hybridfree/eevblog-posts huggingface dataset:
BTLE Keychain - Can I attach a louder BUZZER? - Page 1
Forum section: electronics / repair

author: salil
author_rank: Regular Contributor
timestamp: October 24, 2015, 06:03:26 am
content: These are two of those "anti-lost" bluetooth low energy keychains you see all over eBay. They're both marketed asiTagbut I purchased 2 (each from a different seller) and they appear to have redesigned internals. For the sake of conversation, I've labeled one version V1 and the other as V2. This has no correlation to the board's revision history.In v1 the battery kept getting disconnected which powers the unit off until the user holds down the push button for 3 seconds so it can start up again (big problem when you've lost your keys attached to this thing!). In v2 the battery connection is implemented better with a spring for both terminals of the coin cell battery (not pictured - it's on the other side of the PCB) but the buzzer is really, really quiet. Any chance I can modify either to attach an even louder buzzer (louder than either of them)? Would I need some sort of amplifier and tiny speaker to get anything much louder? Does anyone have any part suggestions? This is the biggest problem with these type of devices, the buzzer is never loud enough to be heard downstairs under a couch.PS: I have tried 3-4 other products of this type over the years and they all have really quiet buzzers so it might be worth investing the time to modify one if it's even feasibleLower pitch buzzers could also make it more useful for older people.

author: amyk
author_rank: Super Contributor
timestamp: October 24, 2015, 03:09:25 pm
content: They're "bluetoothlow energy" for a reason... I doubt the battery has enough power to drive something louder.

author: salil
author_rank: Regular Contributor
timestamp: October 24, 2015, 03:11:09 pm
content: Okay, well let's say I connect a 20c LiFe instead of the recommended CRV2032
HDD sata connector replacement - Page 1
Forum section: electronics / repair

author: Heppie
author_rank: Newbie
timestamp: October 24, 2015, 02:53:06 pm
content: Trying to find a suitable replacement connector for an SSD but having no luck, any tips for search terms?

author: 3roomlab
author_rank: Frequent Contributor
timestamp: October 24, 2015, 03:00:21 pm
content: this ? (SATA 7 + 15pin)https://item.taobao.com/item.htm?spm=a230r.1.14.4.SBEcGE&id=36069133973&ns=1&abbucket=5#detail

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 24, 2015, 03:03:17 pm
content: https://www.google.nl/search?q=7%2B15P+male+sata+connector

author: picandmix
author_rank: Frequent Contributor
timestamp: October 24, 2015, 03:03:41 pm
content: Or to get one quickly from within the uk, if you search ebay with 'ide to sata converter' there are lots of modules with Sata connectors for a couple of pounds, though you will have to unsolder them.
Repairing Tektronix 2213 - Page 1
Forum section: electronics / repair

author: gerovite
author_rank: Newbie
timestamp: October 20, 2015, 01:12:51 pm
content: I appeal to owners Tektronix 2213What should be the waveform in point 9 SWEEP GENERATOR & LOGICthanks in advance

author: singapol
author_rank: Frequent Contributor
timestamp: October 21, 2015, 08:44:16 am
content: There is nothing wrong with the waveform except that maybe your oscilloscope's rise time/bandwitdh is not fast enough. Try using X10 setting on probe. The 74Sxx series logic is pretty fast.

author: oldway
author_rank: Super Contributor
timestamp: October 21, 2015, 08:49:11 am
content: Welcom on the forum.It would be better to describe the problem you have with your scope.What's wrong ?

author: gerovite
author_rank: Newbie
timestamp: October 21, 2015, 09:54:13 am
content: Thanks for your kind replyI can not take a picture on the oscilloscope because currently there is no chip 74f74.Here is the problem:When capture sin in CRT displayed:

author: oldway
author_rank: Super Contributor
timestamp: October 21, 2015, 10:04:53 am
content: That's not a very clear explanation...Is the sine wave sincronised ?Do you display only one channel or both ?If sine wave is well syncronised and only one channel displayed, it seems to be a blanking problem during retrace.

author: gerovite
author_rank: Newbie
timestamp: October 21, 2015, 10:13:16 am
content: Quote from: oldway on October 21, 2015, 10:04:53 amsorry, it's only one ch

author: oldway
author_rank: Super Contributor
timestamp: October 21, 2015, 10:27:19 am
content: Trigger works well or not ?

author: gerovite
author_rank: Newbie
timestamp: October 21, 2015, 10:32:02 am
content: Trigger work

author: oldway
author_rank: Super Contributor
timestamp: October 21, 2015, 10:45:58 am
content: In repair, there is a basic rule:always to start from the beginning and never to rely on the diagnostic made by others.What You suspect does not interest me, what I want is a detailed description of the problem as it appeared originally.I do not need you to copy the service manual, I have it too.Simply answer to my questions !With your way of responding, whe are going nowhere.
[Fixed] Polish Unitra AMS-3 DMM - Page 1
Forum section: electronics / repair

author: felixd
author_rank: Regular Contributor
timestamp: October 21, 2015, 12:27:17 am
content: I've just received not fully working digital multimeter Unitra AMS-3 [Made in Poland] I bought on our local auction portal.What was wrong?* Blown up 2A fuseThat was first thing I've changed. After replacing fuse I've carefully checked current measurements on all ranges. It worked just fine.Seller stated that device is blowing 2A fuse every time they try to "take measurements". I've no idea what and how they've been testing.* Broken connection on higher voltage ranges path.Resistance measurements were working just fine on all ranges but there was still a problem with higher voltage ranges. After taking apart whole device I found broken connection. After fixing that problem device came back to live again!Multimeter parameters/ranges:DC/ACV: 2, 20, 200, 1000DC/ACmA: 2, 20, 200, 2000kOhm: 2, 20, 200, 2000Please find below teardown pictures.Photos:https://goo.gl/photos/Q5eW5fRogkuzXxJTAand some videoshttps://youtu.be/ONOKS6biHAghttps://youtu.be/89kFv7Il_Ow

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 21, 2015, 01:14:35 am
content: Wow, looks like a fantastic piece of kit. Thanks for sharing!
Sencore LC101 Schematic needed - Page 1
Forum section: electronics / repair

author: mskobier
author_rank: Regular Contributor
timestamp: June 14, 2015, 03:10:15 pm
content: All,This is a duplicate post from the one I posted over in the test equipment section. Figured everyone did not vist every section, so I'm posting again here in repair.I just pulled my Sencore LC101 down from the shelf to use today. I haven't needed to use it in a couple of years. Anyway, its dead!. I get a momentary display upon turning it on, then nothing. No display, no LEDs, nothing. I checked the fuse and it was good. Just a beginning guess, but its probably the power supply. Anyway, I need a schematic or better yet a service manual for it. Can anyone help me out, or no where I can find a copy of the schematic?ThanksMitch

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 16, 2015, 03:11:26 pm
content: Mine had a display that would flicker and go out - it was a fixed voltage regulator. Don't remember which one - but it had a tall tab on it. Freeze mist helped to identify. Had to use an NTE part - it was a fairly unusual package.

author: mskobier
author_rank: Regular Contributor
timestamp: June 16, 2015, 09:43:00 pm
content: Mzacharias,Thanks for the reply. Unfortunately, my lc101 is completely dead with only a momentary flash of the display when turning on and off. At this point I don't have any idea where to start. Maybe this weekend, I'll open it up and do a little probingMitch

author: Johnny10
author_rank: Frequent Contributor
timestamp: October 18, 2015, 12:47:51 pm
content: Did you ever repair your sencore unit?

author: singapol
author_rank: Frequent Contributor
timestamp: October 19, 2015, 03:43:54 am
content: Your lucky day?http://elektrotanya.com/sencore_lc101.pdf/download.html

author: Sencoretech
author_rank: Contributor
timestamp: October 20, 2015, 08:51:28 pm
content: Quote from: mskobier on June 16, 2015, 09:43:00 pmI'd check your supplies, I'm guessing one of the filter caps when out and you have too much ripple.Common failures I use to see are: IC32, IC33 and TR8. All are located on the top board.
Quatro CTV-7230 TXT-S Repair - Page 1
Forum section: electronics / repair

author: Vince56
author_rank: Newbie
timestamp: October 18, 2015, 06:14:36 pm
content: I have a CRT Quadro who will not turn on. Signal red LED works, but there is no picture or sound. I do not know where to start to repair. If anyone knows what to do please tell. Greetings from Croatia .

author: HighInBC
author_rank: Contributor
timestamp: October 18, 2015, 06:22:46 pm
content: I don't know what is wrong, but you should be aware that you can get a high voltage shock from a CRT even if it is not plugged in. The charge can remain in the CRT for a very long time after being unplugged. If you touch the wrong part you are going to have a bad time.

author: Vince56
author_rank: Newbie
timestamp: October 18, 2015, 07:14:36 pm
content: I am aware of high voltage parts, and take care to avoid them. By the way capacitors do not look bloated or burned.

author: tec5c
author_rank: Frequent Contributor
timestamp: October 18, 2015, 10:46:47 pm
content: Are there any strange buzzing noises coming from inside the unit when it is powered on?

author: Vince56
author_rank: Newbie
timestamp: October 19, 2015, 08:17:48 am
content: There is a very weak sound. Similar whimpering inductors.

author: Vince56
author_rank: Newbie
timestamp: October 20, 2015, 06:55:46 pm
content: UPDATE - The display shows the white line in the middle of the screen; Similarly in this figurehttp://www.overclockers.com.au/wiki/images/e/e7/Electronics_001small.jpgWhat could be
Uni-t utp3705s - Page 1
Forum section: electronics / repair

author: Westline
author_rank: Newbie
timestamp: October 19, 2015, 05:36:59 am
content: I Hope someone can give me some advice with this since I'm stuck.I recently bought a uni t utp 3705s power supply seams like the same as a tenma 72-8700a.2 channel 0-32v 0-5a.During a anodizing job I messed up channel 1 it blew the fuse and since then is unregulated stuck at 32v.Channel 2 is still fine.I have swapped the power transistors and op amp between the 2 channels and no joy.Can someone give me some advice on where I can start looking, it seems like a common problem on these units.Kind regradsWestline

author: Westline
author_rank: Newbie
timestamp: October 19, 2015, 05:03:33 pm
content: Hi I took another look and I forgot to mention the relays to switch to different coils on channel 1 clicks like crazy and sometimes the voltage jumps as high as 40v.Sent from my iPhone using Tapatalk

author: Rasz
author_rank: Super Contributor
timestamp: October 19, 2015, 06:49:35 pm
content: Quote from: Westline on October 19, 2015, 05:36:59 amwarranty

author: Westline
author_rank: Newbie
timestamp: October 19, 2015, 06:58:06 pm
content: One word... chineeseSent from my iPhone using Tapatalk
IT8512+ DC Electronic Load - Page 1
Forum section: electronics / repair

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: October 18, 2015, 02:18:12 pm
content: Not so much a repair as just documenting this incase others run into the same issue...So the IT8512+ (firmware v1.12) can do 120V, well at some point mine decided not to go above 18V OR 18W, CC worked fine to max 30A, but CV/CW would not go over '18'.Thought that was a bit strange, tore it down, tested loads of things, nothing. put it back together and still the same...So, I was annoyed at the constant 'beep' pressing keys so I turned the beep off and saved it as configuration0 or save0, and had that load when the machine turns on...well, I changed it to reset when it loads, problem solved. just gotta live with the annoying beep.somehow its internal stored settings/calibration? had been corrupted as telling it to use defaults on load fixed it.
Tek 2235 blob on screen - Normal behavior? - Page 1
Forum section: electronics / repair

author: RetroGameModz
author_rank: Newbie
timestamp: October 17, 2015, 10:11:49 pm
content: Hello all electronic enthusiasts.This is not really much of a repair question, since I do suspect that this is a common behavior on some analog oscilloscopes rather than a fault condition. I'm not going to do much about it anyway since it doesn't bother me that much.However, what I'm wondering here is what might be causing this kind of behavior. I'm asking this purely out of curiosity, and I'm pretty sure that there must be someone on this forum who has a pretty good idea of what's going on.It's regarding my analog Tektronix 2235 oscilloscope. There is a big blob on screen following the movement of the actual electron beam. The electron beam drawing the trace and the blob are moving in proportion to each other.I made a short 2 minute video about it to easier demonstrate how this looks like.Maybe you could test this for me on your analog scopes and tell me if they are doing the same thing? That would be very much appreciated.Thanks in advance.

author: c4757p
author_rank: Super Contributor
timestamp: October 17, 2015, 10:22:57 pm
content: Normal. "Reflections" of the electron beam inside the tube. Turn your intensity down, it's probably too high.

author: AF6LJ
author_rank: Unknown
timestamp: October 17, 2015, 10:29:50 pm
content: I have seen that and have always believed it was reflectd light off the glass on to the phosphor. There would be a reflection caused by the transition from the glass to the air, that would generate a reflection that could be seen on the inner surface of the CRT front glass which would illuminate the the phosphor.My Buck-Fifty....

author: Gertjan
author_rank: Frequent Contributor
timestamp: October 18, 2015, 08:32:49 am
content: I checked on my Tek 2235, and on my Hameg HM1004-2. Both have the same behaviour.So I guess it is normal....But I only see the blob when the intensity is set very high. Under those circumstances (like in your video!) I start to worry about the Phosphor layer in the CRT....So take care with your experiments!Regards, Gertjan.
Agilent E3640A Obsolete part need some help - Page 1
Forum section: electronics / repair

author: WuLi
author_rank: Newbie
timestamp: October 25, 2015, 08:55:48 am
content: Hi,I have an Agilent E3640A PS with a defective CS8122 voltage regulator. This voltage regulator was fabricated by On Semiconductors and it became obsolete. I've been looking around the internet trying to find this part but I've been unsuccessful so far. I don't have experience with finding replacements for obsolete parts. Can anybody give me a hand on finding a replacement for this part? Thanks in advance.John

author: tautech
author_rank: Super Contributor
timestamp: October 25, 2015, 08:57:55 am
content: Quote from: WuLi on October 25, 2015, 08:55:48 amCS8122 package?Link to datasheet?

author: WuLi
author_rank: Newbie
timestamp: October 25, 2015, 09:00:48 am
content: Sorry,I forgot that. It's the CS8122YTVA5 Vertical TO220 Package as listed in the datasheet. I've attached the datasheet.John

author: free_electron
author_rank: Super Contributor
timestamp: October 25, 2015, 02:30:01 pm
content: That thing was originally made by cherry semiconductors , later borged by ON SEMI.Lp2957 could do it but cant do more than 300mA ...I weeded out possible candidates. You will have to check their pinout.You can mimic the delayed start by adding an r and c to the enable pin.http://www.digikey.com/product-search/en?pv16=8696&pv16=8698&pv16=12652&pv16=287&pv16=12742&pv16=8169&pv16=8881&pv16=991&pv16=12745&FV=fff40027%2Cfff80182%2Cc00001&k=Regulator&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: October 25, 2015, 02:58:25 pm
content: Hi,This may help.Here is the schematic from the E3633A:It uses the LM2925T this looks to be pin compatible with the CS8122. Here is a link to the datasheet:http://www.ti.com.cn/cn/lit/ds/symlink/lm2925.pdfGood Luck,Jay_Diddy_B

author: WuLi
author_rank: Newbie
timestamp: October 25, 2015, 04:01:50 pm
content: Thank you guys for your input. Someone at the Agilent / hp user groups pointed out the LM2925 device to me. It seems to be compatible with the CS8122. I've ordered this device and will test it in my unit as soon as it comes in. Thanks again.JohnJay_Diddy_B You've found it to ;-) I'll ley you guys know if it works...
Dead Advantest R3131? Not yet! - Page 1
Forum section: electronics / repair

author: nctnico
author_rank: Super Contributor
timestamp: October 16, 2015, 08:04:25 pm
content: A quick note: My Advantest R3131 spectrum analyser threw me a nasty surprise today. Yesterday it already started with an RTC error but no problems. Today it wouldn't start at all. It just showed a half screen with some garbled text.Not a good sign!So I opened it up and checked the RTC battery. Completely flat! Fortunately I had a litium battery lying around so I put that in but no go. Still garbled text and no response to any keys. Switched it off a couple of times, left it on for a while but still no goJust as I need it it bails out on me! I pulled out the CPU board again but it has no EPROMs/FLASH to reseat or anything in sockets. Then I noticed a small push button in the bottom left corner (seen from the rear of the unit). I switched it on again, pressed the button and.... it works again!Appearantly that button is some kind of reset-everything button to re-initialise the RTC data. I ran the self calibration and everything passed just fine.

author: tautech
author_rank: Super Contributor
timestamp: October 16, 2015, 08:18:16 pm
content: Nice catch.Was this reset mentioned in the manual?

author: nctnico
author_rank: Super Contributor
timestamp: October 16, 2015, 08:24:16 pm
content: Nope. I checked the user and maintenance manual but couldn't find. I don't rule out I overlooked it though.

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 16, 2015, 08:28:24 pm
content: Good catch.Quote from: nctnico on October 16, 2015, 08:04:25 pmJust a question, how would a flat RTC battery cause the screen to go garbled?

author: nctnico
author_rank: Super Contributor
timestamp: October 16, 2015, 08:35:15 pm
content: Probably some software bug which doesn't recognise the data stored in the battery backuped RAM. So the software crashes with all kinds of erratic behaviour. Pretty bad engineering! Perhaps they didn't bother because they have the 'recovery switch'.
Samsung SyncMaster T240  LCD screen problem - Page 1
Forum section: electronics / repair

author: stdcall
author_rank: Newbie
timestamp: October 16, 2015, 11:40:09 am
content: Hey guys,I'm been troubleshooting quiet a while with my LCD screen.First, there were these 2-3 seconds blackouts where the screen got black.I replaced all the bad caps, and the issue was stable for about a year.Then, it happened again, but the caps were OK.So I replaced the backlight inverter.The issue was solved, no blackouts. but now, I have these weird green and pink pixel spreaded on the screen. (I attached an image)I'm quiet positive that it's related to the power supply board.What could be the issue now ?

author: Totalsolutions
author_rank: Contributor
timestamp: October 16, 2015, 03:33:35 pm
content: You did use new, branded low esr caps ? ------Sent from my GT-N7100 using Tapatalk
DP-5B Dosimeter - Page 1
Forum section: electronics / repair

author: Trifaziux
author_rank: Contributor
timestamp: October 12, 2015, 02:16:07 pm
content: Hi,I have a soviet DP-5B dosimeter and it has a faulty MP15A transistor are there any silicon transistor replacemets?

author: DmitryL
author_rank: Regular Contributor
timestamp: October 12, 2015, 03:47:57 pm
content: This is just a germanium pnp transistorHere are some parameters:http://elektrouzel.ru/uploads/posts/2011-06/1308404072_3.jpg
Rigol MSO2072A Power Supply - Page 1
Forum section: electronics / repair

author: iDandelions
author_rank: Newbie
timestamp: October 08, 2015, 06:13:21 pm
content: The power supply just let go on my MSO2072A. It was just sat on the shelf on standby with no other connection other than the power lead. It's not been used for days. Loud pop and then some magic smoke.I've removed the power supply and the source of the smoke can be seen. Capacitor C117 is no more. I've removed the associated 2SK3569 transistor and it looks like it has failed. I've ordered a new one but no idea what value capacitor to use. Any suggestions appreciated?Thanks

author: iDandelions
author_rank: Newbie
timestamp: October 09, 2015, 02:09:31 pm
content: Thanks for the picture, Peter.I've replaced the cap and transistor but it seems more than those two components have failed. I'm going to try and get a new power supply from RigolDo you know the voltages/pin-out of the power supply connector? I might try and power up the scope to see if it's ok.

author: SeanB
author_rank: Super Contributor
timestamp: October 09, 2015, 05:59:31 pm
content: Standard switching supply. Change the other transistor as well, and check all the low value resistors and diodes connected to the transistor base, along with the high value resistors that provide a start up voltage to the circuit, along with the capacitors there. Basically all on the primary side will need checking. the high value resistors are very prone to flashing over, as they are not really mains rated.

author: wraper
author_rank: Unknown
timestamp: October 10, 2015, 01:00:07 am
content: When mosfet fails, often driver IC (+some components between them) fails too. Therefore I would suggest to change TEA1750T and check all components which are connected to gate of the mosfet.

author: iDandelions
author_rank: Newbie
timestamp: October 10, 2015, 02:46:10 pm
content: Thanks to everyone who has posted.The driver IC has blown (I've removed it and there's a hole in the bottom). The other MOSFET, SPA11N60C3, has also died along with both capacitors and diodes next to the MOSFETs. Some of the other passives and diodes also look suspicious. I've ordered replacement parts for the IC and MOSFETs but as I don't have a circuit diagram/schematic I don't know what the values should be for the other components.If I can find a circuit diagram I'll attempt a repair otherwise I think I just have to hope Rigol can supply a replacement board.Thanks for the updated voltages Peter. I'm going to try and power the scope up later.Thanks again for your help.
Fluke multimeter repair - Page 1
Forum section: electronics / repair

author: rocknrollnick
author_rank: Newbie
timestamp: October 07, 2015, 02:50:22 pm
content: Hi all, having trouble with a Fluke 73 series 3 multimeter, it worked fine at first other than the 2 amp settings, so i opened it up to replace the fuses, and the battery, but now I'm having trouble with the continuity mode, it either does 1 of 2 things, it either just beeps constantly and displays a random number, or it just starts counting up or down on the screen, in a similar way to the video about the keithley DMM repair... anybody got any ideas or seen this happen before? I'm only just getting into electronics although I'm quite familiar with repairing electronic components in carsthanks in advance

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: October 07, 2015, 04:37:25 pm
content: You likely already tried, but if the problem started right when you changed the battery... Have you tried a different battery?

author: retiredcaps
author_rank: Super Contributor
timestamp: October 07, 2015, 05:45:14 pm
content: This picture is from modemhead's post athttps://www.eevblog.com/forum/chat/i-thought-all-fluke-70-series-were-made-in-usa/The two red circled dots are the connectors to the buzzer. Check to make sure they are clean. Check your buzzer contacts.

author: rocknrollnick
author_rank: Newbie
timestamp: October 07, 2015, 07:02:06 pm
content: tried a different battery from a different make, no luck on that one, will check the buzzer contacts next thanks!

author: rocknrollnick
author_rank: Newbie
timestamp: October 09, 2015, 07:08:33 pm
content: update! just managed to get the ohms function working again! continuity is a bit funny though, all i did was reseat the battery! but this time i also thoroughly checked the components and the board and everything looks ok, but i did notice some of the contacts on the mode selector were a bit bent, i wasn't sure if they were supposed to be like that at the time so i left them, but upon looking at pictures i now know they shouldn't be so will bend them back and update with results!
Creative GigaWorks T40 speakers - Page 1
Forum section: electronics / repair

author: Jckf
author_rank: Newbie
timestamp: January 25, 2015, 06:26:31 pm
content: Hello once again, forum. My speakers, or rather the amp in my speakers, is on its deathbed. They sound as good as new when they're first powered on, but there is progressively more and more distortion the longer they're used, and after about give or six minutes there is virtually no point in trying to listen to them any more. It started out as an infrequent crackle in the left speaker, but this is far from a small crackle. The left speaker is also the one that goes silent first.Granted, these speakers are quite old. I bought them 7 years ago, and they weren't new then. However, a new pair of the second generation of these is going to set me back around 1100 kroner (140 US dollars, 180 Aus. dollars), and I could think of so much more I'd rather spend that money on. And if nothing else, it'll be a learning experience to have a look at the problem.I'm currently uploading some videos of how they sound, so stay tuned.EDIT: c4757p on IRC has suggested I cool components one at a time using cooling spray, so I'll get some compressed air and use the can upside down.

author: Jckf
author_rank: Newbie
timestamp: January 25, 2015, 10:48:37 pm
content: The only problem you can hear right from the start is somewhat distorted bass. About half-way through the video it jumps 5 minutes into the future, and you can no longer make out which song is playing.

author: ramonest
author_rank: Contributor
timestamp: October 05, 2015, 01:23:58 pm
content: Did you managed to get them repared?

author: ramonest
author_rank: Contributor
timestamp: October 08, 2015, 05:25:00 pm
content: I just got ones with similar/same fail they do some noise ten they stop working I'll try te get them repaired. Some help/tips?

author: ramonest
author_rank: Contributor
timestamp: October 09, 2015, 07:35:16 am
content: Tested them, noise for seconds then nothing. I opened case and after turning them on the main IC (TDA8932BTW) got so hot I couldn't touch it. After powering it on and off sometimes to try to test is with the multimeter it stopped powering on. The power supply that regulates the 20AC input works.Is it worth to change the main IC to try it?I can only see a very small burnt spot near the main IC but can't see what component is at the top of it(other side of the board) because there is the hard type white/yellow glue for the vibrations there... how can I get rid of the glue?I also was trying to find schematics but impossible only thing I found was that they don't want you to reverse engineer it so you don't reveal the (secrets) that they keep.It'll be some smd de-solder/solder practice at least x)I'm trying to add an images but I can't see them on the preview.

author: ramonest
author_rank: Contributor
timestamp: October 09, 2015, 07:37:46 am
content: Oh here it's the image ok srry for being noob and thanks.
Heathkit IG-1271 function generator repair - Page 1
Forum section: electronics / repair

author: Shock
author_rank: Super Contributor
timestamp: October 06, 2015, 06:31:23 am
content: Not my video but teaches some basics in troubleshooting a short circuit.

author: Vgkid
author_rank: Super Contributor
timestamp: October 06, 2015, 02:13:33 pm
content: That is actually Radio Tech video, on here,https://www.eevblog.com/forum/repair/vintage-heathkit-ig-1271-function-generator-troubleshoot-and-repair/msg756580/#msg756580
Hung Chang (Protek) 3502c oscilloscope - Page 1
Forum section: electronics / repair

author: Mikeva
author_rank: Contributor
timestamp: October 24, 2015, 07:35:06 pm
content: Hi guys,I recently bought my first oscilloscope used and although all the functions work ok,I'm having problem with the vertical gain on the first channel.It can't measure the voltage right.i connect the probe into the 0.5vcal point and it measures only 0.3Vp-p instead of 0.5Vp-p.The same happens if i try to measure dc voltage from my power supply.For 10 vdc it reads about 7.5-8v.The channel B works ok instead.I found the schematic and tried to calibrate it but the trimmer which is responsible for this is almost fully turned clockwise giving the measurements i described.I checked all the voltages(except the 1.9kv) and all seems within the specs.I didn't found any obvious fault on the components measurements.There is an 15 pin hybrid ic marked AX-1015 (2 per channel) that maybe is the cause for the fault but i cannot find any information about it.Does anyone knows what ic is that?(pics)Or any advice on how to proceed?Any help will be greatly appreciated.Thanks

author: siggi
author_rank: Regular Contributor
timestamp: October 25, 2015, 01:24:28 am
content: Input the same signal on both channels and trace it through, figure out where they diverge. Hopefully this happens in the discrete so before the hybrid.Sent from my iPad using Tapatalk

author: Roeland_R
author_rank: Regular Contributor
timestamp: October 25, 2015, 03:17:45 pm
content: Does the cal potentiometer knob work correct?

author: Mikeva
author_rank: Contributor
timestamp: October 25, 2015, 03:34:16 pm
content: yes it works alright .It has the same gain as the B channel.
electrophysics 7290a vidicon thermal camera - no image - Page 1
Forum section: electronics / repair

author: elor
author_rank: Contributor
timestamp: August 31, 2015, 10:51:24 pm
content: hellocamera doesn't work anymore after a week of outdoor field testi suspect a power issueanyone has data? scheme? anything that will help me start diagnose the problemis there any recommendation where to start?

author: Fraser
author_rank: Super Contributor
timestamp: October 04, 2015, 07:23:30 pm
content: I do not have this camera but I do own an EEV ARGUS 1 that also uses a Pyroelectric Vidicon tube. I have the full service manual and schematics for the ARGUS so can tell you voltages to expect on the tube pins. The camera is very similar to a conventional Vidicon camera but it has a chopper wheel spinning in front of the tube to 'rest' the tube front face. These cameras would suffer chopper wheel and PSU related failures. Normally relatively easy to repair.Be aware that as the camera is quite old now, the bias voltages on the tube will likely need adjusting for best image. I have those details for the ARGUS tube as well. Marconi/EEV made most of the Pyrovidicon tubes so your camera likely uses one either similar of the same as the EEV ARGUS.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: October 04, 2015, 07:28:31 pm
content: With regard to service manuals and schematics for early thermal cameras, some manufacturers try to be helpful but most decline to share such information with the public. I had to reverse engineer my FLIR PM570 for that reason. Thermal imaging is a topic for which very little deep technical information exists on the NET.Fraser

author: singapol
author_rank: Frequent Contributor
timestamp: October 04, 2015, 08:18:38 pm
content: Start checking the esr and capacitance of the electrolytic caps and tantalums, especially the electrolytic cap on the round pcb of the tube.
function generator synthesized ARB half sine out  - Page 1
Forum section: electronics / repair

author: sarepairman2
author_rank: Frequent Contributor
timestamp: October 04, 2015, 02:08:29 am
content: What is a good place to start looking for problems when a synthesized ARBitrary FG outputs half a sine instead of a full sine wave?

author: sarepairman2
author_rank: Frequent Contributor
timestamp: October 04, 2015, 03:43:51 am
content: ok burning out a transistor by accident, makes the uunit works, but heavily attenuated, and zero functionality at low frequencies.im guessing the small signal behavior of the transistor still works but not large signal?draws 0.2A on base now lol
Identify smd part.  Fuse or Ferrite? - Page 1
Forum section: electronics / repair

author: orion242
author_rank: Unknown
timestamp: October 02, 2015, 02:00:25 am
content: Anyone have an idea what this kind of part this is or a suitable replacement? It has no markings, center pads are connected to gnd. Pads on the ends are basically input to an ADC circuit. Normal signals would be DC to <15hz, no more than maybe 20-30vdc <30ma on the pictured one. Smaller ones are downstream of TRIACs switching 24vac @ 0.5A. In the silk screen these are all identified as Fx, so guessing its a fuse or ferrite. If the pictured on the ADC circuits sees 24vac, it pretty well removes itself from the board, saving the rest of the circuit. On the TRIAC outputs, the TRIAC will fail before they suffer any damage.I have a few I can experiment with to try and identify the specs, just hoping someone can narrow it down by looking at it.

author: helius
author_rank: Super Contributor
timestamp: October 02, 2015, 02:28:16 am
content: It doesn't look like a smd fuse, they don't have solder around the middle like that.The magic words are "chip capacitor type EMI filter" and "LC combined EMI filter". It may also be a Pi or "X2Y" filter.

author: orion242
author_rank: Unknown
timestamp: October 02, 2015, 02:43:05 am
content: That would make sense. They are the first component the external wiring ties to on both the input and output circuits on this board.

author: Habropoda
author_rank: Regular Contributor
timestamp: October 02, 2015, 03:07:29 am
content: Three terminal capacitor?http://www.murata.com/en-us/products/productdetail.aspx?cate=luNoiseSupprFilteChip3TermiCapac&partno=NFM15CC222D1A3%23

author: TiN
author_rank: Super Contributor
timestamp: October 02, 2015, 04:22:28 am
content: It's pass capacitor

author: orion242
author_rank: Unknown
timestamp: October 03, 2015, 12:27:27 am
content: Thanks guys that definitely narrows the hunt!
Fujitsu-Siemens P19-2 19" TFT Monitor Service Manual - Page 1
Forum section: electronics / repair

author: yutronic
author_rank: Newbie
timestamp: September 28, 2015, 09:47:11 pm
content: Hi,does anyone have a service manual for Fujitsu-Siemens P19-2 19" TFT Monitor that he (or she) would like to share with me?

author: Rasz
author_rank: Super Contributor
timestamp: September 30, 2015, 11:54:49 am
content: noanswer for this monitor is most likely caps

author: samnmax
author_rank: Regular Contributor
timestamp: September 30, 2015, 12:42:22 pm
content: Some repair hints here (in Czech):http://diit.cz/clanek/fujitsu-siemens-scenicview-p19-2-repase-servis-oprava.
TTi - PL330 Bench Power Supply Repair - Page 1
Forum section: electronics / repair

author: node1e
author_rank: Newbie
timestamp: September 23, 2015, 07:56:41 am
content: HI all,I managed to pick up a Thurlby Thandar Instruments PL330 bench power supply for free knowing that it didn't work but figured I could crack it open and fix it.I've got it open and found a burnt out resistor, it looks like a current sense shunt of some kind. It was open circuit and I've managed to remove it from the board but now are stuck as to what value to put back in there. Image below shows the resistor position, its on the control panel PCB with the 8-seg displays and voltage/current control pots.Any help appreciated.Thanks

author: singapol
author_rank: Frequent Contributor
timestamp: September 23, 2015, 09:29:17 am
content: You can write to TTI and ask for service manual? Like in this thread?https://www.eevblog.com/forum/reviews/hello-(and-the-insides-of-a-tti-thurlby-thandar-pl330-power-supply)

author: Andy Watson
author_rank: Super Contributor
timestamp: September 23, 2015, 09:43:51 am
content: This thread has a link to the early version service manual:https://www.eevblog.com/forum/buysellwanted/tti-pl310-psu-service-manual/I have a copy of the later version, but the forum software won't allow me to attach it (too big).

author: PTR_1275
author_rank: Frequent Contributor
timestamp: September 23, 2015, 03:36:53 pm
content: I've got the full service manual at work, if you pm me your email address I can send it through to you.The 1 ohm resistors on the regulator board normally burn out if there is a overload too. The transistors on the ones I've repaired have never gone bad.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: September 23, 2015, 03:38:20 pm
content: I just looked at your photo in more detail, the gold Aluminium resistor to the left of the red box is the current sense resistor. I can't remember what the one you've marked is but I'll see if I have a copy of the manual on my phone.

author: voltsandjolts
author_rank: Unknown
timestamp: September 25, 2015, 08:04:03 pm
content: Not sure if this is the revision of manual you need...

author: node1e
author_rank: Newbie
timestamp: September 29, 2015, 07:33:28 pm
content: Update:With the manuals received and thanks to PTR_1275 I have been able to successfully replace the burnt out resistor with a 2K2 3W wire wound resistor and the PSU is now working and found a new home on my work bench.Thanks for the all the help.nodee

author: PTR_1275
author_rank: Frequent Contributor
timestamp: September 29, 2015, 11:05:54 pm
content: Awesome to hear you've got it working and there wasn't anything else wrong with it.I know the ones on my bench needed their voltages to be tweaked a little bit, did you do a cal check while you had it open?

author: node1e
author_rank: Newbie
timestamp: September 30, 2015, 07:51:21 am
content: That would of been a good idea! I'll get my meter out and have a check later today.Thanks,nodee
Identifying an SMD component  - Page 1
Forum section: electronics / repair

author: alice
author_rank: Newbie
timestamp: September 27, 2015, 03:14:10 pm
content: I need help. I screwed up a repair job and I chipped off an SMD. Now I can't identify what has gone missing, a cap or resistor.Hoping someone here could identify this one. I think the original one was on the left(1) and the chipped off was on the right(2).Also wondering if it is safe to bypass the component.The board is a Samsung Galaxy S4 USB board. The section was to handle the speaker connection as you can see, the two golden pins are supposed to be connected to the speaker.

author: amyk
author_rank: Super Contributor
timestamp: September 27, 2015, 03:32:37 pm
content: That looks like a ferrite bead. A quick Google finds aschematicwhere you can see that they're called inductors (go to page 60 and zoom in very, very far). You can check the value of the intact one, it won't be very high but they're used to prevent GSM signals from causing interference in the speaker.

author: alice
author_rank: Newbie
timestamp: September 27, 2015, 03:42:59 pm
content: Do you think it is safe to bypass the ferrite bead instead?There should not be any resistance in them I guess so to cause a short with just a bypass solder.

author: DmitryL
author_rank: Regular Contributor
timestamp: September 27, 2015, 04:17:03 pm
content: Didn't look at the schematics, but from the photo it looks to me like a wirewound SMD inductor. Possibly this is a part of a sound PWM amplifier LC filter.Ideally you measure inductance of the remaining part and place the same, worse case: replace it with a resistor (measure resistance of the remaining inductor)

author: alice
author_rank: Newbie
timestamp: September 28, 2015, 11:55:02 pm
content: Thank you for all the replies guys. I got it fixed without having to replace the whole board.You guys are the best!
Ordering Keysight parts in Europe?? - Page 1
Forum section: electronics / repair

author: nctnico
author_rank: Super Contributor
timestamp: September 27, 2015, 01:58:02 pm
content: Does anyone know how to order Keysight parts in Europe? I need a replacement knob + rotary encoder for a PSU.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 27, 2015, 10:36:46 pm
content: I usually send an email to Keysight Germany and in return, they will offer the parts with a price and then I place the order.About 1 to 2 weeks later I have the parts at hand.They are also very helpful in selecting the correct part number, if you are not sure.

author: wraper
author_rank: Unknown
timestamp: September 27, 2015, 10:41:12 pm
content: You can make and enquiry through their website. They will forward it to your local distributor. At least how it worked for me.http://www.keysight.com/my/faces/fapHomePage.jspx

author: dundee
author_rank: Regular Contributor
timestamp: September 28, 2015, 01:13:53 pm
content: I asked my local distributor for a missing knop.They sent it to me for freeVery good service...

author: nctnico
author_rank: Super Contributor
timestamp: September 28, 2015, 05:24:37 pm
content: OK thanks everybodyI will give the route through the local distributor a try.
Want to buy: Fluke 87 SWITCH PAD, MOMENTARY part:809970 - Page 1
Forum section: electronics / repair

author: halexa
author_rank: Regular Contributor
timestamp: September 16, 2015, 08:13:47 pm
content: Hi,Got hold of a cheap Fluke 87 I. The meter works fine but the rubber buttons are a bit messed up.Are the anybody on the forum who has a pair of spare rubber buttons from a non working meter who are willing to sell them for reasonable price?And dose anybody know if the rubber buttons from the 87_V fits on a 87_I, they look the same except for the color.Have scanned E-bay and other part sites without any luck.

author: retiredcaps
author_rank: Super Contributor
timestamp: September 16, 2015, 08:38:36 pm
content: In this threadhttps://www.eevblog.com/forum/repair/fluke-83-main-asic/krivx has a parts Fluke 87. Send krivx a PM.

author: halexa
author_rank: Regular Contributor
timestamp: September 17, 2015, 08:05:47 am
content: Thx.I will PM him.

author: retiredcaps
author_rank: Super Contributor
timestamp: September 17, 2015, 04:45:35 pm
content: Quote from: halexa on September 16, 2015, 08:13:47 pmAs for the above, it will likely work, but I haven't tested it myself.

author: halexa
author_rank: Regular Contributor
timestamp: September 23, 2015, 08:24:45 pm
content: Hi,A big thank you Krivx for excellent service with suppling with my needed rubber buttons.Now my new fluke 87 feels much happier in the gang.

author: krivx
author_rank: Frequent Contributor
timestamp: September 24, 2015, 07:41:08 am
content: It's nice to see instruments of this quality stay in use

author: ModemHead
author_rank: Frequent Contributor
timestamp: September 24, 2015, 01:30:43 pm
content: @halexa, I like your taste in DMMs. @krivx, very generous, good job.

author: halexa
author_rank: Regular Contributor
timestamp: September 26, 2015, 05:05:55 pm
content: Quote from: ModemHead on September 24, 2015, 01:30:43 pmThank you, I also got a Fluke 76 incomming from E-bay.
Washing machine motor control - Page 1
Forum section: electronics / repair

author: MrWizerd
author_rank: Contributor
timestamp: September 24, 2015, 07:18:31 pm
content: My washing machine's motor control board blew out, and while I wait for the post to come I still need to wash cloths. While hand washing is an option I am not fully setup for it. Looking at the control board it looks like the PCB traces blew. Attached is a photo of what they looked like. My question is two gold, what is the purpose of choking the large traces down to the small size and then back up? Are they doing it to increase resistance in that area without using a resistor? The second question is if I use a wire or PCB repair pen on it well it function as it should? (barring any other problem that could have caused the overload was just a surge or something not permanent)Sent from my SPH-L710 using Tapatalk

author: SeanB
author_rank: Super Contributor
timestamp: September 24, 2015, 07:24:14 pm
content: They do that so the thin trace acts as a fuse. Use a single strand out of some 20AWG cable as a replacement, soldering to the pads on each side. There probably were provisions made on the top of the board for 2 solder in fuses in this design.Before replacing check for blown semiconductors, or for a faulty motor or capacitor.

author: Marius Muntianu
author_rank: Newbie
timestamp: September 25, 2015, 11:53:58 am
content: It depends where this choking of the traces is on the board. If the washing is one of the newer models it probably has a brushless DC motor.You can see if the machine has brushless motor by looking at the number of wires going to the motor. A brushless motor will usually have 3 wires for the phases and most likely one for protective ground.If the choking is on the power going to the transistors (usually on the low side of each half bridge) or on the lines going to the motor they could be used as series resistors to measure motor phase currents.In the new washing machine models they use what is called field oriented motor control to minimize vibration and for load compensation.If those are used for current measurement and they are blown most likely there is short somewhere or the motor itself is gone. If they are on the low side of the half bridge you will probably have a blown transistor and if they are in series with the motor than you guessed it, it is most likely the motor.QuoteI don't see any good reason for any PCB designer to make a fuse as a track as it will be hard also for the manufacturer to fix (when still in warranty).

author: Tomorokoshi
author_rank: Super Contributor
timestamp: September 25, 2015, 04:50:40 pm
content: It's hard to tell from the picture, but because the trace wraps around to meet that gap in 2 places, was there ever anything there at all? I don't notice any vaporized debris.I wonder if it's a high-voltage arc discharge ring of some kind.If it is an AC motor with brushes, see if they are almost worn out.

author: N8AUM
author_rank: Regular Contributor
timestamp: September 26, 2015, 03:16:58 pm
content: Can you take a pic of the whole board, both sides ?
MT2400 power graphing multimeter strange measurement problem - Page 1
Forum section: electronics / repair

author: R_G_B_
author_rank: Frequent Contributor
timestamp: September 23, 2015, 10:35:44 am
content: I Have an automotive power graphing multi meter with a problem:It will not measure AC voltage or show AC signals on channel 1 when you select the AC measurement function.However it does show AC signals when in other modes e.g if i go to the menu and select AC pulse generators then channel 1 will happily display AC signals.Also Channel 1 has no problems displaying D.C signals and D.C measurements.Note only channel 1 can measure AC signals. The rest of the meter seems to function OK.The input coupling to this graphing multi meter is D.C on all channels. To get AC coupling requires an AC filter as shown in the link below:I have tried to supply a pure A.C signal to the input channel 1 it will not read or show the signal when in AC measurement mode.http://resources.aeswave.com/old/TechNotes/index1.htmCould this be a firmware issue or corrupt data in the memory eeprom card?R_G_B_Thanks

author: R_G_B_
author_rank: Frequent Contributor
timestamp: September 26, 2015, 01:09:52 pm
content: Selecting in the menu hardware and software test shows no problems with the hardware or software.Also looking at the analogue circuit seems to use peak detecting analogue circuits.Bit difficult to see where the fault is the meter functions in all other modes the only function that does not work is AC voltage over time which seems a bit odd. The graphing meter is directly coupled which implies both D.C AC voltage share the same signal path for channel 1 of this graphing multimeter.The signal is getting to the ADC as a waveform and the other channels of the ADC are receiving detected peaks of this waveform and when adjusting the amplitude of the function generator the signals at the ADC seem to follow the change in amplitude.