Well I got deeper into this. Without a proper cap tester, I tried continuity testing across the terminals of all caps in the PSU. No shorts, most showing a ramp up to charge, discharge, and residual resistance.
Biblits earlier thread about a cap fix relates to a Plessey PSU I think, but the failed component was a high-voltage cap, so I decided de-solder the only large electrolytic on the primary side of my Sony PSU - 4.7uf x 400volt. It still seemed to test OK off the board, so I soldered it back in. There was also a possible dry joint on one leg of a smaller-value tantalum next to it, so I reflowed that.
Test result was a big bang, fluid squirt and impressive flow of grey smoke - while the 11si continued to boot (until I turned it off). So that HV cap was probably in the process of failing and the heat from the de-solder/solder probably finished it off. That can sits about 1mm from a large HV MOSFET and its heatsink, so has probably been cooking slowly over the life of the unit.
Now thinking I should probably also replace the other caps on the primary side - 2 x 220uf @ 250v, plus a couple of smaller filters. I'd rather not swap out the 9-10 electrolytics on the secondary low-voltage side if this is not necessary - not just from laziness, but not wanting to put more heat stress on the board than necessary.
Anyone done a major recap on a PSU like this?
Rick
Biblits earlier thread about a cap fix relates to a Plessey PSU I think, but the failed component was a high-voltage cap, so I decided de-solder the only large electrolytic on the primary side of my Sony PSU - 4.7uf x 400volt. It still seemed to test OK off the board, so I soldered it back in. There was also a possible dry joint on one leg of a smaller-value tantalum next to it, so I reflowed that.
Test result was a big bang, fluid squirt and impressive flow of grey smoke - while the 11si continued to boot (until I turned it off). So that HV cap was probably in the process of failing and the heat from the de-solder/solder probably finished it off. That can sits about 1mm from a large HV MOSFET and its heatsink, so has probably been cooking slowly over the life of the unit.
Now thinking I should probably also replace the other caps on the primary side - 2 x 220uf @ 250v, plus a couple of smaller filters. I'd rather not swap out the 9-10 electrolytics on the secondary low-voltage side if this is not necessary - not just from laziness, but not wanting to put more heat stress on the board than necessary.
Anyone done a major recap on a PSU like this?
Rick