[time-nuts] Defective Z3801 and strange PS board

[bownes]

My educated guess is that they expected to sell these to telcos, who traditionally run everything in a central office on -48v and running off of ac was an afterthought. 



On Jul 9, 2011, at 9:43, Marco IK1ODO <ik1odo at spin-it.com> wrote:

> 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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