KAT500 Blinking "MAN" LED - Bad Astron P/S On/Off Switch

[John W2XS]

The other day I turned on my Astron RS-35M and then my K3, P3, KAT500, and
KPA500. I've done this at least once per day for the last several years.
This time, however, I heard arcing from the Astron's on/off switch. Then I
saw that the KAT500 LED was blinking constantly about 3 times per second.
After doing some troubleshooting, I replaced the power supply switch with
one I had here but the tuner's LED kept blinking and the unit would not
respond to any key press, including the power button. I tried connecting the
KAT500 to the computer but there was no connection to be made. Then the
blinking changed frequency and got faster. Eventually, I was able to connect
and reload the KAT500 firmware and everything has been OK since.
I do have the KAT500 connected directly to the power supply since I am
powering a P3 and a PR6-10 from the K3's aux power connection. I noticed
that, normally, all the LEDs in the KAT500 would blink momentarily as the
power supply was turned on even though I have the KAT500 set to power-on in
the "off" position. Then it would power up and work fine.
Anyway, sorry for the verbage, but my theory is that the bad on/off switch
in the Astron corrupted the firmware in the KAT500. I don't know what the
blinking "man" LED meant, and I don't know why there were 2 different
blinking speeds. I built a little switch box to keep the KAT500 power
disconnected while the power supply comes on and settles down so as not to
have another problem in the future.
(Marlin P Jones sells an in-line power on/off switch with a 2.1 mm barrel
plug on one end and a 2.1 mm barrel socket on the other end. I would have
used that except I cannot normally reach the back of the KAT500 in my
configuration).
73, John W2XS



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[Jim Brown-10]

On 5/3/2021 4:07 PM, John W2XS wrote:
> The other day I turned on my Astron RS-35M and then my K3, P3, KAT500, and
> KPA500. I've done this at least once per day for the last several years.
> This time, however, I heard arcing from the Astron's on/off switch. Then I
> saw that the KAT500 LED was blinking constantly about 3 times per second.

Every Astron I've checked had a manufacturing defect that fails to bond
AC power line green wire to the chassis, thanks to paint under the lug
to which it was soldered. In addition, the V- terminal is soldered to
the same lug, connecting it to the green wire, but not to the chassis. I
suspect that when the switch broke, it put some voltage on V- and
failure to bond stuff properly in the shack coupled some voltage to the
KAT500.

73, Jim K9YC



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