O N K Y O U S A C O R P O R A T I O N

2 0 0 W i l l i a m s D r i v e • R a m s e y N J 0 7 4 4 6
2 0 1 - 8 2 5 - 7 9 5 0 F a x 2 0 1 - 8 2 5 - 8 1 5 0

Model:

General Subject

03/12/99

Classification:

SERVICE TIP:

BIAS TRANSISTOR ALOCATION or INSTALLATION.

On models

whose bias transistor may have been mounted far from the heat sink.

Example: Picture shows TX-SV636 or TX-SV535 amplifier output bias transistor Q622, Q624 and at the center is Q616
used for bias.

An amplifier assembly having its bias
transistor far from the heat sink should
be replaced and rearranged until the
transistor body touches the heat sink. Put
some heat sink compound between the
transistor and heat sink assembly. Such
exercise is basic and could provide
stable bias at high temperature
operation. TXSV636.

Example: TXSV343 may run with higher bias
than it should, causing power transformer to
open.

1. Idle current begins at no more than 3.5mv at
given test points.
2. The bias transistors should be placed up
against the heat sink and heat sink compound
should be added as shown.
3. *** R582, and like resistor value may be best
if changed from its current value 330ohm to
270ohm.

0399GENAMP_1