Do I have bad caps?

[serge4]

I think I've got bad capacitors. I've got an eMac 1ghz. In some of the capacitors on the logicboard there is white seepage coming out of the bottom of the capacitors...a lot, and in others there is a slight bulge at the top with a bit of brown residue. What I need is confirmation that the capacitors are in fact bad. Unfortunately, the ones that are slightly bulging with the brown residue were behind a metal screen so it was tough to get pictures but I did manage to get one that showed some of the brown residue.

http://dynodealz.com/emac_capacitors/

[Super Nade]

Re: Do I have bad caps?

Bulging with residue = bad. You need to replace them.

[serge4]

Re: Do I have bad caps?

So the white seepage out of the bottom is normal then?

[twistedbottlecap10]

Re: Do I have bad caps?

So the white seepage out of the bottom is normal then?

The white residue looks like it is probably an adhesive caulk they intentionally applied to the caps/board to possibly keep them from being affected by vibrations. The bulging caps with the brown residue on top behind the screen are definitely bad.

[serge4]

Re: Do I have bad caps?

ok...i guess i will proceed accordingly and try to get this thing repaired for free. what fun.

[starfury1]

Re: Do I have bad caps?

The caps I can see clearly look ok and are I think the nippon chem ones
(looks like vrm type circuit)

The caps on the vertical pcb (most likely PSU) definitely look popped and need to be replaced.
(use good quality low ESR types...see the FAQ)

Make sure you check can sizes, cause it look like a tight squeeze in there.
Replace with same values for Capacitance and Voltage

Being an emac its probably going to be a pain to work on

Thats the last pic you showed

The white stuff for want of a better word is more or less clue and of no worries as far as the caps are concerned.


Also BE VERY CAREFUL , there are dangerous voltages in there

Not only the PSU but the CRT (tube, screen) circuits

it does have the potential to kill you

[gdegagne]

Re: Do I have bad caps?

You are exactly right that the white material is adhesive... I just finished a complete redux of 9 capacitors on my eMac 1.25 GHZ motherboard... Did it myself with no prior experience. check out the pics here: http://picasaweb.google.com/gdegagne...torReplacement.

I got the replacement capacitors from www.badcaps.net. I wanted to be sure that the replacement capacitors were good quality and not the same crappy ones that I was replacing.

[Krankshaft]

Re: Do I have bad caps?

Also BE VERY CAREFUL , there are dangerous voltages in there

Not only the PSU but the CRT (tube, screen) circuits

it does have the potential to kill you

As far as the CRT stay away from the red anode wire with a suction cup on the end. While it DOES NOT have the potential to kill (too little current) I can say from experience that feeling its wrath is not a fun experience.

Proper discharge procedures must be used before disconnecting this wire.

Also even after discharging the tube it can build up a potential again (around 3,000 volts or so) the theory for this is that high voltage is stored deep in the glass of the CRT.

I had a friend of mine who after removing an old picture tube accidentally touched the anode button while carrying it away and dropped it on the floor. Luckily it had integral implosion protection.

He discharged it but didn't know about the ability of the tube to regain HV.

For this reason when leaving tubes disconnected for a period of time I attach a homemade jumper wire with alligator clips on the end between the anode button and the ground strap.

I wish I was there so that i could get a good laugh.

As for the PSU as long as the plug is pulled make sure that you discharge the PSU caps. Primarily the line filter cap. In most cases they discharge very rapily after pulling the plug or through bleeder resistors.