hybridfree/eevblog-posts huggingface dataset:
resistor over cappacitors - Page 1
Forum section: electronics / repair

author: spdf
author_rank: Contributor
timestamp: July 20, 2017, 11:06:53 am
content: Hello guys, recently I've disassembled old faulty amp and I found on one side a small value resistor acros caps. What is the purpose of this resistor? Is it originally from manufacturer or it was repaired somehow?I have attached a photo of a board.

author: Rerouter
author_rank: Super Contributor
timestamp: July 20, 2017, 11:24:37 am
content: without knowing where it sits in the circuit its hard to say, however the solder colour is the same as the surrounding components, meaning its likely a factory bodge component,up to the early 00's it was somewhat common to see bodge components, where they span there first batch, found under testing or heard back from the early adopters that there was something not quite right, and rather than paying new tooling for a board respin they just added a note for the assemblers to fit that component there.

author: Gyro
author_rank: Super Contributor
timestamp: July 20, 2017, 03:25:49 pm
content: The end of the orange wire is broken.

author: TransistorMan
author_rank: Contributor
timestamp: July 20, 2017, 10:25:03 pm
content: What is exact value of resistor?If that capacitor is used for supply voltage filtering, then it's most likely bleeder resistor, and its purpose is to discharge capacitor after amplifier is turned off.If it's bleeder resistor, it's value should be something like 220-1000 ohms (just my approximation)

author: cncjerry
author_rank: Unknown
timestamp: July 21, 2017, 03:49:04 am
content: I can't tell from the picture, but in cases where you stacked capacitors to hit a higher voltage, you used a resistive divider network to keep the voltage across each capacitor the same (balanced). For instance, if you had 120v you wanted to filter with three, 40V capacitors, you would put three 10k resistors (or a lower value) across each cap in series. This isn't used that often except in much higher voltage supplies. Lower voltage supplies used a resistor as a bleeder to drain down the capacitors when the power is turned off.Jerry

author: spdf
author_rank: Contributor
timestamp: July 21, 2017, 08:24:52 am
content: yo guys, I found it in the schematics
What happened to my alpha lcd ? - Page 1
Forum section: electronics / repair

author: tablatronix
author_rank: Regular Contributor
timestamp: July 20, 2017, 06:14:41 pm
content: anyone ever see this before ?I had this on a shelf to to salvage, cause it was in new condition.Pulled it down to desolder, and it is had artifacts on the sceen, looks like its leaking or growing..

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 20, 2017, 07:37:32 pm
content: Yes there's been a few topics about this in the past. I think the general opinion was that it is some kind of mold.
Datasheet for Lambda Voltage Regulator - Page 1
Forum section: electronics / repair

author: CHexclaim
author_rank: Regular Contributor
timestamp: April 20, 2015, 04:12:08 am
content: HelloI need the datasheet or any information which would help me find the datasheet of a Lambda Power Hybrid Voltage Regulator Part No: FBH-24-024Thank you very much!

author: macboy
author_rank: Super Contributor
timestamp: April 21, 2015, 11:18:32 pm
content: FBH-24-024 sounds like a part number as used in one of their supplies. They also sold the semiconductors or modules, and these had different part numbers even though they are the same thing. For example, my LQD series supply uses a pair of FBT-00-128 which are a.k.a. LAS3700. I don't have a way to cross-reference them, but you may find what you need inthis old Lambda semiconductor catalog. They call it a catalog but it is basically a Data Book. Look at LAS 2000 and higher starting page 53.

author: CHexclaim
author_rank: Regular Contributor
timestamp: April 22, 2015, 01:19:56 am
content: Thank you very much!Yes, it seems to be one of these you mention, but with less pins. I am currently investigating but it seems that the missing pins are internally connected to make it a fixed voltage regulator.By the way, from where did you take this info from? I couldn't find anything similar on the net.Thanks again, regards, CH!

author: macboy
author_rank: Super Contributor
timestamp: April 22, 2015, 01:04:00 pm
content: Some information fromthis other thread. That user posted a datasheet for the LAS3700/FBT-00-128 device. It includes both part numbers, which is how I know about the dual numbering scheme. I don't know where he obtained that datasheet. The catalog can be found by googling "LAS3700 datasheet", just a few hits from the top. It's too bad that the catalog doesn't include the in-house part numbers.Did you see the 4-pin connection diagram on page 55?

author: CHexclaim
author_rank: Regular Contributor
timestamp: April 22, 2015, 09:17:29 pm
content: Thank you for the additional info.Yes, I am around page 55 to derive the correct connections before powering. I believe that the module I have connects input, output and voltage sense lines. Other connections seems to be internal.Regards, Charlie.

author: Johnny10
author_rank: Frequent Contributor
timestamp: July 25, 2017, 02:35:57 pm
content: Old thread I realize...Does anyone still have link to (this old Lambda semiconductor catalog) found in a post in this thread?ThanksLooking for Lambda IC cross references.

author: alm
author_rank: Super Contributor
timestamp: July 25, 2017, 02:52:27 pm
content: Just replace eab1 with eab2:http://electronicsandbooks.com/eab2/manual/Electronic%20Component%20Databook%20Datasheet/Brand/Lambda%20semiconductors/Databook/1982%20Lambda%20Semiconductor%20catalog%20c20121221%20%5B98%5D.pdf
Best quality rotary encoder w/Sw replacement for Rigol DS4024 Oscilloscope - Page 1
Forum section: electronics / repair

author: Paul Price
author_rank: Super Contributor
timestamp: July 17, 2017, 01:02:19 pm
content: Where can I buy a quality replacement for the Rigol DS4024 Oscillocope rotary encoders with swith?

author: ivi_yak
author_rank: Regular Contributor
timestamp: July 20, 2017, 06:14:32 pm
content: hi, BOURNS is high quality encodershttp://www.newark.com/w/c/sensors-transducers/encoders/prl/results?st=encoder
[FIXED] zebra gc420d firmware - Page 1
Forum section: electronics / repair

author: Samogon
author_rank: Frequent Contributor
timestamp: July 16, 2017, 02:06:25 am
content: Hi,Does anyone has latest firmware for the printer? I cant download it form Zebra web site. I think it requires account with them, which i fail to establish.

author: Samogon
author_rank: Frequent Contributor
timestamp: July 19, 2017, 08:47:43 pm
content: Stupid meI thought that label format is hard coded into printer FW, since previous owner had UPS labels in it.I just needed to perform media calibration for non UPS shipping labels duh!
[SOLVED] Help to identify component - Page 1
Forum section: electronics / repair

author: Erwin Ried
author_rank: Regular Contributor
timestamp: July 04, 2017, 09:59:53 pm
content: Hello, I was testing some boards on my msi laptop and I made some magic smoke appear from one of the usb 3 ports. With the smell and everything. The port is dead now. I can see a crack in a 8 pin chip that is near the dead portcan anyone tell me if this is an standard part for (I think manages usb3 power) similar boards? Can I exchange it for one from a usb 3 cheap hub?Thanks!

author: Falcon69
author_rank: Super Contributor
timestamp: July 04, 2017, 10:05:47 pm
content: next to USB inputs, My guess maybe TVS Diodes?

author: Erwin Ried
author_rank: Regular Contributor
timestamp: July 04, 2017, 11:04:12 pm
content: Nice keywordso... Do I check which pin correspond to the usb port and replace it for a similar diode based on the Pinout? I am guessing there is 8 pins for 4 pairs of vcc d+ d- gnd

author: Armadillo
author_rank: Super Contributor
timestamp: July 04, 2017, 11:48:54 pm
content: Likely a distribution switch. See datasheet

author: Erwin Ried
author_rank: Regular Contributor
timestamp: July 05, 2017, 06:15:21 am
content: Quote from: blueskull on July 05, 2017, 12:54:21 amCan you sell me your broken board? This is the same pcQuote from: Armadillo on July 04, 2017, 11:48:54 pmMmm I have to check the position of gnd, sounds feasible too

author: Erwin Ried
author_rank: Regular Contributor
timestamp: July 19, 2017, 01:41:27 pm
content: Just to close the case, I fixed it with asimilarchip.Quote from: Armadillo on July 04, 2017, 11:48:54 pmYou are correct, it was that. I found a TPS2069http://www.ti.com/product/TPS2069in a broken lenovo pc and the pinout matched, so I replaced it and my laptop is fully operational againThanks for the hints, they were really helpful

author: Armadillo
author_rank: Super Contributor
timestamp: July 19, 2017, 03:09:18 pm
content: Congrats!, now that is what I call innovative approach.And you are very kind to the donor board, so many kapton tapes applied for the extraction of 1 IC.Is that a pin to pin compatible, how come the jumper wires are not visible?

author: Erwin Ried
author_rank: Regular Contributor
timestamp: July 19, 2017, 06:38:35 pm
content: Thanks. Yeah, I might need more pieces from that donor boardWhich jumper wires? From my drawing? they are connected inside the chip (to handle more current?... I guess)
Calculator Screen Scratches: Polish - Page 1
Forum section: electronics / repair

author: BurnedResistor
author_rank: Regular Contributor
timestamp: July 18, 2017, 04:28:00 pm
content: Hey All,For school I own a ti nspire cx, and for the longest time it has had four small (2-3mm long) scratches towards the bottom middle of the plastic screen.I know I am being stupid, but they really annoy me as they break up light of the screen. Is there any hope in polishing them out? Or am I only more likely to ruin the screen?If this is doable, what should I look for? Some kind of plastic polish? Most products I can find are car-headlight polish. Would that work?

author: RoGeorge
author_rank: Super Contributor
timestamp: July 18, 2017, 04:54:38 pm
content: Toothpaste is slightly abrasive. Take a soft piece of cloth, or even a paper napkin, put some toothpaste on it, and go Polish!

author: alm
author_rank: Super Contributor
timestamp: July 18, 2017, 05:22:54 pm
content: I have used plastic polish designed for helmet visors on plastic display lenses (Plasticx or something similar). You should probably start by sanding (I used wet sanding), start with 400 grit and end somewhere beyond 1000 grit. Then polish the small scratches left with the fine sand paper with plastic polish. My experience with toothpaste is that it works much slower than 'real' plastic polish.

author: Gyro
author_rank: Super Contributor
timestamp: July 18, 2017, 05:23:53 pm
content: Yes, the finest abrasive poilsh I know of is toothpaste. Make sure it's one that doesn't taste gritty. It might not be abrasive enough to remove significant scratches but on the other hand it's unlikely to do any harm.Make sure you mask off the display area carefully and be careful of any screen printing.

author: BBBbbb
author_rank: Unknown
timestamp: July 18, 2017, 05:54:39 pm
content: Maybe something like this. Haven't tried it, but it looks like it's worth a try:http://www.ebay.com/itm/Polywatch-Watch-Plastic-Acrylic-Watch-Glass-Polish-Scratch-Remover-5g-/262937342142?hash=item3d384970be:g:62IAAOSwj25Y8RxY

author: electr_peter
author_rank: Unknown
timestamp: July 18, 2017, 06:00:32 pm
content: Check some useful info about plastic scratch repair for DMMs and calculatorshttp://mrmodemhead.com/blog/dirty-multimeter-clean-up/

author: BurnedResistor
author_rank: Regular Contributor
timestamp: July 18, 2017, 06:27:54 pm
content: Quote from: RoGeorge on July 18, 2017, 04:54:38 pmQuote from: Gyro on July 18, 2017, 05:23:53 pmI have tried the toothpaste with a cootton pad. Did not do much so I came to ask here. I am slightly hesitant about taking it to the sand paper, but if I just walk up the grits to finer and finer I should be fine?What kind of plastic polish have you guys used?
lambda LLS6120 Power Supply IC needed - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: July 17, 2017, 03:27:01 pm
content: Hi folks,I am trying to repair this power supply.I could find the instruction manual with schematics in the internet.The primary side is not oscillating. After some checks and following the trouble shooting procedure described in the manual I could find that Q102 was opened.Fortunately I had the replacement in my junkbok (an IRF840 ) but that did not solved the problem and no oscillation at all.After checking Q103 (BUZ71), which was OK, the manual points to IC 101, where my problems begins.This is a custom IC marked FBT00-116.I checked the link on this blog that mentioned a Lambda catalog, but unfortunately the link is broken.Does anyone have a copy of this reference or any idea of where I could by this part or an replacement?Thank you all,Roger

author: orbanp
author_rank: Regular Contributor
timestamp: July 17, 2017, 11:37:37 pm
content: Hi Roger,You did not give the correct schematics! All the ICs are denoted IC2xx!I downloaded the manual for the LLS6000 series regulated PSs.Generally Lambda did not make their own ICs, just relabeled commercial ones.It is also possible that they selected the ICs.However, this IC indeed looks like a custom chip, as the pin-out is non standard!Assuming that I am looking at the correct schematics, IC101 is a quad op-amp, but with that non-standard pin-out.It is running from 15V, assuming the note is correct on the schematics.I would take the old IC out, put in a socket, and wire in a "regular" quad op-amp, like an LM324.You could also check out the old IC once it is out, test if they behave like op-amps.If you know the resistor values in the circuit around those op-amps (I did not find any parts list) then you could decide if it needs a FET input op-amp or not.Good luck, Peter

author: duak
author_rank: Super Contributor
timestamp: July 18, 2017, 04:12:32 pm
content: G'day Roger,I was thinking that I'd seen that IC footprint somewhere before. I believe it is an LM339 quad comparator. It makes sense because it looks as if the chip is generating switcher control pulses, probably above 20 KHz and that most of the outputs are pulled up to Vcc since the LM339 is open collector.Best o' luckDuane

author: rodd
author_rank: Regular Contributor
timestamp: July 18, 2017, 06:03:22 pm
content: Hi Peter,Thank you for your comments.There are two pages on the attachment, and the primary side is on the 2nd page - sorry for that.There is no parts list in the version I downloaded also.The resistors values around IC101 are:R116- 10KR117- 14KR118- 5.6KR120- 470kR121- 15KR128- 470KCan you help me to choose the op amp to try?Thank you again,Roger

author: rodd
author_rank: Regular Contributor
timestamp: July 18, 2017, 06:07:15 pm
content: Hi folks,I am sorry for my post.I should have read the answer from Duak before.I think I would try it and post the results as soon as I get them.Thanks to you all,Roger
relay cleaning - Page 1
Forum section: electronics / repair

author: spdf
author_rank: Contributor
timestamp: July 16, 2017, 06:23:39 pm
content: Hi,is there any way to clean this relay?

author: Jeroen3
author_rank: Super Contributor
timestamp: July 16, 2017, 06:49:27 pm
content: Those are sealed relays. Opening them is destructive. So no.

author: EPTech
author_rank: Regular Contributor
timestamp: July 17, 2017, 05:38:45 pm
content: There is an unorthodox way of 'cleaning' them. You could try sparking them. Have the relay switch repetitively, on a function generator for instance and have it switch an inductive load, like another relay, depending on the contact current capacity. Let it spark for a an hour at 1s interval.This is more of a last resort, really. Buy new ones is my advice.It looks like they are general purpose relays. They are often mechanically sealed but not hermetically. Real signal relays are hermetically sealed or even filled with an inert gas. You can tell by looking at the bottom. Hermetically sealed signal relays will look potted.Happy sparking.

author: LabSpokane
author_rank: Super Contributor
timestamp: July 17, 2017, 10:27:26 pm
content: Don't clean/fix unless you absolutely cannot replace it. Once the contacts get worn, all fixes are temporary at best.

author: spdf
author_rank: Contributor
timestamp: July 18, 2017, 09:51:13 am
content: Bought a new one!Thanks for help!
Racal Dana 1992 Frequency Counter Repair - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: July 18, 2017, 08:39:40 am
content: This counter had a fault with input A, it didn't work, input B and C worked fine, this shows my diagnosis and repair of the fault.https://youtu.be/-oI1lA1-_bM
Agilent E3641A repair - Page 1
Forum section: electronics / repair

author: feedback.loop
author_rank: Frequent Contributor
timestamp: July 22, 2017, 09:23:57 pm
content: This power supply had non-functioning front panel (display, keypad and encoder). It turned out that three chips were dead in the front panel module: Intel 80C51 micro-controller, HV518PJ VFD driver and 74HC02 quad NOR gate. Fixing this took quite a bit of SMD and through-hole rework, and quite a bit of luck, especially finding the firmware for the micro-controller.https://youtu.be/E3F59nj6FhoReplacement parts on DigiKey:AT89S51:https://www.digikey.com/product-detail/en/AT89S51-24JU/AT89S51-24JU-ND/1118890HV518PGhttps://www.digikey.com/product-detail/en/HV518PJ-G/HV518PJ-G-ND/4902550Firmware 34401-88804 rev01:http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent/Agilent_34401A_E3646A_Display_board_MCU_firmware_dump_EPROM_34401-88804_RE-34401-88804.zip34401A multimeter service guide with display and keyboard schematic :http://literature.cdn.keysight.com/litweb/pdf/34401-90013.pdf

author: HighVoltage
author_rank: Super Contributor
timestamp: July 22, 2017, 09:46:42 pm
content: I have repaired a few of these power supplies in the past but compared to the problems you ran in to, my repairs were trivial.Thanks for another great repair video.

author: Armadillo
author_rank: Super Contributor
timestamp: July 22, 2017, 10:07:36 pm
content: Great repair video with multiple faulty devices and thermal imaging camera and fluke 97 throw in.Wonder what causes the string of failed devices including the CPU. Run over by a train or strike by lightning?Lucky firmware and schematic are at hand.

author: glarsson
author_rank: Frequent Contributor
timestamp: July 22, 2017, 10:45:13 pm
content: Quote from: Armadillo on July 22, 2017, 10:07:36 pmThe HV518 probably failed and shorted Vpp (up to 90V) to Vdd (5V). Vpp (pin 1) and Vdd (pin 44) are next to each other ...

author: bitseeker
author_rank: Super Contributor
timestamp: July 22, 2017, 11:53:42 pm
content: Great job on another repair. This one was more extensive than HP supplies I've worked on. Always enjoyable to learn new things about fixing them.
HP 4815A Vector Impedance Meter - Page 1
Forum section: electronics / repair

author: johnny_canuck
author_rank: Contributor
timestamp: July 15, 2017, 01:02:20 pm
content: This device performs well except for an intermittent SEARCHING light coming on.I've fed in an external oscillator signal, but get the same result. The PLL circuitry is the problem.I've reseated cards and reheated solder joints without success. Anyone had any experience with these oldies? Thanks.Ken

author: cncjerry
author_rank: Unknown
timestamp: July 17, 2017, 03:44:19 am
content: I have two, one for parts. The unlock troubleshooting is detailed in the service manual.I love mine but it has failed several times. Luckily having the parts unit bailed me out but I am running out of functional cards. The reliability isn't up to the usual HP standards for some reason. In checking the failed cards all of the passive components check out fine so I suspect there are leaky FETs.
Need to identify a component - Page 1
Forum section: electronics / repair

author: sdadsp
author_rank: Newbie
timestamp: July 14, 2017, 07:06:55 am
content: Hi and good day!Does anybody know what the component (SO-8 package) has a "TFT 3M0033" marking on its package (a photo is attached) ?For a first approach, it may be a precision resistors network - the component is installed in the wheatstone bridge measurement unit. But I could not find it in any catalogue...Thanks in advance!

author: Armadillo
author_rank: Super Contributor
timestamp: July 14, 2017, 09:30:24 am
content: Could be an instrumentation amplifier. Is it connected to any balanced power supply? Trace the pins. Example trace Pin 7 and Pin 4.

author: EPTech
author_rank: Regular Contributor
timestamp: July 14, 2017, 11:24:06 am
content: May something from Thin Film Technology corporation. I think they fall under Vishay these days, not sure.

author: sdadsp
author_rank: Newbie
timestamp: July 17, 2017, 02:22:42 am
content: Thank you, guys.This IC is a passive component: it is not powered, but it's installed in the signal chain. Checking with a ohm-meter showed that a resistor matrix inside (seems, it is a custom layout Thin Film Technology product).
Graphic Card gtx 970 Zotac, error 43, please help me. - Page 1
Forum section: electronics / repair

author: Netcrusher
author_rank: Newbie
timestamp: July 16, 2017, 11:42:24 am
content: My Graphic card today starts with the basic windows resolution 800x600 (normally full HD) and shows in the System manager devices that the card is affected by this error 43, the card has worked fine till yesterday, is someone expert about this damned error??? I already made the classic actions, clean the card, new thermal paste, uninstall drivers, cleaning and reinstalling them, nothing worked, can I check something with the multimeter or this erros is just linked with a death GPU and I can´t make so much more???Thanks in advance to all the members for the help you will offer.

author: Rbastler
author_rank: Frequent Contributor
timestamp: July 16, 2017, 11:51:47 am
content: https://www.evga.com/support/faq/afmviewfaq.aspx?faqid=59308Found this with like 20s Google....The error is so common, evga has a FAQ page for it. I'd say that the same resolutions offerd here, are valid for a Zotac 970 too...
Fluke 73 - Page 1
Forum section: electronics / repair

author: retrace
author_rank: Newbie
timestamp: July 12, 2017, 08:49:48 pm
content: Hello guysI have a Fluke 73 multimeter. Its the first fluke 73, with no buzzer. Is there any way to add buzzer inside? It would be very nice to have this function. i saw that Fluke73 II has the buzzer function on diode test.Thanks !

author: retiredcaps
author_rank: Super Contributor
timestamp: July 12, 2017, 09:53:03 pm
content: Quote from: retrace on July 12, 2017, 08:49:48 pmYes, it might be possible. A quick look at the original Fluke 70 series I and II user/service manual shows they use the same U1 processor so the functionality might be built in, but not enabled.I suggest you download both service manuals and do a comparison. The older service manuals are excellent since they have a theory of operation, bill of materials and schematics. From the 3 sections, you should be able to see what is required to possibly add a beeper function.You might have to add some extra components and/or circuitry onto the pcb somehow?

author: retiredcaps
author_rank: Super Contributor
timestamp: July 12, 2017, 09:54:25 pm
content: The original Fluke 70 series I service manual can be found by searching forfluke 70 series pn731034

author: oldway
author_rank: Super Contributor
timestamp: July 13, 2017, 11:30:35 am
content: I have the same, I bought it used in 1993 and I still use itWhat was sometimes annoying is the lack of manual range.I bought a broken 75 for 5 bucks and I used its rotary knob in my 73.You have to make a small and easy modification that I can not remember.My 73 has now the manual range function...So far I know, the touch hold mode does not works in my 73.

author: retiredcaps
author_rank: Super Contributor
timestamp: July 13, 2017, 03:39:10 pm
content: Quote from: oldway on July 13, 2017, 11:30:35 amPossibly something like this?https://groups.google.com/forum/#!topic/sci.electronics/rgEo-5NkMOo

author: retrace
author_rank: Newbie
timestamp: July 13, 2017, 03:46:29 pm
content: Thanks guysAfter some clips on youtube on fluke 75 i saw that the piezo speaker has 2 points where comesIn contact eith the pcb. I took the piezo speaker from a cheap multimeter and soldered it to the 2 points on the pcb. Now i have the buzzer function on diode test. It even makes a small beep when I cycle between the functions

author: BMack
author_rank: Regular Contributor
timestamp: July 15, 2017, 07:20:25 am
content: Quote from: retrace on July 13, 2017, 03:46:29 pmThat's a killer fix! Congratulations!

author: retiredcaps
author_rank: Super Contributor
timestamp: July 15, 2017, 06:09:08 pm
content: Quote from: retrace on July 13, 2017, 03:46:29 pmWould you share some pictures of your modification?

author: retrace
author_rank: Newbie
timestamp: July 16, 2017, 08:09:04 am
content: The two points where i soldered the buzzer
HP 410B - Page 1
Forum section: electronics / repair

author: neo
author_rank: Super Contributor
timestamp: July 12, 2017, 11:18:33 pm
content: If i have a HP 410B is there anything in it that need to be gone over before turning it on?

author: jeroen79
author_rank: Frequent Contributor
timestamp: July 12, 2017, 11:32:25 pm
content: Set it to the right mains voltage.If you have reason to think that something could be wrong you could start with opening it up for a visual inspection.

author: neo
author_rank: Super Contributor
timestamp: July 12, 2017, 11:38:04 pm
content: Quote from: jeroen79 on July 12, 2017, 11:32:25 pmI have no suspicions other than the fact it is almost as old as my father, because of that i opened it up to take a look. I just wanted to know if there were any gotchas with it given its age.

author: alm
author_rank: Super Contributor
timestamp: July 12, 2017, 11:46:43 pm
content: I would do a visual inspection for loose connections, burned parts or loose screws rolling around. Check the line voltage (actual jumpers if present, I do not trust the label on the back). Plus I check the fuse rating with the manual. That way if there is a short, at least the fuse will provide maximum protection. Sometimes people replace fuses with incorrectly rated ones, all the way up to suitable-sized bolts.

author: neo
author_rank: Super Contributor
timestamp: July 13, 2017, 12:27:04 am
content: It seems to work but in trying to adjust it the needle is jumping all over the place. Thoughts? Also, once i do get the needle to settle down it does read accurately.

author: Cyberdragon
author_rank: Super Contributor
timestamp: July 15, 2017, 09:41:04 pm
content: If there are tubes there are most likely nasty old capacitors. Check for excessive ripple (the manual should specify the limit) and change the filter cap if needed.Clean the switch contacts and check for broken solder joints. Also check and clean any dirty tube pins and sockets. It could also be a bad probe connection, just be careful with the vacuum tube inside the probe.http://bama.edebris.com/manuals/hp/410b/

author: Armadillo
author_rank: Super Contributor
timestamp: July 15, 2017, 10:04:53 pm
content: Do not connect the ground clip lead or the ac probe body to any part that are not ground potential, it will create a short circuit and "BOOPM"Treat it like the oscilloscope ground clip.
Repair story: Tektronix 7623 and 7A18 - Page 1
Forum section: electronics / repair

author: capt bullshot
author_rank: Super Contributor
timestamp: July 15, 2017, 11:06:30 am
content: I've found a fix for an interesting "dancing waves" effect on a Tek 7623 scope, and repaired grossly decompensated 7A18 plugins:http://wunderkis.de/tek-7/

author: doktor pyta
author_rank: Frequent Contributor
timestamp: July 15, 2017, 02:56:18 pm
content: Great hint.Thanks !

author: WastelandTek
author_rank: Frequent Contributor
timestamp: July 15, 2017, 03:40:40 pm
content: Man, I got to get me a way to measure D...all the cool kids are doing it.My ESR meter just isn't making me feel up to snuff any more.Good write up, thank you.

author: David Hess
author_rank: Super Contributor
timestamp: July 15, 2017, 08:11:08 pm
content: That is a nice job. I have never run across the static charge affecting deflection problem.
Random ID 780TI - Page 1
Forum section: electronics / repair

author: Papay
author_rank: Newbie
timestamp: July 15, 2017, 01:34:04 pm
content: Hello! I have problems with 780 TI. The video card is defined with different ID 103A (for cold) 102A (for hot), and very rarely is defined as 100A. I removed and put again the resistor R3 (25k) and the resistor 0.3 but the problem did not go away.
Racal Dana 1991 (and similar) frequency counter repair - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: April 03, 2017, 08:22:14 am
content: Hi All, I recently did a video on this, I found some momentary switches which fit pretty well, so if you have a 1991, 1992, 1998 etc then you might be interested in the video, I also have a link in the description of where to get the switches.

author: David Hess
author_rank: Super Contributor
timestamp: April 03, 2017, 10:29:43 am
content: I just pulled the switch tops out and cleaned the contacts on mine to restore proper operation. The gold contacts had a white residue on them.

author: edpalmer42
author_rank: Super Contributor
timestamp: April 03, 2017, 04:12:16 pm
content: It seems that all the switches in the 19xx Racal counters will eventually fail. The 'rubber' membrane inside the switch fails and you lose the restore force that gives the switch its tactile feedback and keeps the switch open. The only thing you can do is replace the switch.I also have an old NEC digital stereo receiver that has the same switches. They also failed in the same manner.Ed

author: Johncanfield
author_rank: Regular Contributor
timestamp: April 04, 2017, 10:12:57 pm
content: I have two of them, one of them I tried to repair with new switches and things went horribly wrong. I'll take a look at your video. They are really good counters, one of mine has an oven.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: April 04, 2017, 10:34:17 pm
content: This unit has a basic reference, not a very stable one (at least it takes a very long time to settle), I have purchased a couple of OCXO modules, I will need to make a pcb to put it on, but that's not a big deal.Once I upgrade it so that its frequency is more accurate I will sell it, I purchased it to repair for a video for my channel.

author: MarkL
author_rank: Unknown
timestamp: April 04, 2017, 10:52:35 pm
content: My 1992 front panel had two fractured PCB traces which rendered about half the keypad inoperable. Seems there's all kinds of different fun lurking in these.Mine's been running great for at least 10 years now. They're nice units.

author: bitseeker
author_rank: Super Contributor
timestamp: April 05, 2017, 05:52:07 am
content: Nice job, Scott. IIRC that empty socket is where the ribbon cable from the GPIB board plugs into.

author: on4top
author_rank: Regular Contributor
timestamp: July 16, 2017, 10:21:24 pm
content: Just got a Racal Dana 2101 with OCXO and A - B - C ports ( c port up to 20 Ghz )A & B port working fine .. C port doesn't trigger ..Service manual for 1991-92 etc seem to be easy to find .. for 2101 still looking ..http://www.sglabs.it/en/product.php?s=racal-dana-2101&id=1613The C port has 3 seperate extra can's ( 1 is sampler where N-connector goes to ) ( when removed/disconnected . port A & B still work fine )
Vibe CBR12 Bass1-v2 amp repair - Page 1
Forum section: electronics / repair

author: lippy69
author_rank: Newbie
timestamp: July 14, 2017, 10:46:14 pm
content: I'm looking for some help in repairing the car subwoofer amp for this enclosure. The FETs and the PSU side of the amp have been tested and there is one burn out resistor. the location of this is R77. Does anyone know that value this may be and also where I can find a service manual/schematicThank you.
Datron 1072 IP-0 displayed - Page 1
Forum section: electronics / repair

author: moebius326
author_rank: Newbie
timestamp: July 11, 2017, 07:59:53 pm
content: Hello All -I purchased a Datron 1072 a few months back and it has been (seemingly) working well. Today I turned on the unit and it displays IP-0. The unit passes self test, but will not otherwise function.The manual defines the Cause as "Input Zero memory error" and suggests the Correction as "Repeat input zero procedure."So, this raises several questionsHow do I perform the Input zero procedure?"Does it require the Calibration mode (I have the key)?Is this indicative of a current - or imminent - failure?Your help is greatly appreciated -Thanks -moebius326

author: dacman
author_rank: Frequent Contributor
timestamp: July 11, 2017, 10:59:36 pm
content: IP-0 can be cleared without being in the calibration mode.1) Short the input2) Select DCV mode3) Press the (Input) Zero keyI think that it will zero all ranges if in Auto Range mode, or just the range selected otherwise. Ohms can also be zeroed, if fitted with that option. Check the specifications. The 1072 may need to be zeroed within 15 minutes of usage in order for the unit to meet specifications. (This is required on some Datrons, but I haven't researched a 1072.)Those units are notorious for electrolytic capacitor failure. If you have a decent LCR meter, I'd check them all, especially the (blue) ones located at the front top left (and the ones on the rearward power supply). There are about 11 aluminum electrolytic capacitors in those type meters.I'd recommend the following:1) Check the 5V power supply (it's adjustable, set to 5.1 Vdc)2) Check the lithium backup battery3) Check the 15V supplies for dropouts (with an oscilloscope)Another problem with those units is that there are a lot of socketed ICs, which makes for easy replacement and troubleshooting, but the socketed ICs can develop high contact resistance and cause problems (like IP-0). Something else that I suspect could cause an IP-0 error is a loss of power during a memory write operation (but that is more likely to cause a FAIL error than IP-0.)

author: moebius326
author_rank: Newbie
timestamp: July 12, 2017, 03:57:39 am
content: Thank you - very comprehensive!I will try this out tomorrow.Sent from my SM-G950U using Tapatalk

author: moebius326
author_rank: Newbie
timestamp: July 13, 2017, 10:46:27 pm
content: Hi dacman -My thanks to you again.I followed your instructions, the IP0 message disappeared and the unit was working fine again.At least it did for about an hour. Then the system went somewhat crazy - all the LEDs illuminated and nonsense on the display. I turned it on and off during the day, but always the same problem.After re-reading your suggestions, I took the unit apart today, reseated all of the DIPs and connectors, checked the battery (good) and looked at the caps (they look ok). I then powered it up - back to life!!! I checked the operating voltages - all good.Fingers crossed (very scientific) and hope for continued functionality.Thanks again, again.moebius326
Samsung LCD TV 8 times blink red diode /wont turn on/ - Page 1
Forum section: electronics / repair

author: coojoe213
author_rank: Newbie
timestamp: July 13, 2017, 04:13:31 pm
content: Samsung le32s86bd, Power Supply: BN44-00192B /https://elektrotanya.com/samsung_model-le32s81-main-bn44-00192a-bn44-00192b_inverter_sm.pdf/download.html/ . Tv won't turn on. If i press power button, red diode on stn by blink 8 time. Black screen, no sound. On every button from remote red diode blink.I open tv and i have 2 caps 1000/35v bad. I replace them, and after that check all caps on power supply with esr meter, they are perfectVoltages from PS:I have all correct voltages on inverter /24v/ stable.5v -correct13v -12.2v12v-11.8vBLU-5VADIM-0VDET-5.3VGND-0VPWM-0VOn connector CNM801, pin1 = Power_On/Off I have stable 3.3v.CM856 (1000MF/25V) was very bad (216mf ) i check with esr meter. After this procedure i remove IC501 (eeprom) and from my laptop with programmer i delete eeprom and put it empty the same chip. In this mainboard i see also IC3208 (on my pic) which is also the same like IC501, but delete only IC501.
Nintendo 2DS motherboard repair - Missing cap - Page 1
Forum section: electronics / repair

author: InBlack
author_rank: Newbie
timestamp: July 12, 2017, 02:46:22 pm
content: Hello,Someone gave me a Nintendo 2DS that won't turn on, to repair. Upon further inspection, i believe the problem is not on the screen but on the motherboard. I found what appears to be a missing cap on it.It can be seen on the following image:https://www.dropbox.com/s/rjws18tslxq5wdc/IMG_20170712_135239.png?dl=0I can't find a schematic for the console online and can't either know the value of other capacitors near that appear to be the same.Can someone help me?Best regards,Miguel

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 12, 2017, 06:54:12 pm
content: It looks like some kind of feed trough, What happens if you connect the top and bottom (if you dare)?

author: Anks
author_rank: Frequent Contributor
timestamp: July 13, 2017, 06:58:32 am
content: Have you checked the designators under the flex cable to see that they are definitely caps?
Replacement 3.5mm stereo jack - Page 1
Forum section: electronics / repair

author: MrQuadehar
author_rank: Newbie
timestamp: July 14, 2017, 11:47:26 pm
content: Hello Ladies and Gents,i need to replace my laptop headphone jack of my asus r753ux. I desoldered it and used the search engine from digikey but i didn't find it. Maybe one of you know the model numer of the jack. Size is approx. : 15 mm x 10 mm x 5 mm, seven pins. Mounded inside a cutout in the main board and then soldered through-hole (kind of). Sadly, there is nothing printed on it. I have attached some photos of the device <http://imgur.com/a/nVfZY>Thanks in advanceMrQuadehar

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 15, 2017, 12:27:53 am
content: First, you almost certainly have a 3.5mm jack, not a 2.5mm jack. So you might have marginally better success searching for the proper part.That said, finding an exact match for a rather obscure connector like that seems pretty slim. You may have to replace the whole main board, or at least get a non-functional "donor" board and do a connector transplant.Louis Rossman has a quite successful repair business and YouTube channel where he keeps a "junk-yard" of old laptop main boards and regularly repairs units for customers by removing parts from "donor" boards and transplanting them to accomplish the repair.

author: MrQuadehar
author_rank: Newbie
timestamp: July 15, 2017, 12:40:18 am
content: Thank you for your fast response. Yes, of course its a 3.5mm that was a typo. Maybe i try to squeeze an off the shelf jack i have lying around into the laptop case and bodge the connections with fine wires. Changing the whole board is most likely not an option for me as i'm on a very tight budget.

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 15, 2017, 12:43:13 am
content: Do you have any possibility of access to discarded laptop hardware where you are? If you could find a discarded non-functioning similar model, you could probably transplant the connector.

author: Rasz
author_rank: Super Contributor
timestamp: July 15, 2017, 05:03:18 am
content: http://www.ebay.com/itm/audio-Jack-Interface-for-Laptop-32-types-set-each-2pcs-total-64pcs-audio-jack-/301437029668heheedit:but seriously, your connector is in related searches on ebay listed at $2
Anker 24W 2-Port Turbo USB car Charger (71an2452CS) replacement fuse - Page 1
Forum section: electronics / repair

author: Neurotox
author_rank: Newbie
timestamp: July 06, 2017, 05:37:49 pm
content: Hello,I'm trying to repair a Anker usb car charger. From what I have check so far, the fuse has blow. I try to figure out what is the correct spec to buy a new one but I'm lost...Model of the charger: Anker 24W 2-Port Turbo USB car Charger (71an2452CS)Input rating: 12-24VOutput: 5.0V, 4,8AThe fuse is a white surface mount and have only a "V" on it. You can see it in the picture.Any way I can possibly identify it ? I'm tinking about contacting Anker...Thanks!

author: Neurotox
author_rank: Newbie
timestamp: July 07, 2017, 05:30:48 am
content: I'm answering my own questionApparently they seems to have no easy way to find back what was the value of a surface mount fuse from what I have read and it make sens...https://electronics.stackexchange.com/questions/35816/replacing-smd-fuses-without-access-to-schematicsLet's try with the manufacturer...

author: OiD
author_rank: Regular Contributor
timestamp: July 07, 2017, 11:03:11 am
content: Look on the outside of the device, it should tell you the max current the device consumes. if its a 24W charger and its 90% efficient lets say it consumes 27W on average and the V*I on the label gives 35W find a fuse that can handle fast peaks for the 35 and a small margin for the 27W.Or play it safe with a fuse to supply 24W of power and see if it works. Fuses normally blow for a reason so you might replace it and it could immeaditely blow again. You'd need to find the cause and fix it.

author: Armadillo
author_rank: Super Contributor
timestamp: July 07, 2017, 11:11:48 am
content: Could be 6.3A;Just measure the size whether its a 1206 device.

author: technogeeky
author_rank: Frequent Contributor
timestamp: July 07, 2017, 08:25:44 pm
content: Quote from: Armadillo on July 07, 2017, 11:11:48 am

author: Neurotox
author_rank: Newbie
timestamp: July 13, 2017, 02:56:43 am
content: Update:Of course Anker did not want to give me the information...They strongly suggest me to stop trying to repair it for safety...But they answer really fast and even send a new unit.
Agilent N9320B Spectrum Analyzer screen model - Page 1
Forum section: electronics / repair

author: romhunter
author_rank: Regular Contributor
timestamp: July 12, 2017, 05:29:20 pm
content: A friend of mine say that he bought a replacement screen for this analyzer from china using the screen model, so can anyone crack their analyzer open to get a screen model for me? Well, can't ask my friend cause he's a d*ck, and internet failed me on this one.Here's an image for anyone who's curious:When I got the thing somebody threw it around and thus the screen is broken...
HP 54601a question/help repairing - Page 1
Forum section: electronics / repair

author: Hrenowsky
author_rank: Newbie
timestamp: July 10, 2017, 11:58:21 am
content: Hi!I recently got an old hp 54601a 4 channel oscilloscope which my company was going to throw away. As i hate to throwing away stuff that works, i gladly gave it a new home.But it has two problems.1st is the common squished vertical display - i have found multiple threads already for fixing it, so that won't be a problem.2nd is more of a question on the oscilloscope's operation. And basically the reason why it was scrapped.It has a problem with displaying square waves. When a square wave is applied, the scope only shows the horizontal lines, verticals are only a few dots (can still kinda be seen just very dimm).My coworker told me, that it's because the scope is so old, but I'm kinda skeptical about thatI've searched the web, but haven't found anything on the issue or did i find any pics or videos of the scope in use (only foud the tetris easter egg )Soo... if anyone has any ideas or can clarify why vertical lines don't work, I'd greatly appreciate the info!Sent from my iPhone using Tapatalk

author: JFJ
author_rank: Regular Contributor
timestamp: July 10, 2017, 02:57:01 pm
content: The maximum sample rate of the HP 54601A is 20 MS/s. Consequently, it does not capture many samples during the fast rising/falling edges of a square wave. Hence, the few dots. Many oscilloscopes in the HP 546xxx range have the facility to join the dots - using the 'Vectors On' option, in the 'Display' menu. The HP 54601B oscilloscope definitely has that option, but the HP 54601A may not.

author: Bushougoma
author_rank: Regular Contributor
timestamp: July 12, 2017, 04:57:38 pm
content: As probably mentioned in the other thread a partially collapsed vertical deflection is a common failure with CRTs in general when one of the caps around the vertical deflection IC goes bad.Sadly the only scopes worth having in the 54600 series are the 54645A and 54645D 200 MS/s scopes they have the first generation Megazoom ASIC and 1 MB of memory per scope channel.I wouldn't use that scope for anything but repetitive measurements but hey you can't beat the price.
1994 Sony Trinitron In-Car Navigation System KVD-6NV1 - Page 1
Forum section: electronics / repair

author: mubd1234
author_rank: Newbie
timestamp: July 12, 2017, 04:06:21 pm
content: Hi all,I've been on a bit of a spending spree online and bought three of these curious little TVs, never exported outside of Japan, for not much on a Japanese auction site and imported them into Australia. Essentially, it's a 6 inch Sony Trinitron CRT TV with a built in navigation system and video CD player, to be used inside a car. They date back to 1994. Two of the TVs I bought work, but the CD drive doesn't appear to read discs. One works and reads discs, but there is no picture on the CRT.Here are a few photos of one which does work properly:With the TV which has no picture, I can feel the static fuzz coming off the picture tube. I've taken the back off and had a bit of a visual look around inside (not touching anything because I don't want to get fried), but I couldn't see anything obvious like bulging capacitors or disconnected connectors. The video and audio outputs on the back work properly, so the video and audio circuitry seem to be in working order.When I turn it on, I noticed that the high pitched noise you usually can hear with CRTs (if you're young enough) has a much lower pitch than normal. It's much easier to hear than my other identical TVs, and sounds like it's turning on and off very very rapidly - it's not a solid high pitched, almost inaudible tone like the other ones I have. Here's an audio recording of the faulty set turning on -The noise is making me think that it could be a fault in the flyback transformer, but would anyone know anything else I should check before poking around there?I only live on the other side of Sydney from Dave, so I can always send it into the mailbag as something interesting to send in if I can't repair it anyway.
Tektronix 7834 storage scope PSU help - Page 1
Forum section: electronics / repair

author: richnormand
author_rank: Unknown
timestamp: July 12, 2017, 03:04:05 am
content: Tektronix 7834 storage scope just idling along and poof! The scope fuse just blew up, hard. Was not doing a measurement at the time and there were not any transients on the line that disturbed anything else on the bench.The line rectifier bridge test OK as do the two main electrolytics.Next step was looking at the two 2N3902 switching transistors. Both are gone with a dead short between base and collector. Open on everything else.So it does look violent but what?Before digging deeper are there any Tek gurus here that would know of such an history or issues with this version of PSU?Cheers and thanks.
Tektronix 5513  slightly out of Focus on both channels - Page 1
Forum section: electronics / repair

author: andypandyplod
author_rank: Contributor
timestamp: July 11, 2017, 05:31:56 pm
content: I have a Tektronix 5513 dual beam scope,which has a small problem where both channels cannot be completely focused with or without being connected to a signal.This has not just happened,it has been like it on getting the scope. In comparison I have an older Tektronix 543 scope which has a brighter better focused beam.Any ideas please?

author: David Hess
author_rank: Super Contributor
timestamp: July 12, 2017, 02:54:55 am
content: I assume you mean 5112 dual beam or 5113 dual beam bistable. Start by checking the astigmatism as described in the manual; make sure the beam spots focus in both the horizontal and vertical directions at the same point where the focus is best.