[time-nuts] time-nuts Digest, Vol 77, Issue 4

Ed Palmer ed_palmer at sasktel.net
Thu Dec 2 22:03:29 EST 2010

Have you checked the Z3801A info at this web site?


There are two versions of the schematic for the outer oven controller in 
the Z3801 and Z3801A directories.


Jerry wrote:
> Thanks to everyone for the pointers on getting my Z3801A/58503A
> working correctly.  The pointer to the realhamradio.com really helped.
>  I was looking for a schematic but the info on the realhamradio pages
> with pin outs and voltages was almost as good.  I have finally decided
> that everything is working except the outer oven.  There is no 14
> volts on the heater and no current is being drawn.  An curious thing
> is that there are 2 DC to DC converters the main power converter is 24
> volts in and +12, -12, and 5 volts out and the input and output
> voltage is plainly marked on the side of the converter.  The power
> supply supplied with the unit is 24 volts DC and the that converter is
> working fine.  The second DC to DC converter is labeled UMR-5/4000-D48
> which according to the data sheets that I found is a 48 volt DC in and
> a 5 volt DC at 4 amps out unit.  I dont understand why the 2 DC to DC
> converters would have a different input voltage with only the 1 power
> supply  If anyone has any thoughts about this I would like to hear
> about them.  Again my symptoms are that the unit seems to work but it
> is moving all over the place and moves in and out of spec which then
> takes it out of lock until it comes back into spec.  I have sent the
> vendor a request but he is in Hong Kong and I havent heard back from
> him yet.
> Thanks, Jerry W5RCQ

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