A request from a non member

[pwdrive]

Searched high and low on the web for any info, no luck so far.

Lawrence.

[Refugee]

We need the wiring between the power supply traced out and then next we can begin tracing the short circuit that caused the fault.

[richard296]

cheers lads for info. i will look tomorrow morning (wednesday) check what the 40v feeds. i thought it fed the amp but after listening to comments it may not be that obvious. get back asap.

[richard296]

the 40v side of power(missing resistor) supply goes to the front panel (volume controls tone control mic etc another wire same gauge from the same solder joint goes to the main board to the right of the amp connects to a large orange cap value 35vl 3000 ohm then there is a terminal of this board next to this cap goes to the amp. these 2 wires are heavier gauge than all the rest.

[pwdrive]

You need to do some resistance checks from the output side of the missing resistor to the common -ve rail plus a good visual inspection/proding for any obvious shorts, from what you have just described the PA should work ok when powered up if you are satisfied that the PSU is all in order, excepting the missing resistor of course.
Powering up the PA is obviously up to you.

Lawrence.

[richard296]

forgot to mention on this large board next to amp output is written with screened wire from it. also marked on this board bass in bass out rev in rev out. hope this helps. its a spring reverb and one of the springs is hanging not snapped just the end connection. i know this is something for later but thought best mention. i have isolated the hanging spring.

[Refugee]

That power arrangement is what i was expecting.
I would guess that the reverb spring has shorted something when it came loose.
It can be re-hung with "O" rings.

[richard296]

large main board next to amp. checked all the blue caps with multi meter. negative probe on missing resistor. positive probe to the common tails on the caps. all gave a reading on the meter then went to no 1 on the meter. exept one no reading at all (checked several times) it.s values 40v 1uf. didn't take it out the circuit but it reads 1.66 ohms with a cap meter. i have ordered an esr meter. does this make any sense. thankyou richie

[Refugee]

It looks like you have found the track with the short circuit on it.
I would desolder the suspect components one by one in order to isolate the fault. You can often just use a solder sucker to clear the joint from the track without removing the part.
Capacitors usually burst if they go leaky with few exceptions.
It is not by any chance a blue tant is it?
These go short circuit and can detonate.
All the blue tants in this photo are short circuit and one was even on its final count down to launching like a missile.

[Refugee]

It looks like you have found the track with the short circuit on it.
I would desolder the suspect components one by one in order to isolate the fault. You can often just use a solder sucker to clear the joint from the track without removing the part.
Capacitors usually burst if they go leaky with few exceptions.
It is not by any chance a blue tant is it?
These go short circuit and can detonate.
All the blue tants in this photo are short circuit and one was even on its final count down to launching like a missile.