Recapping and Bias


Hi,

I’ve recapped a few cheaper things I have, and with good results. I see that recapping is something a lot of people do. But I’m a hobbyist, and I probably don’t know most there is to know. I notice bias is mentioned a lot in regards to servicing amps, but I can't find any information about it regarding recapping.

1) Should you check the bias after recapping on SS amps/gear?
2) If there is no pot for this, would you worry?

I’m especially thinking of newer gear, made just now or during the last 10 years.
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Hopefully you won't need to recap, check resistors, rebuild power supplies (swap filter caps) for at least 20 more years.. 30-50 years is not uncommon. I have Macs that are 1961-65 Never been touched.. 65 + years old..

The bias is something SS and Valve unit both require.. If you have serviced a unit properly. Setting or checking the bias is all part of the tune up.. Keeps them sounding great and running at the prefered temp, too. There is more going on with bias, but the just of it is..It's part of the tuneup or service.. SERVICE manuals will usually give you the information you need as far as "HOW" to do it.. some are a little vague..

Enjoy yourself and be safe...

Regards
First, if there's no bias adjustment then don't add one. Second, recapping will not affect bias. Bias is a voltage and caps don't affect voltage. Resistors do that. Not caps. Finally, when recapping you must use equal value, because otherwise you can screw up frequency response. So I've lost count, but that's like 4 different ways you don't need to worry about what you're worried about.
MC you'll never do a tune up for me.. sputter, sputter put-put.. :-) If you change the caps what good is it if you don't check resistor values..
That half the rebuild.. LOL. Jeez ma neez.. I replaced 100 carbon comps if I replaced one.. BUT that the old Mac. Resistors are 1/2 the sound, GREAT resistors..are expensive too.  Vishay foils..
 
If you replace filter and bypass caps, it's a good idea to scope the unit and of course check the bias. Not all units let you change the bias, BUT if the bias is out of whack, you need to check a resistor value to repair it. VTL is like that.. You check a resistor value FIRST then if it need attention you repair it first and move on to actually bias the valves to their 220-300ma. VTL expect YOU to check that value too, it's not there to NOT be used... 

It's not a bad idea, do all the checks you can with a DMM and scope if you have one or (twenty like most techs). I'm not, I just love to tinker..

Regards