Faulty capacitor? (tested with a VM)

[Blue Jinn]

Hello,

I have an ARP Avatar that is no longer turning on. No power gets to the binding posts from the power supply. Hooked up an external +/- 15v and it did power up. Tested the caps on the psu, both are 10,000uF, with the VM set for resistance. One cap seemed to charge, (meter oscillated) the other one had infinite resistance, so I'm assuming that is the faulty part. The PSU is fairly complex, with 723 regulator etc....thing is I'm not sure what kind of problems would come from that cap appearing to be an open circuit. (It doesn't make sense to me that the PSU wouldn't continue to work, albeit with more ripple.

Going to replace the PSU caps.

 

[diggy_dude]

You're really not supposed to measure resistance in a live circuit. One end of the component to be tested should be disconnected from the circuit to avoid measuring parallel resistances.

 

[dementedchord]

so the power supply is on a secondary board correct?? and is not connected to the main board???... next are there any fuses on the supply board??? with it unplugged and the meter set for rewsistyence it should be essentially 0... if real high its roached... now can you turn the supply over??? look at the power filters... the big caps.. therse onethey have in common... it's grnd... test the resistence across each filter.. should be high and/or building up... if either of them has 0resistence then thats where were heading... your gonna trace that line down and start lifting connections on the componenets until the short (0 resistence) goes away... then your ready for the next step...

 

[Blue Jinn]

so the power supply is on a secondary board correct??

Yes, with a ribbon to the main board

and is not connected to the main board???...

next are there any fuses on the supply board???

A big fuse, but it is soldered in place

with it unplugged and the meter set for rewsistyence it should be essentially 0... if real high its roached... now can you turn the supply over??? look at the power filters... the big caps.. therse onethey have in common... it's grnd... test the resistence across each filter.. should be high and/or building up... if either of them has 0resistence then thats where were heading... your gonna trace that line down and start lifting connections on the componenets until the short (0 resistence) goes away... then your ready for the next step...

I'll pull the PSU board and give that a shot.

Thanks