- rsz_junghans-hightech-24_4610-p1070316.jpg (241.91 KiB) Viewed 31941 times
Other than the movement, the watch appears to be comprised of Junghans proprietary components. The watch case measures approx. 39mm diameter and a 19mm wide bracelet, with hidden butterfly clasp, is attached to a 14mm lug width fitting. The watch is coated in a silver anodized finish, with a gold plated (brass) decorative bezel ring. Other than that, only the crown is gold plated. The pushers are of the screw-in splined type, with double O-ring seals. The watch case construction employs plastic gaskets, giving it a questionable claimed water resistance of 50 metres.
Being a slightly quirky design in two-tone finish, they're something of an acquired taste and despite coming from a once hallowed German watch manufacturer, not a particularly popular choice among collectors of non-Seiko branded 7A38s. I've never been averse to two-tones myself and quite like them, personally. Here's an old wrist shot of one of mine, that I posted on the first page of the old forum's WRUW thread.
- rsz_junghans-hightech-24_4610-wristshot-p1070555.jpg (197.95 KiB) Viewed 31932 times
Thing is, other than posting the odd wrist shot and criticising one particular deceptively described example (fitted with a non-original bracelet) in the 'Wrong Un's thread, I can't remember writing very much about them on the old forum. My omission, which I intend to rectify here, is probably due the fact, that prior to starting the Webs forum in January 2012, I'd already written about them, at some length, in a thread on the UK RLT watch forum towards the end of 2011, here:
Junghans High Tech - Yet Another Non-Seiko 7A38
Unfortunately, due to the manner of my departure from RLT, virtually all the embedded (PhotoBucket hosted) images have been removed from my posts.
That said, there's still a wealth of information in the text, for anyone interested. I also included a short potted history of Junghans Uhren GmbH. Here are a couple of pertinent quotes from that post:Bearing in mind that Junghans were developing their Mega 1 (the World's first radio-controlled watch) at the time, I still can't fathom what could possibly have possessed their marketing department to call this watch the HIGH TECH chrono. It's a complete misnomer and utter travesty !Back in the 1990's and early 2000's Junghans entered into 'master joint development agreements' with Seiko Epson Corp. These agreements covered the joint development of Junghans 'Mega' range of radio-controlled and solar-powered watches. It would seem from Junghans' use of Seiko 7A38 movements in their 'High Tech Chrono', there was also earlier collaboration.
These watches were presumably manufactured in late 1987 or 1988, when Seiko had already been producing their own 7A38's for nearly 5 years. Hence my deliberately facetious title suffix: Rückwärts Nicht Technik. If the movements had been supplied to Junghans as part of any fledgling technology sharing agreement, I'd opine that they got the short end of the stick ! 
That said, it seems to have been a fairly short-lived arrangement. I was browsing Junghans archives, to learn whether there might possibly have been another dial colour variant (there wasn't). I found the illustration below on page 17 of their 1989 catalogue. Please excuse the quality, but their .pdf scans are fairly low resolution. The smaller image of the watch in the 1988 catalogue is even poorer quality. If you view the full page scan of the 1989 catalogue, you'll see that on the same page there are also 3 versions of a rather more attractive-looking Junghans quartz chronograph, powered by the Citizen Cal. 3530 movement: 024/3805.44, 024/3806.44 and 024/3807.44. They're still shown as available in the 1990 catalogue, since joined by another Citizen 3510 powered chronograph (with alarm and date), model 024/3900.00. But no sign of the unloved 24/4610 High Tech Chrono, by then consigned to the pages of history.
- Junghans-24-4610-HighTechChrono-1989-Catalogue-Page17.jpg (64.96 KiB) Viewed 31891 times
Note that the full catalogue number is 024/4610.44 (that '44' suffix was what made me wonder whether there might be another variant) - same as printed on the paper hang tag in a current eBay listing in a subsequent post. That also shows a retail price of 990 DM (equivalent to approx. 500 Euros). Whereas the watch's case-backs are only stamped 24/4610.
- rsz_junghans-hightech-24_4610-p1070312-crop.jpg (217.43 KiB) Viewed 31879 times
Note that there is no manufacturing serial number - so no means of telling how many were produced. The case-back is a press fit (from memory, the only 7A38 not to have a screw-down threaded case-back) - hence the flat at the bottom, to facilitate insertion of a blade for removal. The case-back is sealed and retained using a hard red plastic (Sanfil) gasket similar to these offered by Cousins UK - visible in my first photo in this post.
Harking back to that old thread on the RLT forum and paraphrasing my first post ....
I found the first one I clapped eyes on, purely by accident. At the time, I still fancied a Junghans Max Bill Chronoscope and was idly googling images, when I came across this then long since ended US online auction, by Reata Pass Auctions, dating back to May 2007. The auctioneer's estimate was an over-optimistic $350 - $650. It only made $100 in the sale. I'm surprised that the link still worked after all this time. (Edit: it doesn't anymore).
- Junghans-24-4610-HighTechChrono-RealtaPassAuctions-Lot#396-June2007-Sold-$100.png (111.78 KiB) Viewed 32001 times
- Junghans-HighTech(7A38)-Stainless+Gold-ReataPassAuctions-Lot#396-May2007.jpg (36.71 KiB) Viewed 32007 times
These are a couple of small screenshots I took of the only available parts information, on Boley.de, about 10 years ago:
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- Boley.de-Junghans-24_4610-Detail.JPG (23.63 KiB) Viewed 32004 times
They've since changed the format of their database / search slightly, but it can still be found here.
- Junghans-024-4610-HighTechChrono-Boley.de-PartsInformation.png (20.43 KiB) Viewed 31829 times
There's no part number for the gold-plated bezel ornament ring, nor a spare bracelet link, which are the parts you're most likely to need for any refurbishment. Whether Boley actually have the parts they list in stock is another question.
Other useful information can still be found in that old RLT thread, for example a suitable replacement generic crystal.
A word to the wise (speaking from experience) ....It was 30.4mm x 1.6mm thick, with no beveled edge. So I ordered a Sternkreuz MSM304 as a replacement.
It's almost identical, apart from being 0.1mm thinner, and indistinguishable from the original crystal when fitted.
When replacing a crystal (I've done so in a couple of mine), ensure to check the condition of the retaining gasket !
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The white plastic ones used by Junghans appear to be of an inferior quality and deteriorate over time, becoming brittle and prone to cracking. That's the worst one I've encountered, but I had another which still looked fresh, but broke into two halves when I pressed the old crystal out. I've used both Sternkreuz and Superparts Hytrel gaskets as replacements. Worst case scenario: a damaged gasket will allow water ingress, leading to ruined Tachymeter ring printing, like this:
- rsz_p1670068.jpg (152.9 KiB) Viewed 31791 times
The crown is sealed with a green plastic gasket, rather than an O-ring, adding to the already dubious water resistance:Incidentally the threaded part of the crown stem is 0.9mm (Tap 10) the same as the Yema / C.G.H. Shimauchi V906; The standard Seiko 7A38 stem (p/n 0354728) thread is 0.8mm (Tap 11) by comparison.
- rsz_p1070314.jpg (85.46 KiB) Viewed 31720 times
Meaning that if you're planning to work on one, you'd be wise to invest a quid (£1) in a pack of Cousins p/n P20857P.The links are 19mm wide by 6.5mm deep and removable ones are held together by the usual 1.0mm split pins.
- rsz_p1070319.jpg (151.19 KiB) Viewed 31814 times
As also shown in a couple of my previous photos, the bracelet is attached to the case using 1.4mm Ø pins and tubes:
- rsz_p1670069.jpg (146.6 KiB) Viewed 31791 times
This is a similar fixing arrangement to that used by the Yema Spationaute III and N8 Flygraf. However, the Junghans case has much narrower, shorter, more sharply tapering lugs, which makes it extremely difficult to press (or hammer) out the pins, without accidentally marking the lugs. The way I've gotten around it, when either cleaning or working on a 24/4610, is to leave both halves of the bracelet attached to the case, but shorten it, by pushing out the two 1.0mm Ø split pins nearest the case, thereby removing the adjustment links and butterfly clasp, which makes it less unwieldy.
Although two of my four Junghans 24/4610's are in fairly presentable condition, neither could be described as close to mint. I fancied that NOS example which was listed on eBay Germany in the first week of April. So I emailed the seller, in German, politely asking if he'd be prepared to make an exception and ship to the UK.
To call its fitment 'tenuous' would be an understatement. It fell out when I turned the watch over. 
