[time-nuts] Z3801A recovering

Joseph Gray jgray at zianet.com
Sun May 1 07:30:08 UTC 2016


In past discussions about replacing a 6-channel Oncore in a Z3801A
with an 8-channel VP Oncore, some claimed that the VP had to first be
put into 6-channel mode, others indicated this was not necessary.
Earlier tonight, I put a VP (still in 8-channel mode) into my
malfunctioning Z3801A. Monitoring with Z38xx, I see no signs that this
is a problem. Even the logs look clean.

In reading the VP documentation, I saw that there were several
6-channel commands, along with similar 8-channel commands. That is why
I thought I'd try using the VP without setting it to 6-channel mode.
It was an experiment that seems to have succeeded.

I don't want to jinx things, but so far, my formerly flaky Z3801A is
working normally, after replacing the GPS module. The self survey
finished in two hours (about 25 minutes ago). The EFC and PPS TI/s
graphs are no longer going wild.

I'm going to monitor this for quite a while before I call it fixed.
Then it's on to repairing the Z3801A that I traded for.

In addition to replacing the GPS module, I also replaced three caps on
the power supply board. On initial inspection, C108 and C110 had a
faint white ring around them, on the PCB, as though they had out
gassed. There was also some corrosion on pin TP104, which sits between
C108 and C110. The caps checked fine with my LCR meter, but I thought
I'd replace them while I had things apart. I also replaced C111, which
is nearby. When I removed the caps, there was no corrosion on the PCB.

When I inspected the other Z3801A which is awaiting repair, I saw the
same faint white rings around C108 and C110. There was no corrosion on
TP104, however. I will replace those caps as well, when I get to it.


Joe Gray
W5JG



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