[time-nuts] Defective Z3801 and strange PS board
Marco IK1ODO
ik1odo at spin-it.com
Sat Jul 9 13:43:24 UTC 2011
Hello group,
after many years (about 12, I think) of faithful continuous
operation, my Z3801 failed.
I opened it, and found that there was no supply to the main PCB. The
power supply board in the Z3801 (and Z3805, 58503A, possibly all the
series) is marked 58503-60003. It is a very strange board. It seems
to have a first DC-DC converter taking 48V input, powering two other
DC-DCs that work on 48V (!), one supplying +5/+15/-15V to the main
board, the other supplying 5V 4A to a fourth DC-DC that drives the
outer oven with up to 18V.
Well, it is the first DC-DC that failed. I bypassed it, powering
directly the no. 2 and 3 from 48V, and all works again. The questions
are: does a schematic for that board exist? Anyone knows why such a
complex power supply architecture was adopted? It is not very
energy-efficient, all those DC-DC run hot.
73 - Marco IK1ODO / AI4YF
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