Hi Roy,

On 11-Mar-04, Roy J. Tellason wrote to Greg Mayman:



 GM>> 6 months seems to be very common these days where it used to be
 GM>> from 1 to 5 years. And of course the electronics are
 GM>> unrepairable, you just replace the modules... except that by that
 GM>> time they are no longer made.

 RJT> No,  actually the electronics were repairable.  But they weren't
 RJT> very well made. The cheapest model had a pair of freestanding
 RJT> speaker boxes,  but used only a pair of TDA2040 chips for output
 RJT> devices,  which tended to explode with regularity as they applied
 RJT> 40 volts or so to the supply pin,  which is just at the absolute
 RJT> maximum rating for that part.  Power supply rectifiers were
 RJT> 1N4001! These also often went bad..

You do realise that the voltage rating on low number 1N400X series was
pretty well meaningless, don't you? They used to make a batch of
diodes, then select out for voltage breakdown. Over 1000V and it was a
4007, 800V for 4006, etc. Once they had enough of a type all the rest
would end up in the lower rated types. Anything that wasn't short
circuit (almost) ended up as 4001, so that the devices you got could
have been virtually any capability, and would most likely have been
way over 500V... The most likely killer would have been current, or
even more likely juging by my experience with approving 4004s, the
packaging not being properly sealed. Some makes were really bad...

George

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