Unknown watch

[willholman]

Hi

I just bought this unknown watch.



Uploaded with ImageShack.us



Uploaded with ImageShack.us



Uploaded with ImageShack.us



Uploaded with ImageShack.us



Uploaded with ImageShack.us

I took it apart, cleaned it up and tried to remove the green crud on the module with lighter fluid - with limited success. When I power it up all I get is what you see. Any ideas what I should try next? And does anyone know what make it is? The case is nicely made.

Cheers

Will

[willholman]

It appears that it is an Imado (I assumed it was an after-market strap).

Anyone know who made the module?

[rewolf]

I took it apart, cleaned it up and tried to remove the green crud on the module with lighter fluid - with limited success. When I power it up all I get is what you see. Any ideas what I should try next?

The module is rather badly corroded.
1. Check with ohm-meter if all PCB traces are intact, also the vias (top to bottom connections through holes) - in the photo it appears that some traces are interrupted, but it could also be white residue of battery acid.
2. A single bright digit is a typical indicator for an oscillator problem - escpecially if it's not always the same digit that lights up. Replace the quartz crystal.
3. The trimmer capacitor (round part on battery side) also looks badly corroded, it is part of the oscillator circuit. Replace it - if you can't get a trimmer, used fixed-value capacitor of 15 or 18 or 22 pF.
Soldering will be a bit difficult because of corrosion.

[LEDluvr]

I took it apart, cleaned it up and tried to remove the green crud on the module with lighter fluid - with limited success

Lighter fluid - yiikes!! Try using CLR (Calcium -Lime - Rust), you can find it at any hardware or drug store. (it will be cheaper at Home Depot or Walmar than Rite Aid or Longs.. trust me ). Then, after dry, give it wipe of good ol' fashioned rubbing alcohol using cottton q-tips.
I'd suggest gently removing the black carrier from the circuit board. It should pull right off, but do it incrementally and one side at a time. There is most likely green crud in the areas you can't see and it if left there it will impede proper electrical flow. After completing all this- you will still need to at least replace the quartz crystal as Rewolf said. You have a fixer-upper but it might be saved!

[willholman]

Thanks for the advice, chaps. Where do I get a trimmer cap and the crystal (I'm in the UK)? And the cleaning stuff you mention - any European versions that you guys know of?

Thanks

Will.

[morelite]

The case looks like a Fairchild watch.

http://www.dwf.nu/viewtopic.php?p=24326

[willholman]

It does indeed look like a Fairchild. I like it. It's nicely made.

Any ideas where I'd get a crystal for it? And what's the UK equivalent of this CLR stuff? It doesn't appear to be available over here and US suppliers want 24 quid to post it.

[willholman]

Would one of these do? If so, which one?

http://www.rapidonline.com/Electronic-C ... e=googleps

[LEDluvr]

I'm not sure what the UK equivelant of CLR or Lime Away is, but I'm sure if you go to a hardware store and ask them for a liquid cleaner that is designed to remove calcium and lime deposits (i.e.: on your kitchen sink/facuet area) that they will have something similar to CLR. Mind you, it's not an abrasive substance like water mixed with ajax. It's clear or light green fluid with a watery consistency.

[rewolf]

IMHO the module already looks clean enough, i.e. cleaning it more wouldn't make any difference regarding its working state.

[james_stan]

Lime-lite I reckon is the nearest UK equivalent to CLR - Citric acid
is the active ingredrient I think.

Crystals can be bought from your local Maplin store or ebay, Expect to pay about 50p upwards each.

Cheers

James

[azimuth_pl]

DON'T use bathroom cleaning solutions on your modules as they are to hazardous. you might be lucky but those are very harmful acids.
lemon juice/dissolved citric acid or vinegar should be used for the very first attempt as they are mild enough to apply a 10 minute bath.
afterwards clean with demineralized water and dry.
CLR solutions are good for cases and bracelets with those greenish residues but also don't leave them for a week as there won't be much left ;)

the watch is an Imado and if there is no luck you can find a 1976/N6 Bulova with the same module by Mostek.
these are pretty robust and easy to repair with a quartz swap but since it displays a random digit it might be very likely unrepairable.
cleaning with vinegar might dissolve all the hydroxides that are probably shorting the circuitry.
just because a module looks clean it doesn't mean that it is clean in conductive terms.

[Led-Time]

I've got this exact same Imado watch which also needed a new module, keep an eye on Ebay for a working Timeband LED with the same button positions they are ultra cheap and the module will drop straight in...perfect...

[retroleds]

DON'T use bathroom cleaning solutions on your modules as they are to hazardous. you might be lucky but those are very harmful acids.
lemon juice/dissolved citric acid or vinegar should be used for the very first attempt as they are mild enough to apply a 10 minute bath.
afterwards clean with demineralized water and dry.
CLR solutions are good for cases and bracelets with those greenish residues but also don't leave them for a week as there won't be much left ;)

the watch is an Imado and if there is no luck you can find a 1976/N6 Bulova with the same module by Mostek.
these are pretty robust and easy to repair with a quartz swap but since it displays a random digit it might be very likely unrepairable.
cleaning with vinegar might dissolve all the hydroxides that are probably shorting the circuitry.
just because a module looks clean it doesn't mean that it is clean in conductive terms.

I think the bathroom lime deposit solutions are just fine, and unless you are checking the ph, there is no saying that vinegar is less acidic. My biggest concern is the suggestion of giving a module a whole bath in any of those solutions - the wire bonds on many modules are copper or aluminum, which are going to be eaten in half by the mildest solutions if there is the smallest trace of oxidization. And getting some movements to dry out could take weeks, once the solution has migrated underneath silicone or other materials which were used to seal over the main IC or wirebonds. And once the solution has migrated under there, it is going to be impossible to rinse out. Swabbing a module's traces is fine since you can readily dry them off and/or neutrilize the acid with a little water with baking soda but I personally think the submersion idea a terrible suggestion.

[azimuth_pl]

vinegar is usually diluted 10% acid which you can consume.
bathroom solutions clearly state that rubber gloves should be used for safety which shows that they are hazardous and agressive.
if you have a dead module I guess you're not risking anything by applying a bath.

I have done this dozens of times without issues nor have I experienced any damage to wirebonds what so ever.
the only dissolved material is the green or white powder residues that bubble nicely upon applying the acid.

of course you have to be clever and posses the obvious knowledge that water within silicone fillings might not be removed properly.
this is a quick fix for exposed modules like Hughes and late P2 and P3 and early P2's after removing the silicone.
it can be used for P4 circuit board removed from their carriers and with removed circuit covers.
thanks for pointing this out Ed, it might be obvious but some people might read straight and consider vinegar to be a cure for everything.

[retroleds]

Actually, common vinegar for consumption is 5% acidity, in all countries. 10% would be much too strong for food purposes.