Soundcraftsmen Mods & PCR Regulators

[Zero Cool]

I have owned and repaired quite a few of the little Soundcraftsmen PCR-800 & PM 860, pro power series etc amps and found them to be excellent performers.
Even Audio mag reviewed them highley, slightly better then the Adcom 555 amps.

Has anyone else played with these and done any mods?

How about the PCR, Phase Controlled Regulation power supplies? i have never seen another company use such a design? (maybe for a reason?) any thoughts on the PCR design??

I have done some simple mods like upgraded the PSU caps and added bypass caps, cleaned up the internal wiring and upgraded jacks etc.

These ******s can be had really cheap and they sound pretty good. My Bryston 4B had better bottom end, but these seem a but less harsh on the top end.


Zero

[still4given]

I have one that I am trying to get going right now. Mines a PCR800. One of the PS caps is bad and I am having trouble finding an exact replacement. I see that you upgraded yours. What values did you go to and where did you add the bypass caps at?

I'm showing really high VDC right now but someone said that is because of the PCR and the bad cap. Sound right?

Anyway, I would love to hear what you did as well as looking forward to what others have to add.

Blessings, Terry

[Zero Cool]

I dont remember what i used exactly, it was some time ago. i think i found some 20,000uf caps, i used 4 per amp and upgraded the SCR's to 15 or 20 amp units. I used some nice teflon foil caps i found for bypass .1 or .01 i dont remember anymore....


I have some original SC PSU caps if you need them.


Zero

[still4given]

Originally posted by Zero Cool
I dont remember what i used exactly, it was some time ago. i think i found some 20,000uf caps, i used 4 per amp and upgraded the SCR's to 15 or 20 amp units. I used some nice teflon foil caps i found for bypass .1 or .01 i dont remember anymore....


I have some original SC PSU caps if you need them.


Zero

Help me out here. What does SC PSU stand for. I might need them.

Thanks, Terry

[eLarson]

ZC - you found Teflon -n- foil caps laying around? Man, I want to hang out where you find stuff! *heh*

The ones I've seen have been too expensive for me to contemplate seriously.

Erik

[Zero Cool]

SC = Soundcraftsmen

PSU = Power Supply Unit

I have at least 1 pair if not 2 pairs of Original Power Supply caps if you need them.

In fact, i have a extra transformer, bottom chassis, front plate, rear plate with fan available as well. I would ahve rebuilt that amp but it was missing the top cover!

I have parts Power supply board and a parts mainboard as well!!!


Here in MN we have some pretty good electronic surplus stores! you just never know what your going to find!!!

Plus i ran a home based electronics recycling company for the last 3 years, came across some really fun stuff from local Manufactures etc!


Zero

[still4given]

Originally posted by Zero Cool
SC = Soundcraftsmen

PSU = Power Supply Unit

I have at least 1 pair if not 2 pairs of Original Power Supply caps if you need them.

In fact, i have a extra transformer, bottom chassis, front plate, rear plate with fan available as well. I would ahve rebuilt that amp but it was missing the top cover!

I have parts Power supply board and a parts mainboard as well!!!


Here in MN we have some pretty good electronic surplus stores! you just never know what your going to find!!!

Plus i ran a home based electronics recycling company for the last 3 years, came across some really fun stuff from local Manufactures etc!


Zero

Hey Zero,

So, when you say Original, are we talking NOS or OLD original stock. I have just replaced the PS caps in two Haflers and my PCR-800 has bad caps as well. I'm a little leary of using old caps. If they are used, do you have any idea how old they are? Wish I could find an electronics surplus store. It's hard enough finding a decent electronics store around here.

Anyway, let me know. I do need caps for this amp.

Blessings, Terry

[still4given]

One more question.

When I power up this amp, with the new caps installed, the little green light flashes off and on. The amp sounds fine but i can't imagine they meant fo the light to blink. Also, when I shut the amp off, the two red clip indicator light come on and grow dimmer as time passes until they finally go out.

Any ideas what might be causing this?

Thanks, Terry

[Zero Cool]

S4G, the green light is supposed to blink!!!!! Later models they changed this due to customer complaints.

The light blinks at 2 different flash rates. slow is normal. and when you really kick it in the pants, the light flashes very fast and the fan kicks in on high!

This is completly normal operation dont be alarmed.


The clip lights flash when you shut these amps off as well. thats normal, dont worry.

the clip indicators monitor the negative feedback line and anytime there is .1% distortion of more they light up. very accurate. when you power down, the power supply becomes unstable and the light light up!!!


The power supply caps i have are pulled from an amp i upgraded. so they are old caps, but i have used them for bench experiments just fine. i have not done any other checking of them. but they would get you up and running in a pinch until you could fine something better.


Also, check the power supply circuit board where it mounts to the caps, the board likes to crack and you will lose connection to the power supply caps causing lots of hum!


Zero

[still4given]

Thanks for the info on the lights. I can rest easier now.

Thanks for all your help.

Blessings, Terry

P.S. Would you mind emailing me about the caps?

still4given@yahoo.com