Hi All,
I recently partially re capped my 'Electro' preamp, but since then - it will not give any output once the relay clicks in. Its this one, which is the one with the Electro Power amp and the two supplies.
On turning on the power amp, there is a low volume scratchy output on the L channel, then a fizz noise, then nothing. The output relay clicks in no problem. I checked the output transistors - they're Ok, so am now going through the transistors on the little amp boards - but if anyone has any suggestions I'm all ears.
I've checked the amp operation with another earlier preamp and all is fine.
Many thanks in advance
Joe
I recently partially re capped my 'Electro' preamp, but since then - it will not give any output once the relay clicks in. Its this one, which is the one with the Electro Power amp and the two supplies.
On turning on the power amp, there is a low volume scratchy output on the L channel, then a fizz noise, then nothing. The output relay clicks in no problem. I checked the output transistors - they're Ok, so am now going through the transistors on the little amp boards - but if anyone has any suggestions I'm all ears.
I've checked the amp operation with another earlier preamp and all is fine.
Many thanks in advance
Joe
Attachments
Slight update, so I started checking components and some of the transistors had gone, one with a corroded leg and the other NPN was showing as a darlington.
So now I had sound on both channels - but the preamp would 'crack' through the speakers when playing music. Tapping any component ( with a chopstick) would produce this loud crack and the woofer on the LH speaker would attempt to leave the chassis.
This went on for a few tests, just to see if there was any quick component checks that would solve it. The Tape monitor switch was not making all its contacts either, so this was replaced. One more check - still cracking, then nothing, no output. I have both the AC(31V) and the DC (40V or so) arriving at the preamp but nothing further and the relay doesn't kick in.
Its a bit hard for me - a novice - to check the unit against the other two I have here as,topographically; they're similar, but the wiring off the connector boards is wildly different, with the usual multipin connectors missing and just a few hard wired contacts being used.
I'll check the output transistors again, but if anyone has any ideas on why its cracking I'd appreciate it.
Best
Joe
So now I had sound on both channels - but the preamp would 'crack' through the speakers when playing music. Tapping any component ( with a chopstick) would produce this loud crack and the woofer on the LH speaker would attempt to leave the chassis.
This went on for a few tests, just to see if there was any quick component checks that would solve it. The Tape monitor switch was not making all its contacts either, so this was replaced. One more check - still cracking, then nothing, no output. I have both the AC(31V) and the DC (40V or so) arriving at the preamp but nothing further and the relay doesn't kick in.
Its a bit hard for me - a novice - to check the unit against the other two I have here as,topographically; they're similar, but the wiring off the connector boards is wildly different, with the usual multipin connectors missing and just a few hard wired contacts being used.
I'll check the output transistors again, but if anyone has any ideas on why its cracking I'd appreciate it.
Best
Joe