| Electronics > Repair |
| Bench PSU not much current limit adj range after pots replaced |
| (1/2) > >> |
| Circlotron:
I've got one of these cheapo noisy bench power supplies that I use for rough-enough-is-good-enough purposes. A while back the voltage setting was becoming unstable, jumping up and down several volts. I read somewhere that they have dodgy pots. As luck would have it, I had a big bag full of exactly suitable 10K pots that work threw out, so I replaced all four and things were back to normal, or so I thought. I was so pleased with myself... Some time later I found that the adjustment range on the current limit setting is not what it should be. Should go from zero to 5 amps, but it only goes from about 4 to 5 amps. Now I'm *fairly* sure all four original pots were 10K but maybe they weren't. Does anyone have one of these that they could have a look? Or maybe a schematic. Haven't found a schematic on the interwebz. Seems like the same case is used with any number of different internals. |
| FIXITNOW2003:
only circuit i can find on this not all 10K! |
| Circlotron:
In the meantime I found the info that put me onto the bad pots, but it seems I didn't look too carefully. The fine adjustment pots are both meant to be 1K. It's weird that the volts setting works okay with one wrong pot but not the current setting. |
| Circlotron:
--- Quote from: Circlotron on October 01, 2024, 07:50:20 am ---It's weird that the volts setting works okay with one wrong pot but not the current setting. --- End quote --- Just now I set the coarse voltage pot to 20.0V and with the fine pot I could wind it up to 22.9V Could someone try that with their same PSU and see what the figure is? |
| Circlotron:
--- Quote from: FIXITNOW2003 on October 01, 2024, 06:23:27 am ---only circuit i can find on this not all 10K! --- End quote --- That one is a bit different to mine. https://www.eevblog.com/forum/testgear/mch-k305d-cheap-switching-lab-power-supply/ |
| Navigation |
| Message Index |
| Next page |