Yamaha ca-410

ianniele

Member
Hi all, is it possible to adjust de dc offset in the yamaha ca-410 and what is the mv for both channels. Thanks alot
Ian
 
Ideally, you should have 0mV in both channels, measured between the + and the - speaker terminals.

There is no provision for Offset adjustment in this amp, but it can be adjusted with a very minor "surgery".

Tell me what offset you have in your amp, I will guide you.
 
I also have a Yamaha amp, a CA-810.
My offsets are -2.1 and 15.7.
I'd be interested to learn how to adjust the offset too!
 
The first step should be to match the transistors in the differential input stage for equal hFE

For the CA-410:

They are TR-405, TR407 in one channel, and TR406, TR408 in the other channel.

Then you must trim R443 and R444. If the initial offset is positive, you must reduce those resistors by small increments. If the initial offset is negative, replace them by larger value.

A 2k trim pot should work fine too.

For the CA-810:

Match TR403, TR405 together, and TR404, TR406 for the other channel.

Trim R423 and R424. You may replace them by a 150 Ohm trim pot. It should provide enough adjustment.
 
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