Re: Amp - loss of power?


Chris Hornbeck wrote:

> >> Do you have a sustitute rectifier?
> >
> > I have diodes marked IN4004
> > The schematic specifies IN4007
>
> IIRC, this is just a difference in voltage rating.
> And, in practice, maybe just a difference in pricing
> or specing from the same production run. Whatever;
> 2.5 amp 1000 PIV rectifiers are next to free
> nowdays, so no biggie.

There is the bridge rectifier that used to supply the preamp.


> >> Do you have a substitute load?
> >
> > What do I need?
>
> If I'm reading the schematic correctly, 435 volts
> at, let's say, 100 mA is a load of 4350 Ohms and
> 43.5 Watts. A 4000 or 5000 Ohm resistor from
> Fair Radio Sales or some other surplus supplier,
> mounted in a safe (dangerous voltages; high temps!)
> cage, should do fine. Don't allow children or
> pets into the room, natch.


What type of resistor?
The largest resistors I have seen are 5 watt types.


> >> Also, can you measure line voltage?
> >
> > I have a multimeter and a strong will to live.
>
> Then you'll have already eliminated the Edison as a
> potential problem. But I haven't read (have I missed it?)
> that you've measured the B+ (the high voltage supply
> at the center tap of the output transformer).

You didn't miss it.
Could really use some guidance on this one.


> The obvious inference from your symptoms is that the
> standby switch is failing, so a few DC measurements
> should go a long way. And all this (above) is
> most likely unnecessary.

I am all ears.

.

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