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#1 |
Member
Join Date: Oct 2013
City & State: Adelaide, South Australia
My Country: Australia
Line Voltage: 240VAC 50Hz
I'm a: Knowledge Seeker
Posts: 30
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![]() Hi,
Back after a long hiatus with some old power supplies that need repairing. I've recently picked up a couple of 386SX systems, two 486DX systems, a SiliconGraphics Indy and an iMac G3 that either have verified leaking capacitors in their power supplies, or are likely to in the near future. For the sake of simplicity, instead of tackling all at once, I'm starting with the 386's and one of the 486's. The 386's power supplies are Seasonic SS4040A's, with caps that are visibly leaking, and 9 replacement caps per unit are required. Most appear to be from the Rubycon YXB series, although due to the placement of some others it's difficult to tell if all of them are. Code:
10v 1000uF x3 16v 47uF x2 16v 470uF x2 25v 100uF x1 50v 22uF x1 Mains: "Omats K112" 400v 100uF x1 Code:
Chemicon LXF 6.3v 1500uF x1 6.3v 2200uF x1 10v 270uF x1 16v 2200uF x2 Chemicon SME 25v 47uF x2 Mains: Nichicon CE 200v 470uF x2 For the 386's I'm leaning toward the Panasonic FC series. That's based on another post I read around here a while back that suggested they would be a fitting replacement for the YXB series, they're reasonably cost-effective, and they seem to be more readily available - more so than the other brands - from the various online electronic suppliers that operate in Australia. Other brands are available of course, but either not a complete range (so some mixing and matching is required) or in lower quantities / back-ordered to a future date. As for the Chemicon LXF and SME series, I'm not sure what their ideal equivalents are. These are relatively light-duty supplies, running infrequently and in not particularly hot environments (except maybe an Australian summer sometimes). I'd still opt for 105C rated components as that seems to be what was specified from factory, but other than that, I don't suspect they need anything too fancy or exotic. And if anyone wants to know why I don't just replace them with a more modern power supply - they're AT by spec, but far from the standard AT form factor. Cheers, Mic. Last edited by iMic; 02-19-2023 at 07:00 PM.. |
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#2 |
master hoarder
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 11,249
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![]() Just curious, are the Rubycon YXB caps leaking electrolyte from the bottom of their bungs?
I know Nichicon PR and PL in old PSUs do have this problem from time to time (especially the PR series.) United Chemicon LXF might also be affected, but not as badly. Basically, all of the manufacturers that used Quaternary ammonium salts in their electrolyte are susceptible to leakage from their bungs... though some more than others, it seems. UCC SME is an old discontinued series, I believe. Modern equivalent is SMG seires. You can also use Nichicon VR or Rubycon PX. Panasonic FC is entry-level low ESR. However, those will work fine for the SME's too. Like you said, these PSU don't need anything too fancy. So anything like Panasonic FC will work fine. As for the input high-voltage caps, just check them and feel free to leave them as-is, since they rarely fail, even if very old. But if you do replace them, you can go with either 105C or 85C general purpose series. Save the old ones too, just in case you need them for a future project / repair. They should still be good for re-use. |
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#3 | |
Member
Join Date: Oct 2013
City & State: Adelaide, South Australia
My Country: Australia
Line Voltage: 240VAC 50Hz
I'm a: Knowledge Seeker
Posts: 30
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![]() Quote:
I'll have a look at the Nichicon and Rubycon equivalents too. I don't mind spending a bit extra to get a better cap, as long as I can actually source them and they're correct for this application. Would also like to stick to one or two manufacturer series per supply so I don't end up with Rubycon, one Nichicon because it wasn't available in the Ruby, one Panasonic, etc throughout the unit. The mains capacitors I figured would be fine. All except one unit currently powers up (although I don't run them for long, a half minute at most) so the AC side is working. Given that replacing those caps would add a substantial overhead to the cost of each repair, I'll leave those alone unless I have a solid reason to replace them. |
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#4 | |||
master hoarder
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 11,249
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![]() Quote:
I do have one old-ish (mid 90's) AT PSU with those and Lelon caps. So will keep in mind to check them out before assembling back that machine when I get to it. Quote:
With UCC, you can still get LXZ series, which will cover OK for the LXF series. KYB might be getting a little on the low side of ESR, but should also be OK. I tend not to "discriminate" when it comes to recapping PSUs ![]() ![]() Quote:
Large caps are expensive, so I leave them alone. For modern PSUs with APFC circuits, though, they are always worth checking, because APFC tends to stress them extra and sometimes kill even good Japanese brands. Of course, when it comes to AT PSUs, those haven't even heard of such circuit, so nothing to worry about. ![]() |
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#5 |
Badcaps Veteran
Join Date: Aug 2005
City & State: San Jose, CA
My Country: USA, Unsure of Planet
Line Voltage: 120VAC, 60Hz & 115VAC, 400Hz
I'm a: Professional Tech
Posts: 3,505
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![]() For output caps, older series that are still available pose less risk of stability issues.
From Nichicon, the PS and PM series are RoHS-compliant versions of the 90s vintage PR and PL series, with basically identical specs. The PJ series is a little newer but probably won't cause problems, and the PW series a bit newer still. The PA series night be risky. From Nippon Chemicon, the LXV series is approximately equivalent to Nichicon's PJ series, and the LXZ series is approximately equivalent to the PW series. The LXY series is a somewhat limited intermediate between LXV and LXZ. Panasonic's FC series is approximately equivalent to the PW and LXZ series.
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#6 |
Member
Join Date: Oct 2013
City & State: Adelaide, South Australia
My Country: Australia
Line Voltage: 240VAC 50Hz
I'm a: Knowledge Seeker
Posts: 30
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![]() Cheers for the advice. I opened the second 386 power supply and saw it used Panasonic caps across the board, so figured based on looking at the two that Panasonic FC's were probably a safe bet.
The ASTEC I'd planned to go a mix of UCC and Nichicon, but none of the recommended equivalents were available - different specs were either "on order" or "end of life" at Element14 and Mouser. Given the UCC LXZ series would cover for the LXF, Panasonic FC is approximately equivalent to the LXZ, and the FCs would also be a suitable substitute for the SME series - I just went with the Panasonics across the board for this supply too. It'll probably be a couple of weeks before the order comes in, but when they do, I'll get them fitted and see how it goes. |
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