Does the DC voltage drop to 0v when a load is connected?
Does the noise sound like this:
http://www.bcae1.com/temp/cooleditmixedoscillator01.wav
Does the noise sound like this:
http://www.bcae1.com/temp/cooleditmixedoscillator01.wav
The op-amp closest to the header on the driver board 'may' be defective but this amp has no global feedback for DC.
If you're driving a speaker that can take the full power of this amp, 1.1v DC isn't going to do any harm. I know that some techs will work for hours trying to get the offset to 0.25 or less but you have to look at what's practical.
If you're driving a speaker that can take the full power of this amp, 1.1v DC isn't going to do any harm. I know that some techs will work for hours trying to get the offset to 0.25 or less but you have to look at what's practical.
I changed the opamp TL072 now the dc reduced to 0.45v. And current draw decreased also. Still when I connect speaker I hearing slight hmmmmmm sound.
The sound was just like the file. I left it a while to see if the amp is stable. The inductor getting hot and I am getting peak sounds now from speaker. Like cracking noise
The inductors run hot but as long as it's heating uniformly and there is no peeling of the enamel, it's likely OK.
The noise like that in the sound file is from unsynchronized oscillators (PS and class D). There is no simple fix. It's a common problem in a lot of amps. It's not generally audible in normal use.
I can't explain the crackling. With the scope set to about 2ms, do you see any breakup in the displayed waveform?
The noise like that in the sound file is from unsynchronized oscillators (PS and class D). There is no simple fix. It's a common problem in a lot of amps. It's not generally audible in normal use.
I can't explain the crackling. With the scope set to about 2ms, do you see any breakup in the displayed waveform?