A Not-So-Complete Astec PSU Recap

[CompuNurd]

I took out a working Astec PSU from one of the LCs I got in a lot and began checking for leakage. Sure enough, leaked caps! Not too bad, but better safe than sorry. Got the caps today, noticed three were the short, fat kind that you have to manipulate correctly just to get them to fit. I soldered everything on with no issues, until I began re-assembly. I see a heatsink with white thermal goop on it that I took off the PSU to get to the caps. The new caps are too fat to allow the heatsink to re-attach, and the heatsink doesn't even look like it had any thermal connection to the previous caps! Is this heatsink necessary? If I don't find a way to put it back on will something explode, overheat, or start a fire? The heatsink has a small metal loop that grips a transistor, but the loop is so small, it doesn't look like it could possible conduct whatever heat the transistor was producing. Should I find the right caps to make the heatsink fit, or just leave it like it is?

 

[Elfen]

I had the same problem, but I used long legs on the caps to I could bend them so now the cap rests against the heat sink. It still works fine in this condition.

Personally, I'm leaving it for now until I can get new caps later, this way I know that the PSU works.

 

[CompuNurd]

Is the heatsink necessary? Would it be an issue if I didn't re-install it?

 

[Elfen]

Yes it is, as the power transistors on it need it.

You could resolder the caps so they have a bit of lean on them away from the heatsink. If not, remove the cap and add some long legs and then solder the cap on the legs. That should help.