Yeah, that's not supposed to happen. Was looking for DC offset on my 2nd board- source connected but not playing. No load. I put the black probe on the black speaker terminal and the red probe on the red speaker terminal. Couldn't get a stable reading, which I thought was odd. I pulled the probes to change the scale on my DMM, and when I placed the black probe on the second time it arced. Now my DMM probe is black and pitted.
What went wrong and how can I fix it?
What went wrong and how can I fix it?
I think it's a ground (earth) issue, but I don't know what I should be looking for/fixing/replacing. Could the chip have a short? I know my transformer is (slightly- 28 vs 25) over the recommended range, but the first channel worked right away. I guess I have a different question now.
Is it worth connecting the tested power supply to the oscillating amp? That one step will tell me if it's the power supply causing the issue and it doesn't risk frying the good amp board. If the amp has the same issue with the good power supply, then it's definitely the amp. I think I just talked myself into it. Probably could have checked this last night.
Is it worth connecting the tested power supply to the oscillating amp? That one step will tell me if it's the power supply causing the issue and it doesn't risk frying the good amp board. If the amp has the same issue with the good power supply, then it's definitely the amp. I think I just talked myself into it. Probably could have checked this last night.
The bad amp board is behaving the same on the verified/working PS. I didn't probe the speaker terminals again, but I hooked up my test speakers and got the same noises.
Use caution, this could even be AC line voltage. At any rate, don't connect your speakers until it's fixed.
Voltmeters don't normally cause arcing like that, whether DC or AC.
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Totally agree, I disconnected the faulty board, took reference photos, and posted them in my build thread. Also got in touch with chipamps.com. The other channel of this dual mono kit works fine. Still not sure what the issue is, hopefully I'll have some answers soon.
Can you measure the power supply directly normally, without these symptoms, on the bad channel?
Try all the combinations, though none should spark.
Also, try borrowing another meter just to be sure.
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Well, no sparks, but no measurements either. I think my DMM is toast. Tried testing the working one too- all I'm getting is "1" which is an overload, even at the 2000V scale. I no longer trust this tool and I'm going to go replace it. I'm going to return it and try again with one straight out of the box.
Alright, brand new DMM with brand new battery says 39.4V on the "bad" board between PG+ and V+, matching 39.4V between PG- and V-. The working board is 39.5V on both sides. It's close to the 42V limit, but definitely and obviously under it. I can safely say that the power supply is not the problem.
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