jdirolf wrote:I purchased a partially completed pre amp kit and made the mistake of testing the supply that someone else assembled without doing more research into how it should be wired. Long story short, I ended up with a few experiences of magic smoke from the supply (AC/DC).
The transformer is a digikey amveco 62075. It is wired to the supply as-per your webpage. However, I am using this for a neve clone so I don't need -24v. Should I leave the brown and red wires from the transformer wired together but off of the 0v pad on the AC/DC input? Am I correct to have the voltage doubler jumpered and shorted capacitor on the -24v? (the previous owner installed all of the -v components for some reason)
I've already made the mistake of regulators touching the case (so I replaced the fried 10ohm resistor and installed separate heatsinks). I also unfortunately jumpered the voltage tripler at one point, so I replaced the 48v filter caps that received too much voltage. Should any other components be replaced from these stupid mistakes? Should I just rebuild the whole board?
Any help is greatly appreciated.
Thanks,
Jared
All the above is wrong.
Remove all 3 regs and replace +V reg and +48v reg and any caps that are bulging.
Check none of the 8 x 1N4007 in the center of the PCB have gone short.
That should fix your AC/DC if none of the trim pots were burnt by being wound down with blown regs.
Separate small heatsinks will be enough for only one or maybe 2 neve clone only usually.
Check you have the correct current value mains fuse fitted for the mains transformer.
OK the Amveco 62075 has 2 x 22vac windings so I would use the AC/DC normally (without the Neve Mod no shorted cap on -24v) but both ways can work as shown below.
NO NEVE MOD wiring
Wire red and Brown to 0v terminals.
Wire Green to one AC in and Blue to other AC in.
Negative rail parts or reg can be left on or off doesn't matter.
Set to doubler and set +24v and +48v.
Turn off and connect to mic pres.
Neve MOD wiring
Do Neve Mod to PCB (Short out C8 with wire link.)
Wire Green and Brown to one AC in.
Wire Red and Blue to other AC in.
Nothing to 0v on transformer side.
Negative rail parts or reg can be left on or off doesn't matter.
Set to tripler and set +24v and +48v.
Turn off and connect to mic pres.