Hello Don,
Thanks for the insight. I checked D4 and it seemed to be ok. I went ahead
and removed U1 and the voltage on the D1 anode rose from -3.3 to -11.5! U1
must be bad. The only question is what made it that way?
I'm going to order a couple of 1406's from Mouser and see if that indeed
Larry,
Other than that negative voltage supply, the 5 volt regulator, and the
12 volt line, there is just not other places to look for a problem. The
MAX1406 just handles two RS-232 signals in this application, TXD and
RXD, so there is nothing on the board to stress the chip.
73,
Don W3FPR
Don,
That's indeed good to know. I went ahead and cut the pins to the original
1406 so I wouldn't screw up the PC board. The 1406's are on order now.
I'll let you know how it goes when they get here.
Thanks again!
Larry KT4G
Larry,
Other than that negative voltage supply, the 5 volt
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