"fixing" a pair of Audiolab 8000P amplifiers, where the i/p phono connectors had "crumbled". Most of the Electrolytic caps were wrong, so all changed, including the 4 off 10,000uF reservoir caps (one amp was fine, the other had two failures, interestingly the ones with a slight bulge tested ok) So they sound fine to my ear. Now adjusting the Bias from around 47mV on both channels of both amplifiers back to the 22mV recommended in the service manuals. Problem is it seems to go up and down around the 22mV (from 20mV up to 24mV). Is this normal? (Finding service manuals for these is hard. I have a 8200P cct diagram which is near enough the same plus this one. Measuring across TP13+ and TP13-. Before I adjusted the Bias, the valuse were also going up and down. This is after its been on for some hours now,
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So, it's may be picking up things from the ether? I was attempting to do a bit of FT8 on 6M and the left channel went up by 4-8mV when I was transmitting. The test leads acting as antennas?🙂
Yes, EMI or convection currents affecting the input stage. Are the inputs shorted?
Consider refraining from transmitting while the stereo is on, in any event. That's too big an ask.
Consider refraining from transmitting while the stereo is on, in any event. That's too big an ask.
Ref i/ps no the are left o/c, so I suppose a floating i/p would have an effect. I'll short them out and see if I get a more stable reading, bloody mV huh! ref transmitter, it was only 40W, 8M up in the sky , but I stopped when I realised there was an effect. 🤣
