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Looking good!
Be careful with soldering the output devices - a couple of resistors are placed between the leads
I finished assembling both modules and started the initial fire up the amplifier (without magic smoke). I'm using a SMPS which outputs +/-39Vdc. Seems like I was getting 14Vdc offset and with max adjustment on R8, I can get to 1.4Vdc... Which is weird... Bias seems to rise properly though and voltage on emitter resistors seem to be all the same, or very close... What do you suggest I try? Is the voltage too low?
Thanks
Do
Thanks
Do
Hi Do,
The offset you see is rather high - do you see the same kind of offset in both channels?
Cheers,
Valery
Yes, same exact behavior. I double checked all transistors again to be in the proper places. When assembling I double check and triple check everything and measure before and after to ensure components are ok. Don't know what is wrong here...
I'll stop any more testing just in case... But no smoke and no components going too hot.
Do
I'll stop any more testing just in case... But no smoke and no components going too hot.
Do
OK, I will look into it late in the evening.
I will ask you to measure some things and then we'll see.
For the beginning - can you please measure the voltage across 15V Zeners (1n4744).
Cheers,
Valery
Sounds like the front end isn't getting enough power. A quick and dirty test would be to parallel another 1k resistor on R17 and R18. In normal operation with +/- 48V you would have around 36mA to supply the op amps. With the extra resistors tacked on with +/- 39V rails you would have around 39mA available.