Counterpoint SA12 MOSFETS RFM10P12 RFM10N12

[Rob Hannah]

Trying to source mosfets to get my Counterpoint SA12 back on the go, a tall order I know, but I'm always optimistic!

Need two RFM10P12 and two RFM10N12

Anyone got some they could sell, or know of a supplier?

Thanks 🙂

 

[homemodder]

I think your best bet is to replace those with newer mosfets which have much better specs anyway. You should replace them on both channels. It seems those mosfets are a weakpoint in that design.

Otherwise try here Alta Vista Audio Home Page

 

[Rob Hannah]

Thanks, might be forced into a re-design by the look of it although I was hoping to keep it original. Can't stretch to the alta vista prices for this just now.

 

[Michael Chua]

Hi Rob

I have the higher voltage version - 150V.

RFM10P15
IRF233

NOS by Harris. The IRF233 is the same as the RFM10N15.

 

[Rob Hannah]

Thanks Michael, higher voltage versions sound like a good bet, I imagine they should be pretty much a direct replacement? Have you two of each you would be willing to sell? PM me?

Would love to get the SA12 working again, sad seeing it sitting so forlorn.

 

[Michael Chua]

I have only 9 pairs in stock. No problem selling 2 pairs. I'm quite certain they can replace the 120V version directly.

Price is US$16.50 each. This is my cost when I bought them in the early 90s. Mosfets were pretty expensive then.

Shipping is about US$8-10 (USPS 1st Class Air Mail) in Carton Box (8"x6"x4").

Do you happen to have the SA12 schematic? I always thought they used 2SK135 and 2SJ50 Hitachi Mosfets. I may be mistaken.

 

[Rob Hannah]

I don't have the schematic I'm afraid, would certainly be useful though. I think you're right, some did use the 2SK135s and 2SJ50s, others used the ones that are in mine.

Price sounds fine to me, thanks. Message me direct with payment details please, and I'll send my address.

 

[VivaVee]

I think you're right, some did use the 2SK135s and 2SJ50s, others used the ones that are in mine..

The SA12 used the RCA (then Harris) RFM12N10 & RFM12N10 (120V 10A TO3) and the Hitachi 2SK398 & 2SJ112 and finally the International Rectifier IRF130 & IRF9130(100V 14A/11A). All devices are vertical MOSFETs.

The Hitachi 2SK135 and 2SJ50 are lateral MOSFETS and not usable in the SA12 without modifying the design.

The NMOS and PMOS pairs must be closely matched

 

[quinnling]

This thread has the schematics of the SA100 which is similar to SA12
http://www.diyaudio.com/forums/solid-state/54491-counerpoint-sa100-200-power-amp-scheme.html

You should also check out this thread
http://www.diyaudio.com/forums/solid-state/188029-counterpoint-sa12-whats-smell.html

 

[jacco vermeulen]

RCA (then Harris) RFM12N10 & RFM12N10 (TO3)

Ahh, happy days.
Not the same numbers, better duo actually, but neither are yours. (12A,100V)

 

[VivaVee]

Ahh, happy days.
Not the same numbers, better duo actually, but neither are yours. (12A,100V)

Not sure what you mean, jacco.

The part numbers I quoted - RFM12N10 & RFM12N10 - are taken from the production inventory list. The parts you show are the TO220(?) packaged version - the difference is RFM versus RFP.

It is easy enough to transpose the numbers - so I went back to the archives and checked!

 

[VivaVee]

This thread has the schematics of the SA100 which is similar to SA12
http://www.diyaudio.com/forums/solid-state/54491-counerpoint-sa100-200-power-amp-scheme.html

The SA100 and SA12 output stage is very similar. As in a late production SA12 will be identical to the SA100 but the main board is very different. The SA100 used the main board from the SA20/220.

So the schematic linked to is useful for rebuilding the output stage which is probably all that you need as the preceding circuitry is AC coupled.

 

[jacco vermeulen]

Not sure what you mean

Mea culpa, i enjoy riddle joking.

I'm numbers challenged, very pretty sure that the numbers Counterpoint used were : RFM10N12 + RFM12P10.
So i checked too.

 

[Rob Hannah]

Thanks very much for all the help so far everyone! 🙂

The original ones on my SA12 are RFM10P12 and RFM10N12 (so maybe another revision?)

 

[jacco vermeulen]

Rather unwise one then, using a 100W P-channel with a 75W Pd N-channel as 'complementary' pair is poor engineering (imo).

(that numbers are similar doesn't mean they are alike)

 

[Johnloudb]

Here's another thread dealing discussing SA12 output stage repair ... should be of interest.

http://www.diyaudio.com/forums/solid-state/188029-counterpoint-sa12-whats-smell.html

 

[VivaVee]

Mea culpa, i enjoy riddle joking.

I'm numbers challenged, very pretty sure that the numbers Counterpoint used were : RFM10N12 + RFM12P10.
So i checked too.

Thank you for clarifying that. That makes another 'pair' used in the SA12. Mostly historical interest as the RCA/Harris devices are all long gone.

 

[jacco vermeulen]

Definitely, the plastic parts i posted are spares for something i built ~25 years ago.
Cost me about $8 each back then, speak about changing times.

 

[Rickor]

Hello Dear Friends and Minded!
Trying to bring back to life my favorite oldman SA-12. Perhaps someone still have in stocks old original MOSFET IRF 130 and RFM 12P10 or some substitution?
With big hope and gratitude waiting for good news!!

 

[sathit dokmadue]

Mea culpa, i enjoy riddle joking.

I'm numbers challenged, very pretty sure that the numbers Counterpoint used were : RFM10N12 + RFM12P10.
So i checked too.

thank you schematic..