Ideas on Bias on a vintage SS Amp

[snorbans]

I have a vintage receiver Marantz 2245. Bought recently, super condition no obvious problems, all internals look ok and original. It hasn't been used for some years. Powers up though I needed to swap in a new power switch. I have not used it on speakers yet other than low level one at a time. Sounds OK.

I am just about able to do bias and offset. Offsets done. One channel for bias read high, 100mV approx. I was able to dial it down to the prescribed 10mV. The other channel slightly high, it stabilised at 18mV but thats as far as the pot will go

- do I live with it
- i have a problem which needs investigation
- I equalise the channels to 18mV as the receiver can take it and live with it

I would be grateful for your advice

[Firebottle]

My advice would be to leave the one channel at 10mV and the 2nd at 18mV. Connect some speakers and play at a reasonable volume for a short time then check the two bias readings.

If they are the same or have both increased just a little bit then everything should be OK. You can always repeat with a longer playing time and re-check.
If however the 18mV channel has increased a lot then there could be a problem.

Assuming things are OK evaluate the channel to channel sound quality over an extended time and if good just live with it.

I had the same with my old NEC amp and set both channels at the slightly higher setting and it's been great ever since :)

:cool: Alan

[snorbans]

Thanks Alan, for now I like an answer that doesn't involve much further digging. A job to save for the winter, I shall hook it up to speakers and see where it's at