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| Old Fluke Multimeters |
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| frozenfrogz:
--- Quote from: Neomys Sapiens on August 25, 2017, 06:48:12 pm ---I have encountered those problem occasionally, but never on a meter that was owned by me from first hand. --- End quote --- Being careful is always a considerable option. On the other hand I can not deny that self-tapping screws are usually a sign for cheaply made products. Even the Voltcraft 6010 made in Korea by Hung Chang (rebranded HC601) has brass inserts. |
| drtaylor:
I have 4 restored 8060s functional. I have not been able to calibrate the AC ranges yet. But DCV, mA, and ohms ranges have been tested functional. I have attached a list of the Caps I used. The prices will vary based on how many parts you buy. I was buying for 15 units, with a few spares. All these caps are Alum Polymer types except C36. All are 105deg 5000 hour rated, and should give you many more years of 8060 functionality. The list that Mr. Modemhead published would be fine as well. --- Quote from: Fungus on August 25, 2017, 07:13:09 pm ---I wonder if Dr.T has any insight on this design decision... --- End quote --- I did not have a lot of influence on how the basic case was designed. I had the enclosure designers increase the size of the LCD window and add the four holes for the Elastomeric switch. But the actual design was performed by a mechanical engineer. The SM4 board bracket arrangement was all new for the 8060. Fluke had never hooked circuitry up with elastomerics before. The board to board elastomeric is silver filled which has much lower resistance than the type of elastomerics used for LCDs. The other main change that I influenced was the rigid AC shield. The wrap around shield of the 8020 did not work worth beans for frequency above 1kHz. I also had the bright idea to put the cal procedure on the new rigid top shield and expose a few test points. The first units still had repeatability problems in the AC until we added that little v-shaped bracket on the back of the top shield to hold the main input divider vertical and rigid. Also the bottom stick-on shield was improved for AC performance and we added the screw with the spring to connect the top and bottom shields. It was plenty effective at 100kHz. Remember that Fluke pioneered the handheld LCD DMM with the release of the 8020. The 8060s case was derived from that and the means of screwing the halves together was developed for the 8020 and its derivatives. This type of plastic does get more brittle over time, but for the most part, the self-tapping (designed for plastic) screw sheathes have held up fine. Brass inserts are no panacea as I have seen them pulled out or actually break the plastic they are swedged into. I never over tighten the mounting screws and never use an electric screwdriver to put them in. BTW, I would not lube the screws, just be careful. |
| drtaylor:
Recapping an 8060A: You will remove and replace 10 Caps: C1, C23, C24, C32, and C33 (100uF). C12, C21, and C28 (10uF). C36 (22uF). C19 (47uF). Suitable replacement parts were specified in post #423. Most importantly - Clean, clean, and clean again. Do not leave flux residue. If you do not blot or blow off the IPA to actually remove the flux residue, then you are potentially making a leakage path elsewhere. (I sure miss the spray freon tanks...boy those made a clean board. I probably damaged my liver holding boards with no protection gear). I know many will think I go overboard on the cleaning, but if you want your 8060 to function in high humidity without going wonky, you will clean buddy, and you will be thorough! A lesson learned from countless hours hovering beside a humidity chamber. On a side note, one advantage the 4 layer board gave to the 8060 that older models didn't have, is that I buried as many high impedance traces as I could in the inner layers. But they still have to come out somewhere. A practice learned at Fluke that I still follow with all my designs. Here is the recapping process that I use. By no means the only way to do this. (I apologize for the long length of this post and perhaps too much detail here. But not everyone doing this has your years of experience. Use good ESD practices.) 1- Once the case is open, remove the shield (don't lose the spring). Remove the LCD/SM4 assembly. Although not strictly necessary, I also remove the switch end caps, the green power switch slider, and the fuses. 2- Remove all the old capacitors. There are a total of 10 to replace. Try to not damage the pads. I always add a drop of rosin flux before attempting to remove the part. I used a Pace rework station, but the usual combo of a good solder station, solder sucker and solder wick braid will work fine too. I'm a firm believer in using a fairly large tip on the iron for desoldering. With some stubborn corroded pads, I had to use several techniques including adding new solder. You can usually tell if the cap spewed because those are the ones that are difficult to remove due to pad corrosion. 3- Using a sawed off acid brush, scrub the top and bottom of the pads with IPA (99%). Where electrolyte has spilled, the pads will be off-color and potentially heavily corroded. It is important to clean off all the electrolyte thoroughly. If the pad is heavily corroded, you might have to jumper the connection. If it appears the electrolyte has gone under other components, you might have to remove them too. 4- I use a glass cooking pan with a lid. I place the 8060 in the pan and pour IPA (not directly on the 8060) until it just covers the top of the PCA. Do not use so much that it gets into the gang switch. 5- Soak in the IPA for 30 minutes. 6- Remove the board and blow dry it with an air gun at low heat. (Clean compressed air is how I'd do it I had a compressor). At all times, hold the PCB by the edges. Avoid fingerprints! 7- Install the new caps using fine rosin flux solder (I used 27mil diameter). The standard for polarity with Electrolytics is that the long lead (before you trim it off) is positive. Most (but not all) caps have the negative lead identified with a color band. This is the case with the parts in the attached list. 8- Use a sawed off acid brush dipped in clean IPA to remove all flux residue. Use a lint free swab or q-tip to soak up the IPA before it dries. Clean each cap's pads individually so that the IPA does not dry up before you wipe it dry. Again, this is to help remove the IPA diluted flux. 9- After all your new caps are in and clean, place the PCB in the glass pan, and, using new, clean IPA, fill up the pan to just cover the top of the PCB. Leave for 30 minutes. 10- Remove the PCB and use a clean Acid brush to clean every surface you can reach (not just the new cap areas). Re-wet the board in the pan, and then blow it dry. 11- Now the wait... do not apply power until the whole assembly has had at least a few hours to dry. Use this time to disassemble the LCD and clean all the surfaces and elastomerics with a wooden Q-Tip dipped in IPA. Be gentle with the elastomerics, be vigorous with the PCB surfaces. Use lint free wipes to remove any residue while the IPA is still wet. You can also clean the LCD, Lens, and Polarizer with IPA. This should fix any ghosting or non-functional segments. Be careful not to get fingerprints on anything. 12- Reassemble the SM4/LCD assembly, screw it into the board, and now cross your fingers. Apply power and hope you got all of that nasty corrosion out. I suggest trying the ratio test first (Hold down the continuity key while turning on the unit. Hold until just 8s are showing, then release). If the ratio test is 9992 to 10008, your A/D is probably functioning properly. The other test I recommend is a turnover test. This will reveal leakage. Use any stable voltage source and see if the 8060 reads the same regardless of polarity. e.g. Put in around +1.9V with the meter in the 2V range. Note the reading to the lsd. Turn the leads around, and see if the negative reading is the same. Turn over error of 1 digit or less indicates a healthy A/D and input components. Try it again in the 200mV range with ~190mV. If this all looks hunky-dory, turn on the 200nS range. It should immediately go to 0.00. If it takes a while to get there, that's an indication of board or component leakage (or you didn't let the board dry long enough). Since this post is getting quite lengthy, I'll save troubleshooting tips for a future post if enough people need help. The 8060 User guide has lots of info on testing. |
| Electro Detective:
Many thanks to Mr. Taylor for the generous postings here :clap: :clap: Everyone here realises the plastic post screw casing fiasco isn't on him, nor is it an exclusive Fluke thing, despite it still going on! :palm: Here's one of my Fluke 87Vs that I opened recently for the first time to give it a check and borrow it's fuse to test another meter As I unscrewed I felt/heard a crack type sound, and assumed it was the self tapping screw binding on the post. :-// Upon close inspection...well, a picture is like a thousand words i.e. the sucker was spot welded to the post, so of course any normal force to unscrew it, cracked the post! I'm past ranting about this stuff, the manufacturers charging big dollars and boasting CAT Rated explosive containment that isn't better than many $6.99 One Hung TuLo meters, need to get their act into gear ASAP. Perhaps this issue needs a separate post elsewhere, to keep things here more On Topic :) |
| jh15:
I just lost half hour composing here because when I posted, warning came up that someone was posting at same time. Went to check, then lost my whole post. Anyway need to hit sack. I need a quickie answer. Got 8060a meter today 3500000ish serial. Ratio check ok, fuse check, switch check, leakage check ok. dc cal spot on with my better references. turnover ok at 2.5v, no 200mv reference at the moment. NO AC volts function. I have a couple days to return it. But I would like to know if say an ac coupling cap could cause this. I was planning to recap anyway. Fuses ok in self test. Can a bad fuseable protection device cause only a no AC problem? I will contact the seller now to see if I can open and explore. I'd keep it if I know caps or fusable causes problem. Thanks P.S. best choice for fusables in flukes? Can ptc polyfuses work? I have an assortment on hand. Thanks. P.S. 2 I noticed if I put my 2.5v negative reference while on 2v range I get expected OL. If I put positive 2.5 on 2v range I get 1.96xx P.S. B read all these almost 500 posts. |
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