Odd problem, with a Hughes module

[dodger1954]

Hi gang, I've got a problem with a 29mm Hughes dot-matrix module, and thought maybe you guys could help me out, in trying to figure out how to fix it. Actually, I've got more than ONE Hughes module, that does this same odd thing:

When you connect across the batteries in the module, the display stays on constantly, and it then sits there, continually advancing the hours. AND, the module doesn't even have to be IN the watch case, to do it! It doesn't seem to matter...in the watch case, or outside the watch case...as soon as you install batteries in the module and connect across them, the display comes on, and the hours advance!

Also, if you install the module into a watch case and complete the connection by putting the watch caseback on, it not only stays on and advances the hours, but it will ALSO advance the minutes, if you push the pushbutton on the watch. At first, when the module was IN the watch, I thought that perhaps the setting button was somehow making contact, and making it advance like that. But, as it does this odd thing even when the module is completely out of the watch, I have no idea what could be the problem. Anyone have any ideas? Any help would be greatly appreciated! Thanks, Dodger

[bucko170]

It might be worthwhile removing the plastic carrier and cleaning up the traces on the board with a fibre tipped pen and some isopropyl, I don't if it will cure the problem but it would rule out any unwanted contacts on that side of the board.

[dodger1954]

Hey, thanks, Bucko, I'll get a fibre tipped pen, and try that. I'll let you know if makes any difference, and solves the problem. Thanks again! Dodger

[dodger1954]

Hi Bucko, and everyone...here's my update, regarding the weird problem I was having, with a Hughes module...I tried cleaning the traces on the circuit board, in the manner that Bucko suggested, and...to my complete and utter amazement, it actually worked! As you all know, these modules don't have very many traces to start with, and I could see NO unwanted connections, even when looking through a high-powered eye loupe, with a light. So, even though it looked very clean, and I had already tried cleaning the traces with a can of electrical/electronic contact cleaner (which didn't help), I tried using alcohol as Bucko suggested, and...problem solved! So far it's working, and seems to be keeping time, so...thanks, Bucko!

[bucko170]

Glad to have helped, it's early days so don't thank me just yet

[azimuth_pl]

Sometimes you might be lucky and sometimes not but alcohol is the best first attempt.
I sometimes find it helpful to apply a soldering iron to all the solder points on the module without even removing the black cover.
Old solder tends to produce old microscopic cracks that is invisible so by reheating it you repair the connections.

[dodger1954]

Hi Azimuth, thanks, that's a good idea, too! Fortunately for me, the alcohol seems to have fixed the problem, and the Wittnauer Polara that this module came from now seems to be keeping perfect time after the past two days, and I am very happy about that. I've got one or two other Hughes modules somewhere in my parts stuff, that had this same sort of problem, so now I'm curious to dig them out and try the alcohol, to see if they too can be resurrected and put back into service. Anyway, thanks again for your help, guys! Cheers, Dodger