| Electronics > Repair |
| Tektronix TDS754D - acquisition board test fail |
| << < (7/8) > >> |
| TERRA Operative:
I think the firmware sees the chanel numbering as 0 indexed, i.e. 0, 1, 2, 3 corresponds to physical channels 1, 2, 3, 4. So I would look for problems on channel 4 Try swapping the channel 1 and channel 4 hybrid (don't forget the thermal paste on the chip on the hybrid module!) and see what happens. I keep saying it and will say it again.... Be careful with the hybrids, and make sure they are perfectly seated in the metal holder before screwing it to the PCB! :) Easy tests are easy, so may as well rule out bad relays or bad hybrid module. |
| Rax:
Update on this, as only now I managed to work my way down the projects backlog and get back to this). Putting this back on the bench, I got the error above, but also a new error originating in U208. Suspecting I may have some soldering issues - I absolutely don't love those SOJ packages one bit - I tested continuity pin to pin and indeed I had a short between two of them. Once I fixed that, it seems now to pass all tests, startup or the full range from the Utilities (before this last fix, it would fail both). Given the original issue was reported to occur after extended running (hours), I'll hold back on popping that cork, but I'm hopeful this is it. I think this failure mode occurs due to the heat from U200 nearby, which cooks those SRAMs in time. |
| Rax:
An effusive thanks to TERRA Operative here for his sending me the SRAM ICs (used, but tested) to repair this. Much appreciated! Members like him make this a great place to hangout. |
| Rax:
SPC also completed successfully. This always failed before. |
| TERRA Operative:
Nice. I reckon run it overnight and give it a bunch of SPC tests too. |
| Navigation |
| Message Index |
| Next page |
| Previous page |