Metro Audio CPS2 Power Supply Fault

[DSUK]

Hi all,

I've recently begun volunteering to help out a local community theatre and the comms sets have been in a box of 'not working' for some time. I've started with the PSU (a CPS2) which seems to be, in the main, working. The voltage regulators are giving me a nice 24v output but nothing appears across pins 1 and 2 on the XLR outputs. Both appear to have a burnt out resistor just behind the XLR connections. I suspect this is due to one of the permanently installed XLR cables having been shorted out when it was cut by the retractable seating.

I'm hoping it's an easy fix, or  at least lets me move onto the next part of the problem. Does anyone know what value and wattage rating these resistors should be so that I can replace them?

Even better if someone has a schematic for this unit as I'm drawing a blank and having to rely on my electronics training from a good number of years ago 🙂

[sandall]

Someone here should be able to give you a definitive answer, but in the meantime -

They will be quite low-value, but look like 1/4W, so maybe 10s of Ohms, & presumably acted as fuses when the supply was shorted out. Why don't you bypass them for the time being & see whether the belt-packs spring into life?

[DSUK]

On 3/11/2024 at 6:23 PM, sandall said:

Someone here should be able to give you a definitive answer, but in the meantime -

They will be quite low-value, but look like 1/4W, so maybe 10s of Ohms, & presumably acted as fuses when the supply was shorted out. Why don't you bypass them for the time being & see whether the belt-packs spring into life?

That's going to be my plan now I'm back from working away all week.

[sandall]

Looking again, they look more like 1W or 2W, like the 100R one on the left. The position of the brown band on the toasted ones suggests a multiplier of 10. Unfortunately the Techpro PSU cct diagram doesn't give a value for the appropriate one.