nice bit of kit ,i recently bought a hp8657a sig gen which is rare as rocking horse s..t in the uk ! it has front panel lockup (with no battery leak) but it happens so rarelly its being a pain to fault find
i would advise checking that pcb for conductivity now it carboned up like that if that opamp is jfet or running lots of gain or a low offset type a few 100k of carboned pcb is gonna mess up its output, could always make a little sub board and isolate all that burnt board, oops edit i looked up tl171 low offset opamp not tl191 bimos switch
That chip is not an op-amp, it is an analog switch. You can stack them and reduce the switch resistance by half. (But why not just choose a better part?) With the charred spot, and especially the burned resistor between chassis and mains ground, I bet somebody accidentally connected signal ground to a not-ground output. Maybe a bridge-tied amplifier? This is the same failure as when a beginner doesn't understand oscilloscope ground.
Guess work on how it operates, guess work on the repair, total waste of time replacing capacitors, and the machine is just as likely to stop working again as nothing has been repaired.
![Chris Langan - The Interview THEY Didn't Want You To See - CTMU [Full Version; Timestamps]](/img/n.gif)
Excellent! Just Excellent!
Nice one Trevor going to very useful works in a very nice way.
Great work, Trevor👍
I think you got a real deal here. I was worried at first you were going to have a bad microcontroller.
When the daddy chip and the mommy chip love each other very much...
nice bit of kit ,i recently bought a hp8657a sig gen which is rare as rocking horse s..t in the uk ! it has front panel lockup (with no battery leak) but it happens so rarelly its being a pain to fault find
i would advise checking that pcb for conductivity now it carboned up like that
if that opamp is jfet or running lots of gain or a low offset type a few 100k of carboned pcb is gonna mess up its output, could always make a little sub board and isolate all that burnt board,
oops edit i looked up tl171 low offset opamp not tl191 bimos switch
That's some weird history.
That chip is not an op-amp, it is an analog switch. You can stack them and reduce the switch resistance by half. (But why not just choose a better part?)
With the charred spot, and especially the burned resistor between chassis and mains ground, I bet somebody accidentally connected signal ground to a not-ground output. Maybe a bridge-tied amplifier? This is the same failure as when a beginner doesn't understand oscilloscope ground.
Cadmium, not cadium
Guess work on how it operates, guess work on the repair, total waste of time replacing capacitors, and the machine is just as likely to stop working again as nothing has been repaired.
YET ANOTHER,cHANGE ALL THE CAPACITOR VIDEO BORING
Some of us still enjoy it. I say keep it up.