Bogen BPA-60 Service Manual

TECHNICAL SPECIFICATIONS

Model BPA-60

Rated Output Power:

60

watts (rms) from

I5kHz

at less than 2%THD

into rated load

Frequency Response:
Input Sensitivity:

Low-impedance, balanced: 75mV with accessory transformer Model

Output Regulation:
Hum and Noise:
Inputs (Impedance):

Low-impedance:

Line-bridging with accessory transformers

Output Loads:

Lo-Cut Filter:
Controls, Indicators;

Front Panel:
Rear Panel:

Power Consumption;

I20VAC, 60Hz
@

Full Rated Output:
Overload Protection:
Auxiliary Receptacle:

(not switched)

Dimensions:

Finish:
Weight:
Rack Panel Brackets:
Accessories:

I

I

8-ohm/25V,

25VCT and 70V

Input Level Control; Circuit Breaker Reset Switch; Lo-Cut Filter Switch

AC Circuit Breaker. Thermal Circuit Breaker, Transient Protection Diodes

15.25”Wx8”Dx3.5”H
(38.7 x 20.3 x 8.9 cm)

19

Model BPA- 125

50Hz

to

impedances

-2dB

from

20Hz

125 watts

15kHz

to 2OkHz

(rms)

from

at less than 2% THD

into rated load impedances

High-impedance: 300mV;

Better than 2dB from no load to full load

85dB below rated output

High-impedance:

600-ohms

balanced, with accessory transformer

16-ohms,

50k-ohms

unbalanced;

TLl00

4-ohm/25V,

or TLlOK

16-ohms,

25VCT and 70V

-1OdB @ 1OOHz

(Switch-Selectable)

Illuminated Power Switch

18OW

1

360w

Three-wire grounded* 300 watts maximum

15.25”Wx8”Dx5.25”H

lbs. (8.6 kg)

RPK-53

Model

TL600, 600-ohm
Model

Model TLlOK,

Black

line-matching transformer

TLIOO, 1:1

10,000-ohm

ratio transformer

line-matching transformer

(38.7 x 20.3

x

13.3 cm)

27 Ibs. (12.3 kg)

RPK-54

5OHz

TL600

TL600;

to

1

*This receptacle will be grounded only if the power amplifier has been grounded properly

All specifications subject to change without notice

AMPLIFIER

GND

AMPLIFIER I AMPLIFIER 2

GND COM

A74-2021-01

Figure 1 - Connecting Amplifiers in Series

1

COM 25VCT

l6fi

I

AMPLIFIER 2

GND COM

GND COM

25VCT

lGfI

OUTPUT

TERMINAL

sz&RoF

AMPLIFIER

7OV

AT
AT 25V RI =

RI =

Figure 2

2

10K, 1/2W

3.3K, 1/2W

-

Input From Another Amplifier

-0730-A

IMPEDANCE

INPUT

OF

POWER

AMPLIFIER

Figure 3 - BPA-60 Rear Panel Connection Diagram

CONNECTING AMPLIFIERS IN SERIES. Pairs of the same

amplifier model may be connected in series to effectively dou­ble the power output into the same load line (see Figure 1). Be
certain to remove the link between COM and GND terminals
on amplifier No. 2.

BRIDGING INPUT. The inputs of two or more amplifiers may
be paralleled by installing accessory transformer
to 6 amplifiers) or TLlOK (for more than 6 amplifiers) in the
transformer socket designated XT-l (see Figure 5) on the
printed circuit board. Connect the signal source to the BAL
LO-Z terminal strip and connect the cable shield to the GND
terminal. For an unbalanced input, connect a jumper wire from
the GND terminal to an adjacent input terminal.

INPUT FROM ANOTHER AMPLIFIER. The BPA-60 and
BPA-125 amplifiers may be driven from an amplifier that pro­vides a

25-volt

or 70-volt constant voltage output. Connect the
output of the driver amplifier to one of the HI-Z input jacks via
a resistor network (see Figure 2). These resistors are in addition
to the normal loudspeaker load impedance on the output of the
driver amplifier.

TLlOO

(for up

OUTPUT CONNECTIONS

Connect speaker systems directly to the output terminal strip on
the rear panel. Connect one speaker lead to the COM terminal and
the other to the terminal corresponding to the impedance of the
speaker system. If the load impedance falls between two output ter­minal values, use the terminal of lower impedance. Total power
distribution to the speakers should not be greater than the power

rating of the amplifier. For balanced output lines, remove the link
between the COM and GND terminals. If the line is shielded, con­nect the shield to the GND terminal. For unbalanced speaker lines,
close the link between the COM and GND terminals.

HUM. If the connections between the signal sources and amplifier
are incorrect or defective, hum-type interference may occur. Check
for proper grounding, broken wires, shields, poor connector con­tacts, etc. Keep input cables away from speaker cables and speaker
cables away from AC power lines. Where a turntable or other aux­iliary equipment is used, it may be necessary to connect a separate
ground wire from the chassis of such equipment to a suitable earth
ground.

POWER. The POWER switch applies power to the amplifier; it
does not control any associated equipment which may be connected
to the auxiliary power receptacle on the rear panel. The switch lamp
will illuminate when power has been applied to the unit.

CAUTION

Follow

local electrical codes

when connecting ampljier

output.

Fires 3 and 4 show the location and impedance values for the

output terminal strip. Class 2 wiring is acceptable for output loads.

SPEAKERS. The amplifier may be used with most conventional
speaker systems. For detailed information on the installation of
multiple speaker systems, refer to the Speaker Installation Bulletin
(No.

54-5001)

included with this unit.

LO-CUT FILTER SWITCH. The LO-CUT filter switch, located on
the rear panel, provides

INPUT LEVEL CONTROL.

on the rear panel, adjusts the input signal applied to the amplifier.
Turn the adjustable screw clockwise to increase the level.

Many

loudspeakers

-1OdB

attenuation at

The INPUT LEVEL control, located

CAUTION

may be damaged if

100Hz.

overdriven.

Therefore, always begin system setup with the input

level control fully

counterclockwise

and gradually in-

crease the setting to obtain the desired output level.

4

Figure 4 - BPA-125 Rear Panel Connection Diagram

THERMAL BREAKER.

no audio output; however, the power switch lamp will remain illu­minated. Wait approximately two minutes for the breaker to reset. If
it resets and then opens again, investigate the cause of the
temperature overload. This may be due to improper connections at
the output terminals or to excessive environmental heat with inade­quate ventilation. The thermal breaker will open when the
temperature at the output transistor heat sink reaches 105 °C.

CIRCUlT BREAKER..

switch lamp
however, there will be power at the AUX POWER receptacle on the
rear panel. Set the POWER switch to OFF and momentarily depress
the red button on the circuit breaker to reset it. Return the POWER
switch to ON. If the circuit breaker trips again, do not attempt to
reset it; have the trouble investigated by a qualified technician.

wiIl

go out and the amplifier will have no output;

If the thermal breaker opens, there will be

If the AC circuit breaker opens, the power

MAINTENANCE

CAUTION

There are no user-serviceable parts within the
amplifier.
qualifed technician. The warranty will become void if
repairs are made by other than the
Department or authorized service agency.

BOGEN

Our Service Department is interested in the maintenance of

your

Bogen equipment. If trouble ever develops, do not hesitate
to ask our advice or assistance. Information may be obtained by
writing to: Service Department, Bogen Division, P.O. Box 500,
Paramus, N.J. 07653.

Have all internal servicing performed by a

Bogen

SERVICE

Service

When communicating with us, give the model and series
designation of your unit. Describe the difficulty and include
details on the electrical connections to associated equipment,
such as preamplifiers, speakers, etc. We will send you service in­formation if the trouble appears simple. If the amplifier requires
servicing, we will send you the name and address of the nearest
authorized Bogen service agency.

When shipping the amplifier, pack it well, using the original
shipping carton or similar container and filler material to prevent
damage in transit.

printed circuit board beforeshipping.

and freight prepaid via UPS or other responsible carrier. The
repaired unit may be picked up by you personally or will be
returned to you freight prepaid while in warranty.

Remove any plug-in transformer from the

Send the unit, fully insured

REPLACING COMPONENTS

All semiconductor components on the printed circuit board
are soldered in place to ensure maximum reliability. When
soldering or unsoldering transistors and diodes, use a heat sink
(such as a small alligator clip) between the source of heat and the
component. When replacing driver and output transistors, be
certain to install the case/heat sink insulator, after lightly coating

both sides with a thermal conducting compound (such as Dow
Corning No. 340, or equivalent).

REPLACEMENT PARTS

Most components used in the amplifier are standard parts

available through reputable parts suppliers. The parts listed here
may be obtained through Bogen distributors, service agencies or
directly from the factory. When ordering a part, specify the part
number and the description, as listed. Specify the model of the
unit and give the series designation, which is a letter followed by
numbers, located on the rear panel. For parts on the circuit
board, also give the component board assembly number, which
begins with “45”.

TRANS. SKT. XT1

0

I

PARTS LIST

Designation

­c2

C3,4
C6
CR1-4

:;

;:

Rl
R3
R4
R5
Rl8,19
Sl

-

Cl01

Cl03

Cl04

C201

C202

Part
Number

45-7241-05
79-l 19-001
79-008-065
79-008-062
96-5333-01
96-5643-01
96-5365-01
96-5459-01

96-5458-01

77-001-818

75-154-124
75-154-154
75-154-334
76-

107-096
81-003-067
70-9302-01

78-200-l 16
79-

118-002

79-118-004

79-118-006

79-509-056

Figure 5 -

Description

PC Board

Ptd. Cir. Bd. Assy.

Cap., Elect., 470
Cap., Elect., 10
Cap., Elect., 100
Diode,
Transistor, KTC2240
Transistor,

Transistor,
Transistor,
Control, Scr. Adj., 100 kilohm
Resistor, 120 kilohm, ¼W, 1%
Resistor, 150 kilohm,
Resistor, 330 kilohm,
Resistor,
Switch, Slide, Miniature

Clip, Heat Sink (2)

Chassis

Cap., Cer. Disc, 0.01
Cap., Elect., 13,000

Cap., Elect., 8800

Cap., Elect., 5000

Cap., Elect., 6000

4OOprv @ 1A

.82

(BPA-125)

(BPA-125)

(BPA-60)

(BPA-60)

MPSA56
2N6292
2N6107

ohm, 2W

BPA-60/BPA-125

µF,

63V

µF,

63V

µF,

50V

1/4W,
1/4W,

µF,

1400V

µF,

40V

µF,

75V

µF,

50V

µF,

75V

1%
1%

Printed Circuit Board

Schematic
Designation

CBlOl

CB102

CB201

CR101
CR201 -204
QlOl
4102,103
Q104-107

R101,102

R103-106

R107

R109
R201,203

R202

SW101
TlOl
T102
T201
T202

-

Part
Number

94-0023-10

94-0014-07
94-0023-05
96-5373-01
96-5241-01
96-5213-01
96-5385-01
96-5385-01

76-114-107

76-l 14-102

75-154-182

75-742-101

76-l 14-102

75-154-132

81-009-036
83-831-000
83-492-000
83-814-000
83-491-000

14-9088-01

Description

Breaker, Circuit,

(BPA-125)
Thermostat
Breaker, Circuit, 1.6A (BPA-60)
Rectifier, Bridge (BPA-125)
Diode, 300prv
Transistor,
Transistor, 2N3055H, RCA
Transistor, 2N3055H, RCA

(BPA-125)
Resistor, 3.3 ohm, 5W

(BPA-125)
Resistor, 0.27 ohm, 5W

(BPA-125)
Resistor, 1800 ohm,

(BPA-125)
Resistor, 100 ohm, 7W
Resistor, 0.27 ohm, 5W

(BPA-60)

Resistor, 1300 ohm,

(BPA-60)
Switch, Power
Transformer, Power (BPA-125)
Transformer, Output (BPA-125)
Transformer, Power (BPA-60)
Transformer, Output (BPA-60)
Foot, Rubber

4.OA

@

3A (BPA-60)

2N5089

1/4W,

1/4W,

1%

1%

6