Rectifying a Badly Botched Battery Leak 'Fix'

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Seiko7A38
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Rectifying a Badly Botched Battery Leak 'Fix'

Post by Seiko7A38 »

Last week, I made the mistake of hastily buying a Racer J39908-70 off the Spanish classifieds site Milanuncios.com. :roll:
My primary error was in believing it had a different colour dial. But I've begun to regret it more, for other reasons. :(

The earlier story of my acquisition is here in another thread. In the photos embedded in the first post, the watch was showing different times, with the constant seconds hand in different positions, so naturally I'd assumed it was running. Although he's since conveniently deleted the advert, I've kept a record of the Spanish seller's messages. In response to my initial question whether he was prepared to ship to England, he replied:

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Which translates as: Hello, if you run with the shipment, there is no problem, the hand of the tenths of the second hand works but the one of the central second hand does not work.

Having seen it so many times before, I was half expecting the non-functional chrono' centre seconds would be due to a displaced finger tension spring. Coincidentally it turned out to be quite mangled, but that wasn't the reason. The watch was delivered surprisingly quickly, yesterday morning. I'd already realized my blunder over the perceived dial colour, so that wasn't a surprise. But the watch was as dead as the proverbial dodo, having stopped, showing the time at approx. 8:25AM on Saturday (SAB) 28th. I didn't take an 'as received' head on shot of the watch, but instead quick-set the hands and fitted a strap so I could do the 'side-by-side' shot that I posted in the other thread.

Yesterday afternoon, I gingerly unscrewed the case-back to be met with this horrible botched-up mess. The discoloured movement back-plate shows the watch has suffered a fairly serious battery leak at some point. The two contact arms of the battery positive plate are missing, presumably broken off after having been weakened by the acid corrosion. At first glance, I thought someone had soldered the battery in place. :o

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Closer inspection revealed that it was actually a roughly folded piece of silver paper that had been wedged between the battery and the backplate, thereby making tenuous electrical contact.

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Once I'd established that's what it was (rather than solder), quickly removed with a pair of tweezers.

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In the photo below, you can better see the discoloration of the back-plate around the battery well and also under the battery positive plate. The battery negative terminal has also been polished, thereby removing all its gold plating.

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I decided to do a quick in situ partial strip-down of the movement to examine the extent of battery acid damage. The movement back-plate was comparatively clean, but I suspect someone may have already given it a once-over. The PCB was initially reluctant to be separated from the '710' insulator spacer. Eventually I managed to carefully prise it off. The (-) battery contact, which usually suffers worst, was surprisingly unscathed, but there was considerable potential track damage elsewhere (shown by the copper sulphate deposits), where the battery fluids / fumes had seeped through.

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The lower resolution photo of the exposed '710' insulator, below, doesn't show much. However, the fact that the contact patch of the negative battery terminal still has its gold plating (and oxidized deposits) intact shows that whoever polished its visible parts (in situ, in the battery recess) had made no attempt to check under the PCB. :x

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This close-up shot shows the likely reason(s) for the non-functioning centre seconds hand. The contacts of the (RH) coil have been bridged by copper sulphate deposits. There's also something untoward visible through the inspection hole on the centre seconds bridge, above the main gear wheel (which turned out to be an unidentified piece of plastic swarf).

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My first action was an abortive attempt at cleaning the sulphate deposits off the PCB and contact area of that coil, first using Rodico (which had zero effect), then using a proprietary electronics spray. All I succeeded in doing was exposing the bare copper tracks. I initially tried reassembling it redeploying the old PCB, but all that worked was the 1/10s hand. So I dug out a known good used PCB and fitted that. Now I also had the time running, so the old PCB definitely had a short circuit. I then replaced the chronograph seconds and 30 minute counting coils and finally at the third attempt achieved full functionality. Needless to say, I also replaced the positive and negative battery connections and finger tension spring. In the interests of improving cosmetic appearance I also replaced the anti-magnetic backplate and centre seconds bridge (both originals were scratched).

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So you might think now I'd got it running properly, I'd be happy ? Far from it - in fact I'm probably even more pissed off. There was a hint of further underlying problems in that staged side-by-side photo I'd posted earlier in the other thread.

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Note the discoloration around the upper perimeter of the dial, below '60' and 'Tachymeter' - better visible below:

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Here's what I found to my horror, when I removed the dial / movement from the case:

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Although there's less actual damage to the visible area of the dial, it's little better than my previous example:

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Which I'd written about 6 years ago in the Racer J39 'Spanish Inquisition' thread. The irony isn't lost on me. :roll:

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So that's the second time this particular fool has rushed in and bought a duff example of the same Racer J39908-70. :oops:

Besides a classic example of Caveat Emptor (failed) and Buyer's Remorse, the moral of the story being: if you're dealing with someone for the first time, particularly in a foreign language (and if the watch you're thinking of buying is cheaper than average) - ALWAYS ask for a photo of the movement before agreeing to purchase. I really should have learned that lesson by now. :roll:

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