[ICOM] IC PS-35 Problem
James T Wassell
k3jt at westco.net
Wed Jan 12 15:16:46 EST 2011
Gary,Thanks for finding a source and info on the UPC1042C.I did consult Scott Malcom and his advice was that
it's more economical to buy a $100 external power supply
than spend time to troubleshoot and repair
and to try to replace hard-to-find parts
needed to fix the PS-35. I did take this advice, but the PS-35 got shifted
from place to place on my workbench for about a year
and I finally decided I had to try to fix it.I think replacing the LDR in IC1 with a 1K ohm fixed
resistor, is a reasonable "fix". Even if it means shorter
life for Q1 -- well, I could install a transistor socket and
replace lots of Q1's if needed, but I hope that will not
be necessary. the neon bulb lights up immediately when 110VAC is applied
to turn the power supply on, so how much of a delay (in turning
on Q1) is created by the LDR? not much delay by my observations.
So, I'm puzzled by the need and purpose of IC1 in the circuit. Maybe the idea is to have the switching oscillator (Q2-Q5)
running before activating the regulator IC2 via Q1. If anybody
knows about this, I'd love to learn about it. Anyways, there seems
to be enough "delay" in the circuit, just using a 1K ohm resistor to
achieve the desired results.
Terry, K3JT
More information about the Icom
mailing list