Recapping a LC - TDK PSU

[Elfen]

Did some recapping of boards and an LC Power Supply (PSU) today. I had a few successes here and there. Thus I post a few things I learned in recapping my first LC power supply though I am already used too such similar jobs.

The problem I had was the size of the caps. Uniserver's webpage ( http://maccaps.com/MacCaps/Capacitor_Reference/Entries/1990/10/15_LC_I%2C_II%2C_III_Power_Supplies.html ) was very beneficial and informative to this cause, but this is only a partial recapping which is fine with me. The caps in the LC PSU are tall and skinny. The caps I got are short and fat, I did not take into account the physical size of the caps.

The caps replaced are as follows, as per his website:

2 - 270µf - 25V - ELNA - Long Life Radial

1 - 270µf - 10V - ELNA - Long Life Radial

1 - 56µf - 25V - ELNA - Long Life Radial

Though all of the caps should have been replaced, past posts ad discussions with him tells me that these 4 are the most problematic, and I found that they had all leaked in the LC PSU. But the LC PSU is very tight on space and the smell of rotten fish rose when I started deoldering. Furthermore I did not have a 270µf - 10V, so I another 270µf - 25V in its place. But again, the problem here was the physical size of the caps.

One of the two caps I had to have standing on its long legs so its contact to the heat sink would be minimal. Another cap could not fit into the space the old cap was in so again, giving it long legs I was able to place it in the tight space.

At least the LC PSU is working again, but I will have to recap it one more time with tall skinny caps that ae rated higher in voltage by a bit instead of short fat ones I used now. BTW - the dead PSU is now working again and a dead LC is now living once more!

 

[pintodave]

Nice! I'm going to have to bookmark this. I used to have an LC in my first computer collection about twelve years ago and all I have left of it is the PSU, which powers two 80mm 12v fans for an amplifier. This will come in handy when it kicks the bucket!

 

[Elfen]

Best to get those tall skinny caps, the short fat ones I used were a rabid female dog to put in! But I got them in there! And the PSU works beautifully!

And like Uniserver posted in several places in the forum, those caps will leak, you just wont see them until you lift them off the board! And those bad boys were leaking when I pulled them out!

Now I got 1 more LC (LC III) PSU to recap, but I need to get clips for its molex connector. Two of them corroded and broke off. I found the metal clip at digikey, but you need to buy the plastic connector with it, and at $7, its a waste of a good piece of plastic and too high for the connector. But I need it.

http://www.digikey.com/product-detail/en/ECM100S%20CONKIT/1470-1220-ND/4487601

 

[pintodave]

I have several of those from old AT style PSUs in my inventory. They still have wire on them or are clipped right at the pin, but could be soldered to an existing wire. Let me know if you need some via PM and I will send some your way.

 

[techknight]

I guess if its personal stuff, it doesnt really matter. But for me, I dont half-arse anything when I do recaps. I want it to last 

 

[Elfen]

This was a steep (re-)learning curve for me to get past, but I do agree with you TechKnight and your work of replacing all the caps in the PSU. I just wanted to see if this would work after a partial recap and I'm glad that it does work after a partial recap. I have to give it to Uniserver in that his information was correct in getting it up and running again. The thing I have to ask is this, should I continue with short fat caps or switch to skinny ones on a second recap? I'm thinking of switching to skinny ones but with a higher voltage rating on them but I'm afraid of the tight spacing inside the PSU might not be able to hold the caps in place.

 

[techknight]

It doesnt matter as long as they fit AND they are specced low ESR SMPS use.

 

[Elfen]

I remember the ESR from our last online postings, and got them as they had a low ESR but I did not account physical size.

As is, the PSU works fine. I just need to make it into a neater job with the right sized caps when I replace all the caps. Thanks for all that information not too long ago.