hybridfree/eevblog-posts huggingface dataset:
Repairing a modern LED house light? - Page 1
Forum section: electronics / repair

author: e100
author_rank: Frequent Contributor
timestamp: January 11, 2014, 10:02:26 am
content: Has anyone attempted to dismantle, repair and reassemble one of the new generation of brand name LED lights?I purchased a 6W "Osram parathon CL A 25" which died after only 2 months of use, so presumably the power supply circuitry has failed. No smoke or bang, it just stopped working.http://www.svetila.com/en/light-bulbs-lamps-66/led-lamps-990/led-parathom-classic-25-fr-6w-ww-6241.htmlThere things aren't exactly cheap so I would like to attempt a repair, although it isn't obvious how you pull it apart without destroying it. It's a 4 piece construction - semi-transparent dome which appears to be glass or some kind of hard plastic, a metal heatsink (aluminium or zinc?), a plastic ring then the contact assembly with screw thread.It's a 240V bulb so the repair and reassembly will need to be done with safety in mind. If that is too difficult, then I'll convert it for use with 12v.Mike

author: Psi
author_rank: Super Contributor
timestamp: January 11, 2014, 10:05:53 am
content: This page at least shows what's insidehttp://slenderloris.synthasite.com/parathom.phpSadly it doesn't have any pics that show how it comes apart.

author: e100
author_rank: Frequent Contributor
timestamp: January 11, 2014, 10:19:35 am
content: Here's a pic of similar bulb which perhaps suggests that the dome pulls off somehow.http://www.led-professional.com/technology/light-generation/osram-applies-201cbrilliant-mix201d-led-concept-to-parathom-pro-classic-a-80-led-lamp-and-prevaled-systemOn mine there's no room to put a screwdriver or wedge between the dome and the heatsink.

author: SeanB
author_rank: Super Contributor
timestamp: January 11, 2014, 11:16:29 am
content: It is a potted assembly, and you sadly will find it hard to take apart. the ES base can come off to expose half the power board, but they were never designed to come apart.

author: TheWelly888
author_rank: Frequent Contributor
timestamp: January 11, 2014, 12:01:34 pm
content: It died after 2 months of use - it should be still under warranty so take it back to the shop and get a refund or replacement!Don't bother to faff around repairing the thing!

author: kripton2035
author_rank: Super Contributor
timestamp: January 11, 2014, 01:38:56 pm
content: Quote from: TheWelly888 on January 11, 2014, 12:01:34 pm++++1
LCD Tv repair- sounds like standard capacitor issue, but not - Page 1
Forum section: electronics / repair

author: dbdb2000
author_rank: Newbie
timestamp: January 10, 2014, 04:31:52 pm
content: Hi, I'm a long time reader of the forums and watched most of Dave's Videos and just thought i would post this for any Jedi Electronic experts who like a challenge.I have a broken Sharp LCD TV-Fault--turns on fine everytime (backlight and picture)Then after around 20seconds picture goes black (channel/Av no difference, but backlight still onTurning off and instantly on-works again repeating until maybe 5th ->10th time stays on all nightas the tv goes black the sound crackles leading me to believe it was a capacitor power issue, once opened the tv, very few power capacitorsTested so far.-The tv has separate 12v 5A power pack and have checked with spare 12v supply- still same fault-have checked with esr meter, capacitors on board- all seem fine-most capacitors are low esr Nichican so cannot check easily- have unsoldered a few and checked capacitance outside circuit and seem within limits- with backlight invertor disconnected, picture visible with torch but still turns off.-Have changed the k2503 D N-channel Mosfet (near Yellow sticker) as there was some heat marking on the board but no change and still not sure how to check mosfets correctly.This leads me to believe either a transistor/mosfet or Ic problem- most likely a dry joint as once the tv has warmed up it works fine.Any good ideas what I could check quickly to narrow down problem, otherwise i will use the hot air reflow 858D i recently bought on Dave's recommendation (really useful) and just heat the whole board to try and solve any possible dry joints, before dumping.Thanks and will keep you posted on any changes, I just like a challenge to try and get it going again due to what is probably a 5c piece breaking.Thanks for any suggestionsEdit:It is always a variable time to failure (sometimes 2 secs othertimes 30secs) but always when cold, today with it on and working, I cooled different areas with a freezer spray but couldn't get it to trip until i had turned it off for several hours.Normally it goes cold- 5sec turn off and on 10 secs working off and on then in progressively longer spurts until after 30 seconds never a problemFurther edit to prevent bumping. When turning it on and off fairly frequently it suddenly released the magic blue genie smoke and two surface mount resistors disappeared. As i don't have the time at the moment i will leave it for the moment and come back to it. Dave released a very good video on lcd tv repair showing a similar fault and once i replace the fuse i will check the flex cables and repost.

author: daveshah
author_rank: Unknown
timestamp: January 10, 2014, 04:58:47 pm
content: Is it the same exact amount of time each time, or does it vary (for example, what happens if start it up again while it is still warm)?
Tektronix PS280 Repair - Page 1
Forum section: electronics / repair

author: rpcope1
author_rank: Contributor
timestamp: January 04, 2014, 07:49:26 pm
content: Hello everyone! I've got a Tektronix PS280 power supply I bought a while back at a surplus auction which has got a channel broken. This is a 2 adjustable channel + 1 5V rail power supply, so I've been ok just using one channel, but I would like to try to figure out how to fix it. The second channel will report close to 44V (this is a 0-30V PS) if you bring the current control above near zero, with absolutely no load on it. It does not appear to affect any of the other channels, so I usually just leave the current turned all the way down and ignore it. The only thing I've ever seen on the internet even addressing this problem ishttp://www.electronicspoint.com/tektronix-ps280-troubleshooting-problem-channel-output-t70457.html, which sounds a lot like my problem, however (this has been a couple of years), I think I tried to take the power transistor out and didn't notice anything funny about it. If it helps, I can also open it up and take pictures. I think this power supply is actually a rebadged GW Instek but I'm not sure which. Any help or input is highly appreciated!
UT61E, as new, but needs minor repair: Details within - Page 1
Forum section: electronics / repair

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 19, 2014, 08:11:14 pm
content: So, I tried to do the APO (Auto Power Off) mod to my brand new UT61E, and accidentally bridged some of the pins on the chip, and because I don't have any solder wick, I think I'll just learn my lesson and sell this one cheap to someone who has the right kit to repair it - I'll just buy another one. There is NOTHING wrong with this that a hot air rework and solder wick won't fix (one of the pads looks skewiff - slightly lifted)... but then, I don't have those:Damage:£20, free shipping, boxed with leads and CD etc (no battery) - who's up for it? (UK)

author: Wann
author_rank: Contributor
timestamp: January 19, 2014, 08:17:43 pm
content: You should be able to drag the solder off. Just be sure to have a newly cleaned iron with no solder on it:

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 19, 2014, 08:34:55 pm
content: Quote from: Wann on January 19, 2014, 08:17:43 pmThat's great, but the pitch is MUCH finer than that. I just don't have the time for this right now.

author: Wann
author_rank: Contributor
timestamp: January 19, 2014, 08:47:26 pm
content: Quote from: rolandpenplotter on January 19, 2014, 08:34:55 pmShouldn't be a problem. But flux is a nifty thing in this case.I'm not a big fan of solder wick for removing solder bridges on fine pitch components.Just good to know

author: rolandpenplotter
author_rank: Regular Contributor
timestamp: January 19, 2014, 08:52:48 pm
content: SOLDThank you to the buyer - (you know who you are). Due to the rather confusing "rules" on this forum, I am not sure whether to edit the OP or delete it, in case the mod comes along and "tells me off", so this is just to say... IT HAS NOW SOLD, AND THANK YOUEnjoy your evening everyone, Matt.
Agilent OmniBER 718 repair - Page 1
Forum section: electronics / repair

author: Rachie5272
author_rank: Regular Contributor
timestamp: November 26, 2013, 08:56:00 am
content: I recently obtained an Agilent OmniBER 718 Communications Performance Analyzer from a university sale. Unfortunately, it failed the smoke test. As soon as I flipped the power switch, I heard a snap, and a bunch of relays started clicking madly. I turned it off immediately, and was greeted with the lovely smell of burning electronics.My first course of action would be to isolate and test the power supply, but I can't figure out how to access it. It's fairly easy to remove the individual interface cards, but the power supply seems to be built into the frame. I removed dozens of screws, and it still won't come out.I can't find a service manual, so I'm stuck. I'd rather not remove every single screw just to get at the PSU, and I'm afraid to turn it on again and cause further damage. Can anyone help?Curiously, it has a neat little "computer" module in it running the OS. It uses a compact flash card and a couple SIMMs. What's really strange is there's a second RJ45 jack which is completely inaccessible without removing the module. It will be interesting to investigate if I get it working again.

author: rjyousey
author_rank: Newbie
timestamp: December 29, 2013, 05:53:11 pm
content: If you still need help with this we have a lot of parts units and working units. contact 908-328-3663, randy

author: echen1024
author_rank: Super Contributor
timestamp: December 29, 2013, 10:37:02 pm
content: Quote from: rjyousey on December 29, 2013, 05:53:11 pmWhat sort of test equipment (broken) do you have?
Is it worth buying a broken HP 6200B DC to attempt repair? - Page 1
Forum section: electronics / repair

author: kolonelkadat
author_rank: Regular Contributor
timestamp: December 09, 2013, 04:53:39 am
content: I saw a broken HP 6200B DC power supply on ebay for around 25 bucks after shipping. The listing says it doesnt power up.Would it be worth it to try to fix it or is my money better spent on something else? Im not especially handy at electronics, but im sure I could replace a switch or resolder a wire thats come loose. Maybe this would be over my head to even try?Im really just looking for something to power arduino projects for testing low battery circuits and stuff.

author: Unknown
author_rank: Unknown
timestamp: December 09, 2013, 08:48:47 am
content: They're a tank of a supply, nearly bulletproof, excellent regulation and ripple for their age, and nice and easy to fix. From memory there's nothing in them that's particularly hard to find except the matched transistor amps (which are not difficult to substitute with hand-matched pairs).The downside is they're a tank of a supply, and 40+ years old...For $25 I'd pick it up just for the hell of it. For a raw beginner it might be over your head, but it'd be a good gentle learning experience. But for Arduino-ish use, you might be better off buying or making something with fixed 5 & 12v rails + a simple adjustable regulator.

author: nctnico
author_rank: Super Contributor
timestamp: December 09, 2013, 12:22:20 pm
content: It looks like a neat power supply. But I'm pretty sure the problems will me more severe than a loose wire. I bought some old HP supplies recently. I had to replace all the electrolytic capacitors and a few diodes to get them back to work.

author: c4757p
author_rank: Super Contributor
timestamp: December 09, 2013, 12:28:11 pm
content: I'd expect to replace the caps anyway. 40 years old and it probably has some very large ones that make big booms when they pop... I don't see failed diodes all too often, but they're easy to replace anyway. Did any of the diodes failshort? (If he says yes, than kolonelkadat, you might want to probe those diodes before you turn it on. Wouldn't want to stick AC up the capacitors!)

author: blackdog
author_rank: Frequent Contributor
timestamp: December 09, 2013, 12:36:54 pm
content: Hi,If you like to solder by it!!!It is a powersupply from Harrison division, must by GOOD!!!I have several of these power supply's and afther some work on them the perform like new.Replace the dual voltage settings potmeter with a 10K, 10 turn potmeter and you wil be happy :-)And if you want, replace the current potmeter with a 1K, 10 turn type.Kind regarts,Blackdog

author: kolonelkadat
author_rank: Regular Contributor
timestamp: December 10, 2013, 09:08:53 pm
content: thanks for the input guys. I may have to give it a shot.
Help repair my Samsung CRT SyncMaster 1100DF, please! - Page 1
Forum section: electronics / repair

author: 13hm13
author_rank: Frequent Contributor
timestamp: December 02, 2013, 02:46:43 pm
content: Not mine, but here's what I have ...It had less than 100 hrs total ON time (since purchase in early 2004) before it stopped working (after I replaced it with an LCD, in 2005, it was plugged in, but used VERY sparsely ... and then, one day 3 yrs ago, it ran into the issue below)The bottom line seems to be that either the HV ckt/supply is shot, or it's not getting the signal to turn on -- me thinks the latterWhen I power it ON (via front panel push-button), the green LED on the left of the switch will light after about 1sec. But I get NO display on the CRT. Normally, I used to hear a familar high-voltage THUMP, after a few secs (followed by the usual static pops as the CRT "warms up").In the past (when this CRT monitor was working normally) and when there was no signal (PC was off or the VGA cable was unplugged), I'd still get a on-screen message stating "No Signal -- Check Connection"andthat front pwr-button LED would blink. Of course, now there is nothing on the screen, and the LED is solid (not blinking -- that is what is/wasnormalif there was a VGA signal).I do seem to be getting 5V TTL and IC pwr supply voltage to many of the ICs.I'm looking for a quick, cheap fix, as this monitor is not that important to me.So ... just a hobby fixOff the tops of your heads, some of you experienced techs may know of component(s) that often go bad in these monitors. E.g., caps, regulators, etc. I'm thinking more like Dave Jones' Yamaha receiver fix, that was a bad poly cap (at the mains). I just watched that EEV episode and what Dave ran into reminds me of this monitor's issues.I do have the schematic, I think, but they are poor/cryptic and seem to be meant for several models in the seriesThx!

author: 13hm13
author_rank: Frequent Contributor
timestamp: December 02, 2013, 03:00:36 pm
content: The electro caps LOOK fine -- no swelling.Also, no sight/smell of damage (cooking) on any boards.Methinks it's gotta be something simple ... like Dave's Yamaha receiver cap fix.

author: Jonny
author_rank: Regular Contributor
timestamp: December 03, 2013, 05:52:14 am
content: As they say, check all voltage rails. If you're lucky what they should be will be printed on the board. If not, follow the diodes that come off the power supply switching transformer see if they go into caps or regulators that will give you some idea of what to expect. If there's no EHT (the pops and crackles) check the line output transistor (usually on a heatsink that is beside, and sometimes large enough to enclose the flyback transformer, the thing with the lead that goes up to the top of the tube). These are well known to short out. If you have lights up and the heaters in the tube are glowing then chances are it's that. Good luck!
Tektronix 2215 repair project. - Page 1
Forum section: electronics / repair

author: Six_Shooter
author_rank: Regular Contributor
timestamp: December 01, 2013, 02:36:41 am
content: I have recently received a non-operational Tektronix 2215 O'scope.I've found a couple of things so far, one being an item I can't fully identify, because I'm not familiar with the schematic symbol.From the Service Manual I have that it is "LAMP,GLOW:90V,0.3MA"I have tried to find this on Digi-Key, Mouser, Jameco, Futurlec, Goldmine Electronics, and a few other sites but have not found a match.Any help with finding a suitable replacement, or using others in series would be the same?If someone could look at the schematic and let me know. I will also attach a picture of the item.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 01, 2013, 03:08:28 am
content: It is a small neon bulb------they commonly fire at 90 volts.Tektronix use a lot of them--often they are only "on" under fault conditions.Not sure about in your case.

author: N2IXK
author_rank: Frequent Contributor
timestamp: December 01, 2013, 03:16:11 am
content: Sounds like a standard NE-2 (A1A) neon lamp to me...http://www.digikey.com/product-detail/en/A1A/A1A-ND/4176016http://www.mouser.com/ProductDetail/Chicago-Miniature/A1A/?qs=sGAEpiMZZMucm%2f%252bFOY0TQhPZClhLEOAyzHNdSZM1TUs%3dhttp://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_27351_-1From what I can see of your circuit, I don't think these lamps are going to cause a non-operational issue. They look like they are used as overvoltage protection devices, to protect the Z-axis driver transistors from high voltage breakdown in case of a transient arc inside the CRT. They most likely never light unless the CRT or other component arcs over. The broken one should be replaced, though...

author: Six_Shooter
author_rank: Regular Contributor
timestamp: December 01, 2013, 03:59:11 am
content: I agree, I don't think this is going to cause a non-operational issue, but I would like all of the known issues to be fixed before looking any (or much) deeper.I have also found a broken leg on a MOSFET that I will be replacing, or at the very least re-attaching the MOSFET leg.There's an area on the bottom of the main board that is browned that I have a feeling I should inspect a little closer on the top side, unfortunately this area is under three stacked boards that holds all of the front panel controls.Thanks for the links, I'll take a look at them a little deeper at them and figure exactly what part numbers to order. I didn't seem to be able to locate them through the search engines earlier.
Fluke 8840 Front End Repair - Page 1
Forum section: electronics / repair

author: ItFinallyWorks
author_rank: Contributor
timestamp: November 28, 2013, 05:47:11 am
content: I have a Fluke 8840. Its generally in good condition, but has a bit of an issue. For positive voltages, its reads off, but in the ballpark (its maybe a few hundred mV off with say 10V in). I'm not so concerned about this, since I think its related to my other issue. For negative, it reads approximately correctly up until I get to about -6 to -7V in. After that point, the input is clamped to read about -6 to -7V (it behaves a little like a diode clamp, increasing slowly as the input voltage is increased greatly). Since it looks like a clamped input, I tried measuring the input current during this condition, but saw no noticeable increase in terminal current (as close to 0 as a 34401a can read). My strong suspicion is that this is, in fact, a front end issue. In fact, a coworker of mine used to work at Fluke, on a project to replace the 8840 in fact, and confirmed that it sounds like a front end issue.I have the schematics for this, and I'm capable of troubleshooting it, but I was wondering if anybody here has had this failure and can shortcut my troubleshooting. If not, I'll share what I find when I troubleshoot the issue.

author: Unknown
author_rank: Unknown
timestamp: November 28, 2013, 01:30:57 pm
content: I haven't seen this problem before. Note that there may be a large series resistor at the input (for example a 10x voltage divider with a total resistance of 10 Mohm and a Thevenin resistance of about 1 Mohm, so the current even if clamped may be tiny. It sounds indeed like something is acting like a diode junction somewhere past the voltage divider (so clampling to about -0.6V results in a 6V reading).One thing that comes to mind that you might expect to find in the front-end circuit is two series-connected zeners (in reverse polarity) to clamp both positive and negative voltages. If one of them were to fail short, the other would look like a normal zener in one direction and a regular diode in the other.
Free [UK]: AvoMeter 8 MkV - Spares/Repair - Page 1
Forum section: electronics / repair

author: steve30
author_rank: Frequent Contributor
timestamp: November 24, 2013, 08:45:56 pm
content: I bought this AvoMeter Model 8 Mk V on ebay a couple of years ago, and unfortunately, a while back, the movement broke. Not sure why, but it seems beyond repair (see photo).The rest of the electronics are fine, except for a minor repair on one of the flex cables, and a tiny bit of corrosion on the battery terminals (this cleaned up OK).If you want it (for spares/repair), you can have it for the cost of postage (should be less than £10).
HP 1741A Repair - Page 1
Forum section: electronics / repair

author: deanriverson
author_rank: Newbie
timestamp: November 18, 2013, 10:34:18 pm
content: When I discovered that a friend of mine had an old non-working HP 1741A oscilloscope, I jumped at the chance to try to repair it. The lucky guy got it for free a few years ago. He didn't know what was wrong with it and had never actually played with it. It was just sitting in his basement gathering (a lot!) of dust. What a shame!It came to me dirty and disused, with no power cord or fuse holder. But I was in for a pleasant surprise when I opened it, it was beautiful inside!Filled with optimism, I contacted a friend who works for Agilent and he scrounged a fuse holder that he had laying around. I put in a fresh fuse, powered it up, and was greeted by the sound of a swarm of angry bees coming from the transformer. Luckily I had read Tekfan's awesome post about his restoration of a 1741A:https://www.eevblog.com/forum/testgear/hp-1741a-oscilloscope-restoration-project/So I knew that this was almost certainly a problem with one or more of the bridge rectifiers on the low voltage power supply board. Sure enough, a quick visual inspection revealed burn marks and scorching around a couple of the rectifiers.Removing the rectifiers revealed significant damage to the board.It was difficult to find inexpensive exact replacements for the rectangular rectifier, so I just substituted an inexpensive part with slightly better specs. I decided to look around the LVPS board more carefully in case the shorted rectifier had caused other problems or there were some leaking or obviously bad capacitors. Ah ha! These two certainly look suspicious.Lifting them out of the circuit, the one on the left was definitely bad (pretty obvious), but the one on the right tested good. What the heck, they're cheap and I've already got them out; I just replaced them both. After plugging the transformer back into the LVPS and carefully applying power, all of the voltage test points check out!I also removed the CRT to repair some cosmetic damage to the border. After putting it back together, cleaning it up, and a little tuning and calibration:Success! Thanks to information on this forum, I was able to save a beautiful piece of test equipment from the scrap heap. I returned the scope and gave my friend a quick Oscilloscope 101 lesson. He's now happy and excited to start exploring the world of electronics. It was definitely a fun and interesting project.
Samsung tv repair - Page 1
Forum section: electronics / repair

author: snipersquad100
author_rank: Frequent Contributor
timestamp: November 09, 2013, 11:35:24 am
content: Hi I got a Samsung ps43d490-a1w The tv just blinks the red led when I switch on the power. I cant find a schematic on this set so I am stuck. How do I find out what board is the problem.

author: mariush
author_rank: Super Contributor
timestamp: November 09, 2013, 01:10:45 pm
content: Open it up, measure voltages, inspect components (see if there's bloated capacitors), see what happens when you push buttons (does the psu get out of stand-by?)Check linear regulators on the boards, sometimes they fail...Some Samsung tvs also have problems with corrupt eeprom chips... can't help you there though.

author: tom66
author_rank: Super Contributor
timestamp: November 09, 2013, 01:27:26 pm
content: X-main board 99% of time. Currently nonserviceable (replace board only) due to unknown failure cause.When replacing X-main also replace Y-main and update TV firmware (bug in firmware kills X-main board.)X-main responsible for common electrode of plasma display.

author: snipersquad100
author_rank: Frequent Contributor
timestamp: November 09, 2013, 01:50:55 pm
content: ok thanks

author: snipersquad100
author_rank: Frequent Contributor
timestamp: November 09, 2013, 01:52:01 pm
content: is it possible to rule out the power supply

author: tom66
author_rank: Super Contributor
timestamp: November 09, 2013, 02:46:14 pm
content: Yes. Unplug X- and Y-main. You should get brief Vs:205V or so, Va:55V or so and also TV audio will work. Note, Vs and Va will shut off after a few seconds if X- and Y-main not connected, this does not indicate a fault.Actually that's a good point I thought you had click on-click off symptom but you did not mention this. Maybe I jumped ahead.Try this test (X- and Y-main reconnected):http://www.badcaps.net/forum/showpost.php?p=318461&postcount=2

author: snipersquad100
author_rank: Frequent Contributor
timestamp: November 09, 2013, 04:11:50 pm
content: what should happen when you connect the two pins?
B&K Precision 3011 2mhz Function Generator repair - Page 1
Forum section: electronics / repair

author: Seg
author_rank: Regular Contributor
timestamp: November 05, 2013, 02:54:39 am
content: I bought a B&K Precision 3011 2mhz Function Generator as an eBay fixer-upper. Seller said it powered up but did no other testing. Plug it in, and nope, no sign of any signal coming out. Service manuals for vintage B&K Precision equipment seems to be hard to come by, so I get to fly blind here.Open it up and, hey what happened here?A voltage regulator seems to have spectacularly de-soldered itself for some reason, splattering beads of solder all over the thick later of flux covering the bottom of the board and cooking the board pretty good. 1986 vintage 7815's apparently didn't have thermal protection... Let's clean that sucker up before we do anything else:Probing the pads indicates no apparent shorts, and good power going in. Hmmm. Tried soldering in a replacement 7815, with some heat sink paste for good measure, and power it up with probes attached. The output voltage is low and it gets real hot real fast. There must be a short lurking somewhere. I check capacitor C103 that's right on the output, and what do you know, it's shorted. Wasn't immediately apparent because it couples over to a -15v rail or some such rather than directly to ground.Replace the cap and hey look at that, it's functional again:

author: mcinque
author_rank: Unknown
timestamp: November 05, 2013, 12:32:29 pm
content: Great job!Thanks for sharing

author: SeanB
author_rank: Super Contributor
timestamp: November 05, 2013, 06:45:40 pm
content: 1986 78xx regulators did have thermal protection, just it often did not work well. Relying on parameter shifts to switch off the device while the operation is not tested during manufacture is always going to bite you. I bet that if you clean off the leads and test it it still works.

author: Seg
author_rank: Regular Contributor
timestamp: November 07, 2013, 10:01:35 am
content: Yeah, I tested the regulator with the output pin lifted, it put out something like 4.75v. It's cooked.

author: Stonent
author_rank: Super Contributor
timestamp: November 07, 2013, 10:28:38 am
content: I'm always concerned if I try to buy something for parts/not working off Ebay I'll open it up and find stuff missing inside, or it will look like it went down with the Titanic.
Yokogawa multimeter repair - Page 1
Forum section: electronics / repair

author: Parak
author_rank: Contributor
timestamp: November 03, 2013, 02:14:28 am
content: I've recently acquired what seemed to be a decent condition Yokogawa 73401, and the immediate thing that I noticed is that the amp and temperature range at the beginning of the selector dial are displayed as (non-working) ac and dc mV/V ranges. All functions after that (cap, ohms, continuity, actual mV/V ranges) work perfectly. It's almost like the selector dial is not working properly, but after removing it, I don't see anything that might be out of the norm.When I took it apart, there was a fair amount of leaked battery fallout from a previous incident, that sent the acid all the way up to the pcb as well (bleh). It doesn't seem that any traces were affected after a quick continuity check, but there's a few that seem to have exposed copper as result.Anyway, posting this in hopes that someone has ever seen something similar even with other multimeter brands. In the meantime, I'll see if I can have Yokogawa dig up a service manual for me..Thoughts are much appreciated!

author: retiredcaps
author_rank: Super Contributor
timestamp: November 03, 2013, 05:30:24 am
content: Quote from: Parak on November 03, 2013, 02:14:28 amI suggest giving the pcb and range switch a complete IPA clean and scrub. The following repair is somewhat related and may give you some clues?http://mrmodemhead.com/blog/fluke-23-iii-dmm-repair/

author: Parak
author_rank: Contributor
timestamp: November 05, 2013, 03:32:05 am
content: Quote from: retiredcaps on November 03, 2013, 05:30:24 amExcellent, that's pretty much the same kind of issue that I have, except the corrosion is quite far away from the selector switch and is nowhere as major. Time to do more continuity checks, it seems.Thanks!

author: retiredcaps
author_rank: Super Contributor
timestamp: November 05, 2013, 07:10:28 am
content: I forgot to ask you to post some teardown pictures of your meter. After all, it is eevblog here!PS. Don't forget the IPA bath/clean.

author: zaoka
author_rank: Frequent Contributor
timestamp: November 05, 2013, 03:05:31 pm
content: Can you post few pictures from inside?

author: Parak
author_rank: Contributor
timestamp: November 06, 2013, 06:53:45 am
content: Righto, pictures. Still looking for the fault, but it's getting cleaner at least. Has a bunch of flux residue too which needs to be cleaned better. Desoldered the battery holder as that area needs more cleaning, and I need to get a new one anyway as it's all cracked and corroded. I'll have to take a picture of the selector switch underside too, but it's basically just spring contacts on the bottom of that plastic cover.Some of the things not shown: The pcb is held inside the bottom cover by one small screw under the left fuse. The top case has a lockout feature for the amp inputs when not on the amps ranges. The inputs have a felt washer on the bottom (around) of them for protection/dampening; removed for cleaning.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: November 06, 2013, 02:17:22 pm
content: i can see some corosion on a resistor.
First repair! 3comm 8 port gibabit switch - Page 1
Forum section: electronics / repair

author: apelly
author_rank: Unknown
timestamp: November 05, 2013, 01:48:42 am
content: OK, the subject oversells this somewhat, but I'm still bloody stoked.I was running out of ethernet ports on the switch where I sit to do most of my tinkering, and I remembered I had a broken 3comm switch. The power leds came on, but it didn't function. If it was something simple I might save 50 bucks. It used to get quite warm, so I opened the thing and was going to replace the electrolytics. Had new ones lined up and everything. Then I remembered: "Rule 1:Thou shalt check voltages!." Thanks Dave.Bloody plug pack was screwed. This has happened before, but it never dawned on me this time. A rummage around the junk box came up with two replacement candidates (with wrong connectors of course). Turns out one of those was buggered too, so I don't know what possibly functional piece of kit I threw out when that failed. Sigh.Anyway.Thou shalt check voltages!

author: SeanB
author_rank: Super Contributor
timestamp: November 05, 2013, 06:41:07 pm
content: Still change those caps though, they probably are dying as well if the wall wart has been cooking them with ripple for a while along with the built in toaster oven.
Old scope repair question - Page 1
Forum section: electronics / repair

author: Everton
author_rank: Contributor
timestamp: November 05, 2013, 04:11:23 am
content: Hi,I own a (very) old Telequipment D1010 (analog) scope which until yesterday seemed to be working fine, but out of the blue the normal trigger mode stopped working. Instead of getting a normal trace, I am getting a dot on the left side of the screen. This is consistent on both channels and is independent of any other settings. Also, if I change the trigger mode to Auto or TV then the scope appears to work fine. Similarly, if I press the beam finder button this works too.That being the case, I know that both the vertical and horizontal amplifiers should be working fine and so the problem has to lie in the trigger or blanking circuits. What I am unclear about is how the normal trigger mode works in these old scopes. Is the trace supposed to stay on the left hand side of the screen until a trigger happens at which time the sweep is initiated, or should the display be blanked until a trigger is present? I would guess the latter, but am not sure.Any help would be appreciated.Thanks

author: Whuffo
author_rank: Regular Contributor
timestamp: November 05, 2013, 12:26:49 pm
content: Your service manual is here:http://www.eserviceinfo.com/download.php?fileid=38278
LCD repair - Page 1
Forum section: electronics / repair

author: adoherty
author_rank: Newbie
timestamp: October 30, 2013, 03:38:50 pm
content: Hi,I have a Samsung Syncmaster 204B that was failing. Did youtube/ebay searches, and by the plethora of video results and parts kits, it is obviously a very common problem. Bought the caps (from Mouser Electronics,) put them in last night, now the monitor starts right up like it should, but now I have a new problem, I have about 10 vertical lines on the screen (green, blue, pink, red.) Did I damage something else while doing this repair, is it another part damaged on the power supply board (shorted/overheated?) Or did I somehow damage the LCD screen itself and now it is hosed?

author: rexxar
author_rank: Frequent Contributor
timestamp: October 30, 2013, 04:33:08 pm
content: If all the bars are together in a space less than a few inches wide, I'd suspect one of the column drivers. Check that all the flex connectors to the panel are seated correctly, then reseat them anyway.

author: adoherty
author_rank: Newbie
timestamp: October 30, 2013, 06:00:01 pm
content: Thanks, I will try that and post results.
Another LCD monitor repair - Page 1
Forum section: electronics / repair

author: f
author_rank: Newbie
timestamp: October 30, 2013, 04:12:52 am
content: Hello all, I have an older 2006ish LCD tv that I got for free. It does not turn on, I have traced the problem to the logic board.I have no idea where to start on this thing. The only thing I can get it to do is if I unplug and plug back in the power plug from the supply to the logic board, the power led will come on for half a second and go off. I have looked for cold solder joints, but they all look good. I have tested the board using two different power supplies, so I know its the problem.Anyone know a good place to start? Here's two pics of the board itself.Tv model: Samsung 940mw s

author: Alana
author_rank: Frequent Contributor
timestamp: October 30, 2013, 04:56:56 am
content: I'd try to remove and replug that rom chip in plcc socket and reflow those two main ICs. It helped with my samsung of the same era but only for a while - if i remember correctly those logic boards are prone to falitures.

author: Crazy Ape
author_rank: Regular Contributor
timestamp: October 30, 2013, 05:03:15 am
content: There's plenty of colour adjustments in the service menu.Grab this: Schematics, service menu info, etc.http://linfotech.co.uk/schematics/Samsung/Samsung%20%20940MW_940MG.pdfEdit:Ignore colour adjustment comment, I was getting two threads mixing up. This is your board and schematics though.

author: f
author_rank: Newbie
timestamp: October 30, 2013, 05:14:42 am
content: Quote from: Alana on October 30, 2013, 04:56:56 amI tried reseating the rom, but I have no way of reflowing. By main ic's do you mean the big square ones?Quote from: Crazy Ape on October 30, 2013, 05:03:15 amThank you, this will probably help.

author: Stonent
author_rank: Super Contributor
timestamp: October 30, 2013, 05:28:45 am
content: I've fixed HP printers by baking the motherboard to reflow it. You take the board and put it in an oven, elevated above the pan using balls of foil on the corner of the board and bake at 350 for about 8 minutes then carefully remove it and let it cool for 30 minutes till an hour. If there's a brittle solder joint that can frequently fix it.http://www.fixyourownprinter.com/forums/laser/48992#88Also on monitors, popped capacitors in the PSU, a fried MOSFET or a bad power button are common.
(Attempting to) repair washing machine control board.  - Page 1
Forum section: electronics / repair

author: tiago
author_rank: Contributor
timestamp: October 20, 2013, 01:03:02 am
content: I have a washing machine with a semi functional front panel, its a pain in the ass because you currently cant change from the defaults.I pulled the board(of course its potted). One pin of the transformer is burned followed by TVS1, D8, IC6(TNY267P), D18 and MIG10J503HA.I'm having trouble determining what the transformer is, the top markings are 20A DH 741B. I assume i will need to pull it and measure it out.What does TVS stand for? It visually looks like a diode to me. I tried to upload a picture but failed.I'm also having trouble sourcing a replacement MIG10J503HA which is made by Mitsubishi, i cant find a datasheet. A google and ebay search brings a Toshiba MIG10J503H part. Wondering if anyone can find datasheets so i can determine if this is a suitable replacement as the toshiba part seems to be the same physical package.

author: Hideki
author_rank: Frequent Contributor
timestamp: October 20, 2013, 01:18:56 am
content: TVS diode:http://en.wikipedia.org/wiki/Transient-voltage-suppression_diodeDatasheet for MIG10J503H:http://www.bdtic.com/DataSheet/MITSUBISHI/MIG10J503H.pdfOctopart lists both H and HA, but gives no clue as to what the difference ishttp://octopart.com/partsearch#search/requestData&q=MIG10J503H

author: saturation
author_rank: Super Contributor
timestamp: October 20, 2013, 12:52:45 pm
content: Sorry to hear. Just for info, what type of washing machine is it?

author: tiago
author_rank: Contributor
timestamp: October 20, 2013, 04:46:38 pm
content: Its a nfw7200tw, the board part number is 34001499.I found one for 100 bucks on amazon so i ordered it. Im going to order the two IC's that seem burned and give it a whirl if it works i can say i fixed it. If it doesn't well i found a cheap replacement hahaha.Im going to order the toshiba part that seems readily available.

author: saturation
author_rank: Super Contributor
timestamp: October 21, 2013, 11:50:55 am
content: Sorry to read. Good luck.www.amazon.com/Amana-NFW7200TW-27-Front-Load-Washer/dp/B0012RTF2Y/ref=cm_cr_pr_product_topIt may not be worth servicing given so many flaws.
Repair advice for Starrett electronic indicator, failure to power on, freezing - Page 1
Forum section: electronics / repair

author: jp430bb
author_rank: Contributor
timestamp: October 09, 2013, 02:53:25 am
content: I've got a Starrett 2730-0 electronic indicator that I picked up used on eBay. With a 1-inch range and 0.00005-inch resolution, it's a sweetheart...when it works. Sometimes, I have to hit the power on button five or six times before it will power on. Then it'll work fine for 15 or so minutes, and then it'll freeze.I disassembled it, and along with impressively small passives on the button & display PCB, I could see that some previous owner had used alkaline LR44 button cells in it and let one spew its chemistry on the inside. Some of the PCB tracks are visibly corroded under the solder mask.After cleaning the PCB with contact cleaner, it seemed to behave better, but only for a month or two. Now, it's back to being flaky. Any ideas on what I might try to repair this thing? I haven't started with checking voltages or anything yet, but with such small parts, it's looking like quite a challenge.By the way, this unit is the kind of thing that I think of when I see test gear on eBay "Tested to power on only"!
Sam's Repair Briefs - Complete: 1 to 100  - Page 1
Forum section: electronics / repair

author: Unknown
author_rank: Unknown
timestamp: October 07, 2013, 01:04:15 am
content: http://www.repairfaq.org/sam/rball.htm#rbinthttp://www.repairfaq.org/sam/rball.htm#rbinthttp://www.repairfaq.org/sam/rball.htm#rbinthttp://www.repairfaq.org/sam/rball.htm#rbinthttp://www.repairfaq.org/sam/rball.htm#rbintWhat are the Repair Briefs(c)?This series presents case studies of selected repair problems from my archives. (Archives sounds more impressive than scribbled notes and schematics, doesn't it?). I hope that these summaries are useful for those of you are interested in tackling your own repairs. These will NOT be of the form: "replace C418 when vertical size is reduced on HyperTech TV chassis HT312". Rather, they will document specific but common problems with TVs, VCRs, CDs, computer peripherals, etc. The symptoms, testing, diagnostic procedure, repair procedure, and comments will be included so that you can learn from my approach (and my screwups). If you want specific solutions to well known or repeat problems with your RCA or Zenith, then the repair professionals who frequent this group will be in a better position to help since they work on many of the same line of equipment on a regular basis. However, if you want to develop a general diagnostic approach, then this series may provide some tips and insight based on theory and experience. Not all of these are exciting cast-of-thousands repairs. Many tend to be mundain but address common problems with consumer electronic equipment. You will no doubt recognize some as directly pertaining to some appliance or electronic device that you had repaired (or junked) in the past. There will probably even be some of those 'dogs' that we all hate - the problems that never seem to go away. In any case, these will all be based on my true experiences with minimal embellishment.http://www.repairfaq.org/sam/rball.htm#rbinthttp://www.repairfaq.org/sam/rball.htm#rbinthttp://www.repairfaq.org/sam/rball.htm#rbinthttp://www.repairfaq.org/sam/rball.htm#rbinthttp://www.repairfaq.org/sam/rball.htm#rbint
Agilent 16755A Blade Debug and Repair - Page 1
Forum section: electronics / repair

author: Basstudio
author_rank: Contributor
timestamp: September 28, 2013, 06:59:39 pm
content: I have just bought one of these Agilent 16755Ahttp://www.home.agilent.com/en/pd-30850-pn-16755A/timing-and-state-module?&cc=GB&lc=engblades really cheap for my Agilent 16702B logic analyser mainframe and looking for some debug help to try and repair it. This is probably a long shot but worth a go considering how much these blades still cost.When I install it in the mainframe it is not detected in the software. It looks like the blade interfaces to the bus backplane using a Xilinx Virtex II, does anyone know the backplane pinout so that I can probe it?

author: free_electron
author_rank: Super Contributor
timestamp: September 28, 2013, 08:29:36 pm
content: Stay off of the backplane.Does it have all the cables ? Is the cascade cable in place ?I have seen frequently blades for sale that used to be in a machine in cascade (2 or 3 or 4 blades ganged together ) They sell the blades individually but don't plug in the cascade cable and they don't have the default cable. At that point there is no communication possible and the card won't be detected.look at the side of the card. there is a hole in the card with 5 connecotrs (like 20 pins connectors). on is angled the others are straight. there should be a short ribbon cable going from the center to the one labeled '1' . if that i smissing : bingo. there is your problem.to gang cards together you string the cable from the center , through the hole to '1' of the card above. the center of the second card goes to '2' in the card above and so on... if you use the card standalone you must create the 'patch' locally to yourself.

author: free_electron
author_rank: Super Contributor
timestamp: September 28, 2013, 08:37:13 pm
content: if you grab the service manual on agilents site :page 126 cable W1 is what i am talking about.W2 is the databus expander. you don't need those. but you DO need W1

author: Basstudio
author_rank: Contributor
timestamp: September 28, 2013, 09:30:23 pm
content: Yeah I know exactly what you mean about the cascade ribbon on the second hand market and avoid, also the securing thumb screws missing is a bad sign too.Anyway yeah the ribbon is attached correctly and I buzzed it through to make sure. The service manual isn't much use probably because there isn't much you can service.I havent checked the power rails yet but could be tricky to get access when its installed in the mainframe. Also I havent connected the probe leads but wouldnt expect this to stop it being identified.Mmmmm not sure.Sent from my GT-I9505 using Tapatalk 2
Oscilloscope repair - Page 1
Forum section: electronics / repair

author: DuRoble
author_rank: Newbie
timestamp: September 21, 2013, 09:15:43 am
content: Hey everyone,I'm beginner and my (first) oscilloscope had some weird issue...what I found was the document below...I thought this was very helpful (my oscilloscope is from kenwood not tektronix but the general procedure just worked out well)http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdfMaybe the experts of the forum can say something about whether this is good for general repairs or whether I'm just lucky that it worked out wellHave a nice weekendDuRoble

author: mzacharias
author_rank: Frequent Contributor
timestamp: September 21, 2013, 11:33:15 am
content: There's a lot of information missing here.1. Kenwood and Tektronix scopes are very different.2. You haven't given us a model number of your Kenwood or even disclosed it's vintage or if it is analog or digital type, crt readout type, or what.Yes, sometimes we just do get lucky. Older Kenwood pure analog models are pretty simple and often just cleaning controls and switches is all that is required.More information, please!

author: w2aew
author_rank: Super Contributor
timestamp: September 21, 2013, 01:14:57 pm
content: The general concepts and troubleshooting procedures in that book are reasonable applicable to most analog scopes, so it is certainly very useful. It won't apply much for modern digital scopes however, other than general power supply troubleshooting, etc.