hybridfree/eevblog-posts huggingface dataset:
Pioneer VSX-921-K Analog POWER SUPPLY Error - Page 1
Forum section: electronics / repair

author: stojke
author_rank: Regular Contributor
timestamp: February 03, 2018, 09:14:46 am
content: Hi, I have an Pioneer VSX-921-K in the shop that shuts it self off after 3 seconds due to an (by manual) Analog POWER SUPPLY Error.Is it normal to have 118V on +HIGHB signal pin? This is measured with CP403 (to amplifier) disconnected. CP1 input voltage measured 34.8V (AC to AC with probes).When it shuts down the transistor heatsink and the transformer get hotter noticeably more.-edit-The diode bridge D7 shows normal characteristics (550 / 550 / 988) i think.

author: mzacharias
author_rank: Frequent Contributor
timestamp: February 04, 2018, 02:50:50 am
content: If you are reading a voltage that high - you are using the wrong ground reference, or you have a floating ground. WARNING: under some circumstances, this could put that high voltage across a main filter cap, rated at only 71 volts. It could potentially heat up dangerously, and spew it's contents.I have seen this happen before (not on a Pioneer).

author: stojke
author_rank: Regular Contributor
timestamp: February 05, 2018, 06:45:22 am
content: I understand. I believe I have been making voltage measurements the wrong way this entire time.
Gtx 1080 Barely dead.. - Page 1
Forum section: electronics / repair

author: dani_gv
author_rank: Newbie
timestamp: February 04, 2018, 07:04:35 pm
content: Hello everybody, I was searching google a especialist electronics forum and here i am!First of all i have to introduce myself, I live in a little country of Spain with no knowledge of repair this tipe of electronics.I`ve been repairing smartphones since 2 years, and i have a microscope,soldering station, reballing machine, and many many tools for repairing phones, but with gpu.. i have no idea to begin the repair, is this why i became here.One friend sent me a 1080 he bought from ebay, it was working flawlessly, but he changed his mind and put an aftermarket heat sink, the result.... No video. He was afraid and he had removed the aftermarket heatsink broken one inductor since the small heatsinks where applied with glue.I soldered that inductor, see image:After this no video output. The card was recognized by windows as a 1080 GTX when connected as a secondary gpu, but when i install the driver ive got no video from my primary gpu.How i can start to diagnose the card? I cant see any burnt or fault in any component on the pcb. Anyone have a idea to begin?Thank you!Edit, added a photo of the board.

author: Rasz
author_rank: Super Contributor
timestamp: February 05, 2018, 04:44:31 am
content: Quote from: dani_gv on February 04, 2018, 07:04:35 pmmost likely cracked the chip itself, or solder under itits garbage now

author: stojke
author_rank: Regular Contributor
timestamp: February 05, 2018, 06:42:13 am
content: Nvidia are notorious for bad quality bumps (Joint between the microchip silicon, gray thingy, and its carrier, green larger thingy) that burnout. It is a common case of bad bumps, be them the ones on the carrier or the ones on the silicon, when the system can run the card in VGA mode but looses it in driver operation mode.
Leader 3220 need help - Page 1
Forum section: electronics / repair

author: bob91343
author_rank: Super Contributor
timestamp: January 22, 2018, 11:18:23 pm
content: I have a Leader 3220 that worked well for a while but now seems to perpetually be out of lock.I have diagrams but they aren't all that helpful. What would help would be an extender board but I don't know where to get one.Does anyone have one of these or know anything about them? A source of boards might help so that by substitution I could narrow my sphere of investigation.This unit is composed of an internal rack with a number of plug-in modules, and I suspect one of the modules needs adjustment or repair.

author: B1nary
author_rank: Contributor
timestamp: January 28, 2018, 06:29:01 pm
content: I have a Leader 3226 AM/FM Stereo Gen, a different beast than yours, but I scoured the web including Japan, the US, Canada sources and finally got a reply from the fellows at Leader in the US for a manual. It seems that while various units are not the same, they do possess many of the same boards. Try to find a manual from a model that is numerically close to the one you have. In my case I sourced a manual for the model below mine and it has proven helpful in layout and components issues. eBay often has a seller offering up various Leader Manuals and he might be able to help out. I did a short search and found this link.https://www.ebay.ca/sch/items/?_nkw=Leader+Instruction+Manual+for+Standard+Signal+Generator+Model+3220&_sacat=&_ex_kw=&_mPrRngCbx=1&_udlo=&_udhi=&_sop=12&rmvSB=true

author: bob91343
author_rank: Super Contributor
timestamp: February 04, 2018, 11:09:39 pm
content: Thanks for your response. I may give another shot at calling Leader USA but they ignored my previous request. I doubt they know anything; this isn't anywhere near being a current model.Bob
Identifying trimmer capacitors - Page 1
Forum section: electronics / repair

author: NilByMouth
author_rank: Regular Contributor
timestamp: February 04, 2018, 12:18:28 am
content: Hi,I have an old Acorn Electron floppy drive controller that's suffering from a bit of corrosion. There's a small yellow trimmer capacitor next to the crystal with no markings on it. The plates are green with corrosion so I'd like to replace it. Is there a way to identify its value? It looks a bit like a Vishay 65pF.ThanksMalc

author: daedalux
author_rank: Contributor
timestamp: February 04, 2018, 06:16:07 pm
content: For what i know. And i not shure how much of an standard this is.In ceramic trimmers. I think this complies for some tht Murata and no name ebay ones.blue 2,7 to 10pFred 4,2 to 20pFgreen 5,2 to 30pFyellow 6,8 to 45pFIn polipropilene i can see the values are different but the order is the same more or less. The one i can access to is yellow 5,5 to 65pFThis plastic trimmers are lots of times resetted and fixed by turning them and then leaving in the original position as the insulation is so thin and flexible.

author: NilByMouth
author_rank: Regular Contributor
timestamp: February 04, 2018, 09:21:26 pm
content: Quote from: daedalux on February 04, 2018, 06:16:07 pmThanks, I'll try the Vishay one I saw - it has the 2 pins at 45 degrees like the one that's on the board. It may not even be faulty - I just hate seeing corroded components on a board.Malc
Help regarding Rigol DS1104Z repair, with a twist ;) !!! - Page 1
Forum section: electronics / repair

author: DC1MC
author_rank: Super Contributor
timestamp: February 04, 2018, 12:25:59 pm
content: On a whim, I've bought a complete motherboard for the Rigol DS1104Z scope, that the seller says it was rebooting and has been replaced by the manufacturer.I have no idea if it's true or not, but it doesn't cost too much, so I've got it and I was wondering if somebody has a schematic (service manual will be some kind of a small wonder), even at the connector level to see where the voltages are and what goes connected where.If the schematics is unobtanium, is it there some kind of compatible LCD and has anybody some pictures or a fully dead RIGOL to be used as parts donor, I entertain the idea of a Frankenscope (TM).Any help, including pictures and pointers to opening videos are appreciated.Cheers,DC1MC

author: hexreader
author_rank: Frequent Contributor
timestamp: February 04, 2018, 12:43:36 pm
content: Most of the information known is here:https://www.eevblog.com/forum/projects/rigol-ds10xxz-firmware-re-write/It is all a bit confused and contains errors, but maybe you could pick out a few useful bits of info.

author: DC1MC
author_rank: Super Contributor
timestamp: February 04, 2018, 01:45:58 pm
content: Thank, saved.But now I'm on the display/power supply phase, to see what went wrong with the motherboard and if I can reactivate it.I've found on fleabay the following:https://www.ebay.de/itm/7-7-0-inch-TFT-LCD-Color-Display-Optional-Touch-WVGA-800x480-AT070TN90-AT070TN92/291020324707andhttp://www.ebay.de/itm/ART-US-LCD-800x480-TFT-RGB-7-0-WVGA-with-no-driver-TFTAV-07i0-800RGB480/322172687592I'm wondering if one of them may be compatible, because this is the big thing, the front panel seem to communicate mainly via serial commands, if so that makes the project a bit more feasable.DC1MC
HP 6060A Repair Help (Manual & Firmware Needed) - Page 1
Forum section: electronics / repair

author: deepskyridge
author_rank: Regular Contributor
timestamp: January 22, 2018, 04:32:24 pm
content: I recently purchased a HP 6060B from Ebay for parts. Most of the critical parts are included. The chassis, keypad, display are all from a 6060B, the main board is from a 6060A, it is also missing the EPROM chip (firmware), and some cables, also no fan.I am looking for a service manual for the 6060A. Also I need the firmware for a 6060A.Any help would be appreciated.ThanksGary

author: RobK_NL
author_rank: Frequent Contributor
timestamp: January 22, 2018, 09:22:02 pm
content: Did you look here:http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=Fluke

author: deepskyridge
author_rank: Regular Contributor
timestamp: January 23, 2018, 03:14:12 pm
content: Yes, first place I looked, also posted request on HP Yahoo Group.I have done extensive Yahoo and Google searches.I will send a email to Keysight and see if they have anything.ThanksGary

author: deepskyridge
author_rank: Regular Contributor
timestamp: January 27, 2018, 03:27:00 pm
content: Sill looking for firmware for the 6060A or 6060B. Also Service Manuals (I have 6060B SM)ThanksGary

author: Daxxin
author_rank: Regular Contributor
timestamp: January 27, 2018, 05:57:57 pm
content: Fluke or HP ?

author: deepskyridge
author_rank: Regular Contributor
timestamp: January 27, 2018, 06:05:43 pm
content: It's a HP 6060A Electronic Load.Fluke is a Signal Generator.ThanksGary

author: Jwalling
author_rank: Unknown
timestamp: January 28, 2018, 10:51:40 am
content: Here's a binary I saved off a few years ago from a 6060B. Good luck!

author: deepskyridge
author_rank: Regular Contributor
timestamp: January 28, 2018, 03:27:26 pm
content: OK. thanks.I will give it a try.If anyone has a 6060A and could copy the f/w that would be great.Gary

author: deepskyridge
author_rank: Regular Contributor
timestamp: January 30, 2018, 08:43:56 pm
content: Still looking for 6060A firmware.Thanks

author: deepskyridge
author_rank: Regular Contributor
timestamp: February 02, 2018, 06:38:42 pm
content: Still LookingGary

author: pelule
author_rank: Frequent Contributor
timestamp: February 02, 2018, 08:15:33 pm
content: Found thew SM for the 6060B. May help.http://ridl.cfd.rit.edu/products/manuals/Agilent/power%20supplies/CD1/service/6060ser.pdfKeysight just has the 6060A UM.https://www.keysight.com/main/redirector.jspx?action=ref&cname=EDITORIAL&ckey=2286320&lc=ger&cc=DE&nfr=-536900193.536898294.00/PeLuLe

author: deepskyridge
author_rank: Regular Contributor
timestamp: February 03, 2018, 03:44:14 pm
content: HI, thanks for the links.For some reason there does not appear to be any service info for the 6060A, I have been looking for some time.The 6060A is different from the 6060B so someone must have a manual for it. Just can't find it.Gary
HP 8673B service manual or schematics in good quality - Page 1
Forum section: electronics / repair

author: ingowien
author_rank: Regular Contributor
timestamp: February 07, 2018, 12:15:05 am
content: Does anyone have the 8673B service manual or schematics in paper form or good scan quality?I know that there's 08673-90134 on the keysight server but it's really bad quality and almost impossible to read the details. It's rather time consuming having to trace the signals on the PCBs and check with a continuity tester if a digit was 0, 3, 6, 8 or 9. Currently I'm stuck with the strange behavior that the output level only seems to adjust when RF is turned on, then it doesn't change any more. However the meter varies when the vernier is adjusted.So if someone can provide schematics or is willing to sell, this would be helpful. Can even be an older revision, my 8673 has a very low serial and some older board revisions.best regardsIngo

author: ap
author_rank: Frequent Contributor
timestamp: February 07, 2018, 01:08:12 am
content: It is being sold on ebay US by Artek media, you can also get it online from them which saves you time and cost.

author: ingowien
author_rank: Regular Contributor
timestamp: February 07, 2018, 01:17:14 am
content: Thanks a lot for the hint. I've seen the offer but - incorrectly - assumed that this would just be a collection of the keysight manuals. At least I think to remember that some people are trying to sell manuals that are widely available. But from reading the offer it really sounds like good quality.So thanks for the hint, I'll contact them immediately.best regardsIngo

author: ingowien
author_rank: Regular Contributor
timestamp: February 07, 2018, 01:45:58 am
content: Unfortunately their homepage only lists the 8673A, not the 8673B. Do you know how large the differences are?I just foundhttp://literature.cdn.keysight.com/litweb/pdf/08673-90053.pdffrom 1985 for some 8673E with much better scan quality.Maybe some schematics are very similar or the same, so I'll compare this to my 8673B manual until I get some reply from artek.best regardsIngo
MAXIM MAXREFDES82 repair - Page 1
Forum section: electronics / repair

author: sainter
author_rank: Regular Contributor
timestamp: February 01, 2018, 11:40:31 pm
content: Hey everyone,Few days ago, I received maxim MAXREFDES82 evaluation board. Worked fine for a day, after that it stopped working. After some figuring our, I found out that the 3,3 V rail linear regulator is drawing too muck. About 200-250 hAh (MAX17651 designed to handle 100 mAh normal current and 180 mAh peek current). But I can't track the reason for additional current draw. At first it was around 350 mAh, but after few minutes it dropped.Tried to find a hot spot with isopropyl alcohol, but can't find the bugger that is dissipating 600 mW. The only worm thing is the MCU.Any thoughts ? BTW, when I put STM32 into reset, current drops around 50 mAh.
Unable to track down replacement relay - Page 1
Forum section: electronics / repair

author: Dolore
author_rank: Newbie
timestamp: February 13, 2018, 05:11:05 am
content: I'm having a heck of a time trying to locate a replacement relay for a furnace I'm working on, am I searching wrong, I've attempted varying levels of google-fu, but I'm unable to locate anyone selling this specific relay, let alone a teardown on it, or the other uses for it.Any help would be appreciated on this, I'm coming up blank from every angle lately.

author: DaJMasta
author_rank: Super Contributor
timestamp: February 13, 2018, 05:26:23 am
content: It gives you many of the relevant specifications on the top there, and even if you can't match it exactly, you can probably find a suitable replacement from a different company.I don't know much about HVAC electrical, but it could very well be a fairly standard one among them and that relays sold for the purpose would be a suitable replacement. You want to determine the switching configuration (SPST, SPDT, DPDT, etc.), and then make sure you can find a matching pinout (if you can determine the switch configuration, you should be able to discern from the electronics what's the drive coil and what's the switched elements and verify that the replacement will work). Aside from that, match the specifications listed, 24V drive coil, normally open switch connection (suggests SPST to me), and at least 10A @ 120V or 5A at 240V.
83752A YIG output going into the noise floor on the low band output. - Page 1
Forum section: electronics / repair

author: jadew
author_rank: Frequent Contributor
timestamp: February 01, 2018, 10:34:10 am
content: Hey guys,I bought a used 83752A and it turns out it's broken, although the seller said it's working. Turns out that it's unable to output anything between 2 GHz and about 3-4 GHz (this part seems to vary).It's a Dual YIG oscillator and one side generates signals between 2 and 11 GHz, while the other one between 11 and 20 GHz. The issue is on the 2 to 11 GHz side and I'm wondering if it's repairable.Including customs and shipping, it has set me back a lot and returning it would not even make sense (I live in Europe and it got shipped from the US). The seller had 0 rating,so I suppose they knew what they were selling. Basically I'm stuck with it.Anyway, I'd hate to lose all that money and I was wondering if it's possible to fix the YIG. There are no schematics available for (for anything) so if anyone has any pointers, I'd greatly appreciate it.ThanksEdit: I talked to the seller, she seems genuinely surprised and offered to try to help with the issue.

author: jadew
author_rank: Frequent Contributor
timestamp: February 01, 2018, 12:05:50 pm
content: Do you think it's a good idea to fiddle with the potentiometers at the bottom?

author: vaualbus
author_rank: Frequent Contributor
timestamp: February 01, 2018, 01:03:57 pm
content: Had you verified that the the current on the yig is right?Do the YIG have two coil inside? So maybye on side is working and other side had a defective current sources?

author: jadew
author_rank: Frequent Contributor
timestamp: February 01, 2018, 01:30:51 pm
content: I have not, I don't know how many coils it has. Do you mean 2 main coils?BTW, I won't attempt any repair right now, because I'm in discussions with the seller and I don't want to make any alterations, in case I have to return it.
HP Pavilion 15-AU board repair - Page 1
Forum section: electronics / repair

author: ulltrium
author_rank: Contributor
timestamp: February 02, 2018, 06:42:52 am
content: Hello,I have a few questions about the HP 15-AU motherboard, it is a new board, with i7-7500U (DAG34AMB6D0 901573-601), ddr4, which I believe it worth to have a look and test it. I only have the board and a good DDR4 memory for test, nothing else, not even the heat sink and fan. Did anybody come across with this type of laptop?And here are my questions:1. Does it start with 19V without smart pin power supply? I don't have this type of charger that's why I'm asking.2. Does it start without the battery connected? I'm referring to the main battery (Li-Ion battery) not the bios battery.3. Does it start without the fan?4. What are the main power rails for it? From the measurements I detect 8.7V going almost everywhere, does it make any sense? I expected that the 19V power rail to go everywhere but this is a new model of motherboard and I'm not very sure. The ITE chip seems to have its 3.3v so I don't think there is any problem with it.I attached a picture with the board.Many thanks.
Microsoft surface book charget - Page 1
Forum section: electronics / repair

author: Greid
author_rank: Newbie
timestamp: February 01, 2018, 05:55:12 am
content: Hello does anyone know what the Microsoft surface power adapter equivalent of the DC barrel jack is called? I want to see if I can buy the connector part that plugs into the laptop.Thank you

author: Jeroen3
author_rank: Super Contributor
timestamp: February 01, 2018, 06:23:41 am
content: It's a magnetic connector, I think it's very proprietary.

author: Greid
author_rank: Newbie
timestamp: February 01, 2018, 01:21:47 pm
content: Yes, I'm trying to find the best search term for it, because for the charger I've got like 4 of them and the power bricks work great but it always the connector that gets messed or the wires. My goal is to try and find one so I can mod it to easily removable from the power brick so it's easier to replace, and to make it out of better wire.
Denon AVR-1912 E2/EA - Page 1
Forum section: electronics / repair

author: Studio1@29
author_rank: Contributor
timestamp: February 01, 2018, 07:04:20 am
content: There is an intermittent open cct. in the 40xWay ribbon cable CX4 see (page 129) in the Denon Service Manual - down-loadable from here:< Denon AVR-1912 | Electrical Connector | Insulator (Electricity) - Scribd >The problem is in that acute bend at the HDMI_B'D connector. Is a repair possible - can the end be cut off and a new insertable end be created on a 40xWay ribbon cable??Thank you anyone. Michael at Studio1
Keithley 2400 Error +505 - Page 1
Forum section: electronics / repair

author: JohnPi
author_rank: Regular Contributor
timestamp: January 30, 2018, 04:01:01 am
content: I am trying to calibrate my Keithley 2400. It isn't (wasn't) very far off calibration, but now I get error 505 ('Source offset data invalid') when calibrating the 1 uA current range (calibrating voltage seems to go OK).Basically, I measure about 1.004 uA when sourcing 1.0 uA on the 1 uA range. There are other calibration steps with -1 uA (reads 0.997 uA) and 0 uA (reads about 3 nA) -- but then when I apply the final calculated calibration code, it fails with the 505 error.I think the way the calibration works is that it expects 4 numbers which are close to 1 uA, -1 uA and 0 uA. It then calculates the internal cal constants from these -- but if those are too far off, it rejects the calibration.Does anyone understand how the cal constants are calculated ?Calibration actually ran OK for me during a couple of trials (with shorter settling time etc.) -- but when I ran the slow (more accurate) one, now I get that error -- how do I recover ?p.s. I tried to calibrate manually on the 1 uA range -- I get the same 505 error. My cal is only ~ 0.3 % off (manual says limits for cal are ~ 10 %), so it should be OK. Even when I say it is 'perfect' -- e.g. tell it it reads precisely 1.000 uA when supplying 1.0 uA, I still get the 505 error.
car radio disk power on problem - Page 1
Forum section: electronics / repair

author: menash
author_rank: Contributor
timestamp: January 28, 2018, 01:31:00 pm
content: Hi, I'm trying to fix my car radio disk. the problem is that every time I turn on my car, it wont work until I press the reset button.This radio disk has Vcc and Battery inputs. I found that it happen every time I disconnect the Vcc for more then 5 seconds.I open it and tried to trace the Vcc but I couldn't figure it.Any help would be appreciated, thanks!

author: coromonadalix
author_rank: Super Contributor
timestamp: January 30, 2018, 01:33:05 am
content: would be nice to have a model brand etc ... we have nothing to work with ??
Smd led stock list for HDTV repair  - Page 1
Forum section: electronics / repair

author: jwelch68
author_rank: Newbie
timestamp: January 30, 2018, 01:27:40 am
content: I would like to get a list of the common sizes, voltages and such needed to repair leds that have gone bad in led TVs. Trying to buy some to stock up and have around to make those repairs. I've tried looking around the internet to see if I could find a list of what I might need to no evail. Even a list of manufacturers and what sizes they use In their TVs I could not find. Just wondered if anyone would have information that would be helpful. Thanks.Sent from my Nexus 6 using Tapatalk
Dell PowerEdge 2950 PwrGd problems - Page 1
Forum section: electronics / repair

author: madcorp
author_rank: Newbie
timestamp: January 28, 2018, 10:33:23 pm
content: So, recently the server refuse to start and reported this error code: "E1215 1.8V PwrGd", which basically means that there is a problem with the voltage regulator for 1.8V. On that server, this voltage is created (controlled) by the motherboard (since the PSU only delivers +12V and +3.3V).Till now I have tried to start it with the bare minimum number of components and the result was the same.. even I tried without RAM - no change, same error.The question is - does anyone know where and what to check on the motherboard?Also, I'm thinking for the worst scenario (fried chipset or something similar) - what are the chances of that?

author: AndyMacSteve
author_rank: Newbie
timestamp: January 29, 2018, 03:15:20 am
content: I think the chance of the chipset being fried is low. Before trying anything else, try checking the riser card if yours has one. If it doesn't work, you may have to remove the Motherboard and check any voltage regulators, capacitors, resistors or a combination of them since it's essentially impossible to check voltages while powered onIf you still can't find and/or repair the problem on the motherboard, then it could be something in the power supplies. I honestly am not sure where it could be. There's a small chance it Could be the chipset or the motherboard

author: LA7SJA
author_rank: Regular Contributor
timestamp: January 29, 2018, 09:35:47 am
content: It is not entirely uncommon for buck down converter circuit to fail on Dell servers, but if you're lucky it's just a filter capacitors ESR that has become too high. This can cause the regulator to fail (or supply the wrong voltage). Can you find a spot on the motherboard that should have 1.8V? If you find a spot, what do you measure (AC and DC) / or observe on the oscilloscope? Can you see any bulging capacitors? Or supply some high res pictures of the motherboard?Johan-Fredrik

author: madcorp
author_rank: Newbie
timestamp: January 29, 2018, 09:14:51 pm
content: So far only one capacitor was looking "bad" and was replaced (next to the CPU2) but that didn't change anything. Also, both PSUs are OK too. Riser card and everything that can be removed was removed and the error persist.Investigations will continue after day or two... meanwhile here are some photos -https://photos.app.goo.gl/ldtmQZmpnVvu9Pni2P.S.: is there anywhere in the Internet a datasheet/scheme of that motherboard?

author: coromonadalix
author_rank: Super Contributor
timestamp: January 30, 2018, 01:06:17 am
content: searching for the specified error tend to show the motherboard maybe at problem or the pci-x risers cards ??
rear view safety aft 7 inch monitor issue - Page 1
Forum section: electronics / repair

author: AllMacs
author_rank: Newbie
timestamp: January 31, 2018, 03:54:54 pm
content: Hello,I have a rear view safety camera. It comes with a multiplexer, the camera and a TFT screen. When I turn on the unit, many times the screen show a red LED and then it turns to a blue color. After that the screen would appear. If I just turn off the power to the unit and turn back on the LED would stay blue, but there would be no picture and the screen would stay dark. I will have to turn the screen off first by the power button, before turning off the switch I installed to turn off the power to the unit. Many times when I would turn the unit on by the master power switch it would still stay black.I've opened the unit up and replaced the Capacitors on the multiplexer and monitor. The issue is still there.Is it something that happens with these TFT screens a lot? are there some schematics that could give me an idea of what to look for?Do you guys have any hints?
Help with Advandtest R3765 Network Analyzer / Wiring Documents - Page 1
Forum section: electronics / repair

author: dd7lp
author_rank: Newbie
timestamp: January 29, 2018, 05:44:42 pm
content: Still searching desperately for circuit documents or tech-manualsfor the Network Analyser Advantest R3765, who knows or can do somethingThe analyzer has errors with the keyboard query and the keyboard query.dig. Output on the colour TFT screen. Just too bad to be exploited.maybe someone else has a def. device and also a def. device.you could arrange for each other.are available. The OM that sent me here some time agothat he had spare parts, may you please recapitulate.report.You can also send me a PM to may MailadressThanks for your trouble. 73 Christian dd7lp
Anyone have a High precision LCR meter? - Page 1
Forum section: electronics / repair

author: ampliwire
author_rank: Newbie
timestamp: January 28, 2018, 10:44:13 pm
content: Hello!I have some inductors, that I need to get measured (mH, and Resistance).They don't come with a datasheet, or any marking.. So that's why I need the values.Does anyone here have access to a high precision LCR meter, capable of measuring in the mOhms, and mHenry area?Kindest regards!

author: Samogon
author_rank: Frequent Contributor
timestamp: January 29, 2018, 12:05:45 am
content: Fluke pm6306 in US

author: LA7SJA
author_rank: Regular Contributor
timestamp: January 29, 2018, 11:29:11 am
content: Define High Precision, and how many different inductors do you have?I could be cheaper just to buy the inductors you need than to buy the LCR meter and hope you can use the components you have.I don't know how many some are so I don't know ho much work it would be to test with a signalgenerator and a scope.And finally where in Norway are you located?Johan-Fredrik

author: Tomorokoshi
author_rank: Super Contributor
timestamp: January 29, 2018, 06:20:32 pm
content: 1. How many are there? How big are they? Maybe post a picture.2. What frequency range to they need to be measured at? 100Hz? 120Hz? 1000Hz? 10kHz? Sweep from 100Hz to 40MHz?
SMD  Diode code 75 - Page 1
Forum section: electronics / repair

author: sub2001zero
author_rank: Contributor
timestamp: January 27, 2018, 04:09:38 am
content: Hi need some help finding are replacement. The smd has code of 75 with dot above the 75, has a gray strip on the left with two legs.

author: DTJ
author_rank: Super Contributor
timestamp: January 27, 2018, 04:26:59 am
content: Cut and paste from a case code list I have:75 015AZ7.5 Toshiba75 BAS70-05 Siemens SOT23 Dual BAS7075 BFQ75 Siemens CerecX75 BFQ75 Siemens/Infineon SOT173 pnp fT 5GHz 12V 50mA75 R2DZ7.5 Toshiba75- BAS70-05W Philips SOT323 dual cc BAS70You say 2 legs - do you mean 2 contacts in total or a package that has 2 legs + a tab?

author: sub2001zero
author_rank: Contributor
timestamp: January 27, 2018, 04:30:05 am
content: thank you very much!

author: sub2001zero
author_rank: Contributor
timestamp: January 27, 2018, 04:35:25 am
content: it has 2 tabs on it end with the number 75 in the center, The ones you list has 3 tabs

author: DTJ
author_rank: Super Contributor
timestamp: January 27, 2018, 01:00:05 pm
content: So the package looks like the one in the link below but is marked '75'http://p.globalsources.com/IMAGES/PDT/S1150212377/SMD-Ultrafast-Rectifier-Diode.jpg

author: sub2001zero
author_rank: Contributor
timestamp: January 27, 2018, 05:37:39 pm
content: see attachment thanks

author: DTJ
author_rank: Super Contributor
timestamp: January 28, 2018, 01:29:22 pm
content: Sorry, can't find it in any of my reference docs.
Yihua 853AA with preheater but no hot air - Page 1
Forum section: electronics / repair

author: kripton2035
author_rank: Super Contributor
timestamp: January 28, 2018, 10:50:07 am
content: I bought 4 years ago a yihua 853aa station. it worked fine until now.today, the preheater works ok, but the hot air seems like the gun is in the holder, that is it sleeps all the time.I have 3 dashes "---" on the display, and the air flow is not flowing at all.I opened the station, and the heat gun,I checked the reed switch: it seems ok as it closes when I approach a magnetI checked the thermocouple : it gives millivolts when I heat itthe heater seems not open : I measure 75 omhs between the wires.I traced the wire from the reed switch on the board to the samsung micro controller pin : nothing is cutI measured 5v on the micro controller pin, and zero volts when the reed switch is closed by a magnetso I came to the conclusion that the microcontroller thinks the reed is always closeddo you have any other thing I could do/measure to be sure of that failure ?or any hint that could make this board work again ?thanks.

author: kripton2035
author_rank: Super Contributor
timestamp: January 28, 2018, 12:25:26 pm
content: forgot to mention :I checked the triac BTA16 seems ok, optocouplers moc3041 seems ok too
hantek DSO5102P is death, help me please! - Page 1
Forum section: electronics / repair

author: mandujanor
author_rank: Newbie
timestamp: December 02, 2017, 07:53:16 pm
content: Hello everyone, I need some support, my problem is this:I bought a DSO5102P hantec oscilloscope, I only used it for a couple of days and then I kept it for about a year and a half, and after that I wanted to use it and it did not work anymore, it just flashed and nothing else, just the button the upper right corner lights up and that's it.I do not know what to do, if anyone has any idea that I can verify to repair it or have the schematic I would appreciate it very much, well in advance I thank everyone for their support, see you later.

author: kalel
author_rank: Frequent Contributor
timestamp: December 02, 2017, 08:49:46 pm
content: Just a random question, for that year and a half, where was it kept? Is it possible any water got inside, or a lot of dust, or etc?I really don't think that is the problem, just asking to check.

author: GreyWoolfe
author_rank: Unknown
timestamp: December 04, 2017, 12:47:38 am
content: Check the capacitors. I have a 5102B that I turned on to use and it went pop and died. There were 1 popped and 1 bulged cap on the main board. I replaced them and it came back to life.

author: Terry01
author_rank: Frequent Contributor
timestamp: December 04, 2017, 01:00:14 am
content: I just got one a couple days ago! All of a sudden I don't love it so much

author: carldavis114
author_rank: Newbie
timestamp: January 28, 2018, 03:56:11 am
content: I have one that died also. I finally stopped being lazy and soldered in the Grd Tx and Rx pins so I could hook up my FTDI and view the boot up on putty. I believe from the UBIFS error I am seeing I need to reload the NAND so discovered bad sectors are not written to. Hard to do from the terminal window. For that I need to find "EmbedSky Download USB" software. Have not been successful yet. Anyone know how to upload the firmware from the front panel USB using the USB stick as a boot drive to load in the firmware?
TVS diodes - Page 1
Forum section: electronics / repair

author: stj
author_rank: Super Contributor
timestamp: January 26, 2018, 09:57:13 pm
content: i have to replace one,the original is bi-directional.i have some uni-directional ones,can i use 2 in series or anti-parallel??

author: helius
author_rank: Super Contributor
timestamp: January 26, 2018, 10:08:21 pm
content: Use them in series with their cathodes together.

author: wraper
author_rank: Unknown
timestamp: January 27, 2018, 01:30:32 am
content: Quote from: stj on January 26, 2018, 09:57:13 pmNo, it would be just as 2 diodes anti parallel, therefore clamping at below 1V. Do asheliussuggested.

author: stj
author_rank: Super Contributor
timestamp: January 27, 2018, 03:23:02 am
content: so -----|>|--|<|--------hmm - gonna be fun working out the placement - probably have to be a "tent" style - it's all smd

author: wraper
author_rank: Unknown
timestamp: January 27, 2018, 09:42:52 am
content: Depending on circuit you could just use one unidirectional TVS. I cannot think of that many circuits which would actually require bidirectional TVS.

author: tszaboo
author_rank: Super Contributor
timestamp: January 27, 2018, 10:56:53 am
content: Quote from: wraper on January 27, 2018, 09:42:52 amRS485. The common mode voltage could easily be negative.

author: wraper
author_rank: Unknown
timestamp: January 27, 2018, 11:00:17 am
content: Quote from: NANDBlog on January 27, 2018, 10:56:53 amYep, pretty special cases like this. Usually when I see bidirectional TVS in a circuit, there is no good reason for ir being bidirectional.

author: floobydust
author_rank: Super Contributor
timestamp: January 27, 2018, 01:55:22 pm
content: Many RS-485 bi-directional TVS are lop-sided.ExampleSM712has +7, -12V clamps. I know it is a tiny flea fart TVS, with fake 400W spec (SOT-23), but designed for max. according to RS-485 standard.

author: SeanB
author_rank: Super Contributor
timestamp: January 27, 2018, 01:59:48 pm
content: Bidirectional is good from a buyer's side, you only need a single part for all applications, and putting it it the wrong way round does not cause any issues. If you need unidirectional you just use a regular diode in parallel as well. Yes you will need to build a tower to use the unidirectional ones to replace a bidirectional one though.
Heathkit Sine-Square Audio Generator Problem - Page 1
Forum section: electronics / repair

author: xtjacob
author_rank: Newbie
timestamp: January 26, 2018, 04:53:07 am
content: Hello all,I've acquired an old Heathkit Sine-Square Audio Generator (Model IG-18) with a bunch of old test equipment. I hooked it up to test it and I noticed it has a problem with the voltage staying constant. It seems that the frequency is pretty correct, but the voltage is fluctuating all over the place. Anyone ever worked on one of these and might have an idea what the problem could be?Apologies for the awful oscilloscope picture. I couldn't figure out how to setup the trigger so it would show the fluctuating voltage.

author: xtjacob
author_rank: Newbie
timestamp: January 26, 2018, 05:09:55 am
content: Ok, I probably should have googled first. Turns out the Feedback potentiometer inside needed to be adjusted. Now that's its stable it appears to be ~40hz off on all the settings.
Fluke 8020A - Page 1
Forum section: electronics / repair

author: zvonex66x
author_rank: Contributor
timestamp: January 26, 2018, 03:48:34 pm
content: Does anyone know where I can find display for my Fluke 8020A?

author: rsjsouza
author_rank: Super Contributor
timestamp: January 26, 2018, 05:58:13 pm
content: A part number is mentioned in modemhead's excellent blog post at:http://mrmodemhead.com/blog/fluke-8020a-lcd-replacement/

author: zvonex66x
author_rank: Contributor
timestamp: January 26, 2018, 06:20:12 pm
content: Quote from: rsjsouza on January 26, 2018, 05:58:13 pmYes, I know for this solution, but just asking for original lcd

author: rsjsouza
author_rank: Super Contributor
timestamp: January 26, 2018, 07:02:00 pm
content: The original LCD was really not good; the layers delaminated with humidity and heat.You will have a hard time trying to find one still in good shape - even if you buy a broken "sacrificial" multimeter with a good LCD, there is no guarantee it will last. This happened to me in the past, where the "good" replacement LCD lasted for four months and I had to replace it with a modern one.

author: zvonex66x
author_rank: Contributor
timestamp: January 26, 2018, 08:59:45 pm
content: Quote from: rsjsouza on January 26, 2018, 07:02:00 pmOk, thx to answers... so i should think about new modern one. Thx
Datron 1281 repair - Page 1
Forum section: electronics / repair

author: whatamidoing
author_rank: Newbie
timestamp: January 25, 2018, 10:42:37 pm
content: Hey

author: pelule
author_rank: Frequent Contributor
timestamp: January 25, 2018, 11:28:23 pm
content: QuoteHi whatamidoing,I assume you have done a proper warm-up (powered for > 8 hours) before you did the cal.So it may an issue with the NVRAM write enable circuitry. Means, even you have enabled CAL with the key, the WE of the NVRAM may not. Simple method to test: are you able to change the CAL-Date?If not there may several reasons: the 5V, the power fail circuit, the ASIC or simply a contact issue at the NVRAM socket./PeLuLe

author: Kleinstein
author_rank: Super Contributor
timestamp: January 26, 2018, 09:31:37 am
content: "ratio reference error" would point towards the special transformer and surrounding circuit used to generate internal cal voltages to do the 10 V - 1 V - 0.1 V adjustment step. This is kind of a very stable divider to generate a few internal test voltages used to check / measure the amplifier gain steps.

author: TiN
author_rank: Super Contributor
timestamp: January 26, 2018, 11:17:41 am
content: Could be also problem with switching/circuitry that compares REF1 to REF2, as if I remember correct second reference is just used for self-test purposes? Reference itself is two identical modules on the main analog board, that are based around LTZ1000 circuit.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: January 26, 2018, 12:27:50 pm
content: I also got this error on the first run of the 20 years uncalibrated Datron 1271. In case of Datron 1281 an error flag is being raised if REF1:REF2 ratio is drifted more than 20 ppm since last internal source calibration. If ISC was too long ago, just run it again.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: January 26, 2018, 07:58:41 pm
content: You can just enter to the cal mode and quit from it without any action, then runs ISC. If no other hardware problems, the error code must disappear.

author: quarks
author_rank: Frequent Contributor
timestamp: January 26, 2018, 08:33:59 pm
content: Just in case you have not checked all electrolytic capacitors,My suggestion is to make sure you do not miss one.Also double check all powersupply voltages incl. ripple with oscilloscope.Once I thought I checked all but unfortunately overlooked one little cap and several days of troubleshooting later I finally identified this sucker as the cause of all trouble.
Lenovo S820 USB charge port repair - Page 1
Forum section: electronics / repair

author: panoss
author_rank: Frequent Contributor
timestamp: January 23, 2018, 04:19:01 pm
content: I have the above mentioned phone and in it's charge port pcb, the port is missing.You can see it in the attached images, the first 4 ones.(the fifth image shows how it should be, I found it on the intenet)I 'm trying to fix it although it's a cheap part, because it will take 2 months (at least) to come from China.So, is there some service manual?I found theschematic, but...it only contains the...schematic () NOT the pcb.So I can't find which part in the schematic corresponds to which part on the pcb.Maybe the 'Switching Charge' of the schematic is the circuit of charge port pcb?The phone is "dead".I guess this PCB is the reason why it shows no signs of life.The battery is new.Any help is appreciated.

author: zvonex66x
author_rank: Contributor
timestamp: January 23, 2018, 09:35:47 pm
content: It should working if the battery is full, i'm servising mobiles every day but this is high demage, but not impossible to fix. You can see path for your usb chargeing port and solder it by this.

author: panoss
author_rank: Frequent Contributor
timestamp: January 24, 2018, 07:48:24 am
content: So you 're saying the phone should boot and work despite the fact that the charge port pcb is damaged, right?(the battery is charged)

author: zvonex66x
author_rank: Contributor
timestamp: January 24, 2018, 06:21:44 pm
content: Quote from: panoss on January 24, 2018, 07:48:24 amYes, there are no reason for not turning on

author: zvonex66x
author_rank: Contributor
timestamp: January 24, 2018, 08:20:20 pm
content: Are you sure that battery is charged???

author: panoss
author_rank: Frequent Contributor
timestamp: January 25, 2018, 07:46:48 am
content: Yes I am.

author: zvonex66x
author_rank: Contributor
timestamp: January 25, 2018, 04:24:08 pm
content: Quote from: panoss on January 25, 2018, 07:46:48 amSo.... it should work...

author: panoss
author_rank: Frequent Contributor
timestamp: January 26, 2018, 04:53:58 pm
content: Therefore, I conclude that the main board has a problem...
UPS fixing - Page 1
Forum section: electronics / repair

author: menash
author_rank: Contributor
timestamp: January 22, 2018, 05:31:46 pm
content: Hi, I got a not working UPS -advice prv650- to my hand and i'm trying to fix it.When I connecting it to the main it stays off and none of the light are turning on. I opened it and I couldn't found any damage component, only the battery is dead. so I got the idea to replace the battery with my 12V power supply and see if it work on battery mode (disconnected from the main). it worked, and i measured 230V on the output.now is it ok to connect it to the main when my power supply is replacing the 12v battery? i want to make sure that the problem is the battery only.thanks!

author: EHT
author_rank: Frequent Contributor
timestamp: January 22, 2018, 11:22:57 pm
content: That would depend on whether the PSU and / or the UPS inverter are isolated. Unadvisable unless you are very confident about that.How about charging the battery up then trying it in the UPS. If it won't hold charge then its faulty, needs replacing and is likely to be the only problem. If it does hold charge and run the UPS then it would show there is a fault in the power supply of the UPS.

author: menash
author_rank: Contributor
timestamp: January 25, 2018, 05:38:42 pm
content: Thank you, I will try to get battery to check that

author: gnif
author_rank: Unknown
timestamp: January 25, 2018, 06:32:53 pm
content: Most UPSs do not power on if the battery is completely dead, it is a safety feature.
Use a HV microwave capacitor for HV CRT of RCA vacuum tube scope ? - Page 1
Forum section: electronics / repair

author: lordvader88
author_rank: Frequent Contributor
timestamp: January 25, 2018, 08:36:51 pm
content: I have an RCA-WO33A vacuum tube oscilloscope. Its was dropped hard and the transformer broke loose, cracking the PCB in half and bending the frame/etc. Probably broke 2 tubes as well. The replacement tubes and caps got here today. But I don't have a 0.5uF >700V capacitor. But I do have 2 or 3 big microwave oven caps. I have to dig them up. But if they are rated about 0.5uF is there any reason they might not work well at 60hz from a rectifying valve/tube ? Its for the CRThttp://rhetoricity.com/misc/tubes/oscope/RCA-Oscilliscope-WO33A.pdfIts C40 on the mid-right

author: Yansi
author_rank: Super Contributor
timestamp: January 25, 2018, 08:41:24 pm
content: They will work absolutely fine with 700V.Just note there is usually a discharge resistor built in the cap, so you may see a false leakage current. It may or may not be a problem, depending on the circuit where you will use it.

author: james_s
author_rank: Super Contributor
timestamp: January 25, 2018, 10:14:15 pm
content: Remember that a microwave capacitor is used with 60Hz powering a vacuum tube in its native application.
GSM7224V2 (Managed Switch) Repair - Page 1
Forum section: electronics / repair

author: gnif
author_rank: Unknown
timestamp: January 25, 2018, 06:31:01 pm
content: Today there was a lightning strike in my street, no more then 100m from my house. The noise was so loud that the crack of the bolt made me wince in pain and left my ears ringing.At least one bit of networking gear on my home network blew up, I believe it was my Linksys VoIP ATM as it violently let the magic smoke out.Unfortunately it didn't end there, my nice fully managed 24 port switch has become a 8 port fully managed switchWhat are the chances the damage is mainly superficial (I know there are ferrite transformers in there). I pulled the switch down and couldn't smell anything nor see any obvious damage on the PCB. Some ports meter open circuit between the pins, others meter about 1.20 ohm.
Searching for DATASHEET of Elmax PLCD2417736 inverter for LCD display    - Page 1
Forum section: electronics / repair

author: ciccio
author_rank: Frequent Contributor
timestamp: January 25, 2018, 12:24:58 pm
content: I'm searching for the datasheet of the ELMAX model PLCD2417436 inverter used to drive the monitor in a Mitsubishi digital photo "kiosk".I could do with, at least, the input connector's wiring.Thanks to everyone.Best regards