Wolfgang Smetanig wrote:

Hello,

I have still probs with my new pre-amp. Found three fried transistors
and a zero-ohm cap.

On a *new* unit ? I assume you don't mean actually brand-new.

This is fixed so I can feed the unit with 12V AC
on all inputs and it works.

What kind of pre-amp takes 12V at the inputs ?

But on the very bad copy of the schematics
I could read +/- 24V and +/-15V on the connectors which supply the
preamp stage with power.

Plausible.

On two of the 6 wires I measure +15 and -15
like in the schematics, the two other show +16 and -16 (the other two
are ground).
I think (the schematics shows 3 outputs on the power transformer) that
I need 12V / 15V / 24V AC or 12V / 2x24 V AC. But I will not grill
some transistors:_))

So can someone with this item please measure AC-voltages on the
transformer and post it to me?

Sounds more like a PSU problem than transformer.

Why not measure the transformer secondary voltages yourself ? Either they
will be right or open circuit.

Transformers don't go slightly wrong voltage.

Graham