OK, problem solved. Somewhere along the line, C20, 21, and 22 had been replaced. These are supposed to be 100mfd/10v but had been replaced with 10mfd/100v. This 10x reduction in capacitance was keeping the FG signal from being converted to a square wave, as I interpret it.
So the seller ran the table and it spun, but he/she didn't test the speed.
Thanks. I wouldn't have found this without your suggestion to look at the FG amp.
Cheers.
So the seller ran the table and it spun, but he/she didn't test the speed.
Thanks. I wouldn't have found this without your suggestion to look at the FG amp.
Cheers.
Yes it does. Amazing what a simple mistake can cause. Wish I would have been the one to replace the caps - then they would have been the first thing I'd check after a change.
I did replace the 6562 with a 5532 and it works like a champ. Maybe it wouldn't be a good idea if you were expecting sound from the amp, but it's just the FG amp so fidelity isn't important.
Of course it did and just as well ! It would probably work better in audio too. I have designed in a lot of op-amps, one notable product the Philips PF85 where my design used in total over 1/2 a million op-amps.
It was in the 80's !! And yes it was a good time, fellow engineers are in still touch with each other via Facebook.
Ah, yes. I remember the 80's. Generally a good vintage. It's always good to stay in tough with old friends.
I'm guessing Philips was a good company to work for.
I'm guessing Philips was a good company to work for.
Philips/Pye in Cambridge was a great company to work for. I only stayed a few years and got a good pension. After that I worked for myself for nearly 40 years !