Need to recap my Classe Audio DR-8 Amps - need suggestions

kdross

Here is a post on re-forming, this guy knows more about electronics in his sleep, than some of the aggro know all's here.
 
" Electrolytics will have a very long shelf life.
But will NEED to be reformed slowly to achieve their specified parameters. I am not surprised that high quality 40 year old electrolytic's still meet specification after reforming."
   
Also from Silicon Chip Magazine on how to do it, if you have the gear and knowledge. (you have to pay for the full article)
 http://www.siliconchip.com.au/Issue/2006/October/Reforming+electrolytic+capacitors?res=nonflash.

As I said I've done many, never been a problem, so long as they didn't leak out any of their electrolyte fluid to start with.

Cheers George

kdross Don’t listen to Kosst and waste big money on new caps, your amp are hardly used as you say.
Just take it to a good tech to get them re-formed, he knows not to power the amp, he’ll just use a big variac the bridge rectifiers and the supply caps, to re-form them first. Then after he’s re-formed them, he’ll do the same with the pcb board to re-form the smaller on board electro’s.
Parts cost = Zero, instead of at least $800 for all new caps, $1000 for good quality ones like you have now.
Labour cost = much less time hands on in total than replacing them all.

As you can see for just one amp you have 4 large red power supply caps and 5 smaller blue pcb electros. Double this for two amps. Those red ones for memory, I’m sure are Classe branded Nichicons at close to $100 each.
http://www.hifishock.org/galleries/electronics/classe/power-amplifier/dr-8-1-classe.jpg
This is very similar to the Classe DR25 I had to do.
http://img.usaudiomart.com/uploads/large/1304766-classe-audio-dr25-power-amplifier-excellent.jpg

Cheers George

Caps that need reformed are garbage and should be replaced.

This is not correct, I’ve done it many times with new old stock Siemens that have been on the shelf for 15 years or so, and other good quality ones, and I’m sure the ones in the Classe aren’t rubbish probably Nichicons.
So long as it’s done as I stated above it works great, that (10v-20v) is the volts you increase every hour or so.

kdross
I recently purchased two Classe Audio DR-8 amps. The amps were barely used and are in mint condition, but I think I need to have them recapped due to being over 20 years old.

No not really seeing they were barley used this should be tried first, all they would need is to be powered up very slowly 10-20 at a time over a few hours so all the electrolytic caps can "form" themselves again.
This can only be done by a tech using a big variac that can handle the power, other wise the variac will blow.

There is plenty to read on "forming old electrolytic caps" on Google.

Cheers George

1: If you have any dc offset coming from the amp, you may hear it at switch on by a good hefty thump through the speakers.

2: And if it has a constant large amount of dc offset you can as gergeab said measure it with a DMM if you have one and know how to use it.
Or after the thump look at the bass driver will be in or out a little more than where it normally sits in it's rest state with no amp on, if there is dc present.

Cheers George