- How to repair the LCD display of a digital watch - 4 Updates
- Digital AM/FM Signal Generator - 8 Updates
| sportsbob1.bl@gmail.com: Jun 21 05:23AM -0700 I have an old timex marathon watch. Model number 745 e or f 8. It has water damage to the LCD screen. Will isopropyl alcohol or anything else help get this black streak mark out on the LCD screen? Will cleaning up the rust in the LCD screen help as well or is it just to late? Timex will not replace this LCD screen as this watch is so old it has been discontinued. I would post a picture of the damaged watch with the bad LCD screen but I don't know how. I can also say this, when taking into a watch repair place, they took the LCD screen apart and it when putting it back together the little black streak mark across the watch went from little to big! They made the situation worse! Please help me with this as to anyone having suggestions. My name is Robert! Thanks! |
| sportsbob1.bl@gmail.com: Jun 21 05:31AM -0700 Also, will trying isopropyl alcohol on the LCD screen help if there is already this black line in my old timex marathon watch or is it just to late. If your only suggestion is to call timex and ask them for A replacement for this LCD screen that option won't work as they dont make this watch anymore or service parts for this watch anymore. So any help as to if this watch LCD screen can be repaired would be greatly appreciated. Thanks and hope to be here from you all soon. Robert. |
| N_Cook <diverse@tcp.co.uk>: Jun 21 02:18PM +0100 > Also, will trying isopropyl alcohol on the LCD screen help if there is already this black line in my old timex marathon watch or is it just to late. If your only suggestion is to call timex and ask them for A replacement for this LCD screen that option won't work as they dont make this watch anymore or service parts for this watch anymore. So any help as to if this watch LCD screen can be repaired would be greatly appreciated. Thanks and hope to be here from you all soon. Robert. My guess is black streak was a hairline crack of the glass , from a knock. Close handling then enlarged the crack. Look for a "spare or repair" scrapper on Flea-bay or wherevever, with a different fault of course |
| Terry Schwartz <tschw10117@aol.com>: Jun 21 07:30AM -0700 Most of the Timex Marathon watches are very inexpensive -- any repair would quickly eclipse the price of a new watch. Even if Timex could supply a replacement, it would not make sense to go down that route. |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Jun 20 09:52AM -0700 On Wednesday, June 20, 2018 at 12:16:27 PM UTC-4, Jeff Liebermann wrote: file:///C:/Users/pwieck/Downloads/8640B-Signal-Generator-Operating-and-Service-Manual-08640-90017.pdf Give me the manual-seems to do about everything I want. There is one that would be $350 FOB 19027, and with a 30-day full guarantee. Looks very clean. Thoughts? Peter Wieck Melrose Park, PA |
| Fox's Mercantile <jdangus@att.net>: Jun 20 04:42PM -0500 > seems to do about everything I want. About the HP8640, very nice piece, BUT the lower frequency limit is 500 KHz. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Jeff Liebermann <jeffl@cruzio.com>: Jun 20 04:54PM -0700 On Wed, 20 Jun 2018 09:52:08 -0700 (PDT), "pfjw@aol.com" >On Wednesday, June 20, 2018 at 12:16:27 PM UTC-4, Jeff Liebermann wrote: >file:///C:/Users/pwieck/Downloads/8640B-Signal-Generator-Operating-and-Service-Manual-08640-90017.pdf Ummm... that's the URL that points to your own c: drive. There are downloadable HP8640 manuals all over the internet. However, there are variations, packaging differences, options, and specialty variations such as avionics or military versions. I think I have most everything in PDF form and can snail mail a CD or arrange for you to download them. >Give me the manual-seems to do about everything I want. >There is one that would be $350 FOB 19027, and with a 30-day full guarantee. Looks very clean. >Thoughts? My pitch line is that you can get some really nice used HP RF generators for little money. The danger is that it might be too old to get parts, or have some well hidden problem that you don't immediately notice. A 30 day guarantee is fine, but you pay shipping both ways. At 45.8 lbs (20.8 kg), that's not cheap. There are a few potential mechanical problems. The big one is that the bevel gears in the frequency range and modulation rotary switch mess are cracked. Someone makes replacement gears using 3D printing, but I haven't seen them. I would prefer brass. I'm tempted to make some but would need to buy an indexer for the mill that I'm sharing. Here's what it looks like: <http://802.11junk.com/jeffl/pics/HP8640B/> I can explain how I fixed the gears later. The good news is that once the hole in the plastic gear is enlarged to fit the brass ring, and glued, it stays fixed. Here's a list of some other potential problems and fixes. Some of my stuff is mixed in there, somewhere: <http://www.ve7ca.net/TstH86.htm> I have an HP8640b on the bench (or rather under the bench) that needs a new RF output amplifier. Check the options. Opt 1 and 2 involved the frequency ranges as explained in: <http://electronicsrevisited.com/html/hp_8640b.html> Opt 4 is for avionics. You definitely want Opt 3, which is reverse power protection. Without it, you run a good chance of accidentally burning out the output attenuator. There's a 0.1A fuse in the N connectors, but it's better to let Opt 3 protect the unit. They don't make them like this any more: <http://802.11junk.com/jeffl/pics/HP8640B/slides/hp8640b-fix.html> However, I'm wondering if an HP8640B is what you really need. The cavity oscillator is really low noise, which is what I need for SSB noise and IMD measurements, but not much else. Perhaps a synthesized generator might be better. I have an HP8656A generator: <https://www.ebay.com/sch/i.html?_nkw=hp8656+-Philips> Looks like the average selling price of $350 is over your limit: <https://www.ebay.com/sch/i.html?_nkw=hp8656+-Philips&LH_Sold=1&LH_Complete=1> Maybe haggling with the seller will drop the price into your range. I have an HP8656A: <http://802.11junk.com/jeffl/pics/home/slides/test-equip-mess.html> Upper right, bottom of the pile on the shelf. Over the last 10(?) years I had a few problem. - The rear panel RF output connector is rather inconvenient. - Calibrating the RF output, deviation, and AM modulation, were needed after I screwed things up my not reading the instructions. - The push buttons on the front panel tend to hit the front panel bezel and stick. I'm sure I can fix it if I take it apart, but haven't had the desire or time. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Jeff Liebermann <jeffl@cruzio.com>: Jun 20 05:13PM -0700 On Wed, 20 Jun 2018 16:42:08 -0500, Fox's Mercantile <jdangus@att.net> wrote: >About the HP8640, very nice piece, BUT the lower frequency >limit is 500 KHz. The actual range is 450kHz to 550MHz. It will go to 1024Mhz with the Opt 2 frequency doubler. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Jeff Liebermann <jeffl@cruzio.com>: Jun 20 05:30PM -0700 On Wed, 20 Jun 2018 09:52:08 -0700 (PDT), "pfjw@aol.com" >Thoughts? "Choosing an RF Signal Generator" <http://www.ab4oj.com/test/sig_gen.html> "HP-8640 Service: Hints & Kinks" <http://www.ve7ca.net/TstH86.htm> "The HP 8640B RF Signal Generator" <https://www.ebay.co.uk/gds/The-HP-8640B-RF-Signal-Generator-/10000000010610658/g.html> "Phase noise measurements microwave bricks compared to HP8640B, HP8662A, and HP8656A" <http://www.ke5fx.com/brick/brick.htm> "HP 8640B Repair" <http://jvgavila.com/hp8640b.htm> <http://jvgavila.com/wb1.htm> YouTube videos on HP8640B" <https://www.youtube.com/results?search_query=hp8640B> Gotta run (again)... -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| dplatt@coop.radagast.org (Dave Platt): Jun 20 06:02PM -0700 >> seems to do about everything I want. >About the HP8640, very nice piece, BUT the lower frequency >limit is 500 KHz. And, it's not really "digital" as the OP requested... it's an analog cavity oscillator. The commercial versions (but not the military OPT 323 variant) do have a frequency-lock capability which will lock to the crystal oscillator in the counter timebase, though... with this in use its stability is quite good and I'm told the phase noise level is excellent. It's not quite within the OP's stated budget, but... I recently picked up an 8648B for under $500, delivered. Very nice beast, covers 100 kHz up to 2 GHz, with AM and FM and phase modulation, and good enough GPIB control to be useful. Even without the high-stability oscillator option, it was within 1 PPM after a warmup, and it trimmed quite nicely to within their recommendations (10 PPB) using my rubidium standard as a reference. |
| dplatt@coop.radagast.org (Dave Platt): Jun 20 06:09PM -0700 In article <k9olidteq0j79f2uotf8qr9ooo47k7jrk3@4ax.com>, >the bevel gears in the frequency range and modulation rotary switch >mess are cracked. Someone makes replacement gears using 3D printing, >but I haven't seen them. I would prefer brass. There's a guy in India who has been making sets in brass... I'm in the middle of installing a set now. He posts on the HP test-equipment mailing list, and has some of the brass gears up on eBay. The other issue I've run into, with that switch assembly, is that the two white plastic parts (the shaft which holds the two small planetary bevel gears, and the rectangular piece which clamps onto this shaft and actuates the rear switch decks) are a bit dodgy. The tighten-it- down clamp head on the rectangular piece was cracked, and even after repair it isn't gripping the shaft well enough to prevent slipping. And, the new brass gear which _should_ rotate freely on this shaft, is rubbing and squeaking... either its hole is a bit under-sized, or the plastic shaft isn't dimensionally stable after all of these years. So, I have a bit of adjustment to do. I'd love to replace both of these plastic bits with something more stable (maybe a metal shaft with metal axles for the planetary bevel gears, and a composite or Delrin assembly in back) and might try fabricating something if I can't get the existing plastic parts back into service. |
| Jeff Liebermann <jeffl@cruzio.com>: Jun 20 08:52PM -0700 On Wed, 20 Jun 2018 18:09:22 -0700, dplatt@coop.radagast.org (Dave Platt) wrote: >There's a guy in India who has been making sets in brass... I'm in the >middle of installing a set now. He posts on the HP test-equipment >mailing list, and has some of the brass gears up on eBay. <https://www.ebay.com/itm/Brass-Gears-for-the-HP-8640B-Signal-Generator/153024403695> You should have taken my advice and glued the cracked gear back together with epoxy. The trick is to temporarily put the gear back together with a hose clamp or fixture. Then take a big rat tail file and enlarge the hold in the plastic until the brass lock ring fits easily in the hole. Or, you can use a proper reamer and a mill. Remove the set screw and plug the hole with wax, or a longer screw smeared with a little mold release (grease or Vaseline). Leaving the gear halves clamped together, smear some 24 hr epoxy on the knurled part of the brass lock ring, and let it dry overnight. Remove the temporary clamp holding the gear together, remove the hole plug, clean the threads, re-insert the set screw, and put it back into the gear assembly. I've done about 10 gears like this without experiencing any problems. Well, not quite. The last one I did, I either got the mixture wrong on the epoxy, or used some ancient tube of epoxy which refused to harden. I had to scrape it off and glue it again, which worked. Incidentally, while you have the gearbox apart, bend the other non-broken gears a little to see if they are in any danger of breaking in half. Most will break at the set screw with very little pressure. Might as well have it break now, rather than while you're using the generator. If you still have the old gears, I'll be happy to glue them together for you for the price of shipping and small donation to support my decadent and lavish lifestyle. >and actuates the rear switch decks) are a bit dodgy. The tighten-it- >down clamp head on the rectangular piece was cracked, and even after >repair it isn't gripping the shaft well enough to prevent slipping. I haven't seen that yet. I'll take a look at the two I have when the bench is clear. That might explain some backlash in the shaft. >rubbing and squeaking... either its hole is a bit under-sized, or the >plastic shaft isn't dimensionally stable after all of these years. >So, I have a bit of adjustment to do. I'm not thrilled with the machining quality shown in the photos. It's adequate, but not great. If anything, the plastic shaft has SHRUNK making a loose fit more likely than a tight fit. I can measure mine if you need a comparison. I would bet the hole has burrs, shavings, or is undersized. >gears, and a composite or Delrin assembly in back) and might try >fabricating something if I can't get the existing plastic parts back >into service. Can you generate the G code needed to make the part? I'm helping setup a CNC mill that can possibly make it. <http://802.11junk.com/jeffl/pics/CNC-conversion/> The catch is that we don't have a rotary indexer or gear cutter, so all the teeth will need to be shaped with a small end mill. That's slow and not fun. It would almost be easier to make a silicone rubber mold and cast the gears from resin. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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