hybridfree/eevblog-posts huggingface dataset:
430-5009-Z transformer help (need data) - Page 1
Forum section: electronics / repair

author: mnt22
author_rank: Contributor
timestamp: August 13, 2018, 08:51:06 am
content: HiI need to know any data about 430-5009-Z because I need to replace it I had the same problem in this topichttps://www.eevblog.com/forum/repair/apc-ups-components/I unwind the transformer first 0.75 mm 22 turns then1mm 20 turns then the same 0.75 mm continued for 22 turns and finaly the 1 mm continued for 20 turnsThe total 0.75 44 turns and 1mm 40 turns on EE or EICore .Thanks every one

author: mnt22
author_rank: Contributor
timestamp: August 24, 2018, 04:02:13 pm
content: No one know !

author: coromonadalix
author_rank: Super Contributor
timestamp: August 25, 2018, 11:40:32 am
content: Your answer will be to find the same ups ans take parts in it ... it may be an customized x-former by the way ?

author: mnt22
author_rank: Contributor
timestamp: August 28, 2018, 06:10:23 am
content: it seems it's an isolation transformer nothing special
NOAA Weather Radio is deaf. - Page 1
Forum section: electronics / repair

author: larrybl
author_rank: Regular Contributor
timestamp: August 25, 2018, 10:45:02 pm
content: This unit is over 10 years old and has worked well to notify us of severe weather here in Central Texas. I noticed a message being displayed "Check Reception". I verified the local weather repeater was working with a separate scanner. I took this apart and didn't see anything unusual, just some white crud around the antenna and power connectors. I cleaned those up with contact cleaner, and it is still deaf. I made sure the correct frequencies and SAME codes were programmed. Key pad button press produces a beep (eliminating a speaker or audio amp issue). Any thing else to check before I spend $$$ for a new one. OH, and why would they remove the chip markings on such a low end unit. I understand the Hi-end ones.

author: larrybl
author_rank: Regular Contributor
timestamp: August 27, 2018, 11:43:30 pm
content: Problem Solved.
Looking for service manual/schematics for an 'Emotiva DC-1' audio DAC unit - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: August 27, 2018, 11:19:02 pm
content: Sometimes called Stealth DAC. Emotiva service info seems impossible to come by. Can anyone here share a way to obtain it? Thanks...
Repair of HP8901B Modulation Analyser, live streaming soon. - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: August 30, 2018, 05:44:00 am
content: Hi all,I thought I would do something a little different and give people the chance to catch my live stream this weekend.I will be streaming the diagnostic and (hopefully) repair of a HP8901B at 8am this Sunday morning (New Zealand time), I think that is about 8pm/9pm Saturday night in the UK, I’m not sure of other time zones, will be earlier on Saturday for the US, about 1pm or so I think.So if this interests you drop by my channel and make a note of what time it says it will be for you in your Timezone, and also the link on the upcoming live stream to be reminded, or even better subscribe and click the bell icon to be notified that way.I hope to see you there.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: September 01, 2018, 07:14:16 pm
content: ‪I will be live streaming on my YouTube channel in about 40 minutes.‬
Replace Kzg 16v 470uf gpu capacitor - Page 1
Forum section: electronics / repair

author: FizZzyCap
author_rank: Newbie
timestamp: August 18, 2018, 07:08:39 pm
content: Hi. Would like help in finding a similar capacitor that would replace one on a gpu (GeForce 7300LE 256MB pci-e ddr2) for a pc. The capacitor brand and specs are kzg 16v 470uf. The closest or might be the same capacitor i could find ishttps://www.ebay.com/itm/10pcs-470uF-16V-NCC-KZG-Super-Low-ESR-16V470uF-Motherboard-Capacitor-8x11-5mm-/173274684410, but it read 1(7) 5K and gpu capacitor read 6(k) 8P. Im to novice to know if that have any meaning.Thanks in advance for responces.

author: wraper
author_rank: Unknown
timestamp: August 18, 2018, 07:23:06 pm
content: Don't buy Nippon Chemi-con KZG. Although it's a reputable manufacturer, KZG and KZJ series were bad. Also don't buy capacitors from ebay/China. Most from remotely reputable brand is counterfeit.QuoteYou should not bother abut date code or lot number. You should care about capacitance, voltage and ESR being not higher than original (from datasheet).http://www.nfjapan.com/datasheet/KZG.pdfEDIT: you actually could buy KZG given they are from fresh stock (from reputable distribuitor), as problems should be already fixed by now.

author: FizZzyCap
author_rank: Newbie
timestamp: August 26, 2018, 10:25:28 am
content: Thank for responce.I have a hard time finding a number associated with esr for the cap that needs replacement, finding only the terms "low esr or super low esr" ratings that are not very helpful when comparing to new caps. Do you know what that number might be?Did find thesehttps://eu.mouser.com/Passive-Components/Capacitors/Aluminum-Electrolytic-Capacitors/Aluminum-Electrolytic-Capacitors-Radial-Leaded/_/N-75hqw?P=1z0wrk5Z1yx4aw3Z1z0vn3uZ1z0vhz5Z1yzxe9eZ1z0wl9othat looks to be good based on range of low esr that mouser.com offers. Any opinion if one of those caps would be work would be to great help.

author: Rasz
author_rank: Super Contributor
timestamp: August 26, 2018, 06:35:50 pm
content: > "low esr or super low esr" ratings that are not very helpfulthats very helpful, tells you its used in DC-DC converter and needs lowESR caporiginal datasheetshttp://media.digikey.com/PDF/Data%20Sheets/United%20Chemi-Con%20PDFs/KZG%20Series_WEB.pdf36 mOhmalmost anything fromhttps://www.digikey.com/products/en/capacitors/aluminum-polymer-capacitors/69?k=&pkeyword=&pv724=5&pv724=6&pv724=7&pv724=8&pv724=9&pv724=11&pv724=1844&pv724=13&pv724=14&pv724=22&FV=1140050%2Cmu470µF|2049%2Cmu16V|2079%2Cffe00045&quantity=0&ColumnSort=1000011&page=1&pageSize=25will work
Dell L322X charging circuit - Page 1
Forum section: electronics / repair

author: marhd
author_rank: Newbie
timestamp: August 26, 2018, 11:34:29 am
content: Hi guysI am trying to repair my laptops charging circuit, but I cant seem to figure out what this particular smd component is (image attached), so I can order it.As far as I can tell it says A9EA and 2X on the side (the is E is underlined)Thanks

author: coromonadalix
author_rank: Super Contributor
timestamp: August 26, 2018, 11:56:55 am
content: Why has it been shorted on 2 pinswas it your work ?

author: marhd
author_rank: Newbie
timestamp: August 26, 2018, 12:00:08 pm
content: No not my work, I took it to someone to fix but they couldn't fix it

author: marhd
author_rank: Newbie
timestamp: August 26, 2018, 02:43:13 pm
content: bump

author: Rasz
author_rank: Super Contributor
timestamp: August 26, 2018, 06:24:06 pm
content: looks like there is silkscreen under the partbut blindly replacing parts rarely works, what makes you think its bad whatever it is? and what did the previous person did to it?
BWD160A function generator output amplifier - Page 1
Forum section: electronics / repair

author: IconicPCB
author_rank: Super Contributor
timestamp: August 26, 2018, 02:21:19 am
content: Recently I purchased an old BWS160A function generator whose health was questionable. Price was right and i did not mind.I reckoned i could find the manual on line and after all it was the seventies technology...how difficult could it be ( don't answer)?So sure enough everything bar the output amp ( buffer) was OK. The output amp is a unity gain current amplifier designed to provide notionally 50 ohm output impedance.In fact the only difference between BWD160 and BWD160A models is this buffer ( see the attachment) plus a few tweaks to the rest of the circuit ( looking at the BWD160 manual).A simple enough affair and a simple fault to locate. Replaced the faulty FET (Q1) and the output started to sing...literally.The function generator is designed to allow DC to be added to the signal waveform, the old output DC offset facility.So while the output is below the 0V DC level it is clean and stable. When the output is shifted so that any part of it becomes positive, high frequency oscillations become superimposed only in the positive portion of the signal.I have not sprayed it with new transistors yet, I am hoping someone has seen this kind of thing and may shed some light on it.TIA

author: duak
author_rank: Super Contributor
timestamp: August 26, 2018, 03:00:06 am
content: Is there actually a 1nF cap from the emitter of Q3 to V-?It's not commonly known and actually hard to believe that an emitter follower can be made to oscillate with certain values of load capacitance. It's hard to predict so if the 1nF cap should be there, it might be as a suppressor and may be bad. OTOH, if it's just stuck on, perhaps it was an attempt to cure the oscillation. If the circuit was revised, maybe the manufacturer discovered this and made some changes. I beiieve a resistor in series with the base is one solution.What's happening essentially is that the load capacitance is being transformed into an inductance as viewed from the base and because these elements are in series you can get an oscillation. If memory serves, Dennis Feucht (formerly of Tektronix) wrote up something on this condition. Search for "Feucht emitter follower oscillation".Cheers,

author: IconicPCB
author_rank: Super Contributor
timestamp: August 26, 2018, 03:58:05 am
content: Hello Duak,I was aware that th emitter follower is not unconditionally stable.I might try a ferrite bead on the base lead. It may be sufficient to kill the oscillations.And thanks for the lead for the article.
Has anyone used https://www.servicemanuals.net/ ?  Is it a good resource? - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: August 24, 2018, 04:40:48 pm
content: Thanks...

author: tautech
author_rank: Super Contributor
timestamp: August 25, 2018, 04:21:30 am
content: Quote from: cvanc on August 24, 2018, 04:40:48 pmWhy does it matter, it's another not listed here so added:https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/Had a quick bounce around in it and no doubt it will be useful for someone, thanks.
Weller WES51 ground issues - Page 1
Forum section: electronics / repair

author: AmssmA
author_rank: Newbie
timestamp: August 24, 2018, 09:52:03 am
content: HiMy soldering station is a Weller WES51 for a long time.Today the station died, the LED didn't turn on and the tip doesn't heat.I opened the station and checked the transformer power switch and voltages in the controller board. Everything appears to be ok.When i tried to verify the clock in the micro controller (PIC) and touch the oscilloscope ground probe in the common of the controller the station works.If i connect the transformer core (that is grounded) to one of the secondary outputs the station works(as you can see in one of the attachent pictures).There is continuity between the tip of the station and the ground terminal.Any ideas why this is happening?Thanks.
HP 34970A - 34901A module NVRAM error 913 - Page 1
Forum section: electronics / repair

author: mzzj
author_rank: Super Contributor
timestamp: August 24, 2018, 08:18:36 am
content: Got old HP datalogger that shows error 913 "Module reported nonvolatile memory fault".FAult seems to follow the 20-channel 34901A module.Anyone fixed one of these? I'm guessing I'd need to replace the 24C04 NVRAM chip (and possibly calibrate the thermocouple CJC)https://www.eevblog.com/forum/repair/agilent-34901-mux-card-for-34970-daq-unit/Anyone got a 34901A FRAM dump?
Telequipment S54A repair help - Page 1
Forum section: electronics / repair

author: Hengy
author_rank: Contributor
timestamp: August 23, 2018, 02:39:49 am
content: Recently got a Telequipment S54A. Pulls ~20-30W on turn-on, then 8W steady unless I turn the brilliance up all the way. CRT doesn't display anything, unless the billiance is turned up all the way, then there is a perceivable flicker from the CRT. The illuminated grid works.The ground pin on the plug was hacked off. I replaced the cord, made sure there was continuity with chassis. Still doesn't work.Here is the manual:http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Telequipment/s54a.pdfI opened the case. Looks pretty clean to me. Photos are included. I haven't checked voltages yet, just connections, and for parts that may need replacing.R138 seems to be missing - a 3.3M on page 21 that is part of the trigger circuit.Since it looks so clean, I suspect that the problem lies with the CRT itself.Can anyone see anything obvious from the photos? Suggestions?If not, I shall check voltages and report back.Thanks, Hengy

author: poot36
author_rank: Frequent Contributor
timestamp: August 23, 2018, 04:13:45 am
content: I would at minimum replace D401 and D403 as it is a selenium diode part of the high voltage doubler for the CRT and is known for going bad. They went bad on a similar version of my scope as well (mine has vacuum tubes in it though). You must make sure to match the voltage drop of a selenium diode or else you risk over driving the CRT. I think they usually have voltage drop of around 9V but I could be wrong. Don't forget a current limiting resistor and make sure the components you choose for this are rated to 3.4KV or more. I would try the scope in TV trigger mode and see what happens.

author: Hengy
author_rank: Contributor
timestamp: August 23, 2018, 11:38:50 pm
content: How would I got about replacing those diodes? They are rated 3.4kV, so would 4 1n4007 diodes in series + a series resistor work?I may be getting ahead of myself... I still haven't had a chance to check voltages.Hengy

author: poot36
author_rank: Frequent Contributor
timestamp: August 24, 2018, 02:27:44 am
content: You would need at least 5 1n4007 due to the reverse break down voltage of the diodes as well as a safety margin in case something goes wrong.
Pc monitor Samsung SyncMaster 930BF white screen - Page 1
Forum section: electronics / repair

author: nerko
author_rank: Newbie
timestamp: August 22, 2018, 06:10:50 pm
content: I have Samsung SyncMaster 930BF and start to show white screen. Tryed it on different computor and other cables but still show white screen. I reed on internet that can be bad capacitors so I take it apart to see bad capacitors, top of capacitors are flat. On big capacitor lead show electrolyte leak ( see picture ) is this bad capacitor.

author: Specmaster
author_rank: Super Contributor
timestamp: August 22, 2018, 06:16:12 pm
content: Yes that capacitor is leaking, bu somehow I doubt that is the only fault as normally when a capacitor fails the monitor does not switch on, but yours is and your getting just a white screen so I suspect other issues as well.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: August 23, 2018, 02:15:28 am
content: Quote from: Specmaster on August 22, 2018, 06:16:12 pmYes it is bad cap and yes i doubt it is reason for the trouble.Any case replace it and see what happens.

author: mzacharias
author_rank: Frequent Contributor
timestamp: August 23, 2018, 09:59:58 am
content: If the monitor has a visible T-con (timing and control) board, check to see if the chips on that board remain cold as it's running.If so, I have seen very small "chip" fuses bad on those boards in some monitors and TV's. Might be your problem.

author: mariush
author_rank: Super Contributor
timestamp: August 23, 2018, 10:15:44 am
content: Yeah, big cap leaking, going bad... but not dead yet since you still get backlight so the power supply produces power.Backlight is something like 20v which gets boosted to hundreds of volts by the inverter so that voltage doesn't have to be that accurate, but the psu could otherwise be unstable.The psu will also produce voltages like 3.3v and 5v for the digital board (processor chip) and often a higher voltage like 12v if some models in that series had audio features and therefore audio amplifier chips.These smaller voltages may be unstable.Use multimeter to measure them at connector between boards.the digital board will probably also have some linear regulators that for example podoce 2.5v or 1.8v from 5v. check in and out voltage, check tiny fuses on that board... sometimes (rarely) input caps on that board go bad but visually they look ok.so basically do more checks and report results here.

author: amyk
author_rank: Super Contributor
timestamp: August 24, 2018, 02:02:24 am
content: Unplug the cable between the board and the panel and see if it's still white.
Speaker Grill construction - Cerwin Vega AT-12 - Page 1
Forum section: electronics / repair

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 23, 2018, 10:40:15 pm
content: Hi,This project is more woodworking than electronics. I am going to share the construction of a pair of speaker grills for a vintage Cerwin Vega AT-12 loudspeakers. This shows How I did for the Cerwin Vega's, the techniques should work for other brands.I have bought two pairs of CV speakers, AT-10 and AT-12. The AT-10 speakers came with grills, the AT-12 did not. I used the AT-10 grill as a guide for fabricating the new grills.I cut the new grill frames from 3/4" MDF board. The outside dimensions are 14 x 26 inches.There is a 45 degree bevel on the front side:And recess for the bass driver on the rear side:Here is a picture of the grill attach pins:I found similar pins at two places:https://www.parts-express.com/parts-express-heavy-duty-speaker-grill-guides-12-pair--260-367Andhttps://qcomponents.ca/McBride-GRILL-PIN-LARGE.htmlI bought these pins:To make these pins work, I added some spacer washers cut from 1/4" plywood.To be continued …Regards,Jay_Diddy_B

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 23, 2018, 10:48:34 pm
content: Hi group,The construction continued by staining the frames black:I used Unicorn Spit from the Home Hardware store. (Why use snake oil on an audiophile project, if you can get Unicorn Spit?)I then covered the frames with black speaker cloth that I bought from Fabricland.Here is a picture of the finished project:Regards,Jay_Diddy_B

author: oventech
author_rank: Contributor
timestamp: August 23, 2018, 11:20:09 pm
content: Nice work. Turned out really good. Never heard of "Unicorn Spit" before. Have to keep this thread in mind if i have to redo (make) a new speaker grille. I know some guys on AudioKarma.org would enjoy seeing the result.

author: salvagedcircuitry
author_rank: Regular Contributor
timestamp: August 24, 2018, 12:02:29 am
content: Nice job! My neighbor threw out a pair of AT-12's about 2 years ago. The speaker surrounds were completely rotted out. I was going to fix them but I simply did not have the space to keep them, so I put them up on craigslist free. Crazy.
Help me repair my 1080 ti or diagnose if it can t...  - Page 1
Forum section: electronics / repair

author: enisal
author_rank: Newbie
timestamp: August 23, 2018, 11:03:42 am
content: Hi,My 1080ti aorus extreme edition stop working. So what happen is that i modded with a water cooling solution from NZXT - KRG12 link below for ref.https://www.amazon.fr/NZXT-RL-KRG12-B1-Carte-contr%C3%B4leur-pour/dp/B06XXF4Q68/ref=sr_1_7?s=computers&ie=UTF8&qid=1535020183&sr=1-7&keywords=NZXTAnd i made the mistake to power the fan with a connector attach to my front panel case, and it got disconected, i somehow hit or move the panel to disconect it.So i assume that something went wrong in the area that the fan was suppose to cool down.Could anyone point me what should i check in priority and where to prob for potential problem.Here is the picture of the front and back of the card and the NZXT adapter:

author: Dave_C
author_rank: Contributor
timestamp: August 23, 2018, 12:12:48 pm
content: The fan was supposed to cool down the VRM's, but on that photo I don't see any visible damage. Did it smoke?Look for damages in the Diodes/Transistors, signs of thermal stress on resistors etc.If you can't see anything then troubleshooting it without schematics will be tricky.

author: Shock
author_rank: Super Contributor
timestamp: August 23, 2018, 06:27:38 pm
content: Does it post with the proper power and fans connected?
Amp fuse - Page 1
Forum section: electronics / repair

author: nus
author_rank: Contributor
timestamp: August 22, 2018, 06:59:20 pm
content: beta three ua 2000got and old amp wanted to see if i could repair it, but it seem like the mains fuse is missing. cant seem to find the fuse rating in the manual. it says 220v 1500 va so would i be fine just thowing a 7amp 250 volt fuse in there.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 22, 2018, 08:23:53 pm
content: You could put an 7 or 7.5 amps slow blow, would be enough to take a few boom boom loll1500va / 220 vac is 6.8 amps

author: mzacharias
author_rank: Frequent Contributor
timestamp: August 23, 2018, 09:54:14 am
content: DO NOT simply add the VA rating to get an appropriate fuse value. The value should be printed somewhere near the fuse, if not - post back here with a MAKE AND MODEL number and we can probably look it up.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 23, 2018, 10:54:20 am
content: okay on some audiophiles websites you have an t20 slow blow fuse for 220 vac, t40 slow blow at 120vac is it enough ??Way more than expected and deduced values in my previous post, this one puts tons of amplification wattage ...Stereo w/ch 1000w x 2/8Ω - 1600w x 2/4Ω - Bridged mono 3200w/8ΩThis puppy has no fuses markings on the case ... ask the company to be really surehttp://www.livansud.com/index.php/audio-pro/potencias/beta-3/ua2000.html

author: mzacharias
author_rank: Frequent Contributor
timestamp: August 23, 2018, 11:47:07 am
content: Apparently this is a very high power unit. Therefore I would suggest using ONLY a manufacturer recommended fuse.I suggest ordering from the manufacturer or distributor. There are special safety considerations for very high power equipment.
looking for Phillips PLHC-T801A power supply schematic ? - Page 1
Forum section: electronics / repair

author: kripton2035
author_rank: Super Contributor
timestamp: August 21, 2018, 04:48:26 pm
content: if anyone ?this would be very much appreciated.it is for a 47" lcd tv.thanks.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 21, 2018, 08:26:13 pm
content: Search the part number on the board, it may tell you other tv models / sizes and do an google search ...

author: kripton2035
author_rank: Super Contributor
timestamp: August 21, 2018, 09:59:05 pm
content: PLHC-T801A is the part number ?!?!?google gives you people searching for italso people that seems to have the schematic, but only give clues to fix it

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 22, 2018, 11:22:04 am
content: Not the exact PSU as the schematic given appears to be for up to 42" models:http://www.go-gddq.com/upload/2009_06/LC8-2A-LA.pdfPossibly close enough to at least help understand.From personal experience with these psu's and from a first glance at the schematic beware of, (referring to schematic in link):(bulging secondary capacitors of course...)Bad solders on transformersIC901 (ICE3AS02 standby power PWM)C613,C625,C626 on main powerC310,C311,C315 on backlight power

author: kripton2035
author_rank: Super Contributor
timestamp: August 22, 2018, 04:10:35 pm
content: thanks but this is not the right schematic.the broken circuit is a fairchild FSQ510, there is none in this manual.I replaced it (and a fried resistor) but the power is still ticking (one relay is ticking in fact)

author: coromonadalix
author_rank: Super Contributor
timestamp: August 22, 2018, 08:26:29 pm
content: the tick maybe a synonym of an short circuit still present, the supply tries to start and shutdown because of the short
Datron 1081 and 1065 repair help. huge offset on readings - Page 1
Forum section: electronics / repair

author: ThunderMink
author_rank: Contributor
timestamp: August 22, 2018, 05:46:32 am
content: Hello.Was wondering if anyone have seen this problem on Datron multimeters.I have a 1081 and 1065 that is having similar problemsThe 1065 had a relay problem a while back that resulted in an huge offset in the readings about several 100 volts in the 1000v range. actually all ranges was the same. with shorted inputs the readings was like 0.2 / 2 / 20 / 200 , i thought that it was the relay on the analog board that was acting up again but when i replaced it nothing changed.The only thing positive is that my 1081 is having the exact same problem so i need to find the root cause on the 1065 and hopefully it is the same fault on the 1081Any help would be very helpful

author: Gyro
author_rank: Super Contributor
timestamp: August 22, 2018, 08:42:21 am
content: Hi,Your first stop should be the service manuals...http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=06_Misc_Test_Equipment/Datronif you haven't already found them.Tantalum beads caps with high leakage and degrading Opto-isolators are common failures on Datron meters of that vintage. Your best bet is a methodical rather than shotgun approach, eg. Check the main analogue supplies and the bootstrap supplies. try to find the offset at the input of the A/D circuit block with another meter and either trace backwards across the analogue board or diagnose the issue with the A/D circuit.P.S. A forum search for Datron should bring up a few relevant threads, from what I remember.

author: ThunderMink
author_rank: Contributor
timestamp: August 22, 2018, 10:15:07 am
content: Thank you for the reply GyroI have the manuals and have went through the common faults. Powersupplies, Optocouplers and relevant logic ic's. i think i will replace all tantalums on every board as i have repaired a 1061 and 1071 before and both had problems with unstable tantalum caps.i will try to re-seat all ic's again as the 1065, was working fine last week and have been working for over two year since the first repair.As for the 1081 i need to re check all the power rails again using my scope. May be the lm309 that is acting up. or maybe a bridge rectifier or tantalums.I have went through most of the datron posts here and they are of great helpOn my 1071 the main problem was the bootstrap power supply that produced about + - 12v on the outputs. The problem was IC M16 on the analog board
Telequipment S54A no trace, sawed off ground - Page 1
Forum section: electronics / repair

author: Hengy
author_rank: Contributor
timestamp: August 22, 2018, 12:12:01 am
content: I recently got a well-used (looking) Telequipment S54A scope from auction. First thing I noticed was that the ground pin on the power plug was sawed/hacked off. I tried plugging it in anyways, just to see if it worked, and I didn't get a trace. I followed the instructions for first-time operation, so I think all the knobs were in the correct position, and I was using the front panel 50mVp/p Cal output. The screen illumination works, and it draws about 7W at the plug. If I turn the brilliance up (clockwise) all the way, it suddenly draws 22W, and I can see the screen illumination (or maybe the CRT itself) flicker slightly.I haven't opened it up yet. Could the lack of ground be the problem? Given a working screen, do I need to reattach the ground pin? I assume the AC coupling mode might not work, and obviously the ground plug on the front would be useless...Thanks, Hengy

author: xrunner
author_rank: Super Contributor
timestamp: August 22, 2018, 12:18:16 am
content: Quote from: Hengy on August 22, 2018, 12:12:01 amIt's a bad thing but shouldn't prevent the scope from displaying a trace.QuoteYes! Get a replacement plug and fix the line cord.
Pot match? - Page 1
Forum section: electronics / repair

author: harps
author_rank: Regular Contributor
timestamp: August 21, 2018, 03:19:41 pm
content: helloI need to replace a few pots on a Roland td-12 module circuit board,but i can not open the unit yet until i know it is a likely possibility that i may find a part that may work.I attach an image of the pots that need to be replaced, which I found online,also a picture of a pot (Alps RK12L12) that might fit . and a bourns PTV112-4420A. they are the only ones that look similar.I wonder does anyone know if this type of pot is a standard part, where the footprint is always the same?thanks for any help you may offer.

author: floobydust
author_rank: Super Contributor
timestamp: August 21, 2018, 08:49:16 pm
content: I would say it's a Panasonic EVJ-Y dual potentiometer 12mm. Pic matches. Roland sticks with fellow Japanese manufacturers.They are quite popular, but Digikey shows them as obsolete (EVJ-Y, EVJ-C) with some stock still, Mouser has them too.You just have to find the taper (linear or logarithmic) and ohms value, and if there is a center-detent or not. Some are metal bushing, or plastic with sleeve, or no sleeve.

author: harps
author_rank: Regular Contributor
timestamp: August 21, 2018, 09:10:54 pm
content: Wow, thanks so much. i didn’t see these onesthat is great, i shall try those out.thank you so much : )Edit digikey = Bourns PTV112-4420A-B103-ND worked fine.not as liquid smooth to the turn/feel as a panasonic , but the footprint and pins are pretty much identical also linear 10k.
td-12 potentiometer - Page 1
Forum section: electronics / repair

author: harps
author_rank: Regular Contributor
timestamp: August 20, 2018, 07:37:08 pm
content: helloi wonder does anyone know where to buy the PCB pots for master, mix and headphone on a Roland TD-12?from a photo it seems they have 6 pins. I presume they are analogue dual pots not encoders.Thanks for any help you may offer.

author: floobydust
author_rank: Super Contributor
timestamp: August 20, 2018, 08:31:38 pm
content: Post pics of the potentiometer, there are 100's of different makes/sizes.

author: harps
author_rank: Regular Contributor
timestamp: August 21, 2018, 06:42:21 pm
content: hi i have added photosplease see on this eevblog post.https://www.eevblog.com/forum/repair/pot-match/admin please can you delete this post thank you.i did click remove, i thought i was gone.sorry for the trouble.
My Old Faithful Wavetek 178 Programmable Waveform Synthesizer Won't Start Now - Page 1
Forum section: electronics / repair

author: dfiorijr
author_rank: Newbie
timestamp: August 20, 2018, 11:59:33 pm
content: Help! I'm at my wits end trying to troubleshoot my old faithful. I am the original owner, and happy since about 1985 until just a few weeks ago. It won't get past the usual 1 second display of all segments on the display lit. Attached are a couple of photos that prove all the characters are being scanned with all segments in each character turned on.I still have the complete user manual which includes all the schematics, calibration procedures, troubleshooting guide, and detailed theory of operation. So I have been working on this for a couple of solid days already.It passed all the usual suspects: All the power supplies, isolated and non-isolated are present and are at specified values. Address bus signals on the microprocessors are all active as are the data lines. All the processors have the proper clocks going to them.I know it's an old instrument, and there are a lot of IC's in DIP sockets in the front panel display and keyboard, so I re-seated every IC on the front panel display and keyboard board that had a socket. All the processor are in DIP sockets too so I carefully removed, cleaned pins, and replaced each one. All the IC's in sockets have been removed and replaced now to no avail.The only things worth mentioning that I have noticed are these four things: (1) There is only a single pulse, likely a start bit, output by the front panel display and keyboard board from it's serial output line when the unit is started up and there is no activity at all on the one serial input line from the frequency board to the panel display and keyboard in return. (2) The watch dog timer circuit that watches the processor that controls the frequency board is constantly reseting that processor because without any serial response from it's own output the watch dog timer circuit times out and resets the processor it is watching. (3) There are no keyboard scanning pulses just as there is no activity to the display segment decoder IC. The processor is apparently neither reading the keyboard nor making an effort to use the display. (4) The beep that normally sounds is missing, although the unit appears to make a faint effort when it is first turned on.It's not clear if the front panel display and keyboard board is not completing messages required before the frequency board processor would reply or if the frequency board processor is not able to startup correctly.My hope is that someone has some experience with this problem can share their experiences and offer a suggestion. A little information about the behavior of the system, for example, when one of the serial signals is interrupted, and how that front panel display should react to that might be helpful.

author: picburner
author_rank: Frequent Contributor
timestamp: August 21, 2018, 05:58:06 am
content: From what you said about the watchdog, it could be the firmware corrupted.In this case you can find the files here:https://www.eevblog.com/forum/repair/wavetek-178-need-repair/
DSO 150  - Page 1
Forum section: electronics / repair

author: Smash54
author_rank: Newbie
timestamp: August 21, 2018, 02:28:52 pm
content: Hello AllAny help with this little scope would be greatly appreciated, It worked fine till I adjusted the voltage too low and it died. It comes on shows nothing good on he screen if I adjust the voltage down below 6 volts it starts to work just not right. I only need it for one project viewing AC voltage coming out of a Guitar I added the Schematic.
Eizo S2433W Monitor No Power - Page 1
Forum section: electronics / repair

author: maverick4400
author_rank: Newbie
timestamp: August 20, 2018, 09:22:34 pm
content: Hello,I have a Eizo S2433W monitor which has no power at all. I take out the power supply board and make some measurements. I am suspecting couple of transistors but not sure how to check them. (one of them is Toshiba K2998 which is a discontinued product)I am attaching the picture of the board and some notes on it. I would be very happy if someone has the circuit diagram of the board because I have no idea about the voltage connectors.I would also happy to hear any measurement suggestions.Best Regards,Umut.
PSU Tektronix PS 2510G - Page 1
Forum section: electronics / repair

author: SteF
author_rank: Newbie
timestamp: August 18, 2018, 02:43:54 pm
content: Hello friends,I recently bought a Tektronix PS 2510G PSU;it delivers 3.5A from 0 to 36V, but fails to go beyond 28V;when I try to activate the load with a voltage higher than 28V appears error 013 on the display, it seems to be a problem to one of the relays ...does anyone have the scheme of this power supply available?ThxSteF

author: siggi
author_rank: Regular Contributor
timestamp: August 19, 2018, 12:19:23 pm
content: Quote from: SteF on August 18, 2018, 02:43:54 pmI believe error 13 is when the over voltage protection trips. Sounds like the OVP is set for 28V, have you tried increasing it?Sent from my iPad using Tapatalk

author: SteF
author_rank: Newbie
timestamp: August 20, 2018, 02:13:59 pm
content: Hello,yesI checked it … the OVP is set for 35VIt seems like a problem with one of the three relays …SteF
Replacing NTC thermistor in old coffee maker - Page 1
Forum section: electronics / repair

author: Philly_Dee
author_rank: Newbie
timestamp: August 19, 2018, 03:16:31 pm
content: Hello all,I am trying to get my old coffeemaker to work after it stopped heating. This is a common issue I think after a few years. We've already bought a new one, so this is strictly for "fun" and to learn a few things. It's a KRUPS KM720 that I always liked. I've already bought two thermal fuses to replace the old ones : Microtemp G4's rated at Tf = 184 C. I'm pretty sure they were identical, placed on either side of the heating element.My problem now is replacing the small NTC thermistor (glass-encased bead type), which is placed against the element (with some white stuff in between, for thermal conductance ?) and looked very much like these :http://www.ces-eshop.com/dir/image/cache/data/vnnew/ntc-500x500.jpgUnfortunately I've lost the old one, but before that I was able to measure its resistance at between 10k and 20k Ohms (at room temperature). However at the electronics store, one guy measured it at 100 kOhms on his multimeter. But we were wrongly assuming at that time that it was a zener diode (which can look quite similar except for the black band at one end, not present in my case), so his measurement may have been at the wrong setting.My question is: does anyone know what specs would make sense to replace the NEC thermistor in this coffee maker?From what I understand, the two parameters are resistance at room temp (25 C) and the B / beta which characterizes the rate of change versus temperature change. From what I see on e.g. Amazon, the most common specs are 10 kOhms and beta = 3950. But of course the original design could have called for different specs.Thanks for any advice.

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: August 19, 2018, 04:07:04 pm
content: Hi, first welcome to the form.Since the old one is not available, may be you could get a schematic somewhere and find the old part number.Just off the top of my head I would think you would need to know the temperature vs the resistance of the part in order to find some like part.I'm sure others here have the same coffee maker so they could be of help.Good luck.

author: ogden
author_rank: Super Contributor
timestamp: August 19, 2018, 04:17:30 pm
content: I just googled for few minutes and appears that 1)service manual is available online, 2)you can buy spare parts from krupsusa. Part you are looking for is "44718 NTC­temperature sensor complete.". Disclaimer: it's not my typo.

author: Philly_Dee
author_rank: Newbie
timestamp: August 20, 2018, 02:16:05 am
content: Thanks for the replies. Unfortunately the service manual is for another coffee machine (they don't have it for model KM720), but perhaps it's the same sensor. I'm not sure how to order that part from Krups but I will contact Krups Canada to start (the USA corporate divisions don't always deliver to Canada).I'll let the forum know how it goes...
Looking for a legible copy of HP8566B spectrum analyzer service manual - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: August 18, 2018, 12:01:46 am
content: I am trying to troubleshoot HP8566B spectrum analyzer. Its issue is YTO unlock.What I would like to have is a Service Manual with legible circuit diagram. HP/Keithly website has a downloadable version. Its text are decent but fold out circuit diagram are awful because it's reduced in size. I cannot read most labels or figures.Does anyone know of a place where I can download or buy LEGIBLE copy of this manual?

author: Tony_G
author_rank: Super Contributor
timestamp: August 18, 2018, 12:39:14 am
content: Artek Manuals has this -http://artekmanuals.com/manuals/hp-manuals/I've bought many manuals from them, they're licensed by Keysight to do this and thus invest in high quality scans.Can't recommend them highly enough.TonyG

author: tkamiya
author_rank: Super Contributor
timestamp: August 18, 2018, 01:54:25 am
content: THAT'S the name I've been trying to recall....! Thank you.

author: tkamiya
author_rank: Super Contributor
timestamp: August 18, 2018, 02:57:15 am
content: Purchased!

author: Tony_G
author_rank: Super Contributor
timestamp: August 18, 2018, 07:37:45 pm
content: Good to hear, look forward to you thread on the repair of that beast.TonyG

author: PaulAm
author_rank: Frequent Contributor
timestamp: August 20, 2018, 01:13:59 am
content: If you can get access to a large format printer you'll find their scans produce wonderfully crisp and legible schematics.I got an old designjet 650c for $50 and now I can print schematics as big as I want. For something like the 8566b that can be helpful.

author: rx8pilot
author_rank: Super Contributor
timestamp: August 20, 2018, 01:15:53 am
content: Artek is a great resource - I have a few pieces of gear saved by their manuals.
Tektronix 475A repair - Page 1
Forum section: electronics / repair

author: iainwhite
author_rank: Unknown
timestamp: August 18, 2018, 06:54:47 pm
content: I picked up a Tek 475A to learn about analog Oscilloscopes as numerous posters recommend doing so (e.g. W2AEW, Dave's EEVblog #86 video)I am creating this thread to document my experiences and repairs for myself, and maybe to help other members.It came with an Instruction manual, an undamaged front plastic cover and two old-ish probemaster 10x probes and a temp probe for the DM-44.I noticed a couple of issues fairly soon - the ext trigger BNC shroud is bent and the channel B trigger +/- switch is not "clicking" into the detents - just a vague quarter-turn in each direction.Initially, the scope seemed to work fine and I got a cal signal up on the screen (picture 1).However, after a day or so (and maybe an hour total time powered-up) I switched it on and there was no display on the screen.I took the case cover off and proceeded to check the test-points on the power supply board as recommended in the service manual.The +5V, +15V, +50V, +110V were all fine and within spec.The -8V and -15V were both wrong (-0.02V and -22.8V respectively)I checked the Bridge rectifier CR1462 and found that there was a 120Hz 0-14.5V signal rather than a smoothed half-wave you would expect.This pointed to a failed filter Cap C1462 (picture 2,3).

author: iainwhite
author_rank: Unknown
timestamp: August 18, 2018, 06:56:08 pm
content: I desoldered and removed the Cap. Needed a big D32 chisel point tip and good solder braid (I used Chemtronics SodorWick SW-80 series; MG SuperWick 400 series is also good) (picture 1)I purchased a Nichicon LGY-series 5600UF 20% 50V Cap (DigiKey 493-8658-ND) to replace the failed Sprague cap.I also purchased a 3300UF cap from the same series (DigiKey 493-8651-ND) in case I had trouble with the equivalent cap on the power supply.I also purchased a selection of Tantalum caps, as I expect I will need to replace some of them.From DigiKey:478-4171-ND CAP TANT 10UF 35V 10% RADIAL478-4179-ND CAP TANT 4.7UF 35V 10% RADIAL478-1877-ND CAP TANT 22UF 25V 10% RADIALFrom Tayda Electronics:A-265 1uF 35V Radial Tantalum CapacitorA-1609 4.7uF 25V Radial Tantalum CapacitorA-422 33uF 16V Radial Tantalum CapacitorI ordered an adapter pcb from OshPark to adapt the 2-pin Nichicon Cap to the Tektronix 4 pin layout and some Harwin H2101-01 PC-pins (DigiKey 952-1433-ND) to mount it (picture 2).

author: iainwhite
author_rank: Unknown
timestamp: August 18, 2018, 06:57:45 pm
content: I made up the mounting board for the new 5600 uF cap and soldered it in place.I needed to trim the pins on the top side (under the cap) to provide clearance. (picture 1)Tested it OK and ready to solder in to the scope.

author: PaulAm
author_rank: Frequent Contributor
timestamp: August 20, 2018, 01:19:47 am
content: Nice scope. Generally, if I have to replace one of the filter caps, I replace all of them. It's not that much more work and it will save you having to do it again in a couple months. Those caps are a well known failure mode.The PCB adapter makes for a very nice repair.
Corsair TX650W won't start, controller IC cycles - Page 1
Forum section: electronics / repair

author: lordvader88
author_rank: Frequent Contributor
timestamp: August 19, 2018, 07:09:12 pm
content: I have this TX650W that hooked up to a PC, just keeps cycling. The 5V STBY DC-DC section seems fine. The 12V,5V,3.3V seems fine except for some spikes that might set off the over-volatge?, but IDK.The controller chip on the secondary is PS229https://www.techpowerup.com/articles/160/images/ps229.pdfthing cycles through the normal start-up, FaultProtectionOutput goes low for 300ms as it runs the rails at load levels. And the voltages do look well within spec's except for some spikes on different run's I tired on a Tek2430A using its fancy capture features.I've mapped out a lot of the schematics, but not all yet, and lot's I don't understand/new to me of how these work. The primary side is a lot more straight forward in my mind.Basic ESR in-circuit cap test seems about right...but I'm really new to using this LCR meter. The opto's are working about what makes sense to me.On other incredibly similar contoller ICs, they say that 5mV difference between Vsense and Isense will trigger over-current-protection and FPO will go back to high. I really don't know it thats the problem. I don't really trust my Tek2430A trying to measure 5mV between 2 channels.I have a BM869 and a Keithly 171 microvolt DMMBut to really get a 5mV measurement, in the 300ms that it tries to run normal..........I don't see that working well either for me.What normally causes cycling problems ?And with regards to under/over voltages spikes, some of which would be higher/lower than the ref. voltage, how long is the time duration of them that would trip OV/UV and , Would the chip wait the full 300ms before going back to FPO high state...meaning an opto shuts off the power to the PFC/PWM chip on the primary side.
I need boardview samsung np530u3c - Page 1
Forum section: electronics / repair

author: eletmoraes
author_rank: Newbie
timestamp: August 18, 2018, 01:39:12 pm
content: I am the same user who posted on the problem of charging the lithium battery, but now I need the boardview of the np530u3c samsung card to be able to identify possible power failure in the BQ24735
samsung NP530U3C-AD5BR laptop does not charge battery - Page 1
Forum section: electronics / repair

author: eletmoraes
author_rank: Newbie
timestamp: August 18, 2018, 12:26:16 pm
content: platform: BA41-02040AN Y BA41-02022AGCE BA41-02021AThe owner of the notebook changed the battery by putting one of the bestbattery but the problem continues.I searched the internet and found this battery to buy only that I saw that the wires of the 9-pin connector differ from one battery to another according to the attached images. Maybe the problem is in the battery or in the charges circuit.voltage at the J506 connector pins (lithium battery connector):pin 1 --> 3vpin 2 --> 3vpin 3 --> 3vpin 4 --> 3.38vpin 5 --> 3.38vpin 6 --> 2.61vpin 7 --> GNDpin 8 --> GNDpin 9 --> GNDobs: only obtained using the AD4019A power supply and without the use of the lithium batteryI ask colleagues, what is the correct voltage of all the pins of the BQ24735 when I am not using the lithium battery?
Anyone experience with Crown XTi amplifier repair ? - Page 1
Forum section: electronics / repair

author: prutser
author_rank: Regular Contributor
timestamp: August 18, 2018, 08:15:29 am
content: Somebody at Crown had a nice idea to save cost. They clamped 2 heatsinks on top of each other. To replace to power transistors the topheatsink needs to be removed. So far I managed to get 2 off, but needed to apply a lot of mechanical force, which I do not like ) and it took me about 10 minuteper heatsink.Anyone experience with this amp and knows how to remove those heatsinks nicely ?

author: Shock
author_rank: Super Contributor
timestamp: August 18, 2018, 09:47:48 am
content: Quote from: prutser on August 18, 2018, 08:15:29 amNot removed them. Some ideas though.Getting them apart in place I'd try using a wide L shaped wedge tool with short edge and use slight fulcrum motion moving between spots to part the heatsinks. Google "paint can opener". The other is if you found something suitable to wedge into the gaps, a C clamp could be used to pry them apart.From the looks of them though, compression would be required to reassemble. Then I would say remove the whole pcb, then removing the heatsink assembly from the PCB would be the best idea as it seems the safest for reassembly.