Hi all,
I inherited a Soundcraftsmen PM860, "Phase Regulated Switching Mosfet Amplifier" years ago, and have used it now and then inbetween tube projects. It's good sounding to my ears at least, except for the fan noise.
Anyone else own one of these, or have any info? I'm not a solid state guy, and I can't find anything on the web regarding them. I think it's from the late 60's or early 70's...
Thanks!
Joel
I inherited a Soundcraftsmen PM860, "Phase Regulated Switching Mosfet Amplifier" years ago, and have used it now and then inbetween tube projects. It's good sounding to my ears at least, except for the fan noise.
Anyone else own one of these, or have any info? I'm not a solid state guy, and I can't find anything on the web regarding them. I think it's from the late 60's or early 70's...
Thanks!
Joel
I got one! But it's a RA7501. Fanless. Class H. 750WRMS Bridged.
It's working well when the protection circuit is disabled.
The problem is in the prot-circuit itself. As I also don't have a schematic I'm unable to fix it.
There a site here you can order schematics from theses amps:
http://www.compufind.com/schem.html but I still hope someone over here has it.
Pics are for JOE!
/Hugo - likes to make people dream...
It's working well when the protection circuit is disabled.
The problem is in the prot-circuit itself. As I also don't have a schematic I'm unable to fix it.
There a site here you can order schematics from theses amps:
http://www.compufind.com/schem.html but I still hope someone over here has it.
Pics are for JOE!
/Hugo - likes to make people dream...
Attachments
Only numbers on the output transistors.
Here's another site but they don't list the one you have:
http://www.rangeraudio.com/manuals3.htm
Here's another site but they don't list the one you have:
http://www.rangeraudio.com/manuals3.htm
Attachments
Joe,
What makes you think that, besides popularity?
If you're right they could be replaced by MJ15015!
Also, why is Sound-smith talking about mosfets.
Looking at my amp, the output transistors look very much like the K135 series.
I will take one out and measure it when I have some time.
/Hugo - Too bad there is so little info on such nice amps
What makes you think that, besides popularity?
If you're right they could be replaced by MJ15015!
Also, why is Sound-smith talking about mosfets.
Looking at my amp, the output transistors look very much like the K135 series.
I will take one out and measure it when I have some time.
/Hugo - Too bad there is so little info on such nice amps
Far out, glad to see this thread.
I use a pair of bridged (through my DX4200 pre-eq) PCR800 in my big stereo, driving a large pair of JBL CF-150 (98dB/w/m). The combination of lots of watts and very efficient speaker systems provides tremendous dynamics and the edge of realism in the reproduction of music.
Sometimes I wish that among my 26 or so pair of speaker systems I had just one with a difficult load to drive adequately!
The 205 wpc 'family' of Soundcraftsmen amps are probably STILL the best bargain to be had. I mean for serious, quality sound. Maybe mine are 'special,' but I think they're more the norm. They have a firm grasp of the bottom end, and smooth clear delivery throughout the upper registers.
I also have the A5002, PA5001, and a b-channel out MA5002 that I'm trying to determine what the power transistors are. Anyone know, please post! The MA5002 has the most visual appeal, y'know those big ol' VU meters just do something for an amp.
I use a pair of bridged (through my DX4200 pre-eq) PCR800 in my big stereo, driving a large pair of JBL CF-150 (98dB/w/m). The combination of lots of watts and very efficient speaker systems provides tremendous dynamics and the edge of realism in the reproduction of music.
Sometimes I wish that among my 26 or so pair of speaker systems I had just one with a difficult load to drive adequately!
The 205 wpc 'family' of Soundcraftsmen amps are probably STILL the best bargain to be had. I mean for serious, quality sound. Maybe mine are 'special,' but I think they're more the norm. They have a firm grasp of the bottom end, and smooth clear delivery throughout the upper registers.
I also have the A5002, PA5001, and a b-channel out MA5002 that I'm trying to determine what the power transistors are. Anyone know, please post! The MA5002 has the most visual appeal, y'know those big ol' VU meters just do something for an amp.
Heavy Metal
I have a Soundcraftsmen PM1600. The PCR power supply is an interesting design. I had a power supply capacitor fail catastrophically; the SCRs protected the transformer and everything else by acting as fuses.
Soundcraftsmen (Martron) was absorbed by MTX in the early 90s. I believe their amplifier designs became mobile versions after that...
I have a Soundcraftsmen PM1600. The PCR power supply is an interesting design. I had a power supply capacitor fail catastrophically; the SCRs protected the transformer and everything else by acting as fuses.
Soundcraftsmen (Martron) was absorbed by MTX in the early 90s. I believe their amplifier designs became mobile versions after that...
MTX
Soundcraftsmen was absorbed by MTX and MTX does not want to know you if you need something like a schematic. I know I tried. I got the " We don't support this product anymore. " response from what passes for tech services. They were kind enough to attatch an advertisement for thier car stereo products. Needless to say I was not thrilled. Contrast this with the Hafler tech site. Downloadable manuals with schematics for just about everything. Oh well such is life.
Soundcraftsmen was absorbed by MTX and MTX does not want to know you if you need something like a schematic. I know I tried. I got the " We don't support this product anymore. " response from what passes for tech services. They were kind enough to attatch an advertisement for thier car stereo products. Needless to say I was not thrilled. Contrast this with the Hafler tech site. Downloadable manuals with schematics for just about everything. Oh well such is life.
I have been searching for the transistor type labelled "Power 8" in my MA5002 (250 wpc) which corresponds to Q11-Q16 in the schematic. I have just learned the proper type is the 2SD424.
The MA5002 is from the late 70s, but I am convinced the A5002 and PA5001 (which I also have) use the same devices (and they are all 250 wpc Class H amps of virtually the same size and weight).
Hope this helps somebody keep one of these superb old guys running!
The MA5002 is from the late 70s, but I am convinced the A5002 and PA5001 (which I also have) use the same devices (and they are all 250 wpc Class H amps of virtually the same size and weight).
Hope this helps somebody keep one of these superb old guys running!
I'll second Pete's reply.
I talked to MTX's service department years ago when they did support Soundcraftsmen products. Was told D424 and B554 were the replacement transistors.
Due to cost break, I have used MJ15024/25 without any trouble or audiable difference. My MA5002, RA7501, and A5002 are all running flawlessly. The RA7501 has been running stereo 2-Ohm subwoofer loads at high levels since 1995
The tech also said the number on the transistor was assigned when they were matched. Although I believe them to be house part numbers as I have seen mostly numbers 4 or 8 with 25 or 26 "switches".
I talked to MTX's service department years ago when they did support Soundcraftsmen products. Was told D424 and B554 were the replacement transistors.
Due to cost break, I have used MJ15024/25 without any trouble or audiable difference. My MA5002, RA7501, and A5002 are all running flawlessly. The RA7501 has been running stereo 2-Ohm subwoofer loads at high levels since 1995
The tech also said the number on the transistor was assigned when they were matched. Although I believe them to be house part numbers as I have seen mostly numbers 4 or 8 with 25 or 26 "switches".
Some potentially useful info & links etc here
Soundcraftsmen Reference Site Soundscraftsmen Repairs
Disappointing rats nest wiring in here Soundcraftsmen LA 2502 Amplifier
https://en.wikipedia.org/wiki/Soundcraftsmen
Soundcraftsmen Reference Site Soundscraftsmen Repairs
Disappointing rats nest wiring in here
Soundcraftsmen LA 2502 Amplifierhttps://en.wikipedia.org/wiki/Soundcraftsmen
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