Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

Counterpoint SA-220 Capacitor Question
Counterpoint SA-220 Capacitor Question
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 17th March 2016, 07:08 PM   #1
BassAmp is offline BassAmp  United States
diyAudio Member
 
Join Date: Mar 2016
Location: CA
Default Counterpoint SA-220 Capacitor Question

I just bought a set of replacement tubes for my father's Counterpoint SA-220 which he has had since the early 90's. The tubes have never been replaced so I was really hoping he would realize some sonic improvement.

However, when I removed the top cover, I discovered this:

Click the image to open in full size.

Remarkably, the amp still works. We have no way of knowing when this may have happened. My father says he has never seen smoke come from the amp. I'm thinking maybe this was a serendipitous discovery as this might have been a precursor to disaster. I know by reading on this forum that if you blow an output channel on this amp, it is pretty much game over.

The capacitor is labeled as C50. C51 is right next to it. I don't know the value yet. I know it needs to be replaced, but I have some questions.

1. Should I replace both C50 and C51?
2. Can anyone recommend good replacement caps?
3. Is it a simple matter of simply replacing the caps or are there any other special considerations I need to make? Are there other components that should be replaced as well?
4. Should I replace ALL the caps in the amp?
5. Once the cap(s) are replaced, will it be ok to simply replace the old tubes?

I am very comfortable replacing components like capacitors etc. but I don't have any real testing background. For example I don't have a scope and a variac etc.

As a side note, it appears that getting access to the bottom of the main board will be quite a chore.

Hopefully someone here can shed some light on this.

Thanks for looking
  Reply With Quote
Old 17th March 2016, 07:20 PM   #2
Algar_emi is offline Algar_emi  Canada
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Counterpoint SA-220 Capacitor Question
Counterpoint is know for using sub-specs parts. This cap seems pretty standard, replace both with the higher voltage that fit in that location.
  Reply With Quote
Old 17th March 2016, 07:27 PM   #3
BassAmp is offline BassAmp  United States
diyAudio Member
 
Join Date: Mar 2016
Location: CA
Quote:
Originally Posted by Algar_emi View Post
Counterpoint is know for using sub-specs parts.
Amazing. I had better not tell my father this!

Quote:
Originally Posted by Algar_emi View Post
This cap seems pretty standard, replace both with the higher voltage that fit in that location.
That's it? As simple as that? That's good news. Is there a brand you can recommend?

Does it seem strange to you that the amp still works? By the way, he isn't using it until this is fixed
  Reply With Quote
Old 18th March 2016, 02:11 AM   #4
Algar_emi is offline Algar_emi  Canada
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Counterpoint SA-220 Capacitor Question
The kind of failure we see on the picture is usually done by overvoltage. For example into a tube equipment, most of the time the power supply is not regulated. If you start the amp without tube, some supplies may be highers, and the design and parts specs have to take that into account. Counterpoint seems to always have a few parts that are under rated. I repaired a Counterpoint amp where some under specs power resistors had overheated and burn, taking the PCB and some traces/pads with them. Sometime also some caps are too close to a heat source (tube, big wattage resistors) and were not specs 105C but just 85C, and had aged rapidly until death.

The amp I repaired (a SA-12 I think) was really good sounding thought. The guy sold it after a little while but know he regretted. He should had kept it.

Watch when you'll replace the caps for the PCB traces and pads. Counterpoint PCB are easy to damage and are of rather poor quality...

As I said these caps seems to be 'Generic' type. I would use about anything, same value, higher voltage as possible that fit, but don't go overboard. These caps are probably just around 50cents each.

When I said 'the higher voltage that fit' I also meant within reason (that was implicit if they are 16V, used 25 or even 35V for example...

I think that one member here, ANALOG_SA, used to be an authorized repair guy for Counterpoint, well I think he doesn't like the designer that much... I think he said 'Stay away from Counterpoint as far as you can'. I'm guessing he's talking from experience.

Last edited by Algar_emi; 18th March 2016 at 02:22 AM.
  Reply With Quote
Old 18th March 2016, 03:10 AM   #5
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by BassAmp View Post
1. Should I replace both C50 and C51?
For now replace only the bad cap, unless you want to do a full refresh of all of them.
This cap may have had greater ripple current from its position in the circuit, and so failed sooner.
If you intend to keep this for years, a full cap refresh would be in order after the initial repair works.
  Reply With Quote
Old 18th March 2016, 04:08 AM   #6
BassAmp is offline BassAmp  United States
diyAudio Member
 
Join Date: Mar 2016
Location: CA
Thank you both for your responses.

I think my father would like to keep the amp. I think it is a good match with his SA-5000 preamp.

I opened it up again and found that the caps are Xicon 6800uF 10V 20%. There is no temp rating on them.

Remarkably I happened to have two brand new Nichicon 6800uF 16V 85C VR(m) series caps that are the same size . What are the odds of that? I had these from another repair. From what Algar_emi said, it sounds like these will work. Is 85C ok?

The real trick here is getting to the bottom of the main board. It looks like a total nightmare just to disassemble this thing. Both of the heatsinks/output boards need to come off each side and I will have to desolder a bunch of leads just to get the board out. What were they thinking? Maybe this is why ANALOG_SA said to avoid Counterpoint.

Since it will be so much work just to remove the board, might it be worth while to replace the bad cap with something "nice"? On another forum I read a recommendation for CU teflon or silver caps in these amps. But maybe that was for the huge caps in the front.

Rayma, are you sure it wouldn't at least be a good idea for starters to also replace the one identical cap (C51) right next to the blown one?

Thanks again for your help!
  Reply With Quote
Old 18th March 2016, 09:37 AM   #7
sgrossklass is offline sgrossklass  Germany
diyAudio Member
 
Join Date: Nov 2004
Location: Germany
Quote:
Originally Posted by BassAmp View Post
Remarkably I happened to have two brand new Nichicon 6800uF 16V 85C VR(m) series caps that are the same size . What are the odds of that? I had these from another repair. From what Algar_emi said, it sounds like these will work. Is 85C ok?
Those should be fine. Looks like it's a "general purpose" series, but from a quality Japanese manufacturer at least. 85C is plenty OK in most places except directly next to a regulator or something.

The cap failing like that may also be an indication of an overvoltage condition, so you'll want to check voltages as well.
Quote:
Originally Posted by BassAmp View Post
The real trick here is getting to the bottom of the main board. It looks like a total nightmare just to disassemble this thing. Both of the heatsinks/output boards need to come off each side and I will have to desolder a bunch of leads just to get the board out.
Joy. And you can't get to it through the bottom of the case? Not service-friendly indeed. And it seems people have found about this before, if this old thread is any indication.
Quote:
Originally Posted by BassAmp View Post
Since it will be so much work just to remove the board, might it be worth while to replace the bad cap with something "nice"? On another forum I read a recommendation for CU teflon or silver caps in these amps. But maybe that was for the huge caps in the front.
Probably not, but rather some small coupling caps.

Anyway, you'd probably be well-advised to hunt for more underrated parts while you're at it.
Quote:
Originally Posted by BassAmp View Post
Rayma, are you sure it wouldn't at least be a good idea for starters to also replace the one identical cap (C51) right next to the blown one?
Might not be such a bad idea indeed if these amps have a history of using underspec'd parts.
  Reply With Quote
Old 18th March 2016, 12:38 PM   #8
Algar_emi is offline Algar_emi  Canada
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Counterpoint SA-220 Capacitor Question
When I repair stuff, I always try to repair just the problem and not to cause others

In this case since we know these parts are bad, without touching the PCB I would simply cut them apart with a cutter and let the leads exposed, then I would desolder them from the top. Then I would try to reinstall the new ones, again from the top, and if possible solder their pins from the side, leaving the cap standing a few millimeter off the PCB.

These are small caps, and there won,t be any mechanical stress on the leads because the case is light. I do that all the time in my home made double sides PCB without issue.

This way you can replace the caps, and not touch the PCB...

It all depends on the space inside the thing.
  Reply With Quote
Old 18th March 2016, 08:25 PM   #9
BassAmp is offline BassAmp  United States
diyAudio Member
 
Join Date: Mar 2016
Location: CA
Again, thanks for the replies

Quote:
Originally Posted by sgrossklass View Post
Joy. And you can't get to it through the bottom of the case? Not service-friendly indeed. And it seems people have found about this before, if this old thread is any indication.
Unfortunately, there is not a removable bottom cover. Yes, I read that whole thread while I was researching this problem. I am definitely not alone here!

Algar_emi, that is a great idea! I don't think I would have thought of that. This could make this process MUCH easier. I will have a serious look inside to see if this is possible.

It appears that these two caps are sitting right next to a heat source.

Click the image to open in full size.

I don't know how hot it gets.

Can anyone tell by looking at my pictures what these two capacitors are actually doing? What is their function?

Would it be worthwhile to use a couple of these instead of my VR series?

UKW1C682MHD Nichicon | Mouser

Thanks again
  Reply With Quote
Old 18th March 2016, 08:34 PM   #10
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Counterpoint SA-220 Capacitor Question
Hi Algar_emi,
Not the way to repair these amps at all!

That capacitor blew due to high ambient temperature coupled with high ripple current. Counterpoint did not use substandard parts at all! What they did was use the parts at too high a level for current and voltage.

In case you are wondering, I was a Canadian warranty service shop for Counterpoint. I still repair them as well.

There are a number of issues with this equipment, servicing them on your own is not advised because of the number of "gotchya's" that exist. If you manage to blow an output, you are in for an expensive repair. Not to mention that the amplifiers are not easy to work on either.

Most of the preamps and power amps have design issues with the power supplies. The best advice I can give is to not get creative. That generally makes things worse then they were. I see enough of these poorly serviced come in. I'd rather they weren't hacked before they arrive. A hacked service attempt is the #1 reason for surprise estimate increases.

-Chris
__________________
"Just because you can, doesn't mean you should" my Wife
  Reply With Quote

Reply


Counterpoint SA-220 Capacitor QuestionHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
counterpoint sa-100/sa-220 schematics? Williams Audio Solid State 15 12th June 2017 09:45 PM
Counterpoint SA-220 problem... Pars Solid State 149 7th May 2014 06:45 PM
Counterpoint SA-220 ampzilla Tubes / Valves 0 25th April 2013 02:20 AM
Counterpoint SA-220 mods civiced Tubes / Valves 0 9th April 2012 02:12 AM
counterpoint sa-100/sa-220 schematics? Williams Audio Analog Line Level 3 24th February 2006 06:46 PM


New To Site? Need Help?

All times are GMT. The time now is 10:20 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki