Harmony H500

[nosaj]

I have a harmony h500 I'm looking at and I have to say if I'm reading all this right . It is the first transformerless SS amp I've ever worked on. With an Output transformer The only other solid state amp I've seen with an OT was a 70's Peavey head and cabinet. Is what I'm reading correct? And if so Isolation transformer would be a necessity to leave my hands.

nosaj

[Enzo]

Anything in your Peavey was nothing like this. This is a real simple amp. The transformer output is not at all unlike say a Fender reverb drive. And yes, I would tell the customer either he gets an iso transformer added, or I don't work on it.

In your shop, hopefully you have a bench iso, just plug into that while you work on it.

You got only the chassis? Do we KNOW the speaker works?

[The Dude]

Looks like a good donor cabinet and chassis to gut and build a real/tube amp into.

The customer might not agree, but I wouldn't bother fixing that- parts, time, isolation transformer, etc.

[Enzo]

Y'know, looking at it, it makes me think: glorified Pignose.

[nosaj]

Yea i have a bk precision 1604 isolated supply i have the whole shebang( cabinet chassiss) And the speaker does work sounds cheap. Jensen special design 5 inch I believe. one 2n3391 dead.
The way I'm seeing this in my head because its transformerless , one transistor goes down everything goes down Like series filaments.

nosaj

[nosaj]

Looks like a good donor cabinet and chassis to gut and build a real/tube amp into.

The customer might not agree, but I wouldn't bother fixing that- parts, time, isolation transformer, etc.

Well that was his initial idea till we started running some numbers. just because I have a shop of salvaged parts doesn't mean a cheap amp for someone, now me on the other hand want to build out of my junkpile whole nuther story
nosaj

[nosaj]

So what is a voltage dependant resistor? R10
Ok so its a varistor.

nosaj

[Enzo]

The way I'm seeing this in my head because its transformerless , one transistor goes down everything goes down Like series filaments.

What does transformerless have to do with it? The signal; path uses three transistors, one goes out, no sound. I see no difference between that and a three tube amp. One tube goes out, no sound.

[nosaj]

Power no power thing is what I was referring to . One component out no circuit.
nosaj

[Jon Snell]

Two pin plug and a live chassis, plug it in wrong and the guitarist is DEAD.
No wonder they don't make them like that anymore ... too many law suits I expect.

[g1]

Power no power thing is what I was referring to . One component out no circuit.
nosaj

There aren't series components like in a tube widow maker where the heaters are in series.
In this one it's just straight up rectification of the AC line. One side of the AC line is grounded, the other side is rectified by D1 (via R9). If those basic parts are functional there will be power. C7 appears to be a 3 section can, but shown upside down to what we are accustomed to.