Does the audio look clean (driving a load) on the scope?
It's likely offset but it's also likely a 10-turn pot, so if you adjust it, count the turns so you can put it back where it was, if needed.
It's likely offset but it's also likely a 10-turn pot, so if you adjust it, count the turns so you can put it back where it was, if needed.
This amp reminds me a lot of the old earthquake amps using hip 4080 for output drivers, they also had a pot like this. Once I adjust 3 or 4 turns the dc voyage drops but it goes into fault, once I turn it back it comes out of fault.
Well that didnt fix it will get scope out and check the audio wave form. I did try swapping out the hipa4080 and that had no change on it either
As soon as it drops to zero the goes into fault, almost like it has no affect on the dc offset. But if you play audio it will clip powersupply unless you give it a few turns almost like a current limiter
The audio is not clean driving a load. Without a load the audio start distorting on the peaks of the 60hz waveform as you increase the gain
Does the audio get distorted before the final op-amp that drives the input of the 4080? Or is it clean up to there?
U2. Lm837N has audio in out 1 & 2, audio waveform is fine until you go about halfway with gain then it starts to become noisy. Out 3 & 4 are thick noisy line no waveform.
Which pin of which IC drives audio into the 4080?
I don't know if it was a typo but the 2274 is the IC part number. The 1 is actually an I. It stands for industrial.
I don't know if it was a typo but the 2274 is the IC part number. The 1 is actually an I. It stands for industrial.
The pinout for lm837 and the 2274 are the same. Pin 1 has audio on it and pin 14, pin 7 and pin 8 do not have a waveform.