I am getting voltage readings at half of what they should be on the collector of the power outputs. The amp will idle fine with no signal input, but when input audio starts the amp will shut off the channels. relays will go out and back on and the channels back on for a few seconds.
If half of the bridge rectifier fails it will put out half of the expected DC voltage at a nasty sawtooth wave.
Thoughts ???
Can a CS800 run on half power and not blow fuses ?
Re: Can a CS800 run on half power and not blow fuses ?
Curious how old this amplifier is?
Have the power supply caps ever been replaced? Have any electrolytics been replaced in the amp?
Unplug power supply from amp boards and measure power supply output. Unplugged do you have full voltage or is it still half?
If those amp boards are working I'd leave them unplugged if you are having a power supply problem. Avoid damaging them while supply is being repaired.
Bridge rectifiers can be replaced for peanuts. Caps cost more.
Just checked ebay and a 1,000 volt 25 amp bridge rectifier to your door with free shipping is only $7.50. Three times what they used to be when things were sane.
Not sure which CS-800 you have, but early versions have 81 volts DC + & -, and 16 volts + & -, while the newer version has 74 volts DC + & - and 15 volts + & - according to schematics. So be careful in there.
And I just checked with Mouser for the 15,000mF caps at 100 volts and they range from cheapies at less than $20 to nice ones priced at $253.00. Make sure to check physical measurements for good fit in amp.
https://www.mouser.com/ProductDetail/Un ... wRRsnQo%3D
https://www.mouser.com/ProductDetail/Co ... 20jqMQs%3D
I wonder how much Peavey spent on their caps?
Have the power supply caps ever been replaced? Have any electrolytics been replaced in the amp?
Unplug power supply from amp boards and measure power supply output. Unplugged do you have full voltage or is it still half?
If those amp boards are working I'd leave them unplugged if you are having a power supply problem. Avoid damaging them while supply is being repaired.
Bridge rectifiers can be replaced for peanuts. Caps cost more.
Just checked ebay and a 1,000 volt 25 amp bridge rectifier to your door with free shipping is only $7.50. Three times what they used to be when things were sane.
Not sure which CS-800 you have, but early versions have 81 volts DC + & -, and 16 volts + & -, while the newer version has 74 volts DC + & - and 15 volts + & - according to schematics. So be careful in there.
And I just checked with Mouser for the 15,000mF caps at 100 volts and they range from cheapies at less than $20 to nice ones priced at $253.00. Make sure to check physical measurements for good fit in amp.
https://www.mouser.com/ProductDetail/Un ... wRRsnQo%3D
https://www.mouser.com/ProductDetail/Co ... 20jqMQs%3D
I wonder how much Peavey spent on their caps?
Re: Can a CS800 run on half power and not blow fuses ?
There is no "nasty sawtooth wave" without significant current draw from the power caps: they will top off just fine. I've seen sort of an unusual architecture for various high-power amps from Peavey where the power transistors don't connect to the output rail but to the main amp ground and pull the power rails of the floating speaker power supply back and forth. This architecture keeps the whole driving stage at fixed voltage levels but actually drives the speakers via the center tap of their separate power supply.
If this separate power supply is flaky, the center tap will not be centered between the power rails solidly enough to provide the necessary current.
Replacing the bridge rectifier is sort of a no-brainer, followed by checking any of the power capacitors for defects.
If this separate power supply is flaky, the center tap will not be centered between the power rails solidly enough to provide the necessary current.
Replacing the bridge rectifier is sort of a no-brainer, followed by checking any of the power capacitors for defects.