Another day, another project!
This transformer (Paulmann 105H) failed ages ago, and I looked at repairing it today. It is a 230v AC 50Hz to 12v AC 40khz transformer for halogen lighting.
The actual fault was the microtherm thermal fuse glued to the top transistor in the attached photo.
I replaced this with a wire link to test and it then worked - for a few minutes! The thermal fuse was obviously doing its job. This was the only apparent fault.
The transistor is now out (short circuit) and it took a few resistors and another transistor with it.
I have a few questions relating to repair of this supply:
1. Is the transistor failing the likely root cause of the problem?
2. The transitor beside the one that failed was a fairchild e13009f - is the one that failed probably the same in this basic smps (the fuse was glued to it and no markings show)?
3. I have identified an PHE13009 from NXP as a replacement - very similar, but not identical - should this be OK?
4. I cannot find a similar thermal fuse - does anyone have any pointers, or should I just leave it out?
Thanks for your help
This transformer (Paulmann 105H) failed ages ago, and I looked at repairing it today. It is a 230v AC 50Hz to 12v AC 40khz transformer for halogen lighting.
The actual fault was the microtherm thermal fuse glued to the top transistor in the attached photo.
I replaced this with a wire link to test and it then worked - for a few minutes! The thermal fuse was obviously doing its job. This was the only apparent fault.
The transistor is now out (short circuit) and it took a few resistors and another transistor with it.
I have a few questions relating to repair of this supply:
1. Is the transistor failing the likely root cause of the problem?
2. The transitor beside the one that failed was a fairchild e13009f - is the one that failed probably the same in this basic smps (the fuse was glued to it and no markings show)?
3. I have identified an PHE13009 from NXP as a replacement - very similar, but not identical - should this be OK?
4. I cannot find a similar thermal fuse - does anyone have any pointers, or should I just leave it out?
Thanks for your help
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