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Soundcraftsmen 900X2
Soundcraftsmen 900X2
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Old 11th July 2005, 07:11 PM   #11
still4given is offline still4given  United States
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Soundcraftsmen 900X2
First thing I would do is measure for DC on the outputs. I would also measure for AC on the filter caps. My first PCR-800 did that and all it needed was new filter caps. My second one had some drivers out on the power supply. I just swapped those out and it plays perfectly. Cost me something like $10.

Blessings, Terry
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Old 11th July 2005, 08:56 PM   #12
oPossum is offline oPossum  United States
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I have a ProPower 4 that did the same thing. Loud buzz, lights, and a horrible stink. One of the filter caps gave out and vented.

Remove the regulator board that sits on top of the caps and check for signs of venting or bulging.

It is a good idea to replace the SCRs and their drivers in addition to the bad caps. At least check them if you don't want to replace. A bad SCR will quickly destroy the caps.
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Old 11th July 2005, 08:59 PM   #13
cygnusxi is offline cygnusxi  United States
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Default Soundcraftsmen 450X2

I meant shorted.
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Old 12th July 2005, 07:32 AM   #14
destroyer X is offline destroyer X  Brazil
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Default Hello guys!, have you some Soundcraftsmen schematic?

Please, send it to me, i never constructed any circuit of this brand.

As i can remember, a genuine US Industrie, and a very respectable brand.

I will be happy to hear the sound produced, or, at least, inspect the schematic thopologie.

Thanks in advance.

nanabrother@yahoo.com

regards,

Carlos
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Old 12th July 2005, 02:29 PM   #15
cygnusxi is offline cygnusxi  United States
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Thanks for the responses. What does SCR stand for?

No bulging on the caps, but there were small burn marks scarttered on the board bolted to the caps.
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Old 12th July 2005, 03:04 PM   #16
still4given is offline still4given  United States
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Soundcraftsmen 900X2
Here is the schematic I have for the PCR 800.

Click the image to open in full size.

Blessings, Terry
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Old 12th July 2005, 03:34 PM   #17
oPossum is offline oPossum  United States
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Are the burn marks on the bottom of the board? Take a carefull look at the top of the big caps. Compare to this picture . Notice the blown vent of one cap. Some caps have black vents rather than white, so it may be hard to tell if it has vented. Burn marks on the circuit board directly above the vent is a sure sign the cap has died.

SCR is Silicon Controled Rectifier. It is a triggerable diode. There are four along one side of the board, they have a small heat sink. They are used as the bridge rectifier in these amps. Voltage regulation is done by changing the phase angle they trigger at (PCR - Phase Control Regulation).

If you don't have experience with electronic repair, it is probalbly best to just replace the caps. Make sure the polarity is correct (+ to +, - to -).
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Old 12th July 2005, 04:12 PM   #18
oPossum is offline oPossum  United States
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Carlos: Do you build a new amp every week?

I have a collection of Soundcraftsmen shematics at www.soundcraftsmen.info

The PCR800 is very similar to the 450x2, and ProPower 1,3,4 & 10. It is rated at 205 W per channel at 8 ohms, and 325 per channel at 4 ohms. This is by far the most common Soundcraftsmen MOSFET amp design.

Hitachi MOSFETs where used until they stopped production, then Exicon MOSFETs where used for a few years.

Most of the MOSFET amps have a Phase Control Regulation (PCR) power supply.


Terry: Do you have a larger version of that schematic that you could send me? Power supply too???
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Old 12th July 2005, 04:23 PM   #19
still4given is offline still4given  United States
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Quote:
Originally posted by oPossum
Carlos: Do you build a new amp every week?

I have a collection of Soundcraftsmen shematics at www.soundcraftsmen.info

The PCR800 is very similar to the 450x2, and ProPower 1,3,4 & 10. It is rated at 205 W per channel at 8 ohms, and 325 per channel at 4 ohms. This is by far the most common Soundcraftsmen MOSFET amp design.

Hitachi MOSFETs where used until they stopped production, then Exicon MOSFETs where used for a few years.

Most of the MOSFET amps have a Phase Control Regulation (PCR) power supply.


Terry: Do you have a larger version of that schematic that you could send me? Power supply too???

Yes I do. Let me dig them out. A fellow sent them to me through snail mail a while back. Let me search for them and I'll get back to you. Send me an email so I won't forget. These threads get buried sometimes. Out of sight, out of mind.

Blessings, Terry
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Old 12th July 2005, 04:53 PM   #20
cygnusxi is offline cygnusxi  United States
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The burn marks (light brown squiggly lines) I saw were on the top side of the board. I'll try to take some pictures of what I see and post them. I don't recall the caps being vented, but I'll look again and try and take a picture of those too.

Thanks again.
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