[time-nuts] update on Z3801A repairs

[Artek Manuals]

I had reported earlier that the power supply went south in my Z3801A ( 
and then the receiver) became a suspect as well

In the final analysis I am not sure which went first the Z3801 supply or 
the external power supply I use to power the unit.Both have a clear 
failures.But both were down creating a little confusion at first about 
the problem

The external supply has an adjustable current limit setting which is now 
nonadjustable at 150ma..have not dug into that one yet

Once I figured out that my external supply was bust I switched to 
another supply I have here in the lab to find that the internal Z3801A 
supply still had a problem. As I noted in an earlier post there is a 
"pre processing" section  which I am told was really a over-voltage 
protection section and the DC-DC converter section. The problem 
fortunately is in the the voltage protection section and I have not 
bothered to run it down.Instead I  have reverted for now to bypassing 
the front end of the supply and am now feeding 36V directly into the 
DC/DC converter an easy thing to do at the output of L1 with a simple 
and convenient trace cut. SO not sure which supply took out which supply 
but for now the unit is powered on another supply .with the overkil / 
over-voltage circuit bypassed

A few days after I started things back up the receiver began to error 
out. At first it would  error after 8 hours, then after an hour and now 
it only lasts about 20 minutes. Again no obvious suspects on the 
receiver board in terms of smoked caps etc. At that point another list 
member who has a cache of Motorola Oncore boards that I knew well from 
another list offered to send me a replacement Moto receiver, which 
turned out to be plug and play compatible. the new-used receiver fixed 
the problem in spades so we are back with a working Z3801A. I will cover 
the receiver update from an Moto 6CH Oncore to a 8CH VP Oncore in a 
separate post
-- 
Dave
Manuals at ArtekManuals.com
www.ArtekManuals.com

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