Preamp Circuit Question

[petertub]

In the late 1980s, I bought a Quicksilver KT88 amplifier. Simply as a matter of maintenance and the possibility of needing to repair the unit someday, I wanted to have a schematic on file. I called Mike Sanders and asked him for a schematic. He told me he had never drawn one out and that I should draw it out myself. So that's exactly what I did.

Then publish your schematic here ( and on as many sites you can )

 

[rayma]

What? The designer/manufacturer of an electronic product never drew a schematic of it? That's not even remotely believable. He could have just said that he was not going to give it to you. At least that would have been an honest answer.

Yes that's ridiculous, but if they were that disorganized, then how good can the circuit be?

 

[kodabmx]

I've designed a lot of circuits in my head and created a schematic after the fact - seems plausible to me...

 

[Ray Waters]

That might be believable coming from a hobbyist but not a commercial vendor. How did the circuit board designer determine how to lay out the board without a schematic? I'm not arguing with Mike's right not to publish schematics for his products (although I don't agree with that practice). I just think he should own up to that instead of making a lame excuse. But that's just my opinion.

 

[rayma]

Also it implies there was no concern for future repair after the designer is gone.

 

[JMFahey]

I've designed a lot of circuits in my head and created a schematic after the fact - seems plausible to me...

But you DID draw it later, before building it.

What´s not believable is he never ever drew one, even when he did build (and sell) it. WTF?

You can do that on something very simple, say 4 or 5 components, as in a cabinet crossover or a power supply, even with a simple regulator such as LM7805 or similar, definitely NOT in a KT88 power amp.

 

[kodabmx]

No, I drew it afterwards. In any case, If I make something to sell to someone, they get the schematic... I make my designs public domain.