[time-nuts] Z3816 Oscillator Saga

Chris syseng.greenfield at btconnect.com
Tue Apr 29 19:07:27 EDT 2014

I seem to have painted myself into a corner with a Z3816 and wonder if 
anyone can help. Originally bought from Ebay US over 5 years ago and 
used since to drive several items of test gear and an hf receiver. It's 
the ac line model and the only mod was to fit a small fan to keep the 
insides cool.

Over the past year or so,  the efc started to get noisy, spikes on the 
plot, which settled down if the  box was moved, or given a tap. Assumed 
that the oscillator had a dry joint internally, so decided to replace 
it.. Initially carefully unsoldering the existing oscillator,  refitting 
with thin slice of polystyrene at the pins to isolate the heat from the 
board, but no change in the efc after a few weeks. Removed it again, but 
the pliers used to loosen the pins on the pcb (after solder sucking) 
slipped and damaged a couple of sm caps and resistors at the sma 
connector end of the board. No idea what value these were, so can't 
replace. The original oscillator was an MTI 260-0558, while the 
replacement is an MTI 260-0624. Needless to say, it fails to lock with 
the replacement, but because of the board damage, not clear if this is 
due to incompatable   efc  range, or due to missing (damaged) parts. 
Meantime, also carefully opened up the original oscillator, but nothing 
obvious and that now doesn't lock up either, so perhaps best to stop 

Ideally, I would like to find another Z3816, as this would provide a 
spare as well as visual id of damaged parts to allow repair, but haven't 
seen any for sale recently. The other point is that the unit (replaced 
oscillator) doesn't seem to do a search through the whole efc range, but 
always seems to go back to the setting for the original oscillator. Some 
way of resetting this to search mode would be helpful, but again, no 
info, or schematic. Have found the cpu reset pins on the dil header from 
the cpu data sheet, which does save some gps init time on a restart, but 
not clear what the other pins are for.

Any ideas ?. It's been a great lab standard and it would be good to keep 
it running for a few more years...



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