Hot U1 and U3 (Rev 1.9.2)

[rtroast]

Finally back to trying to troubleshoot two Rev 1.9.2 modules. I initially placed some combination of Q5/Q6 and Q9/Q10 in the wrong spots. Recently, replaced all those parts, along with all descrete transistors and the tantalum caps. Fired the modules up today and set the voltages (+/- 18v). The friend helping me noted that U1 and U3 got very hot and advised powering down. We never tried to pass audio through them. Is this normal or should I consider them still not working?

[rtroast]

Working! I think I got gun-shy after two failed attempts. The first time I just replaced the parts I had mis-installed, but still had problems (excess current draw... quite noticable). The second time, I replaced evertyhing "associated" with the mis-installed parts (transistors and tantalum caps). Re-checked evreything this morning, fired them up and checked voltages, then ran audi through them. They seem fine. Going to need them next month when tracking... can't wait!

[tpryan]

Hot op-amps are normal with earlier revisions. Rev 2.x and later add a separate current source.

[rtroast]

Thanks!

[rtroast]

Ugh... apparently not working. Not sure why the power supply didn't exhibit this behavior when I tested the C84s individually, but when I turned on the loaded chassis just now, the pilot light cycles up and down in brightness; clearly something (assuming the C84s) is drawing excess current. Unless there's somethng obvious I can look at (or a test I can perform) I probably have to abandon the effort. So stay tuned, if that's the case I'm happy to send them free-of-charge to whoever is willing to pay the shipping.

[rtroast]

I'm an idiot!!! Opened up the box, was checking each of the C84s individually, by disconnecting the power supply and noticed... I had one of the molex connectors shifted by one pin (towards the back). Don't know if I damaged anything but if not, fingers-crossed, I should finally have a whole box o' preamps.