Axiom EP600 v2 hum (capacitor help)

S

stasik80

Enthusiast
My recently bought used Axiom EP600 v2 subwoofer has developed a low level hum. Its there even when fully disconnected from the reciever. I tried several quick fixes like disconecting the ground prong on the power line and trying different outlets and the hum still persists. After some research online I discovered that the cause might be failing capacitors. Im not an expert with electronics but I can solder so want to try to replace them my self. I would like to ask for some help on sourcing the capacitors. Attached is a picture of the capacitor. The markings are Chang CD292 33000uF 63V 25/085/21. I can't find that exact capacitor. I found some that appear to be similar but I'm not 100% sure and also, the places where I found them only sell in bulk. Could someone assist in sourcing 2 of these?

Edit:
After looking at my own picture I realized that I'm not certain which capacitors are the relevant ones. The bigger black and white ones or the smaller black and blue ones. Does anyone know how to determine that?

Thanks, Stas
SUB_CAP_1.jpg
 
slipperybidness

slipperybidness

Audioholic Spartan
My recently bought used Axiom EP600 v2 subwoofer has developed a low level hum. Its there even when fully disconnected from the reciever. I tried several quick fixes like disconecting the ground prong on the power line and trying different outlets and the hum still persists. After some research online I discovered that the cause might be failing capacitors. Im not an expert with electronics but I can solder so want to try to replace them my self. I would like to ask for some help on sourcing the capacitors. Attached is a picture of the capacitor. The markings are Chang CD292 33000uF 63V 25/085/21. I can't find that exact capacitor. I found some that appear to be similar but I'm not 100% sure and also, the places where I found them only sell in bulk. Could someone assist in sourcing 2 of these?

Edit:
After looking at my own picture I realized that I'm not certain which capacitors are the relevant ones. The bigger black and white ones or the smaller black and blue ones. Does anyone know how to determine that?

Thanks, Stas
View attachment 33102
To test a cap properly, you need to remove it from the circuit and put it on a cap tester. At that point, you may as well just install new caps as the hard part is getting them off the board.

It's hard to see what's going on here with the smaller caps, I'm wondering if those are bypass caps to help handle transient peaks better than the filter caps can. Regardless, almost certainly the large caps are the filter caps.

You also don't need "exact replacements" for the caps in a P/S. But, certainly choose the same or better specs when replacing them.

I'm assuming you are in the USA?

My favorite vendors are
parts-express.com
mouser.com
digikey.com but they tend to be a bit more pricey.
 
slipperybidness

slipperybidness

Audioholic Spartan

You should have no problem sourcing them (or just about anything else) here! Mouser is located in Dallas and tends to have some really fast shipping.

Note that sometimes if you hit a minimum quantity, the price per part will go down. So, for example you may end up with 10 parts for the price of 8, etc. Nothing wrong with some spares on hand, especially if they are cheap or free.

But, mouser sells singles too.
 
slipperybidness

slipperybidness

Audioholic Spartan
Thanks for the sources. How can I tell the termination style and pin count of the capacitor?
I found this doc which seems to suggest its a Snap-In 4 pin cap but as its a different manufacturer I'm not sure the model numbers are consistent:
Again, it is hard to tell from that single pic! Have you ever done this type of work? Do you have the tools? Do you have a friend with more experience and tools too?

NOTE--THESE TYPES OF CAPS CAN HOLD A CHARGE FOR A LONG TIME AND GIVE QUITE A PAINFUL ZAP IF THE CHARGE IS NOT BLED OFF AND YOU CONTACT THE 2 TERMINALS! GOOD DESIGNS TEND TO HAVE BLEED RESISTORS, BUT I HAVE COMMERCIAL AMPS FROM REGARDED BRANDS THAT DO NOT HAVE BLEED RESISTORS.

SAFETY IS YOUR #1 PRIORITY!

If you use that Mouser link in post#3 and apply filters to the search results, then compare the pictures on that page vs. the actual parts on your board, you should be able to figure it out.

YOU DEFINITELY NEED TO DO SOME MORE COMPARISONS AND RESEARCH ON YOUR OWN TO BE SURE.
 
S

stasik80

Enthusiast
Yes, Im aware that the caps can hold a charge. I dont have extensive electronics experience but I have some. What I was taught to do with large capacitors is to short the terminals to bleed the charge. When I did that on these, one sparked which I assume mean that it still carried a charge.
 
slipperybidness

slipperybidness

Audioholic Spartan
Yes, Im aware that the caps can hold a charge. I dont have extensive electronics experience but I have some. What I was taught to do with large capacitors is to short the terminals to bleed the charge. When I did that on these, one sparked which I assume mean that it still carried a charge.
LOL!

You would be better served to use a resistor to connect the terminals, leave it there and let it bleed away the charge. Of course, you need a resistor that can handle enough power to not burn itself out.
 

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