Correction: for the sake of exactness, 1kHz -6dB should read cca 1V at the output but any voltage will do. I got confused between digital and tape decibels.
Update #2😡
Here goes, I swapped out the op-amps. And thats all I did. Powered it up and sure enough the voltages had changed. Tried playing a disc, no go...The spindle would not spin. Sure enough regulator 79M12AUC or 6223 on the schematic was not putting out the -12v. But funny bit is the -19v( -17v actually) was coming into pin2, but not putting out -12v. The REG next to it, which is 6222 on the schematic gets -19v and puts out the +12v.
Question here is if its receiving the -19v, why isn't it putting out the -12v on the output pin? What would cause this. The REG is good as I used a new one to make sure it wasn't bust. The guilty regulator is 79M12AUC.
thanks
Here goes, I swapped out the op-amps. And thats all I did. Powered it up and sure enough the voltages had changed. Tried playing a disc, no go...The spindle would not spin. Sure enough regulator 79M12AUC or 6223 on the schematic was not putting out the -12v. But funny bit is the -19v( -17v actually) was coming into pin2, but not putting out -12v. The REG next to it, which is 6222 on the schematic gets -19v and puts out the +12v.
Question here is if its receiving the -19v, why isn't it putting out the -12v on the output pin? What would cause this. The REG is good as I used a new one to make sure it wasn't bust. The guilty regulator is 79M12AUC.
thanks
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These negative regulators may have a different pin out, watch out for that. Check the data sheet.
Perhaps . It's seems very likely. Will follow the trace and check. Not sure what might be causing it.
Okay its up and running and it sounds perfect. All the voltages are spot on.
It turned out to be bad op-amps and a shorted 22n ceramic capacitor .
So many Thanks to Rayma and Will Studer your suggestions really helped especially with the swapping out the op-amps. I installed holders so if I ever want to swap around Op-Amps I can without having to pull desolder them. Again many thanks😀
It turned out to be bad op-amps and a shorted 22n ceramic capacitor .
So many Thanks to Rayma and Will Studer your suggestions really helped especially with the swapping out the op-amps. I installed holders so if I ever want to swap around Op-Amps I can without having to pull desolder them. Again many thanks😀
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