Flickering numbers

[Fitron]

My Wittnauer Polara (early hughes module) has been displaying some unusual characteristics. In cold weather when I go outside stops. When I get back inside it starts at whatever time it stopped at and continues normally I'm not talking about extreme cold but at around 6C or so.

Sympton 2: When I hit the time button it can flicker through the time eg if it's 8.31 it will display 1, then 3 and lastly 8. All the numbers are quite faint compared to normal and it'll continue to do this until I hit the date button which also comes up faint but doesn't flicker. This can continue then suddenly I push the time and everythings normal. While it's flickering it continues to keep the time,unlike the cold. Suggestions (it's not the batteries) gratefully accepted.

[rewolf]

Looks like the oscillator stops at lower voltage (cold or LEDs on).
Could be the crystal or a problem with the supply voltage (bad solder joint, PCB trace, battery contact).

[Fitron]

PCB trace? Lost me there.

[rewolf]

PCB = Printed Circuit Board

[Fitron]

Should have made it clear, what's the trace part of it?

[rewolf]

The traces on a PCB is the conductive material (copper). A trace can get interrupted, sometimes the gap is so fine that it's hard to notice with the bare eye - but this is rare.

[Led-Time]

Does the display flicker like mad then go off, or flicker slowly then stay on one digit, or when you first press the button does the whole display come on together or does it look like a few of the digits lag behind just for a fraction of a second.

I've rescued a few Hughes modules by putting the watch in the fridge for say half an hour then on a warm radiator for the same period then repeat a few times and see what happens, sometimes its magical.

If that doesn't work send me it and I'll check the quartz connections under the microscope for you...

[Fitron]

Flickers non stop until I hit the date button, then that appears faintly but constant, then all goes blank when I take my finger off it. I'll try the fridge idea though. Cheers for the help so far everyone.

[digibloke]

A couple of possible causes...

When the time stops running on a hughes it can sometimes be because the connection at the side of the minus side down battery isn't doing it's job (looks like a pusher connection but facing towards the battery). Start by giving it a clean and making sure that it is making contact.

The flickering sounds more like a loose connection on one of the 3 legs of the quartz crystal. This is a right royal pain to fix. Best case scenario is remove the crystal carefully, clean the ends of the legs with alcohol, push a tiny amount of conductive epoxy into the holes on the circuit board and push it back in. If this doesn't do it then you've got to take the protective cover off the display side to get at the connections from the front and it's an open wire bond nightmare in there.

Always rule out every other possibility before removing a quartz crystal from a hughes as it's a tricky fix to get it back on and working.

[Fitron]

Update: I tried Klippies method on Tuesday (and got some wierd looks from my wife when she went to get the butter) and I've worn the watch since. So far it's working just fine with no hints of flicker and everything is nice and bright.*

Voodoo or not it seems to have worked. Is this related to your leaving modules by your laptop fan cure that you mentioned a while back?

Digi - I promise to clean my contacts with something like progold every time I change my batteries but never a scratch pad.

*Bet it fails now I've posted this...

[Led-Time]

So far it's working just fine with no hints of flicker and everything is nice and bright.

Laptop cure, yes that got me thinking about putting the electronics through several heat cycles to see if it helped, sometimes it does and sometimes it doesn't but if it worked then good stuff...

I've got a duel time 24hr dot display National Semi module that works perfect at 34.5 deg/C but if it drops below that figure a single digit is displayed, bummer, I can't find anything wrong with it either, heat treatment didn't work on this one...

[digibloke]

I've got a duel time 24hr dot display National Semi module that works perfect at 34.5 deg/C but if it drops below that figure a single digit is displayed, bummer, I can't find anything wrong with it either, heat treatment didn't work on this one...

Try sticking it in the toaster...

[retroleds]

I've got a duel time 24hr dot display National Semi module that works perfect at 34.5 deg/C but if it drops below that figure a single digit is displayed, bummer, I can't find anything wrong with it either, heat treatment didn't work on this one...

Have you swapped the quartz crystal? Some develop temperature related faults...it is a crystal after all.

[Fitron]

Sell it to Nigeria Just make sure you take cash only

[Led-Time]

Try sticking it in the toaster...

Ed,
I've tried several crystals and trimmers I think its lost which is a shame as there are not many like it around, it must be a chip problem which is unfixable as its the module with the clear rubbery protection over the wire bonds.

Sell it to Nigeria Just make sure you take cash only

Will do, I'll post an Ebay buy it now auction for £50,000 that should do it.

[rewolf]

I've tried several crystals and trimmers I think its lost which is a shame as there are not many like it around, it must be a chip problem which is unfixable as its the module with the clear rubbery protection over the wire bonds.

Try a 10MegOhm resistor soldered parallel to the crystal - if it doesn't help, try 4.7MegOhm. This often cures problematic oscillators.
If this still doesn't help, sell to Nigeria

[Led-Time]

Thanks for the tip, I'll give it a try.