Parasound P/LD 1500 transformer question

[Wolfgang Smetanig]

Hello,

I have still probs with my new pre-amp. Found three fried transistors
and a zero-ohm cap. This is fixed so I can feed the unit with 12V AC
on all inputs and it works. 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. 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?

Thanks

Wolfgang

[Pooh Bear]

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

[Wolfgang Smetanig]

@ Pooh Bear

> On a *new* unit ? I assume you don't mean actually brand-new.
>
Ok, not clearly defined - my new acquired pre-amp.

> > This is fixed so I can feed the unit with 12V AC
> > on all inputs and it works.
>
Caught twice:-)) Meant the internal inputs

> Sounds more like a PSU problem than transformer.
>
Sorry for my bad (technical) english - meant the PSU = transformer

> Why not measure the transformer secondary voltages yourself ? Either they
> will be right or open circuit.
>
> Transformers don't go slightly wrong voltage.
>
But they could be destroyed - like in this case. So the output is on all wires 0

Wolfgang