Counterpoint Sa 220 Service Manual
Hello I am reviving this thread, not common to have a SA-220 on the workbench. This amp has one channel blown (at least, visually) all output transistors are shorted, and so are the gate resistors (on the + side). The transistors are RFM10N15 and IRF9241, and wonder if this is correct. There is also a resistor blown in the main board near the led wires, R140 I checked the regulators and the MJ340's and they are OK no user manual, and of course no schematic. Any hint will be appreciated regards Alexander. Not sure if anyone will respond or not.
Quercus 3 posts 4:05pm 'I see I am a bit late posting about a Counterpoint SA-220 and what is now a NP-220. I have been busy listening and not reading audio blogs. It has been a rock solid amp providing organic, emotional content through the loudspeakers. I could never overdrive the amp and it has provided 22+ years of service. We have 2 Counterpoint Diagrams, Schematics or Service Manuals to choose from, all free to download! Counterpoint sa 3 1 preamplifier service manual 857 KB counterpoint sa5 1 new 79 KB.
We wound up abandoning fixing the SA220 because I fried the transformer inadvertently. My brother moved on to a Class D amp that he put together, and honestly likes it better than the Counterpoint on his Apogees. Your transistor numbers appear to be correct. The problem with these amps is that with no source (or is it drain?) resistors, the MOSFETs had to matched incredibly tightly. Couple that with the fact that it is difficult to get them, let alone suitable quantities to match that closely, and you are kind of between a rock and a hard place, so to speak. As far as I know, there are no replacement output stages since Mike Elliot is no longer doing business as Alta Vista. A few thoughts.
Counterpoint Sa 220 Service Manual Youtube
While Alta-Vista Audio is closed, he does list a way to obtain a service manual for $50 which includes a schematic. While the FETs are not available from AVA or on the open market, is offering a FET-replacement/upgrade for the SA-12/100 series. While his upgrade design would be a LOT easier to apply to a SA-20, it may be possible to do apply it to an SA-220, especially after getting the service manual. I expect he could supply the FETs he uses and technical expertise, for a price.
Greg in Mississippi P.S. Pars, bummer you didn't post anything about killing the transformer, I have a spare SA-20 transformer here (after doing the AVA Plitron upgrade). If you still have the carcass & any interest to re-kindle that project, contact me via PM. Greg, Thanks for the offer, but my brother sold the carcass (before Alta Vista closed).
This was probably the least enjoyable audio repair/DIY project I have done, as this amp is a pain in the. to work on. Greenstreet is using Exicon devices in a TO-247 package.
Counterpoint User Manual
The Exicon devices are not pin compatible with the SA220 MOSFETs, and you still have the extremely tight matching to consider, (unless you were to use source resistors, which was the method I had nearly working until the tranformer failed.) I think I had emailed them back when I was helping my brother, asking if they were considering offering anything for SA20/220, and they said no. Download update windows xp sp3 offline 2013 calendar pdf. This amp has one channel blown (at least, visually) all output transistors are shorted, and so are the gate resistors (on the + side). The transistors are RFM10N15 and IRF9241, and wonder if this is correct.
There is also a resistor blown in the main board near the led wires, R140 I checked the regulators and the MJ340's and they are OK no user manual, and of course no schematic. Finding and selecting matched output MOSFETs to the required match is not practical. It is possible to use unmatched MOSFETs and add source resistors, which is what everyone else except Counterpoint did/does on their amps.
Counterpoint Sa-220 Craigslist
The penalty is an amplifier output impedance which is higher (because the global feedback network does not include the output stage) but still lower than many amps on sale. And, even then the available TO204 package MOSFETs are still very limited and expensive. Or replace the output stage with something else completely -do both channels at the same time and sell off the one functioning set of MOSFETS to someone. Or gut the amp, and replace the circuitry with something else that is happy to run off +/-70V rails. Finding and selecting matched output MOSFETs to the required match is not practical. It is possible to use unmatched MOSFETs and add source resistors, which is what everyone else except Counterpoint did/does on their amps.
The penalty is an amplifier output impedance which is higher (because the global feedback network does not include the output stage) but still lower than many amps on sale. And, even then the available TO204 package MOSFETs are still very limited and expensive. Or replace the output stage with something else completely -do both channels at the same time and sell off the one functioning set of MOSFETS to someone. Or gut the amp, and replace the circuitry with something else that is happy to run off +/-70V rails. What value of resistor would be suitable?.47 @ 2 watts? Thanx for the replies.