Bill,
Make certain you have +12 volts on U4 pin 1 and +5 volts on U4 pin 16
and about -25 volts (-8 to -27 volts) on U4 pin 8.
If those are correct, replace U4 and it should work)
73,
Don W3FPR
On 11/4/2021 3:29 PM, Bill Coleman wrote:
About 10 days ago, I was having trouble with the K2/100, as it was no longer
talking to WSJT-X correctly. I could get the audio running, but it would never
contact the radio.
Trying to set up for CQ WW Phone, I had the same trouble with N1MM.
Tried to use the PORT TEST feature by going to the SEC menu, selecting PORT,
going into EDIT, and pressing the DISPLAY button. It would say TEST, but I’d
see no characters transmitted.
Since I use USB serial adapters, I tried two of them, to no avail. Can’t get a
peep out of the K2/100.
Opening up the rig and digging out the scope, if I send characters on the
serial port, I see pulse trains on KPA100 U4 - the MAX1406 chip - pin 11
(R3OUT). So, it would appear that characters are reaching the main CPU.
If I put the scope probe on pin 12 (T2IN), it remains locked on ground, never
moving, even when I do the PORT TEST.
If I remove the P1 connector from the control board, and put the scope probe on
pin 1 of that connector, I DO see pulse trains from the PORT TEST. This
indicates to me that the CPU is OK, but something is wrong at the MAX1406 chip
in the KPA100.
In addition to not getting a response from the K2, it doesn’t appear to obey
commands. If I send RT1; or XT1; it doesn’t turn RIT or XIT on.
I tried using a different main CPU chip (I have one with older firmware), but
that doesn’t appear to make a difference. I’m wondering if my problem is a
blown MAX1406 chip.
Any recommendations or advice? It’s a big pain to remove the KPA100 board, so I
want to make sure what I’m replacing before I go after it.
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