Bose 1800 Service-Handbuch - Seite 26

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Subject: Interchangeability of repaired amplifier PCB.

Torroidal Power Transformer.

1800 Amplifier used with a TC-18 Transit Case.

Remarks:

The 1801 power amplifier board ( part # 102735 ) will no longer be shipped as a standard

repair part. Instead, a universal replacement board ( part # 102735-1 ) with a special thermo-

static clip connection allowing the use of this board in the 1801 and early production 1800 wire

harness assembly.

In the case of the 1801, amplifier boards may be intermixed with no difficulty, using the clip

connection.

In the case of the 1800, amplifier boards may be intermixed below serial #750. However, for

serial numbers above 750, use of the larger heat sink version (102735-1) is required.

When replacing amplifier boards in either unit, be certain to use additional thermal grease and

to tighten the screws holding the board to the chassis.

The 1800/1801 amplifiers are now using a torroidal power transformer that reduces the unit's

overall weight by 20 Lbs. The new transformer, ( P/N 107968 ) is found in 1800 amplifiers ( S/N

1630 and above ) and in 1801 amplifiers ( S/N 6838 and above ). Connections for the trans-

former are the same as indicated in the Service Manual for both units.

The 1800 power amplifier, when used with the TC-18 transit case, should be inspected periodi-

cally for dirt and dust accumulation on the heat sink surfaces. Any accumulation should be

removed as this significantly reduces the amplifier's ability to dissipate heat and increases the

likelihood of thermal overload.

SERVICE BULLETIN

Date: 09/19/1977

Bulletin #13