SWR Super Redhead Power Amp Board Question

[dorrisant]

I have a SR here on the bench. I opened it up for a quick once over and now curiosity is getting the better of me. I noticed a carbon comp resistor that just stands out like a turd in a punch bowl. Besides looking as if it was installed with a 100 watt iron, it also looks as if it has been heat stressed. I am hoping that some of you may be familiar with these and know more about the power amp board layout.

This one has had a few small repairs done to it prior to my ownership, so I want to be sure it is correct before I put it through its paces. I would like to confirm the correct value for that component position. Does anyone know what part number it is? I'm sure I could figure it out from there.

Tony



This is where it is located... Bottom right of the board attached to the heat sink.



With the power amp board rolled up for better visual, at the top left of the board in this shot. Just to the right of the burnt Wima cap...

[TimmyP1955]

Based on the SM500 schematic that I have (and guess is similar to your amp), I believe that the resistor and cap are in series, run between the output and ground. In the 500, it's a 22 Ohm 2W in series with a .022uf. These are in parallel with a 1.5 Ohm 1/2W (surely that's 1.5k!) in series with a .047uf. Dunno what kind of amp issue would cause the resistor to fail. That's sure some nasty work.