short cut in a out ng

[boops]

Hi all,i 've got a short cut between the -12v and the +12 not the ground in my out ng,without IC3,C4i 've rechecked the solders many times(many hours) :) with schematics...no found

the question :is it possible that a bad multi tour trimmer(fried) make this short cut?

how can i test a soldered trimmer?

best regards

[seppoman]

you can't really test a trimpot as long as it's soldered in place. But as the trimpots are not directly connected to either +12 or -12V at any point, a damaged trimpot can't be the reason for your short. Just check everything again, with a magnifying glass if you have one. The only places where the supply rails are somewhat close to each other are between R44<->R36 and R45<->R37 and maybe around J3,J4 or C1,C2. Or the short is not on the pcb but on the PSU/wiring.

If you still don't find a reason for this short, maybe post some high resolution pictures of both sides of the pcb, including wiring. Maybe someone else can spot a suspicious solder joint.

S

[boops]

Thanks for the fast response,the psu is the psu of my Fm and it's works fine..i will check the crucial points and give (i hope) the result...best regards

[nILS]

Shortcut? Didn't we measure the resistances between +12V-GND, -12V-GND and +12V--12V in the chat last night and came up with values >5k for every one? Did that change?

[boops]

we 've founded 3;5 and 14....then i 've tried with my FM psu and as i 've saw the led don't light...i test the out ng alone and find this short cut in j3 and  J4 beetwenn c1 ,c2 too...i continue my research..thanks

[boops]

hi all ,some result of my trouble,i 've  checked many components after i ' ve desoldered them,following the shematic no problem; ,i 've cuted the +12V rail on a track,also i saw a half of the circuit was fine,cause it is symetric...i desolder all the component in this bad area,first the bipolar area and there was always the  shortcut check again and again...but finded nothing ...incredible...i think ,perhaps a mistake in this pcb...(build malfunction?)today i resolder the cv area and i have 8cv and gate but only the the cv 1-4 works in the bipolar option...just an advise for anyone...just cut a track of one of the rails and you will win lot's of time..excuse for my bad english...best regards