Hartke HA 4000 Power Cap Blown

[chunkitup]

I am trying to fix a friends amp. One of two huge power caps has the top blown off. I started a thread awhile ago and was asked to check the rectifier. I finally got around to it and the bridge rect. is fine. I measured a little over .5 on all the diodes using the diode check. The cap is from a co. called SamWha and the cap is discontinued but was said to have a life of 1000 hours. Could the cap just go bad by itself? What else should I check and does anyone have a schematic?

[52 Bill]

Yes a cap can fail for no reason other that it was manufactured with the wrong amount of something or another. It could also have been hit with a power surge, or it could have been overheated.

If the bridge rectifier tests ok, then just replace the cap with one of equal or higher voltage and temp ratings and power it up. If everything works, then I would replace the other matching filter cap with a new one and call it done.

[Enzo]

Parts can just fail. Doesn't mean the amp was not engineered well, or that someone abused it in some way. Sometimes shit just happens.

I have replaced that exact cap myself, in one of those.

I don't know that you'll find Samwha or whatever unless you order parts from Samson. if I recall it was a large value high voltage cap. I more often use Mouser for general parts, but in this case, I think Digikey will be easier place to find a similar cap.

SOmetimes caps come in more than one shape and more than one footprint. As top the shape, you often get tall and skinny versus short and wide. Like my women. In rack gear, watch the tall ones, make sure there is room under the lid. And the wide ones? Make sure ether is space. DImensions are in the catalogs.

I think these are "snap-in" caps. SOme of those use two legs, and some three or four legs - two of which might be dummies for stability only. If the suitable replacement doesn't match the holes on the board, you may need to drill a new hole. Just be careful where you put it if you do.

[chunkitup]

Ok, I got the bad cap out and I can see the writing on the side better. There is a
CE-HM 85degC and then a 100WV10000uf What does the WV represent? I dont believe it is a snap in though because there is only 4 terminals and that is it. I am having difficulty finding a replacement. Any help? samwha.com is not up, atleast for me.

[chunkitup]

Perhaps I am confused on what snap in means

[52 Bill]

"What does the WV represent?" Working Voltage

Are the 4 terminals all active or are 2 just for support?
I wouldn't be too concerned about finding a Samwha branded cap. Measure the diameter of the case and the lead spacing, then go to Mouser or Allied or Digikey and find an equivalent replacement that will fit the board and the physical space around and above it.

[chunkitup]

Yes two terminals are for support. I cant seem to find anything with the two extra blank terminals.

[chunkitup]

I think I found what I need. Please just take a quick look and let me know if I right.
http://www.cde.com/catalogs/381-383.pdf

[Enzo]

From that list, the 100 volt 10,000uf cap to use is:
381LX103M100A102

Forget Samwha, you won't find it, the brand doesn't matter.

This is a snap in cap. The caps on your data sheet are snap ins.

You will usually see ecaps in three forms:
Screw terminals - obviously not here
Wire leads - where plain old wires come out the end of the part
Snap ins - where short slightly curved pins are riveted to the ends.

They are called snap-ins because the size and shape of the legs allow them to snap into place on the board to hold themselves steady while you solder them. Wire leads in contrast have to be bent to hold the part steady.

Electrically there is no difference between the types. If you could find wire leaded cap of same value, you could use it. You won't though, not this large a cap.

If you find one with the exact lead pattern as the original, great. But all you really care about is the two active legs. It is not necessary to find all four legs on a new part. As I mentioned before, you may find yourself needing to drill a new hole in the circuit board to fit the new lead spacing.

CHeck out this stock number:
Digikey - P10038-ND

MOuser and Allied both have caps in your value, but they both cost twice as much or more, and they are in screw terminals.

[chunkitup]

Enzo, Thanks for the info. I quickly learned alot about this cap while trying to find a replacement.
My caps dimensions are 40mmx60mm so the Digikey P10040-ND was the one I was looking at. Thanks again.