Peavey GPS 1500

[PfeifferElectronics]

I have a GPS 1500 pa amp that isn't producing the amplitude that I would expect. I probed the outputs for DC and found none. However, I was shocked..(literally) when I touched the heat-sink. I was surprised to find 88VDC on both heat-sinks to the ac ground at the 120VAC input. Is there supposed to be voltage on the heat sinks? I wouldn't think so but I'm not an expert by any means. Any help would be appreciated. If this voltage is bad, I would think I need to replace all the amplifier transistors. Thoughts?

Thanks

[nosaj]

I have a GPS 1500 pa amp that isn't producing the amplitude that I would expect. I probed the outputs for DC and found none. However, I was shocked..(literally) when I touched the heat-sink. I was surprised to find 88VDC on both heat-sinks to the ac ground at the 120VAC input. Is there supposed to be voltage on the heat sinks? I wouldn't think so but I'm not an expert by any means. Any help would be appreciated. If this voltage is bad, I would think I need to replace all the amplifier transistors. Thoughts?

Thanks

Hell yea those heatsinks are hot.
So first off schematic contact Peavey to get a schematic.
Do you have a signal generator? These amps really need something with a preamp to drive them. I used to use a Drum machine plugged into the power amp and a dummy load plugged into the power amp. Then measure the AC voltage on the dummy load.

nosaj

PS. what you expect could have something to do with the input or the output(speakers ohms)

[J M Fahey]

Half the current threads are about "putting out less that expected" but nobody offer *numbers* to qualify that subjective statement.

So: what do you expect (in V RMS) and what are you getting (again in V RMS) ... all into a proper load of course.

What are you driving it with? Again in V RMS.

[Enzo]

Most Peavey amps print the output voltage next to the output watts by the speaker connections. SO there should be little confusion as to what the amp should produce. I think 68v into 4 ohm on your model, for example.

[Jazz P Bass]

Here is the spec sheel on the Peavey GPS series of amplifiers.

peavey_gps900_1500_2600_3500_specs.pdf

The GPS 1500 has an input sensitivity of 1.12Vac.
That is the signal amplitude required to drive the amplifier to full power.

(A guitar by itself will typically output 0.100 Vac)