Mitsubishi CNC switching power supply board dead / relay board bad diode failure

[sam_sam_sam]

Re: Mitsubishi CNC switching power supply board dead / relay board bad diode failure

The Rifa caps have clear epoxy that cracks and they bulge too. Even new old stock sitting in a parts bin, I had some that got plump and cracked.
That looks like C4, C5 4,700pF Y-caps. I replace them on sight - many incidents where they short and burn because they are on mains. But you have a fuse so any damage would be limited.
They are metallized paper dielectric. You can still buy them as PME271Y series like P271HL472M250 LS=10mm. I'm using Kemet or Vishay instead.

Big X-cap C3 is a different make but these go low value with age, so I would test as well. The board has no MOV's and I think these caps help a little with mains spikes. Their EMI filtering is kind of ignored.

How do you look these on DigiKey I have never looked for this type of capacitor before so any help would be appreciated thanks

[redwire]

Re: Mitsubishi CNC switching power supply board dead / relay board bad diode failure

Digi-key, passives, film capacitors. 85,051 Results.
Then input what you know like: mounting type through-hole, 4,700pF or 10mm lead spacing, Ratings any Y1 or Y2, in stock... down to 42 results.
Mouser has a checkbox for "safety capacitors" which makes it easier.

[sam_sam_sam]

Re: Mitsubishi CNC switching power supply board dead / relay board bad diode failure

Okay thanks