[But I cross my fingers about the Chinese OPTs when I think about them.
I don't expect them to last a long time. The leads coming out of the
OPT box have insulation far too thin, nowhere as good as what you'd
find on any Hammond OPT and the the Chinese saw fit to use green wire
with yellow stripes for the CT lead to B+. This color is normally used
for chassis earth wiring. I hate to think of the Feng Shui karma
issues surrounding chinese OPT designs.
Patrick Turner.[/quote]
Ya, I've had my share of crap right out of the box too. One I remember around 1960 in particular at U of T Physics was a TEK 540 Series scope I used a lot doing research on core memory, before SS memory looked like a sure thing.
The one volt p-p calibrator looked OK on the top half of the screen but intermittely showed less than a volt on the bottom half. This fault would come & go at random. Finally I traced it down to one of the tubes in the vertical amplifier. Heater connexions on 9-pin tubes for 6.3 volts are usually 4 & 5. Pin 4 was very well soldered in with the TEK silver doped solder but the wire just stuck thru Pin 5. So the fault came & went in a random way.
Last summer thought I had a alternator failure on my Kubota tractor. The charge indicator was on all the time, but oddly only half lit. I put a scope on the 12 volts & saw what seemed to keep time with the engine RPM. Figured a busted stator, a 3-phase thing with a full bridge of rectifiers so $450 dollars later I got another on. No change.
Turns out after a lot of tracing I found the wire from the on-off switch (diesels don't have electrical ignition) to the voltage regulator broke off inside the insulation. I guess the guy stripping the wire at the factory squeezed to hard on his cutters as he stripped the wire.
Not sure what will fail next. Got a new charger on order for my 2 year old Dell laptop on order now.
Cheers, John
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