Hi!
I'm trying to repait a SMPS in an induction cooktop hope it's not a problem that only the repairment is DIY...
I attached the schematic, the problem is: it's providing the desired 24V for a few minutes but after 5-10 minutes it goes down.
0V at output, 310VDC is till on and the TOP254 is trying to boot (C pin jumping between 4.8V and 5.8V) but can't get up I don't know why.
What should I check? What can be the cause? Is it a thermal warming up that turns it down?
And after it warmed up even if I turn it off and on again it wont start so something is built up that's causing the problem.
After letting it cool down for on hour than it goes again for a few minutes...
History:
- originally it produced just 16V instead of 24V
- I measured all passive parts (diodes, resistors) with DMM and they look OK
- then I replaced all the electrolytic caps (and so far now for low ESR/L types unfortunately)
- then I replaced the Opto, the TL431 and the TOP254
- then the 24V came back but it's not stable...
- even the load is not cut off from the SMPS
Please help!
Thanks in advance!
Cheers!
I'm trying to repait a SMPS in an induction cooktop hope it's not a problem that only the repairment is DIY...
I attached the schematic, the problem is: it's providing the desired 24V for a few minutes but after 5-10 minutes it goes down.
0V at output, 310VDC is till on and the TOP254 is trying to boot (C pin jumping between 4.8V and 5.8V) but can't get up I don't know why.
What should I check? What can be the cause? Is it a thermal warming up that turns it down?
And after it warmed up even if I turn it off and on again it wont start so something is built up that's causing the problem.
After letting it cool down for on hour than it goes again for a few minutes...
History:
- originally it produced just 16V instead of 24V
- I measured all passive parts (diodes, resistors) with DMM and they look OK
- then I replaced all the electrolytic caps (and so far now for low ESR/L types unfortunately)
- then I replaced the Opto, the TL431 and the TOP254
- then the 24V came back but it's not stable...
- even the load is not cut off from the SMPS
Please help!
Thanks in advance!
Cheers!
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