VintageKustom.com: Repairing Kustom Amps » Tantalum Capacitors sub w/ Aluminum Electrolytics?

Re: Tantalum Capacitors sub w/ Aluminum Electrolytics? [message #26435 is a reply to message #26433]

Wed, 13 December 2017 11:31

chicagobill
Messages: 2005
Registered: April 2003

Senior Member

Before you start tearing apart the amp, please supply a little background information. Do you own this amp? Has it been used recently? What is the main problem with the amp that you are trying to fix? Are you using both a lamp limiter and a variac at the same time?

Without knowing more about your situation, it might be that what you are seeing is normal start up condition. I suggest that you plug the amp into your limiter (I assume a 60 or 100 watt bulb) and with no speaker connected to the amp turn it on. The lamp should flash slightly and then turn off. If this is true, then measure the dc voltage on the output jacks.

If the lamp lights up bright and stays lit, then you have a problem that needs to be addressed. Until then, please refrain from fixing anything until you know what is broken.

As for the cap discussion, there are good reasons on both sides for shotgun replacement and for replace as needed approaches. Cap life is affected by many things, age, construction, how the amp was used, how the amp was stored, etc. I feel that Kustom chose to use tantalum caps because they were state of the art at the time and they wanted to design an amp that would last a "lifetime". How many other guitar amps used 1% metal film resistors to reduce noise back in the '60s? And remember that these parts cost two and three times the price of typical caps and resistors.

I've been repairing guitar amps for more than 40 years and in my personal experience, I have not seen a high failure rate for the tantalum caps in any of the K200-B series amps. When I repair these amps, I usually test and replace as needed.

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