On 11/30/2017 10:20 PM, Gene Heskett wrote:
I'm thinking its losing high side charging time because
I've blown a chip.
It could be a bad FET driver or a bad opto-coupler. It
might not take a lot of reverse voltage to harm the LED, and
then it would slowly weaken over time. Then, it could
become temperature sensitive. if you somehow got 12 V into
the PWM input, it could easily fry the LED in a second.
This is the second one I bought, about 3 years ago now.
The first one, after I'd put a bigger toroid in the fwd
leg, is still running TLM just fine. But I may have blown
something in the inputs as I was trying to replace the
bob, which had a long string of slow opto's with one that
was all buffers with a 10 MHz bandwidth both ways, and had
forgotten exactly how I had arrived at the 12 volt enable
signal. I got that sorted eventually so I know I've got
good signals to it. That 12 volts is from a wall wart, all
it powers is this enable signal, and I measured it a
couple times today while it was miss-behaving, and got
around 12.9 volts both times, so that s/b ok. Regardless,
can you repair it, and if so, the turn around time? I can
paypal you the charges since its at least 99.9% my fault,
and not exactly a new one now.
Sure, I can repair it. I only HOPE it shows the same
symptom here so I can know it is solved. First test is the
"thumb" test -- do any of the chips get hot? if so, replace
immediately, then try again. When nothing gets hot, and the
12 V current draw looks right, then start doing operational
tests.
Jon
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