Products > Test Equipment
Brymen BM235 InEr issue
Sebaxtian:
--- Quote from: ebastler on July 28, 2024, 03:59:32 pm ---But the marks on the green soldermask are much less pronounced, if they are present at all.
--- End quote ---
Maybe it hasn't been used as much as mine.
Fungus:
--- Quote from: ebastler on July 28, 2024, 03:27:14 pm ---
--- Quote from: Fungus on July 28, 2024, 03:16:45 pm ---Are they they really relying on solder mask to prevent the switch from making contact? That doesn't seem believable to me.
--- End quote ---
Maybe it does not matter whether or not the switch contacts the trace in that position, since other contacts remain open?
--- End quote ---
I guess not. The switches make contact between adjacent tracks so if both contacts touch the same track, that's OK and if there's nothing to the side then that's OK too. Contact pairs circled below.
It just looks bad...
floobydust:
OP I would clean the inside of the banana jacks. Jack detect is a high impedance circuit using the half-shells and any leakage currents there between them will give troubles.
I use IPA on a Q-tip and stuff it in there, give it a spin to clean out crud, then let it dry out. One of yours (V?) looks black at the top compared to the others, so might be grease or oxide something from your test leads contaminating them.
The two-pin header to the jack board has the mA, A jack detect signal. Make sure it's clean on the jack board as well.
The Brymen rotary switch I think is a poor design. It shows amateur PCB layout and the wiper is cave man tech, I think they could do much better. It also shows in new models if you look at the traces there, a few mistakes.
Sebaxtian:
--- Quote from: floobydust on July 28, 2024, 05:13:47 pm ---OP I would clean the inside of the banana jacks. Jack detect is a high impedance circuit using the half-shells and any leakage currents there between them will give troubles.
I use IPA on a Q-tip and stuff it in there, give it a spin to clean out crud, then let it dry out. One of yours (V?) looks black at the top compared to the others, so might be grease or oxide something from your test leads contaminating them.
The two-pin header to the jack board has the mA, A jack detect signal. Make sure it's clean on the jack board as well.
--- End quote ---
I already cleaned the banana jacks with IPA and checked the continuity on the split banana jacks, and it was ok.
floobydust:
It seemed to get worse after you took it apart and cleaned it, then got better, is that right? I think it just needed to dry off, some IPA has added water.
What lube did you use on the rotary switch? That topic will start another war here. How did the rotor wipers look, I use a paper swipe to clean it.
I thought they used mineral oil on the PCB. I use DeOxit F5 with PPE with no problems, although it has little lubricant in it.
Grease is a bit much - lithium salts conduct a little, silicone grease reacts with nearby components.
I thought the BM235 has had issues with the rotary switch needing a spacer, and the input jacks might crack. Not sure but just to alert that it could be a mechanical problem.
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