hybridfree/eevblog-posts huggingface dataset:
Help Trouble Shooting Rigol DS1102E White Display - Page 1
Forum section: electronics / repair

author: Vietk123
author_rank: Contributor
timestamp: August 12, 2016, 03:28:29 am
content: I recently bought a broken Rigol DS1102E off ebay. The unit turn on but have white screen on the display. I been doing research on how to go about and find the problem and maybe get a solution to fix my unit. I am totally new to electronic repair and need all the expert guidance. I found this site for schematic,http://rigol.codenaschen.de/index.php/Schematics. Hopefully this is the right schematic for Rigol DS1102E. Anyone here have seen the white display problem and point me in the right direction or what should test for? My first repair I can document and at lease have this for others with the same problem.

author: singapol
author_rank: Frequent Contributor
timestamp: August 12, 2016, 04:44:02 pm
content: First check the power supply voltages. If all is present then do a visual inspection for burned or charred areasand components.Lastly look for cold solder joints ( reheat with iron) or cracked ones. It's obvious that there is no signal to the video circuits so where is the fault?

author: Vietk123
author_rank: Contributor
timestamp: August 12, 2016, 06:21:03 pm
content: Thanks for the quick reply singapol. I really appreciate it. I just found out today that the unit is still under warranty till 2017 so the person at Rigol is sending me a RMA to send it in for repair at the company. I really wanted to repair this but gonna take the safer route of send it in since its still under warranty.

author: bitseeker
author_rank: Super Contributor
timestamp: August 12, 2016, 06:46:25 pm
content: Congrats on it still being under warranty. Good thing you checked.

author: Vietk123
author_rank: Contributor
timestamp: August 12, 2016, 07:40:28 pm
content: Yeah the cool thing about this was they can check your serial number and see if its under warranty so i strongly suggest contacting manufacture first before any repair for future preference.

author: bitseeker
author_rank: Super Contributor
timestamp: August 12, 2016, 09:53:44 pm
content: Yes, some manufacturers have warranty search capability right on their web site.
fixing my Zoom H2 help for FPC cable - Page 1
Forum section: electronics / repair

author: Teodor
author_rank: Newbie
timestamp: August 12, 2016, 05:08:58 pm
content: HelloI need a little help and advice. I have open my Zoom H2 Mic because two of the buttons on the front wont work. I have deduce that the problem is a brak somewhere on the FPC cable but i cant see where so I hesitate to :A. Skip the cable and solder three wires to the PCB and wire two new buttons glued to the front of the device.B. Because its a hard place for me to solder, buy a newFPC board bridgeand aFPC cable. And making a new keypad for the device with 7 new keys.In my country its very hard to find uncommon electrical parts so I can order from aliexpress and wait..... but I am not sure if all the FPC cables are the same thickness I measured it 8 pins with 1 mm between connections... Witch way will you do it ? Is there an option C. ?Thanks for the help and cheers from Bulgaria
Fluke 335d dc voltmeter null detector dosen't working - Page 1
Forum section: electronics / repair

author: sdk.61
author_rank: Contributor
timestamp: August 11, 2016, 05:11:30 am
content: Hi I am here Fluke 335d dc voltmeter dosen't working .The device doesn't give output Checked out the device there is no feed of cards the card comes all voltagesPlease waiting for your helpthank you

author: dacman
author_rank: Frequent Contributor
timestamp: August 12, 2016, 12:13:18 am
content: You need to find someone that is well versed in the Turkish language. It does not translate well to English at all.Have you checked the filter (aluminum electrolytic) capacitors?Switches are another point of failure, but they can usually be repaired.
Voltcraft VLP-2403 lab psu  - Page 1
Forum section: electronics / repair

author: Danielw
author_rank: Contributor
timestamp: August 17, 2016, 08:06:51 pm
content: Hello!I just bought one Voltcraft VLP-2403 psu (http://www.conrad.com/ce/en/product/511815) Its a Conrad branded PSU. Or maybe even their own manufacture.I got the schematics for it and thought firstly I would share it to the world and why not here?I also modified the schematics to match my version. The grayed out areas are not in my PSU.My questions are, Mod 1 and 2 any guesses why they are added?And second question, on small loads and if CC get triggered - I get negative ~0.1v, havn't killed anything but annoying..Any looking at the schematics, see anything that you would modify?//Daniel

author: Kleinstein
author_rank: Super Contributor
timestamp: August 18, 2016, 05:13:20 pm
content: The two extra diodes are likely to improve crossover from CC to CV mode and for protextion of the OP. It depends on the OP type of these diodes are needed or make sense. Usually the diodes should be anti - parallel, not in series.The extra transistor helps a little to turn off the ouput stage a little faster. However this mainly makes sense if there is an additional diode / resitor from base to emitter at V3.The part left out are for an analog meter - so not needed in the Version with digital display.The current to provide the slghtly negative voltage, when current limit is set all the way to zero (or actually slighly negative) comes through R14. One way to fix this, could be adjusting the offset of the CC setting, so you can't set the current limit below about 1 mA. An alternative might be something to pull down the votlage at R14, if the ouput of OP4A is really high (e.g. > 2 V). However this might be a little tricky and should be simulated fist, as it could also effect (could be well be positive) the CC to CV transition and stability in CC mode.

author: Danielw
author_rank: Contributor
timestamp: August 19, 2016, 11:01:29 am
content: Thanks! I'll experiment some later!I'll publish some more photos. The cabling isn't the most beautiful nor the soldering, but it works.. I've touched up some of the solder joints. I've also ordered 10w r22 resistors instead of 5w, they get over 100c rather fast..
Need help with old hitachi oscilloscope - Page 1
Forum section: electronics / repair

author: digitalundernet
author_rank: Contributor
timestamp: August 11, 2016, 03:52:50 am
content: Ive got an older hitachi oscilloscope v-1065a, I was using it to probe around on an audio filter I was working on when the traces vanished. The scope powers on, all the other info on the screen shows up I just cant see the traces. I can tell its still reading info from the probes because this model has a function where it can show frequency and it accurately shows the frequency of the reference signal on the scope. Ive tried every knob and function but I just cant find the traces. Has something like this happened to anyone else on an older CRT scope like this one? Its the only one Ive got, I need to fix this

author: poot36
author_rank: Frequent Contributor
timestamp: August 11, 2016, 04:01:53 am
content: If you are still getting display on the CRT the power supply is most likely ok. I would suspect something to do with the circuit between when the signal is picked off to display the frequency and the actual sending of data to the CRT. Here is a link to the service manualhttp://www.eserviceinfo.com/downloadsm/11465/Hitachi_V-1065A.htmlyou will have to download the various parts and then open them up with a unzipper program.
Pioneer SC-61 Region File - Page 1
Forum section: electronics / repair

author: zambrock
author_rank: Newbie
timestamp: August 10, 2016, 09:19:40 pm
content: I am in the process of repairing a Pioneer SC-61 A/V Receiver. The main controller IC behind the front panel is dead (PN: LC87F5NC8A). Based on the service manual if this IC is replaced I must update a "Region File" Via USB. I've looked everywhere online for the file and even contacted Pioneer but they said they couldn't give me the file because I am not an authorized service man. Any help would be greatly appreciated.
a problem with sec/div knob on front panel of Tek2465b - Page 1
Forum section: electronics / repair

author: franksummerrain
author_rank: Newbie
timestamp: August 09, 2016, 04:41:14 am
content: Hi guys,problem: The sec/div knob can't be pull out to intensify the waveform.what I have done: I have tear down the front panel and no idea to do next. Seems to need to solder some points to see the knob circuit.Thanks for any suggestions and solutions.ps.Sorry for the same topic at the Beginners.

author: tggzzz
author_rank: Super Contributor
timestamp: August 09, 2016, 07:57:56 am
content: Quote from: franksummerrain on August 09, 2016, 04:41:14 amHave you run the exercise routine (see the manual) to determine whether the processor is reading all the front panel controls correctly?

author: siggi
author_rank: Regular Contributor
timestamp: August 09, 2016, 08:21:20 am
content: Is the button stuck, our non-responsive? My 2467 was non-responsive, which was simply due to contact oxidation. I managed to tease some deoxid into the switch, and that fixed it.Sent from my Nexus 5X using Tapatalk

author: franksummerrain
author_rank: Newbie
timestamp: August 09, 2016, 09:54:02 am
content: Quote from: siggi on August 09, 2016, 08:21:20 amForgot to say that the function will be ok unless I pull it very hard and hold it, otherwise it goes back to "A sweep".It seems my situation is similar with your 2467 and I want to know how you tease the deoxid.Do I need to tear down the front panel further? No more screws is visible but the PCB can't be taken from the panel. Need some soldering on red circle in pic 2?Thanks.

author: siggi
author_rank: Regular Contributor
timestamp: August 09, 2016, 04:11:22 pm
content: I didn't do any soldering for sure. Either I got the switch from the backside, or else I teased the deoxit from the front, by dabbing a q-tip full of it against the shaft. Don't forget to work the switch after trying to wet it.Sent from my Nexus 5X using Tapatalk

author: franksummerrain
author_rank: Newbie
timestamp: August 10, 2016, 04:06:34 am
content: The knob problem is fixed. When the 'var' knob on sec/div is taken away, I found the pull out function is ok. After some tests I figure out that the stick in the knob was broken and in order to hold the 'var' knob someone before pushed the sec/div back and screwed the 'var' in that situation. So the pull function is disabled unless pull it very hardThanks all you guys?
How to adjust smd trimmer ? What type Screwdriver design for ? - Page 1
Forum section: electronics / repair

author: chihaxinh
author_rank: Regular Contributor
timestamp: August 08, 2016, 08:38:04 am
content: Hi every one!When i repair oscilloscope , need adjust some setting like Low Volt , HV for CRT or Vert - Horiz position !But in PCB i have some SMD trimmer like this . Hard to find screwdriver compability .Any one can show me how to turn trim pot or can diy one screwdriver for this ?

author: negativ3
author_rank: Regular Contributor
timestamp: August 08, 2016, 08:52:09 am
content: I use one of these...http://uk.rs-online.com/web/p/trimmer-tools/0543434/

author: Jeroen3
author_rank: Super Contributor
timestamp: August 08, 2016, 03:05:00 pm
content: Those are good. They other side fits around the multiturn knob to easily rotate without slipping off.

author: LeonV
author_rank: Contributor
timestamp: August 09, 2016, 05:33:39 am
content: I just hammered the trimmer driver that came with my scope probes into an old damaged handle of a bit driver.Works amazingly well for what it is.
Agilent/Keysight 34410A schematic diagrams? - Page 1
Forum section: electronics / repair

author: carl_lab
author_rank: Frequent Contributor
timestamp: August 08, 2016, 01:05:56 pm
content: I'm looking for Agilent/Keysight 34410A schematic diagrams...Can anybody help?

author: Zucca
author_rank: Unknown
timestamp: August 08, 2016, 01:38:30 pm
content: https://www.eevblog.com/forum/testgear/faulty-agilent-34410a-multimeter/

author: plesa
author_rank: Frequent Contributor
timestamp: August 08, 2016, 03:21:00 pm
content: Unfortunately the link does not work for while.I posted the schematic to TiN FTPftp.xdevs.com/Plesa/Schematic_34410A.pdf

author: HighVoltage
author_rank: Super Contributor
timestamp: August 08, 2016, 04:05:32 pm
content: I repaired a few of these 34410A meters.May be this helps:https://www.eevblog.com/forum/repair/agilent-34410a-repair-attempt-of-2-dead-meters/

author: carl_lab
author_rank: Frequent Contributor
timestamp: August 08, 2016, 07:43:04 pm
content: Quote from: plesa on August 08, 2016, 03:21:00 pmThank you!This download link worked without login:https://doc.xdevs.com/doc/HP_Agilent_Keysight/34410A/34410-66521_schematics.pdfIs there a component placement diagram, too?Where is calibration data stored? In U1001-A (flash memory)?
Someone assist me with repair - Page 1
Forum section: electronics / repair

author: mrartuka
author_rank: Contributor
timestamp: August 05, 2016, 06:39:31 pm
content: Hello again,after fixing last motherboard tnx to few people here, my friend gave me his motherboard to repair it.Motherboard is the same,but problem seems to be different.Ok, for anyone new here, you can see other motherboard repair thread here:https://www.eevblog.com/forum/repair/need-small-help-on-this/msg927556/#msg927556This motherboard is dead 100% or there is something that we can do to fix it.Power supply is tested and working properly, cpu, gpu everything works.When u plug power supply in, and try to turn on pc, nothing happens. Power supply also will not turn on (fans usually spins).So im assuming there is short circuit somewhere.Can someone guide me where to check first?

author: mrartuka
author_rank: Contributor
timestamp: August 05, 2016, 07:46:45 pm
content: UPDATE:i just check both motherboards side by side and found some wwird mosfet values.I dont know can this be caused by some other component on the motherboard or its mosfet fault only.There is 4 mosfets above pci-e slot - bellow northbridge or what is called - and next to ramp.Hopefully you can see those on pic.So long story short: every mosfet of those 3+1 shows me bigger value then on the working motherboard.Between 3 mosfet and mosfet on the side is small smd cap which is giving me direct short.I'm not sure are those mosfets for PCI voltage regulation or?Mosfets marked in red.Can anyone figure out for what are those ? So i can inspect further.

author: Refrigerator
author_rank: Super Contributor
timestamp: August 05, 2016, 09:21:42 pm
content: Tell us what's written on those MOSFETs.If they're shorted then you should replace them all, check for bad/bulging/leaking caps around the board.

author: mrartuka
author_rank: Contributor
timestamp: August 06, 2016, 07:45:01 am
content: Quote from: Refrigerator on August 05, 2016, 09:21:42 pmHere is mosfet details and picture which show values.You can see that smd cap which is shorted, also there is one smaller next to it, and it shows short on those also.Il get my working board out of pc and check again some values.NIKOSP1703BDGONASNOE04 (Not sure is it 0 or letter O)

author: Refrigerator
author_rank: Super Contributor
timestamp: August 06, 2016, 09:56:56 am
content: Yup, those MOSFETs are bad.Here's the PDF for it:http://www.cheertech.com.tw/Niko-sem/Data%20sheet%5CP1703BDG.pdfReplace all the shorted MOSFETs, with the same kind/spec part.

author: mrartuka
author_rank: Contributor
timestamp: August 08, 2016, 08:58:34 am
content: Quote from: Refrigerator on August 06, 2016, 09:56:56 amreplaced all 4 of those mosfets, and still there is someone else short -_- cant figure out where could it be.It seems this will be my first mobo to give up
[SOLVED] Stereo amp cracking and popping one channel only - Page 1
Forum section: electronics / repair

author: negativ3
author_rank: Regular Contributor
timestamp: August 06, 2016, 04:43:17 am
content: Hi all,I have a Creative Inspire T3130 2.1 channel amp connected to my Raspberry Pi running Openelec.The audio right channel audibly cracks and pops intermittently regardless of the volume setting (turned all the way down it still presents the problem).Left and sub channels work just fine.What in your opinion could be the cause? A lot of hot snot on the board is brittle and has just falls off at the slightest touch.Thanks all.

author: cncjerry
author_rank: Unknown
timestamp: August 06, 2016, 04:59:55 am
content: Inter-stage coupling cap if it uses them. Could be a poor/cold solder joint on the input side. Try moving the cables around and flexing the board a little. A little work with a scope should find it quickly.

author: jh15
author_rank: Frequent Contributor
timestamp: August 06, 2016, 05:10:51 am
content: noisy transistor too. Try some cooling spray. I think of 2sc 1458 memory maybe wrong of this, but was common.

author: cvanc
author_rank: Frequent Contributor
timestamp: August 06, 2016, 01:21:42 pm
content: Several questionable solder joints on the board...

author: voltz
author_rank: Frequent Contributor
timestamp: August 06, 2016, 09:27:39 pm
content: Quote from: cvanc on August 06, 2016, 01:21:42 pm+1 (and well spotted)And that is the Audio IC. Possibly explains the fault even with volume down. Re-solder all audio IC pins.If that still does not work, try tapping the PCB with insulated handle of a screwdriver and see if you can locate the area of the PCB that has biggest effect on the noise.If no effect, then could be an unstable component, try 'freeze it' spray and locate the component that way.

author: negativ3
author_rank: Regular Contributor
timestamp: August 07, 2016, 03:10:13 am
content: VERY well spotted cvanc. I will go over the whole board for good measure.Thanks all for the tips. Will determine the audio IC and get the datasheet as well in case the dry joints do not fix.

author: negativ3
author_rank: Regular Contributor
timestamp: August 07, 2016, 04:54:14 am
content: Re soldering those dry joints did the trick. Thanks all for your excellent contributions.
Dell U2412Mb dead (no lights at power button, no back light) - Page 1
Forum section: electronics / repair

author: twinsen
author_rank: Newbie
timestamp: August 06, 2016, 04:18:26 pm
content: Hi,My PSU board is almost the same ashttps://www.eevblog.com/forum/repair/dell-u2412m-schematics/except my board is labelled "4H.1GH02.A02".The first symptom:The back light and the light at the power button blinks altogether repeatedly (about 2 times a second). The screen and OSD seems to be okay. Signal from PC and OSD correctly displayed.After turned off for a few days:No sign of life. No lights at all at the power button. No back light. No OSD.I took it apart and checked the PSU board with power cable (no logic board and other cables connected). The HV part until the 4-leg diode bridge module BD601) is working. Nothing beyond that part seems to work. Not sure it's under protected mode by any shorted circuit or being without load.Couldn't find any schematics of the PSU on the net at all.Any ideas or suggestions to revive the unit?Regards,

author: singapol
author_rank: Frequent Contributor
timestamp: August 07, 2016, 03:17:46 am
content: Sorry no service manual to be found only user manual. It is obvious fron your description that either the mainpower supply or other auxilary power is dead.There are protection circuits of course so look for shorts of power transistor ,capacitor or diode.If all these are ok then check capacitors with esr meter. Google MESR100 version2 cheap and good esr meter.Mesr100V2 :ttps://www.youtube.com/watch?v=UWNVdfQcXrYwww.ebay.com/bhp/mesr-100
One battery fairy tale (repair of nV-meter FE). - Page 1
Forum section: electronics / repair

author: TiN
author_rank: Super Contributor
timestamp: August 04, 2016, 04:58:37 pm
content: Almost a year ago I traded one of my 2001's to182-M nV-meter.Used it for few experiments back then and had it sitting on the bench unpowered since then. Today got it back online, but was greeted by some jumping values on magnitude of few tens of mV.What happen?Perhaps 9V battery went poo? Yes this 182-M has battery inside, powering front end amplifier even when meter is OFF.Three screws, cover removed...Woohoo, self-destruction mode activatedReplaced it with new fresh 9V, put meter cover back in, turn on...All fine again. Will get some datalogs going, as 3458A is pretty useless for measuring 200 microVolts here..Destroyed bat still reads 7.5V btwEnd of story. Don't forget to replace those batteries inside instruments.

author: fire219
author_rank: Newbie
timestamp: August 06, 2016, 12:44:37 am
content: Now that's what I call bad design...
Agilent 6633B Repair. - Page 1
Forum section: electronics / repair

author: vaualbus
author_rank: Frequent Contributor
timestamp: August 06, 2016, 09:13:41 am
content: So I was luck and buy on ebay for 35$ (originnaly 50) a not working Agilent 6633b power supply.When it arrive I found that a resistor(R300) was missing and there was sign of burning. After changing the resistor I was not having high hopes of having a working psu.Anyway I power it on and apparently it works!.But there is a thing that could be wrong.The supply have 3 output pins. + - and gnd.So I suppose that if I set 20v i would get 20 between +/- and if I take the ground as reference I should get +10v and -10v.So I try it and it not working as I excpeted. I can get -10 between gnd and the - terminal but I get nothing between gnd and + terminal.It is normal and the ground is just the chassy ground or the supply have some problem I have to fix?Thanks, Alberto Vaudagna

author: Andy Watson
author_rank: Super Contributor
timestamp: August 06, 2016, 09:23:58 am
content: QuoteThere is only one output - which should measure 20V between + and -. The ground is there for convenience and the power supply output will be floating with respect to the ground.

author: vaualbus
author_rank: Frequent Contributor
timestamp: August 06, 2016, 09:43:41 am
content: a ok than it is working. Thanks.But anyways that resistor is getting very hot. it is a W resistor but it get very hot. (don't have a term camera but it burn if I touch it).I don't undestand what can cuase the resistor to be hot..

author: Kleinstein
author_rank: Super Contributor
timestamp: August 06, 2016, 12:42:26 pm
content: R300 is just for discharging the filter caps. So it's normal it dissipates quite some power - the supply would even work without it. It's more a safety thing, so it the caps will discharge for a possible repair / service. If it's too hot, one might consider a larger form factor or a slightly higher value.

author: vaualbus
author_rank: Frequent Contributor
timestamp: August 06, 2016, 01:33:12 pm
content: A ok thanks for the clarification
Please identify SOT23-3 marked ESBR - Page 1
Forum section: electronics / repair

author: albert22
author_rank: Regular Contributor
timestamp: August 04, 2016, 08:18:39 pm
content: I cannot find any info about this component. Please helpConnected as followsPin 1 - Pic16f818 RA2/AN2/VREFPin 2 - GND/VSSPin3 - Pic16f818 RA3/AN3/VREF+ and A77260 accelerometer VDD and /SLEEP and Cap to GNDDoes not seem to be a regulator or a voltage reference, perhaps a switch or mosfet. This device is powered by a CR2032 and it is very low power.Thanks

author: amyk
author_rank: Super Contributor
timestamp: August 05, 2016, 01:09:20 am
content: MCP112T-240E/LB

author: albert22
author_rank: Regular Contributor
timestamp: August 05, 2016, 02:41:02 pm
content: Thank you very much !!!Regards
Need help identifying these smds for repair - Page 1
Forum section: electronics / repair

author: zeeawk
author_rank: Contributor
timestamp: August 04, 2016, 02:59:35 pm
content: This board is out of a retron 5 game console.Two of the smds look like they got a bit toasty.I think the first three letters/numbers on this one are: CU5 ?https://drive.google.com/open?id=0B4LmKz1_fz3zeEdFWERfZ0VXOEp2SWc0dW1MZkVVOHd6UDdBhttps://drive.google.com/open?id=0B4LmKz1_fz3zVC1YN0lPOWJ2UUJYdEl0N1hzZ3B2M3NFbm5vThis higher res image I found on the web is the same board but I *think* they must have changed parts on it or mine.You can clearly see the numbers on them: C041FB and CU40BI'm not sure if those are zeros or letter Os.https://drive.google.com/open?id=0B4LmKz1_fz3zSHJNMkNSckl6SjgAny help is appreciated.Thanks,William

author: bktemp
author_rank: Super Contributor
timestamp: August 04, 2016, 03:45:52 pm
content: I couldn't find any part number using those marking codes, but from the location near the inductor it is clearly a synchonous stepdown regulator.

author: zeeawk
author_rank: Contributor
timestamp: August 04, 2016, 09:12:24 pm
content: Ya I tried several sites searching for them also and couldn't come up with anything.The connectors on the right side of the board in the last picture from top to bottom are:5v dc power plug, micro usb, reset switch, HDMI, sd card slot.

author: amyk
author_rank: Super Contributor
timestamp: August 05, 2016, 12:53:56 am
content: CUxxx =SY8009BCOxxx =SY6280

author: zeeawk
author_rank: Contributor
timestamp: August 05, 2016, 01:12:57 am
content: awesome I think this is just what i need!Looks like I have to get these from China but that gives me time to finish setting up my work bench.replacing these are going to be "interesting". I guess next step is to figure out if anything elseis wrong that caused them to blow. I'm hoping someone just plugged in the wrong power supply.
Fluke T5-600 - Page 1
Forum section: electronics / repair

author: kardacz
author_rank: Contributor
timestamp: August 01, 2016, 07:55:27 am
content: Hello; I possess a current clamp Fluke T5-600 whose batteries were cast. Opening it, I found that a voltage regulator SMD 5 feet was completely oxidized and not identifiable to its code ... Someone not you it's features? Thank you in advance for your help! (I attached photos)

author: kardacz
author_rank: Contributor
timestamp: August 01, 2016, 08:18:02 am
content: the picture

author: kardacz
author_rank: Contributor
timestamp: August 01, 2016, 04:15:39 pm
content: re; is it you a SMD family of controller: TPS .....?

author: kardacz
author_rank: Contributor
timestamp: August 04, 2016, 06:15:54 am
content: SNIFF!
VIDEO Tektronix 455 No Trace- Trace shows up when I put my hand on side of unit  - Page 1
Forum section: electronics / repair

author: MistaMun
author_rank: Contributor
timestamp: June 29, 2016, 07:05:48 pm
content: Hello! I found my problem today.https://youtu.be/4PLOMSEy2dgI turned on my Tektronix 455 and what do you know, I don't see neither of the traces anymore. Out of curiosity, I started to slap the side of the oscilloscope and found out that the traces were starting to cycle more I put my hand closer to the side of the unit.Has anybody else have faced this problem before? What is the problem and how can I fix it?Thanks!

author: tec5c
author_rank: Frequent Contributor
timestamp: July 03, 2016, 02:13:54 am
content: Have you had the cover off of the unit at all?My initial guess would be that the shielding on the cover is not making good contact. I could be wrong though.

author: Ray.B
author_rank: Contributor
timestamp: August 02, 2016, 08:25:26 am
content: I think the problem with the scope is the horizontal leads have come loose from the CRT.First unplug the scope from the wall, use a grounding strap to protect the electronic parts inside-like a computer uses.Undo the cover, using a quarter six places. remove the time base module, phillips screw next to CRT bulkhead, and the rear of the time base module phillips screw. Remove both, pull module up and remove. The horizontal leads are on the bottom of the CRT , 3/4 of the way back, attached to the main board. Using tweezers or needle noose pliers to push the leads gently onto the glass CRT, use very little pressure. Use the reverse reinstall procedure to put everything back together. If this doesn't fix it, it is on the horizontal module, probabily.This is the easiest solution. Ray B.

author: iXod
author_rank: Frequent Contributor
timestamp: August 03, 2016, 06:28:01 pm
content: Get good and experienced with left-handed probing?
Repairing a solar desulfating charger.... (unknown diodes) - Page 1
Forum section: electronics / repair

author: ja421
author_rank: Contributor
timestamp: July 31, 2016, 04:00:59 am
content: A friend asked me to look at his solar charger & we figured it would be something had burned up... well; it turns out it got wet and rusted a bunch of parts out -- the resistors were easy enough to identify (is there a way to tell how many watts a resistor is by it's diameter? The most like like 1/4w but one is 2.8mm in diameter..)The problem I have is identifying some diodes. I was able to get some marks off the diodes, but can't locate replacements...As you can see by the images, it's pretty rough; still need to pull some jumpers and a couple more resistors; but we got all the broken parts off....Marks on the broken diodes are "F41 48" which I could identify, but the other is labeled "5 C3" (or "C3 5")It's a 12v 15w charging system; any ideas if replacements are easily found or w/o schematics is it just a crap shoot & not worth it?

author: edavid
author_rank: Super Contributor
timestamp: July 31, 2016, 04:54:32 am
content: 5C3 is a 5.1V 500mW zener diode.

author: ja421
author_rank: Contributor
timestamp: July 31, 2016, 04:20:05 pm
content: Quote from: edavid on July 31, 2016, 04:54:32 amThank you.

author: CJay
author_rank: Super Contributor
timestamp: August 01, 2016, 12:24:27 pm
content: I'd take a wild stab in the dark and guess the 4148 diodes are 1N4148 (possibly the most common diode in the world?)

author: Enigma-man
author_rank: Regular Contributor
timestamp: August 03, 2016, 03:52:17 am
content: The resistor at the top of your pic is a 1/2 watt. If there were resistors smaller than the 1/4 wattthey would be 1/8 watt and going the other way 1 watt, 5 watt, etc.You might want to get some 99% Isopropyl Alcohol and Q-Tips to clean any residue from the top of the board.The diodes are likely 1N4148 as JClay mentioned and it won't set you back much to replace the diodes and resistors.If it still doesn't work, some of the transistors may have shorted out.

author: ja421
author_rank: Contributor
timestamp: August 03, 2016, 06:13:08 pm
content: Thanks. decided to give it a quick try. Going to solder in some diodes & resistors jut at the ends & see if it works. If it comes back to life, great, if not; I can easily salvage the parts. I have everything but the 5.1 .5w zener & the 1/2 watt resistor. I'll use a 5.1v zener & a 1/4 watt resistor to see if it powers on; if it doesn't; I'm most likely giving up on it. upon using a microscope, just about all the leads are really pitted/corroded, so it may be a fools errand in not replacing everything. At that point, I don't think it's worth the headache of re-tuning it w/o any info on how.I appreciate the help; I'll post if it the quick try was a success or not.
keyboard rubber thingy - Page 1
Forum section: electronics / repair

author: 10101
author_rank: Contributor
timestamp: August 03, 2016, 04:59:27 am
content: So i had a aproblem in which the bluetooth keyboard of my tablet would randomly start clicking the letter "m" indefinitely.I removed the key and the rubber thingy under it was damaged so I've put a bit of super glue and works well again but it made the clicking a bit more stiff.So my questions are what's the correct name for the rubber thingy and were can i get a replacement ?

author: helius
author_rank: Super Contributor
timestamp: August 03, 2016, 06:36:02 am
content: There are two basic types of key switches that include rubber sheets like that.In the more common type, the actual switch is formed between two mylar flexible printed circuits with a spacer sheet between them. This is the most common "membrane keyboard" design. The spacer has holes cut in each key position, so when a key is pressed the two circuits can make contact through the hole. The rubber membrane is just a protective cover that has domes molded in it to provide a semi-tactile response.The other type actually uses the rubber domes as part of the switches, by impregnating them with carbon particles. When the domes are pushed in they make contact across two () shaped circuit pads, on either mylar FPC, or regular FR4 PCB. That type is more common on remote controls and other low-duty cycle devices and is much less repairable. Kits exist to replenish the conductive coating on the rubber, but that is only a temporary fix.
WaveSurfer 454 repair saga part 2 - Page 1
Forum section: electronics / repair

author: vaualbus
author_rank: Frequent Contributor
timestamp: May 08, 2016, 09:49:59 am
content: So after a while I was able to repair the power supply of the lecroy wavesurfer 454 that a find a while ago in a trash at my university.Now I have a big problem though, the hardisk is missed.So as far as I understand i can install windows xp on different hard disk but when I will go to install the lecroy software it will fail because I don't have the cal data that are store in a partition of the original hard disk.There is some here that can make a backup of cal data? Or there is a way of restore default "factory" cal data? Or there is a way to calibrate the scope?On the other hand some have the restore cd that is mentioned in the service manual?

author: vaualbus
author_rank: Frequent Contributor
timestamp: July 09, 2016, 12:59:11 pm
content: No progressi since this post.Anyone have some idea?

author: McRoy
author_rank: Newbie
timestamp: July 13, 2016, 09:06:09 pm
content: Try contact LeCroy service department?

author: vaualbus
author_rank: Frequent Contributor
timestamp: July 31, 2016, 08:40:26 am
content: Ya i, but i hearth that lecroy is very unpolite in giving information/schematics to the people.I wish that Simeone here or in lecroy Yahoo Group to help me!

author: Jwalling
author_rank: Unknown
timestamp: July 31, 2016, 09:50:18 am
content: Quote from: vaualbus on July 31, 2016, 08:40:26 amHave you tried asking on the Yahoo group?Jay

author: vaualbus
author_rank: Frequent Contributor
timestamp: July 31, 2016, 09:28:29 pm
content: Ya, bu no answer what's so ever

author: Ice-Tea
author_rank: Super Contributor
timestamp: August 01, 2016, 11:39:01 am
content: Paging Dr.Wuerschthund, paging Dr.Wuersthund...

author: vaualbus
author_rank: Frequent Contributor
timestamp: August 01, 2016, 11:25:04 pm
content: Quote from: Ice-Tea on August 01, 2016, 11:39:01 amWhat do you mean, i don't understant!

author: iXod
author_rank: Frequent Contributor
timestamp: August 02, 2016, 02:59:21 pm
content: Quote from: Ice-Tea on August 01, 2016, 11:39:01 am?? Google comes up empty...

author: Ice-Tea
author_rank: Super Contributor
timestamp: August 02, 2016, 04:43:48 pm
content: Wuerstchenhund is a member here that knows vis LeCroy

author: vaualbus
author_rank: Frequent Contributor
timestamp: August 03, 2016, 06:43:13 am
content: A ok.
Kelvin Varley will not balance - Page 1
Forum section: electronics / repair

author: kkayser
author_rank: Contributor
timestamp: August 02, 2016, 12:31:15 am
content: I have a Fluke Kelvin Varley that will not balance on 3 positions of the "A" decade. When I attempt to get a null, the voltage changes but gets nowhere near zero at any setting of the pot. We pulled one pot, and it is ok. All three positions demonstrate the same malfunction. I figure it is a resistor or connection, likely the same on all 3 positions. Since all three positions have failed in the same manner, it could be a weak spot in the design or manufacture. The 3 positions that cannot be nulled are as accurate as any other position: 1ppm measured with a 732B and 3458A. There are a few positions on the entire divider that are over 1ppmDoes anyone have any ideas where I might look for the problem?

author: Bill158
author_rank: Regular Contributor
timestamp: August 02, 2016, 04:56:41 pm
content: Quote from: kkayser on August 02, 2016, 12:31:15 amTry following this thread from the "volt-nuts" forum.https://www.febo.com/pipermail/volt-nuts/2015-September/004477.htmlThe resistors in the oil bath are well matched for temperature coefficents, but not for absolute values. This is why there are "factory selected" trim resistors in the adjustment circuits. As explained in this thread the resistors in the oil bath can drift and some have experienced this drift.Bill
Computer repair simulator , The revolutionary teaching tool  - Page 1
Forum section: electronics / repair

author: CRSMK
author_rank: Newbie
timestamp: August 02, 2016, 02:49:55 pm
content: Hello!My name is Euthimis and i am developing a really useful program that can help newcomers to computer and electronics reparis! It is called "Computer Repair Simulator" . Essentially it is an interactive guide on (for now at least) repairing computers and computer hardware . A demo will be released soon for Windows . If you want to find out more check out our development blog athttp://computer-repair-simulator.com/
Should I try and replace this SMD capacitor? - Page 1
Forum section: electronics / repair

author: mzry
author_rank: Newbie
timestamp: August 01, 2016, 11:40:41 am
content: Heya,I have an Arcam Rdac and while poking around inside I noticed one of the surface mounted capacitors has either disintegrated or blipped out of existence. The capacitor in question is C406 and in this service manual you can see what it does:HereMy electronics theory knowledge isn't good enough to tell if this is a serious issue or not, I'm kind of hoping someone is kind enough to lend me some adviceThe unit seems to be functioning OK, except sometimes it randomly will reset itself...Here is a really bad blurry photo if it helps:Image

author: Rerouter
author_rank: Super Contributor
timestamp: August 01, 2016, 11:44:57 am
content: The fact the regulator pin is burnt and the capacitor is popped would have me making sure the regulator output is not shorted and that the input protection is still intact.I would say if you have no short you should replace the regulator and the cap at the same time,Stuff like this is not that hard, for the regulator flow a nice blob of solder onto the top tab and wait a bit and the other putns should reflow from the conducted heat.

author: tatus1969
author_rank: Super Contributor
timestamp: August 01, 2016, 02:01:37 pm
content: to me it looks like that pin on the regulator REG401 is just covered with tin. Would you say that it is burned or tinned?The LM1117 has output short and overtemp protections, and is very robust. Check the output voltage, must be 3.3V.The device will probably work also with C406 broken. Quickly browsed the circuit diagram, +3V3 supplies the digital part, and they have 100nF local bypass caps all around the place.

author: mzry
author_rank: Newbie
timestamp: August 02, 2016, 12:38:00 am
content: Thanks for the replies, yes the regulator is covered with tin. Looks like it was resoldered. What I was thinking is that if it's not too much of an issue I might leave it, because I don't have the tools required to do such fine soldering. I could attempt it but I'm just worried about stuffing it upIf it was a big deal I'd pay a professional to do it I think.

author: CJay
author_rank: Super Contributor
timestamp: August 02, 2016, 09:53:16 am
content: Given the general crispy looking nature of the regulator pin I'd expect the track underneath to lift really easily, which leaves you with the problem of repairing the potential PCB damage (should be simple with the right tools and a steady hand)I'd definitely check the output voltage of that regulator though, it's the ground pin that's burned so it may be somewhat higher than it should be.

author: tatus1969
author_rank: Super Contributor
timestamp: August 02, 2016, 10:36:21 am
content: If the unit is working, leave it as it is. The supply is a bit overengineered anyway, it will still be rock stable with the remaining bulk capacitance.
USB A port high resistance - Page 1
Forum section: electronics / repair

author: oliver602
author_rank: Regular Contributor
timestamp: July 31, 2016, 08:20:26 pm
content: I seam to be plagued with crappy USB chargers or cables. The connection seams to go flaky at the USB A connector at the usb charger. Wiggling the cable or propping it up at an angle is usually a temporary fix.Is this a common issue?Any advice for purchasing cables and replacement connectors?Thanks

author: electr_peter
author_rank: Unknown
timestamp: August 01, 2016, 05:05:18 pm
content: Some USB plugs and sockets are very low quality, especially sockets. They are too loose. Sometimes solder joints or inside cables break.Higher quality ones always seems to be a bit tighter.I suggest to test with known good cables and throw away bad ones. Buy new USB socket/cable and replace. This means de-soldering/re-soldering, but USB A/B cables, sockets and plugs are easy enough repair (4-5 cables at most).

author: Jeroen3
author_rank: Super Contributor
timestamp: August 01, 2016, 05:34:42 pm
content: Quote from: oliver602 on July 31, 2016, 08:20:26 pmBuy proper ones. Not 5$ supermarket c**p.

author: electr_peter
author_rank: Unknown
timestamp: August 01, 2016, 06:23:45 pm
content: Another tip - if you see a good USB cable for a decent price, buy at least few so you won't need to constantly search for them. You will probably lose some cables here and here, some will be stolen/borrowed/etc. so having few extras does not hurt.Same goes with all types of connectors, including the newest USB C form factor. Cheap USB C cables are worthless - one can read reviews online.

author: SeanB
author_rank: Super Contributor
timestamp: August 01, 2016, 06:30:10 pm
content: If you can get genuine Nokia or Samsung USB cables, they are a lot better quality wise. You can even buy the genuine parts ( at a price) from most large cellular retailers.

author: wraper
author_rank: Unknown
timestamp: August 01, 2016, 06:53:10 pm
content: Cheap/fake USB cables have hair thin strands in the power wires. Also they completely lack any king of shielding. No chance to charge at more than 500mA current with them, voltage will drop ridiculously low at the other end.

author: oliver602
author_rank: Regular Contributor
timestamp: August 02, 2016, 12:50:46 am
content: Thanks everyone.I purchased 3 Amazon basics branded chargers in the past, had to return 2 because they were bad out of the box. After that I purchased some from CPC Farnell in the UK a couple months ago and one of them is on the fritz already. They had a recall on those too because of insufficient adhesive holding the cover closed. I'll have to step it up.

author: Monkeh
author_rank: Super Contributor
timestamp: August 02, 2016, 01:33:31 am
content: Full size USB connectors are not rated for large cycle counts. Don't keep disconnecting them. I'm running out of ports on my desktop hubs, it's a pain.Micro-USB is much better suited.
FLUKE 175 - Page 1
Forum section: electronics / repair

author: kardacz
author_rank: Contributor
timestamp: July 29, 2016, 08:28:48 am
content: Hello; I research the characteristics of a voltage regulator mounted on the board of a FLUKE 175; it is a SMD component to 5 legs, with the marking on the housing: PCY1. Somebody could you help me? Thank you very much!

author: kardacz
author_rank: Contributor
timestamp: July 29, 2016, 03:20:15 pm
content: help!

author: Monkeh
author_rank: Super Contributor
timestamp: July 29, 2016, 03:28:35 pm
content: Quote from: kardacz on July 29, 2016, 03:20:15 pmPatience is a virtue.It's a TPS77050. The ability to distinguish between a 1 and an I helps here.

author: kardacz
author_rank: Contributor
timestamp: July 29, 2016, 03:41:33 pm
content: I am patient, that's why I asked for help! Thank you for your prompt response.....

author: Monkeh
author_rank: Super Contributor
timestamp: July 29, 2016, 06:11:02 pm
content: That's why you waited not even seven hours for an answer..

author: kardacz
author_rank: Contributor
timestamp: August 01, 2016, 07:46:02 am
content: Hello; I'm in France, not in Australia or the United States ......

author: Monkeh
author_rank: Super Contributor
timestamp: August 01, 2016, 11:33:42 am
content: .. what does that have to do with anything?
2n3251a Compliment - Page 1
Forum section: electronics / repair

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: August 09, 2016, 07:50:09 am
content: Anyone know the compliment of the 2n3251A?I need a TO-18 package.Thanks.

author: setq
author_rank: Frequent Contributor
timestamp: August 09, 2016, 07:58:50 am
content: Looks like germanium. There may not be a complementary NPN for it.

author: SeanB
author_rank: Super Contributor
timestamp: August 09, 2016, 09:26:38 am
content: 2N2484, providing you do not need the 200mA current rating. If you do not need the 60V rating the common 2N2222 will work as well if you can live with 40VAny reason you need the metal TO18 can, there are better choices in TO92 package, like C1815 or 2N5401 for example.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: August 09, 2016, 05:35:59 pm
content: Thanks. I think I will go with the 2n2222a in the metal can. I am looking for a metal can because I am repairing an IEC F34 sig gen.https://www.eevblog.com/forum/repair/damaged-my-iec-f34-really-dumb-mistake/Specifically Q17 here. I have the other original parts for Q18, Q19, and Q20 on the way.I put in TO-92 case transistors (2n2222 and 2n2907) and they are getting quite hot (92 deg C for Q19 and Q20).The original BJTs were metal can packages, and they had these nice round heat sinks that slide on the can. I figure going with the same package would be best, as I can use those heat sinks. The thing has no fan.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 10, 2016, 06:03:22 pm
content: Normally the 2N2222 is TO18 - the TO92 version has a slightly different name, like PN2222.There is also the slightly larger TO-39 case with the same chip, as 2N2219.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: August 10, 2016, 06:32:04 pm
content: Thanks for the reply. I am sorting these out in the repair thread.https://www.eevblog.com/forum/repair/damaged-my-iec-f34-really-dumb-mistake/
How to restore corroded galvanized chassis while maintaining conductivity? - Page 1
Forum section: electronics / repair

author: eltopo
author_rank: Newbie
timestamp: August 01, 2016, 01:19:14 am
content: Hi all,I made the mistake of storing a piece of equipment in a garage without adequate protection (should have at least wrapped it in a plastic bag); picked it up a year later to discover rust/corrosion from a mysterious water source which apparently dripped out of the ceiling.Fortunately, there was no significant water damage, apart from corrosion along one edge of a galvanized steel chassis (this happened at the bottom of the unit to which any dripping water would have flowed). I removed the rust easily with abrasive pads and tools, but the galvanized coating is now gone from that edge.As it happens, the chassis is designed to make an electrical contact to a rectangular EMI shield along all 4 sides- so to me, that rules out painting over the chassis edge to cover up the raw steel.What would be the best restorative option? (to cover the exposed steel edge and prevent future corrosion, while maintaining electrical conductivity) I've looked up various conductive paints (brush-on nickel coatings, etc), though they seem to be typically intended to adhere to plastics and I'm unsure whether such a coating would be low resistance to the underlying steel surface.The actual surface requiring repair (corroded edge) is relatively small, approximately 5mm wide by 20cm long (the width of the bottom edge of the chassis). Will upload a picture in a bit once I find a USB cable... thanks in advance!

author: tautech
author_rank: Super Contributor
timestamp: August 01, 2016, 01:40:34 am
content: For touch ups something like CRC Zinc It should do the job well.I get a few years exterior protection of repairs to galvanised steels in our damp NZ climate.http://crcindustries.com/ei/product_detail.aspx?id=18412The datasheet doesn't mention conductivity but an email to CRC should clear that up.IIRC there is little resistance to striking an arc with a welder unlike normal paints.