Electronics > Repair

Hameg HM1008, blowing rifa cap.

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Yamin:
Hi everyone,
I had couple of HM1008 scopes repaired 5 years ago all with the input capacitor blown. Each unit started to fail one after  the other (couple of months apart) giving out thick smoke *magic blue smoke. I replaced the rifa caps and the units have been working fine since.
But I had the same problem occur couple of days back, and it was the first scope which became faulty and the first scope I replaced the cap. Now I'm afraid the rest of the scope are soon to follow.
I know Rifa caps are notorious to blow up like this, but from what I have seen they should last for a long time. 5 years is too soon no?
Any idea what could cause this? Could varying mains voltage cause this?Also noticed that the cap is very tightly packed with the heatsink touching it.
Finally any suggestion on a suitable replacement which could be more reliable? When I replaced the caps I replaced them with the exact same one.
Thanks in advance.

bd139:
Where did you buy the replacement RIFA caps from?  They have a shelf life and can be compromised when not even powered up. Honestly I'd replace them with a different brand X2. Any one will do, just not another RIFA.

And yes I've had a couple blow up on me  :-DD

BreakingOhmsLaw:
Yes, there is a thread here somewhere where the new old stock RIFA already has cracks. These things have a shelf life.

Never replace with RIFA with RIFA. I recommend the WIMA MKP-X2 series as a replacement.

Yamin:
Actually I misspoke these were actually WIMA caps (I might have been thinking of another project).
It was originally WIMA caps and I replaced them with the exact same type.
Are WIMA caps known to blow up?
Any suitable replacements for these?
Thanks

bd139:
Never seen a WIMA blow up. That's new.

Anything X2 rated, same voltage and capacitance and lead pitch will do the job.

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