Need help with Soundcraftsmen RA6501

grmmusic

Member
2010-10-27 8:27 pm
I have a Soundcraftsmen RA6501, which is a Class H Amp, 750Wpc 4 Ohms. Weighs around 50 pounds, give or take.

Problem is this. I turn on the unit, and immediately the "Protect" light is lit. About every 3-5 seconds, I see the "clipping" lights for channel A and B flash, which is accompanied by what sounds like a cycling of some sort within the unit. With the cover off, it sounds like the transformer itself is what is cycling, but it's hard to tell without schematics and more knowledge about the unit itself.
 

mixerjv

Member
2010-11-24 9:56 pm
Most likely one of the final output transistors is shorted, they can be removed individually with a screwdriver.

Also, check the .27 ohm transistors for an open (white ones opposite side of the power transistors) which would idle one of three output transistors causing the others to overload causing the failure.
 

Zero Cool

Member
Paid Member
2004-09-20 6:10 am
MN
These amps have a traic that controls the transformer. it is part of the protection circuit. it clicks the transformer on and if there is a problem, shuts the transformer back off again. for example if there was a shorted speaker wire...it then cycles the transformer looking to see if the problem has been cleared....

If there is a shorted output device. it will act exactly as described. pull each output device and check for shorted devices as MixerJV suggested. These output devices are very hard to get as they are out of production. do not use a substitute. use only an original device or change/upgrade all the devices.