OT but leds are leds ...



#2

ciao a tutti,

first of all forgive me if this is too much OT, if this is the case please delete this post.

I have purchased some Bulova parts, with the idea of putting them together and make at least one working N6 Computron out of these.

Unfortunately, it wasn't such an easy task, and the following photos will show what remains :










Well, the cases ARE working :), and so the modules, or at least one module.
What had suffered most from the manipulation are the LEDs,so the question is :
how difficult is to recover the missing segments, given that at least one of the two display was entirely working
before I had a chance to work on it ??
Did anybody had a similar (bad) experience ??


Thanks for any help, take care Alberto


#3

Sorry to bring bad news ... but you may not have a chance to swap segments from one display to the other.

It can not be seen from the pictures if the segments are single chips or all segements of a digit are on one chip. In any case the chips are glued to a pad by conductive glue and bonded with wires which connect to another pad.

I assume that the bonding wires are broken, because they are not protected by anything. If you can't find a fully working display, your only chance is to use the one with the most working segments. If you are very lucky, you may bend the wire in such a way that it gets contact to the display. But this required a steady hand, patience and good eyes and it will probably not work for a long time.

You may look for a company which does chip bonding. If you find one, they may even be able to repair both displays.

Have you checked the displays? With a 3V voltage source and an 3.3k Resistor you should be able to test which segements are working.

Electronic watches are an very impressive technology but even more difficult to repair than calculators.

Greetings,

Thomas


#4

Ciao Thomas

the back of the display PCBs include the chip, which is covered by what seems back epoxy resin.
The display PCBs were connected to the main modules (hosting the trim and the quartz) by a small flat cable which broke off
I was able to swap the PCBs, they are from to identical watches, only the led layout is slightly different since one is newer.
The first unit I had received had a blank piece of plastic covering the ultrathin wires.
However, during the work, the plastic protection came off, and some segments, I should say most, went off.

I have read some posts, and posted as well, on the www.dwf.nu where I hope someone can sell me a working module.
Is bounding the thin wires really so tough ??? (I was kind of knew it was bad news...)
Thanks anyway, greetings from Italy


#5

Ciao Alberto,

Quote:
Is bonding the thin wires really so tough ???

IIRC for wire bonding you need at least a professional tool. We did such work nearly 20 years ago, so my memory may fail, but bonding means micro-welding so it was definitively not for amateurs.

Cordialmente,

Walter


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