Repairing old 18V pedal(s) that take two 9 volts (help?)

[solewheelin]

I have 2 older 18V pedals. A Roland AP2 big box phaser and a Univox M1000 Effectomatic (mutron copy) that are in need of repair.
When I opened them to change the batteries they just stopped working. They both worked fine, now they don't.

The last sound the Roland gave off was a short high pitched degrading squeal when i was moving the batteries around to close the box (no screws).
The Univox worked and now it just doesn't. So upsetting. I don't think it's a loose solder joint because I definitely poked around but who knows?
Input jack gives no noise when plugging in, but I get a crackle sound from the amp when plugging in the output jack. I also cleaned the footswitch with deoxit and compressed air to no avail.

Though I was careful handling them, they were just so fragile I guess. Any help on fixing either would be much appreciated. The Univox is the one I would like to fix soon because its not mine and was in for a simple switch repair.

Thanks

[drolo]

perhaps some old caps gave up and died
old gear can break in so many ways
I guess you will need to do some troubleshooting, see if you can get the schematics, test the supply rails, probe the audio path etc

[crochambeau]

There's really nothing fundamentally different between troubleshooting a bipolar circuit versus a single pole circuit.

Start by exposing the guts, inserting fresh batteries, and then grabbing your multimeter and measuring your rails from common. The malfunction may jump right out at you..

[solewheelin]

I hope there are no dead capacitors but if there are, i will change them out.

Thanks crochambeau. I will get back to this thread with more info.