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Old 13th March 2012, 07:17 PM   #1
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Default Need Counterpoint SA-3 Board Photo

Short request: I need a clear photo of the bottom of a Counterpoint SA-3 main board.

I'm putting a very abused SA-3 preamp back together, and I'm down to the last problem (I hope). I get a nasty motorboating thing on the phono stage. A previous owner tried to do a star grounding thing with three jumpers from the underside of the board to ground at the back of the chassis. I suspect there's a ground loop in there somewhere that's causing the motorboating. They're clearly owner mods -- different wire, poorly dressed etc. My schematic reading skills are terrible and I can't figure out whether these three points are supposed to be jumpered or not, and if so, how.

Thanks in advance gentlemen.
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Old 27th October 2012, 03:57 AM   #2
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I've got a friend's SA-3 here, trying to install a switched ladder attenuator in the very minimal space available. The documentation for the unit is kind of marginal with a truncated schematic that inconveniently omits details and leaves me suspecting the 3.0 has significant differences from the 3.1. For now I'm not going to attempt any other upgrades, just do any servicing needed on the power supply caps and FRED rectifiers. I've got decent test equipment to verify performance.

Did you learn anything from your experience?
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Old 27th October 2012, 04:04 AM   #3
TerryO is offline TerryO  United States
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Quote:
Originally Posted by Damon Hill View Post
I've got a friend's SA-3 here, trying to install a switched ladder attenuator in the very minimal space available. The documentation for the unit is kind of marginal with a truncated schematic that inconveniently omits details and leaves me suspecting the 3.0 has significant differences from the 3.1. For now I'm not going to attempt any other upgrades, just do any servicing needed on the power supply caps and FRED rectifiers. I've got decent test equipment to verify performance.

Did you learn anything from your experience?
Damon,

You've got the test equiptment, the knowledge and skill to do a first class, top notch job. It would be nice if there was a schematic available though........

Best Regards,
Terry
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Old 8th November 2012, 02:51 PM   #4
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There must have been a few different board layouts throughout the production the SA3. The schematics and documentation that I found on the net for the SA3 and the SA3.1 only partially match the board layout on my SA3. (SN: 43016)

Below is a low-quality picture of the top side on my SA3 prior to recapping . . .

Click the image to open in full size.

Next time I have the bottom cover removed, which should be next week sometime, I'll post a few good quality pictures of both the bottom and top.

Link to schematics and docs referenced above:

http://www.audio-circuit.dk/download...e-sm.pdf&cat=1
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Last edited by Forrestc; 8th November 2012 at 03:09 PM.
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Old 11th November 2012, 02:05 PM   #5
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Shot of the bottom . . .
Attached Images
File Type: jpg DSC00179.jpg (969.5 KB, 157 views)
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Old 12th November 2012, 01:08 AM   #6
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The power supply component layout is substantially different in the unit I have here; the series regulator TO-3 heatsink is mounted directly on the board and the orientation of most of the electrolytic caps is different.
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Old 14th November 2012, 01:48 PM   #7
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FWIW, the board shown in post #5 is marked Rev. "B".
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Old 27th November 2012, 04:19 PM   #8
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I too have a counterpoint Sa3, and would like to Upgrade/mod it. Can't justify sending 2200 to Altavista to do this. Anyone successfully modded this pre?

Thanks,


Mark
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Old 27th November 2012, 05:42 PM   #9
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I notice that in photos published of succesful commercial products, most of them use single-sided PCB's. AFAIK double sided in good quality mass production costs about the same. Any reason for that? Or they are just being cheap?
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Old 1st September 2013, 04:12 PM   #10
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I know this response is way late, but it may help someone. There are at least three different layouts of the SA-3/3.1 preamp. Motor boating can be caused by a number of things. If it is only in the phono stage, then first make sure that any shielded cable in the phono stage has its shield grounded. Try grounding it to the ground side of the phono stage grid resistor (I'd say cathode resistor, but this design grounds the cathode).
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