A12 v1.4 i got used doesn't seem to work...

[scottwilson]

I got an old A12 v1.4 used. The guy knew it didn't work and gave me a good deal, so I didn't get screwed.

Anyway, it had a number of problems:

The trim pot had been abused and was half broken off. I replaced that.
There was no R21 - literally it just wasn't there! I replaced it with another 100k that I had from another project. I verified that R20 is also 100k. Measured them as well... got 100k and 99k.

After fixing all that, when I use the original SC25 (that may or may not be working) or a Purple opamp from another working A12, I can't change the output voltage. No matter what I change R19 to, it stays 3 something volts. Both cases, the regulators are hot to the touch (too hot really).

Anything else I should look for before coughing up the $175?

thanks,

Scott

[tpryan]

What voltages do you get in steps 32-26 of the assembly instructions?