My work place recently threw out a totally dead AFG 2020, A tek function gen, beast of a machine.
At first glace it looks to be an issue in the early stages of the PSU. Mains make it from the filter to the psu then nothing, not even the hard wired fan.
However by removing power cable I was able to deduce that it might be the CPU board and not the psu. IF a certain 3 wire cable is plunged in AND the cpu board is plunged in it won't do squat. Any other time the fan get power.
The cable in question the the small unplugged orange-red-brown cable right above the large PCB(cpu board). When not plunged in this wave form is present. Interestingly enough when the cable isn't plugged in nothing shows on the display. It's not booting either way it seems.
When plugged in this is what I see. It looks like the signal is being really loaded down, a short I presume. I measured ~100 ohms to ground and 14 mA of current.
The short to ground made tracing the line impossible. The continuity tester keeps picking up ground pins.... I had a brief moment of happiness thinking I found it only to stupidly discover the pin was just ground...
I'm running short of ideas of what to try next.
I might try to tear into the psu more to try and find what that pin does exactly. But I'm leaning more to the blow the snot out of it approach.
I've got a constant current power supply and I'm thinking that if I run 50-100 ma though it by providing a supply it can't pull low I may be able to track down the hot chip.
Interestingly enough the 10 MHz out still works as long as the cable is unplugged. I could use it as a very large 10 MHz reference.
What do you repair guru's think so far? Any idea's? I could reallyyy use a signal gen so it'd be nice if it's not totally dead.
The biggest issue is that I can't find the service/manual for it. I emailed Tek but I don't have high hopes.