rev “B” ONLY

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 rev "A" SCHEMATIC 1 of 2

G

F

E

1

2

3

4

5

G

2
f
o

1

F

BU-120/HTS-20

Schematic

E

D

C

B

A

D

C

B

A

1

2

3

4

5

26

Amplifier/Subwoofer BU-120/HTS-20

BU-120/HTS-20 rev "A" SCHEMATIC 2 of 2

G

F

E

1

2

3

4

5

G

15

Bulletin

page

See

Service

INF2000-01

F

E

D

C

B

A

2
f
o

2

BU-120/HTS-20

Schematic

D

C

B

A

1

2

3

4

5

27

28

MAIN PCB

Semiconductors
050-002400-100 zener diode 24V HZ-24-2 D11 1

050-003300-100 zener diode 33V 1N4752 D31 1
050-006200-100 zener diode PN:HZ6C2/Hit 6.2V 1/2W D2 1
050-414802-100 Diode 1N4148 D121,122,123,124 4
050-524500-200 zener diode P/N:1N4744ARL 15V/1W D3,4 2
051-101501-000 Transistor pnp 2sa1015gr TO-92 Q13 1
051-181502-000 Transistor npn 2sa1815gr TO-92 Q11,12 2
051-540101-000 Transistor pnp 2n5401 TO-92 Q31,32 2
051-555100-000 Transistor npn 2n5551 TO-92 Q33 1
052-401001-000 Diode Bridge P/N:KBU4A 4A/100V D1 1
053-007400-000 IC TL074CN Quad Op-Amp IC101 1
053-455801-000 IC BA4558 (ROHM) Dual Op-Amp IC102 1

Resistors
020-100497-120 Carbon resistor 1K 1/4W J R15,37,38 3

020-100597-120 Carbon resistor 10K 1/4W J R11,107,108,111,112, 8

113,124,125
020-100697-120 Carbon resistor 100K 1/4W J R23,105,106 3
020-100797-120 Carbon resistor 1M 1/4W J R13 1
020-150497-120 Carbon resistor 1K5 1/4W J R126,127 2
020-150797-120 Carbon resistor 1M5 1/4W J R31 1
020-220497-120 Carbon resistor 2K2 1/4W J R12 1
020-220597-120 Carbon resistor 22K 1/4W J R130,121 2
020-220697-120 Carbon resistor 220K 1/4W J R122 1
020-270697-120 Carbon resistor 270K 1/4W J R116 1
020-300497-120 Carbon resistor 3K 1/4W J R16 1
020-330497-120 Carbon resistor 3K3 1/4W J R33 1
020-330597-120 Carbon resistor 33K 1/4W J R22 1
020-330697-120 Carbon resistor 330K 1/4W J R109 1
020-360597-120 Carbon resistor 36K 1/4W J R114 1
020-470197-121 Carbon resistor 4R7 1/4W J R4 1
020-470497-120 Carbon resistor 4K7 1/4W J R17,123 2
020-470597-120 Carbon resistor 47K 1/4W J R128,128,32 3
020-470697-120 Carbon resistor 470K 1/4W J R14 1
020-680497-120 Carbon resistor 6K8 1/4W J R119,115 2
021-100096-120 Metal oxide film resistor 0R1 1/2W J R34,35,36 3
021-100301-120 Metal oxide film resistor 100R 1W J R101,102,103,104 4
021-100598-100 Metal film resistor 10K 1/8W F R6 1
021-165597-100 Metal film resistor 16.5K 1/4W F R117,118 2
021-220402-021 Metal oxide film resistor 2K2 2W J MO-200 R3 1
021-470498-100 Metal film resistor 4K7 1/8W F R131 1
021-680598-121 Metal film resistor 68K 1/8W F R5 1
022-680305-020 Cement resistor 680R 5W J P/N:SQM5M R1,2 2
026-500495-252 VR Volume POT 5K VR101 1

Capacitors

030-100247-300 Ceramic capacitor 0u1/50V Z P:5 C5,6,7,9,10 5
032-100263-301 mylar capacitor 0u01/100V J P:5 C129,103,121 3

HTS-20 (rev B) ELECTRICAL PARTS LIST

Part Number Description Ref Designator Qty

29

032-100364-300 mylar capacitor 0u1/100V K R C3,4,33,26A 4
032-220163-300 mylar capacitor 0u0022/100V J C104 1
032-3300025-300 mylar capacitor 0u0033/50V M C130 1
032-330263-300 mylar capacitor 0u033/100V J P:5 C119 1
032-330354-303 mylar capacitor 0u33/63V K P:5 C118 1
032-470353-303 mylar capacitor 0u47/63V J P:5 C31 1
033-220543-200 elec capacitor 22uF/50V C32 1
033-220645-300 elec capacitor 220uF/50V C101,102 2
034-100635-300 elec capacitor 100uF/35V C11 1
034-470415-301 elec capacitor 4u7/50V C8 1
034-470745-200 elec capacitor 4700uF/50V C1,2 2
035-100393-300 mylar capacitor 0u1/63V J P:5 C114,115,116 3

POWER AMP MODULE 217-9902102-000 CN1 1
050-414802-100 1N4148 Taping D1-9 9

053-530000-100 Mosfet N-Channel IRF530 To-220 Q2,3 2
051-555100-000 Transistor NPN 2N5551 TO-92 Taping Q1 1
053-035301-000 IC LF353N Dual Op-Amp U1 1
053-741400-000 IC (Dip Type)P/N:74HC14N Hex U2,3 2

Schmitt Trigger Inverter
015-090500-100 MODULE PCB DOUB 99x55mm FR-4 REV:C 1
020-100297-120 Carbon resistor 10R 1/4W J Taping R11,12 2
020-100397-120 Carbon resistor 100R 1/4W J Taping R7 1
020-100497-120 Carbon resistor 1K 1/4W J Taping R4,5,3,9 4
020-100697-120 Carbon resistor 100K 1/4W J Taping R2 1
020-100797-120 Carbon resistor 1M 1/4W J Taping R10 1
020-220397-121 Carbon resistor 220R 1/4W J Taping R6 1
020-330497-120 Carbon resistor 3K3 1/4W J Taping R8 1
020-680497-120 Carbon resistor 6K8 1/4W J Taping R1 1
032-100394-302 mylar capacitor 0u1/100V J P:7.5 Taping C9 1
034-100525-303 elec capacitor 10uF/25v m sm 4x7 p:1.5 105 C7 1
039-100343-100 mylar capacitor(axial) 100pF/50V J NPO Taping C1,2,3,5 4
039-100345-100 mylar capacitor(axial) 0u1/50V M Z50U C4 1
039-100464-100 mylar capacitor(axial) 0u001/100V K X7R Taping C8 1
039-330344-101 mylar capacitor(axial) 330p/50V K X7R Taping C6 1
072-040170-000 Connector P/N:211-215-000-000 1
073-014023-900 Shield cover 103.9x14x0.3t 1
073-032050-000 Heat sink 102.3x58mm 1

FUSE PCB ASS’y
011-080203—000 FUSE PCB BORD SWD80 82x21x1.6mm 94V0 1

072-040039-000 Terminal (PCB TYPE) PC205 (t=0.8mm) T205MA 4
091-000096-000 FUSE P/N T2A/250V 5x20mm 1
091-000130-000 FUSE HOLDER P/N CQ-203SP 2

Miscellaneous
008-061007-200 GASKET MODULE BLK CR C4305 1x7x80mm 1

008-061610-201 GASKET PCB PU FOAM SM-55 3x6x200mm 1
015-131700-101 MAIN PCB;FR-4 REV:F PCB;127x165mm 1
043-240130-010 choke coil 2.4mH (YT-8719) L1 1
043-260330-001 filter coil 0.11mH (YT-8712-1) L22 1

HTS-20 (rev B) ELECTRICAL PARTS LIST (Cont.)

Part Number Description Ref Designator Qty

30

050-505200-001 LED P/N:LT-2402-25 LED11 1
062-050800-000 Push Terminal 8P P/N E801 JK101 1
065-001540-090 P/N15L 1.5x1.8mm
070-560891-108 SCREW BTS-3 2.6x8m/m MODULE-PCB 4
072-010058-000 RCA JACK 2P P/N:052000W1G (Red,Wht) JK102 1
072-040032-000 Terminal P:3.96 3P CON3 1
072-040039-000 Terminal PCB TYPE PC205 (t=0.8mm)T205MA J101,102 2
074-030002-000 Toggle sw P/NL101 sw101,102 2
091-000143-000 EMI BEAD P/NEM11-RH-3.5x0.8x9-PA 2
165-001540-090 P/N15L 1.5x1.8x40mm 2
042-010028-001 Transformer YT-9161-2 75W-120Vac 1

HTS-20 (rev B) ELECTRICAL PARTS LIST (Cont.)

Part Number Description Ref Designator Qty

31

HTS-20 REV B CIRCUIT BOARDS

32

HTS-20 REV B CIRCUIT BOARDS (cont.)

33

213

CON3

321

SW101

0

180

D1

KBU401

.1u

C4

.1u

C3

123

4

CHOCK-COIL

L1

13-12

+

14

IC101:D

TL074

C103

.01u

R108

10K

R107

10K

3

1

2

VR101

5KA

.0022u

C104

2

1

3

JK102

VOL.

L

LINE IN

R

R109

330K

D123

1N4148

D124

1N4148

SPK OUT

1

2

3

4

+

-

LCH

RCH

-

+

JK101:A

5

6

7

8

+

-

LCH

RCH

-

+

JK101:B

R105

100K

R106

100K

100 1W

R104

R103

100 1W

R102

100 1W

R101

100 1W

C102

220u 50V

C101

220u 50V

SPK IN

3

2

1

2SA1015

Q13

1M

R13

LED11

(G.R)

R17

4K7

3K

R16

3

2

1

2SC1815

Q11

3

2

1

2SC1815

Q12

C11

100u 35V

2K2

R12

R11

10K

R14

470K

R117

16K5

10K

R112

R113

10K

R111

10K

C116

.1u

.1u

C115

R116

270K

D11

1N4749A

24V

1K

R15

R115

6K8

C114

.1u

R114

36K

1

2-3

+

4

11

IC101:A

TL074

6-5

+

7

IC101:B

TL074

C118

.33u

R119

6K8

.01u

C121

R121

22K

R118

16K5

C119

.033u

R122

220K

R129

47K

D121

1N4148

10K 1/4W

R124

R126

1K5 1/4W

.0033u

C130

R130

22K

68K

R5

10K

R6

R2

820 5W

R1

820 5W

4.7R

R4

C6

.1u 63V

4700u/50V

C2

4700u/50V

C1

D4

15-3

D3

15-3

C7

.1u

6.2V

1N5234

D2

.1uC9.1u

C10

C5

.1u 63V

2K 2W

R3

6-5

+

7

BA4558

IC102:B

OFF

123

SW102

ON

9

­10

+

8

IC101:C

TL074

1K5 1/4W

R127

1N4148

D122

R128

47K

C129

.01u

R123

4K7

10K 1/4W

R125

1

2-3

+

8

4

BA4558

IC102:A

R131

4K7

R22

33K

J102

J101

L41

F.B

L42

F.B

C32

22u 50V

C33

.1u 100V

L22

110uH

C26

.1u

V+

+6V

V-

4u7 50V

C8

4IN3

GND2-15V

5

S/D6+15V7V-8V-9V-10O/P11V+12V+146V13V+

1

FB

15

LIMIT

PWR MODULE

CN1

SWD120 / HTS-20 SUB AMP

-15V

+15V

R33

3K3

.47u

C31

3

1

2

Q33

2N5551

47K

R32

R31

1M5

D31

0.5W 33V

1N5256

R23

100K

.1 1/2W

R34

1K

R37

.1 1/2W

R35

.1 1/2W

R36

2

3

1

Q32

2N5401

R38

1K

2

3

1

2N5401

Q31

B

C

D

E

F

G

H

1

2

3

4

5

6

1

2

3

4

5

6

A

7

8

9

10

A

7

8

9

10

H

G

B

C

D

E

F

00360

L

N

X'FORMER

FUSE 2A

HTS-20 REV B SCHEMATIC

1413121110987654321

15

C16

200uF

C15

200uF

L IP
RCA

RCA

330nF

SPDT

R IP

LOPASS
100k Lin Pot

C14

10

9

SPKR LEV IO

R

L

High Level In

U1

LM324

R37

8k66

LO-PASS

R30

16k5

R27

8k25

8

R54 100R

R55

100R

R56
100R

36k5

R49

C7

33nF

C31

6

U1

5

R51

7

38k3

47nF

383k

2

3

U2

TL 082

R59

1

4k7

R4

47k

HI-PASS / EQ

D4

C20

100nF

C19

C18

R39

100nF

100nF

R48
6k98

R42 100k

R43 100k

R53 100R

R44
10k

R45

10k

10nF

R35

332k

13

14

U1

12

LM324

5k LOG

R40

68k

C33

220pF

4

+15V

2

U1

3

-15V

11

C9

100nF

C13

LEVEL 1

1

POT.

1

C17

100nF

R20
4k7

R18
330k

2

3

2 Clr LED

LED

DRIVE

LED2
N/F

Q2
2N3906

R26

1000K

R32

C11

470k

100uF

To AC Feed

To GND

To AC Return To Power Cord

1N4148

R50

150R

R52

1k

REMOTE

1

2

3

V+

V-

LED1

R21
10k

R22

2k2

D3

FUSE (On FUSE PCB)

TRX

MCI 4340E

0.5A

R19
1k

1N4749A

Q1

MPSA13

TRANSFORMER IS MOUNTED ON FACPLATE

700Hz Lo-Pass

+6V Supply

C2

4700uF

1N5234B

C29

0R

J4

N/F

J5

N/F

J6

N/F

J7

N/F

C8 100nF

D6

R16
470R

C5
100nF

R17
470R

100nF

S53
MODULE

R46

47R

R9
2k

UVLO

D1

1N5256B

R1

1M5

C4

D10
1N4744A

D9

1N4744A

BR RECT

V+ V-

RS604

H-Pass Pot.

2

1

1

2

2

3

1

4

2

5

1

6

2

7

1

8

+6V

V+

O/P

V-

+15V

S/D

FR

I/P

GND

-15V

D add
1N4735A

From L IP RCA

From R IP RCA

R3
33k2

6

5

DIODE CLIPPER

SW

C27

3n3F

U2

TL 082

To Power Cord

7

R58
4k64

C1
4700uF

R25
47k

R24

22k

C26

10nF

D2
1N4148

R33

150R

R57
1k

C add 10nF

SHORT CIRCUIT PROTECT

R7
3k3

Q3

2N4401

Q4

L2

C3

330nF

C7A

CMC

C7B

2m2H

C25

N/F

R11

N/F

C32

N/F

R13
N/F

Part No:

Model Name:

Date:

17-Oct-2000

Drawn:

MS/LL

Rev.

2

R8
47k

MPSA56

R5
1k

R4A

R4B

0.1R

0.1R

2.2uHL1110uH

OUTPUT FILTER

100nF

100nF

C12

N/F

R10
N/F

C30

N/F

R12
N/F

MBD-04020102

BU-120E

Sheet:

1of1

Q5
MPSA56

R4C

0.1R

3

2

5

6

R6
1k

C6

10uF

R15

100k

AC Feed

QUICK FIT TERMINAL

GND

QUICK FIT TERMINAL

AC Return

QUICK FIT TERMINAL

+15

1

U3

TL 082

-15

7

U3

TL 082

C24

100nF

L4

Jumper

L3

Jumper

L OP
RCA

N/F

R OP

N/F

RCA

N/F

N/F

a

I

LOPASS
100k Lin Pot

R31

H

G

F

E

D

C

B

A

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

16k5

PHASE SW

SPKR LEV IO

R

L

High Level Out

R36
8k66

R2
8k66

RCA Connector

LINE LEVEL INPUT

QUICK FIT TERMINAL

SPK-

CZ

N/F

QUICK FIT TERMINAL

SPK+

CW
N/F

C10
N/F

C28
N/F

I

H

G

F

E

D

C

B

A