Xr600c mixer amp, advice.

[Oldmactech]

Here is the bottom pics. I guess they are snap on?

[The Dude]

That looks like a dual cap- 2 caps in one can. There should be a legend on the side of the cap that says what the symbols mean on the leads of the cap.

Edit: It may not even be defective if you didn't test it as such.

[Oldmactech]

Thanks. I’m no expert but I think the 4 outer pins are just mounting posts. They are not electrically connected to anything.

Thr

[Oldmactech]

I didn’t capture in the photo but the line on the side says the “triangle symbol” is Negative. I’m actually wondering if I could replace with axial caps or other and get around trying to try to find an actual replacement.

[The Dude]

Gotcha! Yes, you are correct. After looking at the schematic, one of the caps has + to ground, so there's no way they could be in the same can. My apologies for the detour.

[nosaj]

I didn’t capture in the photo but the line on the side says the “triangle symbol” is Negative. I’m actually wondering if I could replace with axial caps or other and get around trying to try to find an actual replacement.

Yes you can and its fairly easy on older Peaveys. I just use a pcb drillbit drill where I need it pop new cap in and solder it in.
nosaj

[The Dude]

I'd just look for a 4700uF at 63V, as g1 said. I'd get a radial cap and match up the lead spacing.

[Oldmactech]

Thanks, I’m going to do that.

[Tassieviking]

Make sure they are not too big to fit on the PCB, you don't want any capacitors that have a larger diameter then original or they will not fit with the resistor between the capacitors.
Pin spacing is good to get the same or as close as possible so you can fit it straight on the PCB, you don't really want to drill new holes in the PCB.
Never drill new holes in modern PCB's as they can have hidden tracks inside the PCB.
Voltage rating must be equal or higher then original
Capacitance anywhere from 4700uF to as big as you can get to fit on the PCB. Sometimes the more capacitance the better.
Try to get low ESR caps if you can.

If you are worried about the capacitors vibrating loose over time, use a hot glue gun to glue them down with.(Or silicon etc)
Vibrations can be a big concern if it was a combo amp, especially Bass as the vibrations are massive (hopefully)
Good luck

[g1]

Make sure they are not too big to fit on the PCB, you don't want any capacitors that have a larger diameter then original or they will not fit with the resistor between the capacitors.
Pin spacing is good to get the same or as close as possible so you can fit it straight on the PCB, you don't really want to drill new holes in the PCB.

Modern caps should be smaller so there is quite a bit of room there. Agree you don't want to get close to that 5W resistor though, heat is bad for caps.
Should be able to match the pin spacing without any drilling, but the original holes might need to be enlarged a tiny bit, depending on how the modern snap-in leads compare to the old pins.

[Oldmactech]

Got and installed two 4700uf 63v caps and fired it up. ( separated from the preamp entirely)
I have a bulb current limiter 75 W bulb.
Turns on bright than almost immediately goes to dimly lit. I have never understood exactly how the bulb limiter should react except that bright indicates a short. Should the light be all the way off if there are no issues?
Anyway, I connected it to a speaker and got fairly pronounced 60 cycle hum but the crazy noise from the beginning is gone.

Still testing but out of time Tonite.

[g1]

At idle the amp normally draws a little current, so bulb will be dimly lit.

[Tassieviking]

I always feel the caps are like a battery, they charge up and hold power and then release it as it is needed.
The bright light right at the beginning could be the caps charging up with power, try it twice in a row, the caps should contain the power for a little while and they would not pull as much the second time maybe.
The caps keep the voltage steady, imagine a heavy loud slow bass beat, each beat the caps discharge a bit and then recharge ready for next time they are needed.
Some caps can charge and discharge quicker then others so they will pull more power as they are powered up initially, once charged they go to idle and the light dims.

The light bulb restricts the maximum power that can get past it, a power point say has 240V and a fuse or circuit breaker about 16 amps (Australia where I am).
240V x 16 Amps = 3,840 watts of power going into a shorted amplifier on test before you blow a fuse or trip a breaker.
A 60 watt globe uses 0.25 Amps when fully lit, so if your amplifier is shorted the maximum amps going through your amp will be 0.25 amps instead of 16 amps.
The more the light globe lights up the more volts are across the globe and the less volts are across your amplifier as well.
I really am bad at explaining stuff, I hope it makes some sense.

[Oldmactech]

Thanks all, I’m somewhat confident that replacing the caps did the trick. Still have the power section separated from the preamp side but when I connect the power to a speaker there is a small thump on turn on, pretty quiet after that, tiny bit of white noise.

Waiting on some XLR replacements and a few 1/4” inputs to reassemble.

thanks all for the help and support.

john

[Oldmactech]

I think its headed to the junk pile….
After reconnecting and reassembling the power section to the preamp section I fired it up and although there is a subtle bump from the speaker and a small bit of white noise on startup there is no sound from the preamp and indeed the status LED is not lit. I am checking/double checking the connections but I’m just short of 100% that it’s reassembled correctly (using pics I took when I pulled it apart.)
Sad.