| Electronics > Repair |
| BERNINA power supply board (Switch Mode) issue diagnosis and beyond (fixed) |
| << < (15/15) |
| tautech:
Now showing a China flag ? :-// I thought you were in Wellywood Max ? |
| max.wwwang:
--- Quote from: tautech on December 26, 2024, 10:08:46 am ---Now showing a China flag ? :-// I thought you were in Wellywood Max ? --- End quote --- >:D >:D >:D Have been and still in Wellywood. :popcorn: |
| max.wwwang:
Ordered parts all arrived sooner than expected. Replaced apparently blown R35, R37, and R38, as well as MOSFET T131 (measured as gone). Tried to power up the board without replacing the UC3844. No luck – Vcc had 1.2V or so. Then proceeded with a new 3844. It immediately went back to where it was, i.e. power supply working except for the 6V rail. When I was about to execute my reflow-all-related plan, one joint popped out as clearly suspious. Not sure if I just missed it before (unlikely?) or it became more visible after the time of handling and sitting idle. Anyway, redid that point, everthing is now sweet as. Thanks for all the help. It's been very enlightening (and occasionally refreshing my memory). Also had several reads of the IC datasheet, which helped a lot in understanding its working. Yet more reads are required. |
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