hybridfree/eevblog-posts huggingface dataset:
HP54815a infiniium repair - Page 1
Forum section: electronics / repair

author: meriororen
author_rank: Contributor
timestamp: April 20, 2017, 01:31:25 am
content: Hi,Hello from Japan. There're plenty of old electronics here that can be picked up from japanese "eBay", the Yahoo Auction Japan.Recently I bought an old HP 54815a, no probe for about $150. It doesn't boot, only brings me to that old AMI boot display then itsays "Battery Low" and gives me 2 choices: F1 to do bios setup, F2 to load defaults.So I did the BIOS setup (the setup is WINBIOS, with GUI! I can use mouse),looking at the manual (just basic one from keysight website), I set :- clock- IDE controller to be primary (this one is disabled by default)and do save and exit.However, when it boot again, the "Battery Low" is still there, entered the setup again, and saw that- clock setting is retained from the previous setup- IDE controller is back at disabled!!I checked the battery, and it still has 3.2v in it, just to be sure, I bought a new battery, this one hascr2354 battery with seat, so I had to desolder it to replace a new one. The original one is Panasonic cr2354/GUNI couldn't find that here in Japan, so I bought similar replacement that is cr2354/GUFK. checkedit has 3.2v and soldered it in.The problem persisted. It still says "Battery low".I am guessing the problem is in the bios memory itself (hopefully not the mobo). However I am not really surebecause the clock setting is ok.The bios memory is a combination of volatile cmos sram (sony cxk58257cm-70ll) with dallas ds1210s nvram controller.So now I am waiting for replacement ds1210 and sram (I couldn't find cxk58257cm anywehere, so I am ordering cxk58257am,hopefully it's the same)Anyone have thoughts on this?

author: meriororen
author_rank: Contributor
timestamp: April 21, 2017, 02:54:35 am
content: OK, quick update.I was looking at wrong battery all the time..That was probably backup battery for calibration data, since it's on IO Board! Silly me.The correct battery is a Dallas DS12887A, basically integrated RTC + NVRAM + battery. It's easy to rework this chip apparently if I googled it down a bit..http://www.mcamafia.de/mcapage0/dsrework.htmSo there it is, it boots up perfectly! 4th channel seems dead tho..
HP-8569 Manual?? - Page 1
Forum section: electronics / repair

author: AF6LJ
author_rank: Unknown
timestamp: February 08, 2017, 11:55:13 pm
content: Does anybody know where I can get a readable copy of an HP-8569 operating and service manual??The online copies I have seen are garbage to put it nicely.

author: tautech
author_rank: Super Contributor
timestamp: February 09, 2017, 11:52:50 am
content: Quote from: AF6LJ on February 08, 2017, 11:55:13 pmFound a few Sue from the links in the repair board sticky but can I ask is it a 8569, or A or B you're looking for ?

author: AF6LJ
author_rank: Unknown
timestamp: February 09, 2017, 01:42:15 pm
content: Quote from: tautech on February 09, 2017, 11:52:50 amIt's the B version...

author: tautech
author_rank: Super Contributor
timestamp: February 09, 2017, 07:54:09 pm
content: Quote from: AF6LJ on February 09, 2017, 01:42:15 pmOK. To help narrow down a different copy than those you've seen, what was the size (Mb) of the not so good ones you've looked at ? That would otherwise have me downloading and checking each oneso better you do that.

author: AF6LJ
author_rank: Unknown
timestamp: February 09, 2017, 09:27:49 pm
content: The one from the HP archive which is 33 or so MB is unreadable in many of the schematic pages...That copy seems to be all over the net...The operating manual is not a problem since it doesn't contain any of the service information. I have good copy of the operating manual.

author: MadTux
author_rank: Frequent Contributor
timestamp: February 09, 2017, 11:36:52 pm
content: Artek has it, for $17,50.Isn't exactly cheap, but in some cases, I rather pay a little bit than be without any (usable) service manual.And their manuals are mostly excellent quality.

author: AF6LJ
author_rank: Unknown
timestamp: February 10, 2017, 12:06:18 am
content: Quote from: MadTux on February 09, 2017, 11:36:52 pmThanks, I'll check them out....I am not adverse to paying for a decent copy of the manual.

author: tautech
author_rank: Super Contributor
timestamp: February 10, 2017, 06:26:25 am
content: Yep, most of them are that 34 Mb file and they look quite OK for a scan except a section of diagrams in the middle of the pdf that are unreadable.But try this one Sue:http://docplayer.net/20826948-Operation-and-service-manual-8569b-spectrum-analyzer-includes-options-ool-and-002.htmlI haven't checked it all the way through.

author: AF6LJ
author_rank: Unknown
timestamp: February 10, 2017, 02:03:40 pm
content: Quote from: tautech on February 10, 2017, 06:26:25 amThis Operation manual isn't bad...I am about to enter a repair mode so that won't be much help...Thank You for looking.

author: AF6LJ
author_rank: Unknown
timestamp: April 19, 2017, 11:30:33 pm
content: Woops..Wrong thread..
capacitor replacement - Page 1
Forum section: electronics / repair

author: mensahotoo
author_rank: Newbie
timestamp: April 19, 2017, 07:12:22 pm
content: please I have an adapter and will like to replace the capacitor of 47uf and 400v with 68uf and 450v.will it work?

author: Samogon
author_rank: Frequent Contributor
timestamp: April 19, 2017, 07:37:01 pm
content: That will work, going up in parameters is safe.

author: agehall
author_rank: Frequent Contributor
timestamp: April 19, 2017, 07:50:23 pm
content: You don't say where the capacitor is being used. Going up in voltage is not a problem but changing the capacitance of it may or may not be OK. I'd recommend getting a 47uF cap instead of your 68uF one.

author: rob77
author_rank: Super Contributor
timestamp: April 19, 2017, 07:56:30 pm
content: if it's the main filter cap after bridge rectifier and there is no active PFC then it's safe to replace 47uF/400V with 68uF/450V. but i'm wondering if it fit's mechanically... 68/450 will be twice the volume of 47/400...

author: donmr
author_rank: Regular Contributor
timestamp: April 19, 2017, 08:05:09 pm
content: Quote from: rob77 on April 19, 2017, 07:56:30 pmBut a new 68/450 may still be smaller than an old 47/400. I've had troubles getting new caps to fit into old devices because they are too small.

author: james_s
author_rank: Super Contributor
timestamp: April 19, 2017, 08:09:36 pm
content: I'm not going to make a blanket statement that it will always work, but in this case I think it is 99% likely that going from 47uF to 68uF will not cause any problems at all. If it physically fits I would try it, usually for things like this physical size is the limiting factor.

author: wraper
author_rank: Unknown
timestamp: April 19, 2017, 08:28:30 pm
content: The only problem going up with capacitance is higher inrush current, therefore more stress on current limiting resistor and rectifier.

author: rob77
author_rank: Super Contributor
timestamp: April 19, 2017, 08:48:59 pm
content: Quote from: wraper on April 19, 2017, 08:28:30 pmyes agree that might be a problem for bigger PSUs in a case of significant capacitance change like 150uF to 470uF.but in this case 47uF would suggest it's a small SMPS up to 50W approx. , so the rectifier is definitely safe , and the inrush limiting will be a NTC.

author: wraper
author_rank: Unknown
timestamp: April 19, 2017, 08:55:51 pm
content: Quote from: rob77 on April 19, 2017, 08:48:59 pmVery unlikely, in small power PSUs usually there is just a resistor, no NTC. Though this adapter might have PFC with a soft start.
hats off to ART - Page 1
Forum section: electronics / repair

author: danmcb
author_rank: Regular Contributor
timestamp: April 19, 2017, 07:59:48 pm
content: I have an an old stereo mic preamp in for repair made by ART. Turned out the issue is a dual 5k log pot with a small footprint that I cannot find in any of the usual places. Looks like it was specially made for the product, and no manufacturer markings on it.My heart sank a bit, as my past experience has been that getting "special" parts from OEMs is often a hopeless task. but anyway I shot them a mail.Had to chase a bit, but eventually got really good response, super friendly service, and a very fair price from them. Really a nice company to deal with, and they are looking after their old product owners.I know something like this should be the norm but it is not. Many manufacturers won't release any schemas, give any tech support, and requite you to send stuff to the Kingdom of Far Far Away (if you can get it fixed at all). Real nice to see a company that takes care of the little people, and it deserves a shout out.
Another Tek 465 repair question - Page 1
Forum section: electronics / repair

author: NickR
author_rank: Newbie
timestamp: April 18, 2017, 09:01:39 pm
content: Hello everyone,I decided not to go to the Testing Equipment forum with my likely to be trivial question, and searching didn't yield any related result.I have recently bought a Tektronix 465 (not B) oscilloscope. It was in a rather good condition, written-off military equipment (last calibration sticker is from 2004). Power cord was missing, so I made a new one. Probes were missing too and I bought a pair of Hantek P6100 100MHz ones.After setting up the capacitance of probes and stuff, I was pleased to see the traces nice and clean. However, there are slight (like 1% of amplitude) overshoots still visible from calibrator output.Other issue concerns me a bit more. When I move up the vertical position and trace crosses 100% mark, it becomes very fuzzy and somehow gets reflected down a bit (like to a 60% value). After that I can move that fuzzy trace all the way up. If I move it back down, it becomes clear again once the top of the signal crosses 100% mark.What could it be? CRT failure or something with the electronics? I have already got the service manual, but any advices on where to start looking are much appreciated.

author: james_s
author_rank: Super Contributor
timestamp: April 18, 2017, 10:27:53 pm
content: Sounds like one or more of the glass support structures in the CRT neck have been broken, does it change if you turn it upside down? Don't write off the tube until you're certain but I can't think of anything else that would cause that effect.

author: MarkL
author_rank: Unknown
timestamp: April 19, 2017, 12:52:30 am
content: You could try reversing the wires going to the vertical deflection plates on the CRT.The traces will now be upside down, but if the problem stays near the top at the 100% line as you describe, the CRT is bad. If the problem moves to the bottom, you have a circuit issue somewhere.

author: NickR
author_rank: Newbie
timestamp: April 19, 2017, 12:17:17 pm
content: Hi guys and thanks for the suggestions.After I left the scope working for 2 hours, its behaviour has changed a bit. Now it allows me to go little higher than 100% mark on channel A and artifacts are not as severe as before. I tried to rotate the scope as James suggested, but image didn't change at all. Also tried to tilt it gently, no effect on image whatsoever. So hopefully the CRT is intact.I haven't tried reversing CRT vertical deflection polarity yet, waiting for HV caps to discharge.

author: james_s
author_rank: Super Contributor
timestamp: April 19, 2017, 03:40:15 pm
content: It should be discharged within a few minutes, and you don't have to mess with the HV to get to the deflection pins, they're on the side of the CRT neck.
Marconi Spectrum Analyser TF2370 - Page 1
Forum section: electronics / repair

author: gergard
author_rank: Newbie
timestamp: April 18, 2017, 02:55:36 pm
content: I have a spectrum analyzer Marconi TF2370 not working, power on is ok, but it certainly has some problems, there are known faults in the power supply?

author: Andy Watson
author_rank: Super Contributor
timestamp: April 18, 2017, 03:57:59 pm
content: Are you aware of this group:https://groups.yahoo.com/neo/groups/marconi_test_instruments/info

author: gergard
author_rank: Newbie
timestamp: April 18, 2017, 05:29:30 pm
content: No, thanks for the information

author: gergard
author_rank: Newbie
timestamp: April 19, 2017, 01:45:00 pm
content: The defect is, graticule ok, line present, noise none, scan locked, output square vawe 10MHz (25) is present, amplitude1,5Vrms, counter is on but locked at 04800000.0If I connect 10MHz out (25) to the input (24), set sweep in manual mode and move bright line position, I see something.
Finding alternative cable for Agilent N4011A - Page 1
Forum section: electronics / repair

author: cslee
author_rank: Newbie
timestamp: April 19, 2017, 01:32:12 pm
content: Hello, everyone!I've recently acquired an Agilent N4010A (Wireless Connectivity Test Set) and an N4011A (MIMO/Multi-Port Adapter).But, N4011A did not come with a cable (Part Number N4011-21002 or N4011-61804).The cable is necessary to connect N4010A and N4011A, but the price is about $300 if I order from Keysight part store.Both of connectors at the rear panels are DB25 female type.So, I'm planning to try DB25 male-to-male cable, but not sure whether the genuine cable has some pin crosses.The cable with which I will try ishttp://assmann.us/specs/AK401-2.pdfDo you guys have any suggestion on this try?Cheers,Chungsub
beloved broken bose  - Page 1
Forum section: electronics / repair

author: mandlebrot501
author_rank: Newbie
timestamp: April 18, 2017, 07:42:47 pm
content: Once apon a time when I was younger and perhaps wiser I bought a Bose Radio. Astonished at once by it's unique wonderful tone it was love at first tune!Over the years from pillar to post it remained unbroken and whilst matrimony and business followed it's cyclical sine wave of heaven and hell, good old bose (even when seperated itself from it's sweet remote(control)) never wavered from it's stable position.Decades past, remote was found....still worked....Case grubby, used in the car workshop...gearbox oil and thinners et all#. Still working.Am I boring you yet?You get the picture.....a stable thing in a universe of chaos.Well I decided to take it to bits and clean it......stupid me.My dear daughter, sensing my brave grief got an IDENTICAL twin on ebay for my bday. Pleaased.Could someone encourage me ....gently to fix it. ta and ciaoNew to this. DJ a great inspiration to me on many fronts.Will post pics if interested.

author: Shock
author_rank: Super Contributor
timestamp: April 19, 2017, 06:01:46 am
content: Quote from: mandlebrot501 on April 18, 2017, 07:42:47 pmI recommend since this is so precious to you and likely an untrained hand like yourself could do unmeasurable further damage to the device that you find a local amateur radio club near you and see if you can find a radio repairer or restorer. On their websites they normally list contact details and will know who in your area does a good job, very nice folks as well. Best to take both in when getting it repaired in case parts are a problem or it's a tricky one.

author: helius
author_rank: Super Contributor
timestamp: April 19, 2017, 06:11:46 am
content: Is the problem that you aren't sure how to reassemble it? I don't remember it being that hard, the screws are mostly all the same size and it isn't that cramped inside. The Bose Wave Radios do have a few common failure modes: beside the audio amplifier chip, there is an electrolytic capacitor that is too close to it and dies from overheating. If the radio crackles that's usually the cause.

author: Shock
author_rank: Super Contributor
timestamp: April 19, 2017, 06:16:26 am
content: I think it's a vintage Bose radio, helius.If you want to repair it yourself mandlebrot, if it is not easily spotted visual damage or a contamination issue (clean carefully off with pure isopropyl alcohol) then get a multimeter, soldering iron, solder, braid or sucker together as the basics, hunt for a schematics and then start with some basic electronics troubleshooting and take some voltage measurements and confirm that the radio is powering up and which stages have power and then if still not obvious get an oscilloscope to trace the signal, using the working one as an example.

author: helius
author_rank: Super Contributor
timestamp: April 19, 2017, 06:21:43 am
content: With respect to powering up, keep in mind that they are always on and the "power" button is more of a mute. Idle power draw indicates that the power supply circuit never turns off.
sony bravia kdl-40xbr2 problem - Page 1
Forum section: electronics / repair

author: kgavionics
author_rank: Regular Contributor
timestamp: April 19, 2017, 01:16:36 am
content: Hi guysi have a sony bravia kdl-40xbr2 problem and i have a pretty weird problem that i'm trying to fix.TV doesn't turn on.when i plug it to the power the green led on the button turns on and i see nothing on screen, but if i unplug the tv for a long time like a few hours and plug it back in the tv turns on directly and i can see the menu.if i turn the tv off from the remote then i loose the picture.I tore the tv apart and checked all the power supply voltage , they seems good no problem or what so ever.i don't have any idea what could be the problem.can someone give me a little guidance how to fix this tv?Regardskais
Hitachi CP-x253 Power supply Repair - Page 1
Forum section: electronics / repair

author: Icom
author_rank: Newbie
timestamp: April 19, 2017, 01:05:00 am
content: Hi, I am working on a Hitachi cp-x253 projector. It is not powering on. Power supply pop and now I am trying to fix it but need some help. I think IC 1 is bad it is a MR4020, but that is no problem. D107 blew! It is a smt anyone have a clue of what type of diode it is and how many volts it should be?I hope the attachment of the schematic works.Thank you.Erik
HP EEVE3610A power supply range failure? (solved) - Page 1
Forum section: electronics / repair

author: Debunque
author_rank: Newbie
timestamp: April 18, 2017, 11:23:01 pm
content: This has been brought up in another thread, but without a clear resolution.I have a EEVE3610A, and it looks like the max current in CC mode stays at 2.1A even when switching from 2A mode to 3A mode. Except sometimes it goes into 3A mode. And sometimes tapping on the button makes the current jump between 2.1A and 3.1A. Does this sound like a bad range switch, or could it be something else?If a bad range switch, can anyone suggest if the right approach is to get a can of contact cleaner and try spraying it when still in the board, or should I replace the switch?If replacing the switch is the right way to go, does anyone know of a suitable mouser, ebay, or digikey replacement? (that's really my main question)Or is the switch so hard to find that I should just wire in a DPDT toggle and some washers?EDIT:solution was to spray lots of contact cleaner into the switch. Hope this helps someone in the future.
Lenovo T400 fails POST - Page 1
Forum section: electronics / repair

author: mlefe
author_rank: Regular Contributor
timestamp: April 16, 2017, 10:14:41 pm
content: Dear all,I have a T400 that turns on, briefly displays the boot up screen and suddenly shuts off without beeping. I've checked during the time that's on and, as far as I can see, all voltages (including VCCCPUCORE) are present.Quite strangely, if I press on the VGA chip while it's booting, the screen keeps turn on longer but never completes/passes POST nor it shows nothing different.At this point I'm inclined to think that there's an issue with the BIOS chip or the VGA one, but I'm not sure how to diagnose them.What will you suggest?Thanks!

author: vaualbus
author_rank: Frequent Contributor
timestamp: April 16, 2017, 10:25:32 pm
content: Just do not lose your time here and take the pc to a repair center.This is 100% cold solder joint under the cpu/gpu bga chip so without a solder station is very very hard to resolve the problem.Sorry for the "bad" news.

author: Smith
author_rank: Frequent Contributor
timestamp: April 17, 2017, 09:10:16 am
content: you can do a basic repair with a hot air gun, or in an oven, but even if you get it working again it will stay a weak spot. I have done some with a hot air gun, and they still work, except for one. I made the mistake of playing a simple game, and it quit working within minutes. I did a second repair, but it had problems some weeks later.Under normal operation, it can last quite some time, but you have to keep it cool (no heavy 3D work or games), and do not restrict the cooling fans.

author: mlefe
author_rank: Regular Contributor
timestamp: April 18, 2017, 12:36:33 am
content: I feared that much... I do have a hot air station, so I guess this will become my first victim/try at reballing a VGA... I'm doing it for the sake of learning and It's not a big loss if it doesn't work.I guess if I really want to play with this I'll have to buy a stencil/solder balls and don't count on simple air to do the trick, right?

author: mlefe
author_rank: Regular Contributor
timestamp: April 18, 2017, 01:08:04 am
content: Also related to this: how can I know that it's a cold joint and not a fried chip? Is it the fact that's able to show something?Thanks!

author: Rasz
author_rank: Super Contributor
timestamp: April 18, 2017, 09:06:26 pm
content: replacement motherboard should be <$50, probably closer to $20
magic smoke escaped? - Page 1
Forum section: electronics / repair

author: firstcolle
author_rank: Regular Contributor
timestamp: April 18, 2017, 11:26:04 am
content: it's the first time I see a hole in a capacitor... I suppose the magic smoke was escaped.can you confirm that?

author: Jeroen_Bezemer
author_rank: Contributor
timestamp: April 18, 2017, 11:31:39 am
content: Usually there is some mechanic deformation involved like bulging out. At least this cap is suspect, as it can/will/already has dried out.Verstuurd vanaf mijn ONEPLUS A3003 met Tapatalk

author: wraper
author_rank: Unknown
timestamp: April 18, 2017, 11:37:30 am
content: That capacitor is certainly faulty. If some rapid failure happens, sometimes gas escapes without capacitor having a time for bulging and only a hole is left. Usually it is either because of rapid overvoltage or AC applied to the capacitor (like rectifier fail). This capacitor looks suspicious though, looks like bended inside a bit, and some punctures around. Might be that it was damaged by external mechanical impact.

author: firstcolle
author_rank: Regular Contributor
timestamp: April 18, 2017, 11:43:55 am
content: I exclude some external impact. i'm going to change it and check if it's the only issue in the circuit
Testing a transistor In-Circuit? - Page 1
Forum section: electronics / repair

author: rodm1
author_rank: Newbie
timestamp: April 16, 2017, 08:10:45 pm
content: HI everyone I have an automotive electrical problem. I think it's the dash light dimmer switch that is the problem. If I remove the dimmer switch from the circuit it won't blow the fuse but If I hook the dimmer up the fuse will blow after fixing burnt trace.Taking the dimmer switch apart I noticed and fixed a burnt trace on the N lead of a A1012 PNP transistor. If I test it in circuit I get .3 on one side and 598.1 on the other side. Is that a good enough test to weren't removal for further testing?

author: Kleinstein
author_rank: Super Contributor
timestamp: April 17, 2017, 08:29:53 am
content: It is difficult to test transistor in circuit. As many, especially larger transistors most often fail with a dead short, there is a chance to find those cases in circuit. So if the emitter - collector connection ready like a short, chances are good the transistor is blown. However transistors might also blow in a different way.So 0.3 Ohms or 0.3 mV on the diode/continuity test somewhat points to a short.However just the blow transistor should not cause the fuse to blow. A shorted transistor would more like turn the light on full power or not at all.So very likely there is something else wrong, like short in the cabling that than causes the transistor and fuse to blow.

author: Armadillo
author_rank: Super Contributor
timestamp: April 17, 2017, 10:30:57 am
content: Replace the shorted transistor and you should be good to go.OR;Take out the transistor, use a 12V light bulb jumper wires over the fuse connection [without the fuse], if the bulb don't light up, means confirm without the transistor, there is no short.But if I will you, I will just replace the transistor and give it a go.

author: madires
author_rank: Super Contributor
timestamp: April 17, 2017, 10:36:13 am
content: The "N lead" would be the PNP's base. So there seems to be too much base current. And that could be caused by a short circuit in the driver for the 2SA1012. Could you please post pictures of the dimmer's PCB (front and back)?

author: Samogon
author_rank: Frequent Contributor
timestamp: April 17, 2017, 09:11:24 pm
content: Shorted EC on power transistor is one of most probable reasons to blow fuse.
LCD PSU - Page 1
Forum section: electronics / repair

author: RyanG
author_rank: Regular Contributor
timestamp: April 21, 2017, 01:46:39 am
content: I have a PSU here that isn't putting out power. I checked the easy stuff and I am not getting anything on the secondary side of the T1 transformer, but I am reading no open circuits on the primary or secondary. The primary has a 2k-ish resistance. Primary side has ~350v. I attached the schematic that I found online. It also has an on/off pin on one of the connectors, so should I connect 5v to it?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 21, 2017, 02:28:47 am
content: Ryan,I have looked at the schematic. I think if you connect pin 1 (on/off) to pin 6 (5V standby) on CNS1 the other rails should turn on.In fact measure the voltage on pin 6 of CNS1 to pin 7 or 8 GND and see if the standby supply is working.Regards,Jay_Diddy_B

author: RyanG
author_rank: Regular Contributor
timestamp: April 21, 2017, 03:16:00 am
content: I did check the standby and it is good at 5v. I will try connecting it to pin 1 when I get home from work. Thanks

author: RyanG
author_rank: Regular Contributor
timestamp: April 21, 2017, 05:47:12 am
content: Connecting pin1 to 5v turned everything on. I had a very terrible 24v output bouncing between 23v and 26v. I changed out the EC2 cap and it was a smooth 24v after that.
Tektronix 2467B NVRAM content .bin file inside - Page 1
Forum section: electronics / repair

author: adrianni
author_rank: Contributor
timestamp: April 17, 2017, 01:06:36 pm
content: Hello,I decided to replace the Dallas DS1225Y NVRAM in my 2467B because I didn't want to wake up one day and see that I lost the calibration data. The code says manufacturing date 1995 so...I desoldered it from the board, read the content, saved the buffer and wrote it to a new Dallas DS1225AB NVRAM. I mounted a socket, installed the new memory and the scope works perfectly, passes all tests.I used the Dataman 48Pro2 universal programmer.Attached you can find the .bin file that I saved. It has .txt extension because otherwise it cannot be attached. All you have to do is change the extension back to .bin. Hopefully someday it will help you out of a desperate situation.Cheers,Adrian
Tektronix TX3 / Fluke 185 UNCAL Error Help - Page 1
Forum section: electronics / repair

author: santiniuk
author_rank: Contributor
timestamp: April 17, 2017, 12:54:07 pm
content: Hi folks,Just discovered my old Tektronix TX3 meter during a garage tidy. I believe this is also branded Fluke 185 ?Unfortunately on power up I get the error UNCAL.I still like this meter, any advice how to get this error fixed?Many thanks
beginner try to repair old HP 54720A scope - Page 1
Forum section: electronics / repair

author: Daxxin
author_rank: Regular Contributor
timestamp: April 05, 2017, 07:48:29 pm
content: looks like something wrong while OS firmware loading ..it hangs try to viewthis short videohttps://youtu.be/dC2fFuHED0Eany hal or experiencevery apreciated

author: tpowell1830
author_rank: Frequent Contributor
timestamp: April 05, 2017, 08:30:07 pm
content: Do you have the service manual?If not, here is the link:http://dedisol.unsads.com/~squalyl/kurteries/manuals/HP%20Agilent/HP%2054710A,%2020A,%2017A,%2018A%20Service.pdf1. Did you try to reseat the boards as suggested on page 5-22?2. Do you have the original floppy with the firmware? If so, then you may need to reload it as per page 5-15.I hope this helps. Good luck.

author: Daxxin
author_rank: Regular Contributor
timestamp: April 06, 2017, 04:09:28 am
content: thanks Tpowell im taking apart soon , about system disks ..nothing even googoling never foundif someone has please share them.

author: Daxxin
author_rank: Regular Contributor
timestamp: April 16, 2017, 10:24:37 am
content: Battery totally discharged 0v , i have only 3.6 lithium same size to solder its ok to replace with this? Original its cr17450se 3V

author: Daxxin
author_rank: Regular Contributor
timestamp: April 16, 2017, 03:28:07 pm
content: Replacing the battery back to alive but calibration of mainframe gone need specific module 54717Ato calibrate it.

author: sahko123
author_rank: Frequent Contributor
timestamp: April 16, 2017, 06:44:33 pm
content: Whats the blue mod wire for?

author: Cyberdragon
author_rank: Super Contributor
timestamp: April 16, 2017, 09:49:24 pm
content: Quote from: sahko123 on April 16, 2017, 06:44:33 pmThey probably needed to connect those pins but had a perpendicular track across there on every layer. #autorouted
OSCILLOSCPE TESLA BM566A PROBLEM - Page 1
Forum section: electronics / repair

author: BEHnam
author_rank: Newbie
timestamp: April 16, 2017, 10:44:20 am
content: HII have an old Tesla BM566A oscilloscope.it works some years without any problem. yesterday I tried to see a signal but it shows nothing! even zero line.I'm sure that display is working because when I push "beam finder" button it works correctly.I opened the case cover and in first I found no problem like capacitors crack.anyone can guide me how to fix the problem?

author: vidi
author_rank: Contributor
timestamp: April 16, 2017, 11:44:28 am
content: Hello,I'm afraid I cannot help you directly, but if you need schematics, layouts, .. they are available at:http://www.telehistoria.org/index.php?option=com_content&view=article&id=151&Itemid=595&jsmallfib=1&dir=JSROOT/Meracie_Pristroje/Ceskoslovenske/Tesla/BM566a_Osciloskop#filePageTopwith description in Czech, Russian and English.

author: BEHnam
author_rank: Newbie
timestamp: April 16, 2017, 01:45:33 pm
content: thanks for your replay.schematics is not useful at this time because I have no idea which unit cause the problem.
12V/240V -> 12-20V laptop power supply with 12kHz whine - Page 1
Forum section: electronics / repair

author: moz
author_rank: Regular Contributor
timestamp: April 07, 2017, 07:23:57 am
content: I bought a cheapUNIVERSAL100W 12V-24V 5A Max Laptop AC Adapter Power Supply Charger with Carplugoff eBay for $40 (did not come with car plug, but I didn't want that anyway). It actually works quite well for my intended purpose - running the laptop off a 100AH 12V SLA in my shed. Laptop draws about 20W so it's no big strain on anything, but it runs noticeably warm to the touch. Opening it up there are a few tear-down comments:some of the end-cap screws are pre-stripped for your convenienceonly the display driver chip has had the markings ground off, and that was done badlythere are isolation slots in somewhat random locations, and plastic-coated isolation barriers under the main board and between the 240V input and restthe transformer seems really awful to methere's a weird tiny contact between the inside heatsink and the caseThe really annoying thing is that there's a 12.1kHz whine coming out of it, and I'm not entirely sure exactly where from. My inclination is to hot-snot or silicon the inductor and see if that helps, but I'd appreciate the expert opinions of anyone with an oar to poke in. Am I likely to wreck it by running amok with some silicone sealant/glue (construction adhesive), or with a hot glue gun (assuming I steer clear of the heatsinks)?I will take better photos tomorrow with a proper setup, but for now here's some cellphone snaps to hopefully give you some ideas.

author: capt bullshot
author_rank: Super Contributor
timestamp: April 07, 2017, 07:50:27 am
content: Don't use random silicone for electronics. Some of them realease acetic acid.

author: moz
author_rank: Regular Contributor
timestamp: April 07, 2017, 08:07:41 am
content: Quote from: blueskull on April 07, 2017, 07:43:03 amSadly "This item does not ship to Australia.". But I can buy it here...for $90.I do take your point about the lack of grounding, but I have no intention of plugging it into 240V ever, for that reason. I bought the supply because there's no mains in my shed, which helps me avoid that temptation. The mains cable supplied is also a cheap non-approved chinesium one that was surprisingly rigid for its diameter.

author: amyk
author_rank: Super Contributor
timestamp: April 07, 2017, 12:06:23 pm
content: You can use a drinking straw as a stethoscope to determine which of the magnetics is emitting the whine. It might be a ceramic cap too.

author: moz
author_rank: Regular Contributor
timestamp: April 16, 2017, 03:42:00 am
content: The noise is worse, and I have a better spectrum, again using a simple spectrum analyser on my phone. But I'm also having (more important) issues with a new solar charge controller only giving about half the expected output, so I have not opened this thing up again yet.
Problems with an oscilloscope's horizontal/vertical amplifier - Page 1
Forum section: electronics / repair

author: Gip-Gip
author_rank: Contributor
timestamp: April 15, 2017, 04:31:05 pm
content: I'm working on an old Heathkit IOW-102G and I have run into trouble with the horizontal/vertical amp. I recapped everything hoping it would work but when I went through the testing instructions in the manual the collector voltage on Q208 is 10 when it's supposed to be around 100. Even worse, when I check the Vertical amp the voltage is >150 on Q9 and ~40 on Q10. I'm going to replace some suspicious transistors, but other than that do you guys have any experience/suggestions?Manual's right here:https://archive.org/details/HeathkitIO102Manual

author: w2aew
author_rank: Super Contributor
timestamp: April 16, 2017, 12:56:37 am
content: Just general troubleshooting advice. Wrong voltage appearing at a collector of a transistor does NOT always mean it's bad. Is it biased right? Did any components around the transistor fail or change value? Are there dodgy solder joints? Are you sure you respected the polarity of the caps you replaced?These are some of the things you should be asking yourself. When making measurements, do a little basic analysis. See if the measurements jive with basic ohms law and circuit behavior.For example, where you are reading a 10v collector voltage instead of 100... Is the supply voltage right? Do other measurements jive with a lot night collector current, or did the collector load change?Learning to think this way when troubleshooting will give you a a greater understanding of the circuit and become more effective at debugging problems.
Attempt to repair my Extech LCR-200 - Page 1
Forum section: electronics / repair

author: icemachine
author_rank: Newbie
timestamp: April 13, 2017, 08:12:46 pm
content: Hi,I try to repair my Extech LCR-200 witch I have demage.I think it has happend diuring measurment charged capacitor in cuircuit few days ago.At the present LCR-200 consume 190mA at 9V DC.Base on specyfication it should take approximately 35mA @ 9V DC.At the present when it is supply from 9V it show Er01 on the display and shutdown itself.I have discover some parts which are demage diuring optical inspection.I have replace 5 parts 2x SMD resistor, 2x truehole resitor and one transistor. I marked it by red dot.It not help.I have discover that decrease supply voltage form 9V DC to 6.9 V DC could help me to keep multimeter alive diuring investigation.It simulate weak battery. On this voltage multimeter do not shout down imadiately.However it stil consume to much power 216mA @ 6.9V DC and do not measure anything.I suspect that the problem could be ES51920A chip.Base on that I have measure temperature of it under power suplly 6.9V @216mA DC.It has 42C deg after few seconds.I think ES51920A chip has died and I has looking for replacement for it.I have already read this topic:https://www.eevblog.com/forum/repair/extech-lcr-200-repair/Mladen thank you for help!

author: mladen82
author_rank: Contributor
timestamp: April 15, 2017, 07:05:55 pm
content: Hi there,yes its probably ES51920Asend email to Cyrustek and ask for repair for your LCR200if you lucky like me they will send you 2 pieces
What is this SMD component? - Page 1
Forum section: electronics / repair

author: SaintGimp
author_rank: Contributor
timestamp: April 13, 2017, 08:34:19 am
content: Can anyone help me identify the component in the center of this photo, marked 033A? I'm pretty sure it's blown and I'd like to replace it, but I don't know exactly what it is. It's some sort of switching device, maybe a FET? The top pin is the control pin. The intended behavior seems to be that when the top pin has 3.8V, the two lower pins are not connected. When the top pin has 1.4V, the lower left pin is connected to the lower right pin which is tied to ground. Any ideas? I've done Google searches every way I know how but haven't gotten any positive results yet.

author: helius
author_rank: Super Contributor
timestamp: April 13, 2017, 08:41:37 am
content: Searching for "Holtek 033A" returns useful results. HT7033A-1 is a "voltage detector".tldr; if input is >3.3V, the output is disconnected (Hi-Z). When the input falls below 3.3V, the output is pulled to ground.

author: TheAmmoniacal
author_rank: Unknown
timestamp: April 13, 2017, 08:44:57 am
content: I also need help identifying a part named "NMR1", all I can find is this:http://www.ic-smd.com/ssot23.asp?g=7800&s=NMR1but it doesn't tell me much.

author: SaintGimp
author_rank: Contributor
timestamp: April 13, 2017, 08:46:29 am
content: Quote from: helius on April 13, 2017, 08:41:37 amYes, that totally makes sense! That's exactly what it is. Thanks so much! I didn't recognize the trademark which is why I couldn't find it myself.

author: ataradov
author_rank: Super Contributor
timestamp: April 13, 2017, 05:03:16 pm
content: Quote from: SaintGimp on April 13, 2017, 08:46:29 amYou need thishttps://www.westfloridacomponents.com/manufacturer-logos.html

author: SaintGimp
author_rank: Contributor
timestamp: April 13, 2017, 05:55:51 pm
content: Quote from: ataradov on April 13, 2017, 05:03:16 pmYaaaaas!!!
[SOLVED] Recommended QN7002 n-channel MOSFET alternative - Page 1
Forum section: electronics / repair

author: cyferc
author_rank: Newbie
timestamp: April 11, 2017, 01:53:04 pm
content: I am a complete noob with hardware so I apologize in advance.I have a damaged SOT-23 component in the voltage regulation area of my PC motherboard. It has the code "G28" and I figured it is a Renesas QN7002 N-channel vertical type MOSFET. I just looked up the code onhttp://www.s-manuals.com/smd/g2.Here is the data sheet:http://www.s-manuals.com/pdf/datasheet/q/n/qn7002_r1.0.0_renesas.pdfI cannot seem to find that part anywhere so can someone recommend a readily available drop in replacement?Thanks!

author: rob77
author_rank: Super Contributor
timestamp: April 11, 2017, 02:21:01 pm
content: 2n7002 mosfet is jelly-bean part available from lot of manufacturers (ST, dioides incorp., fairchild... virtually anyone makes it) . so feel free to use any sot-23 mosfet which has the number 7002 in it's part number.

author: Ian.M
author_rank: Super Contributor
timestamp: April 11, 2017, 02:22:24 pm
content: http://www2.renesas.eu/_pdf/D18259EJ4V0PF00.PDFgives some cross-references. It looks like its a re-packaged 2N7002. Caution SC-59 and SOT-23 package dimensions are *NOT* quite the same so check compatibility with the actual board footprint before ordering.

author: cyferc
author_rank: Newbie
timestamp: April 11, 2017, 06:38:37 pm
content: Very helpful, thank you very much!
Fluke 19x scopemeter channel problems - Page 1
Forum section: electronics / repair

author: wictor
author_rank: Regular Contributor
timestamp: April 11, 2017, 05:40:34 pm
content: Hi,there seems to be a lot of these 19x scopemeters with broken input channels. Either one or both of the channels are bad... Is it the ASIC or what goes bad? I guess they are not easy to repair since there is no information available or at least it's hidden well.Thanks,Wictor
Assistance on part value for HP 8647A Signal Generator - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: April 05, 2017, 06:04:12 am
content: Hi All,I just picked up a 8647A signal generator from eBay, it was all working fine whilst I did my initial testing, and then POP... smoke... yucky smell. just like the IEC line filter smell from the 8904A!I traced it back to the power supply, a metalized paper capacitor had blown apart, its designation is C7 and it is located between the smaller u shaped (live) heatsink, the transformer and the large 470uF capacitor.Its only identifying numbers were 630V/300V MP and 40/070/56 which I traced back to a part, however, based on its dimensions, its value is either 0.047uF or 0.068uF, I am hoping that someone out there can take a look at there unit, (or even better has a diagram!) and tell me which is the correct one ?I have ordered both values, which will take a few days to arrive, so it would be nice if I could have this information to hand by the time they turn up, otherwise I will have to take a chance and just try one.I was doing a video at the time, so expect to see another "Who let the smoke out" episode on my channel in the near future!This power supply is also the same as the one featured in The Signal Path's TSP#16 for the HP8648A, I tried to see the value in his video but I could not see it clearly enough.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: April 11, 2017, 12:52:29 am
content: FYI, I managed to find a photo yesterday which was just readable enough, it is a 0.047uF, just in case anyone else has the same part blow up on them ! (its likely if you use >220V AC)
Schonstedt TraceMaster II repair - Page 1
Forum section: electronics / repair

author: SRecker
author_rank: Newbie
timestamp: April 10, 2017, 05:13:10 am
content: So I come across one of these underground pipe and cable locators on Craigslist for almost nothing. I checked on E-Bay and these things have sold recently for quite a bit of money, so I figure it's worth repairing. It was listed as base unit not powering on, I hoped that it was just a bad connection from the batteries or other simple mechanical fix. No such luck.I snapped a couple of pics of the unit here, including the main board which I think has the problem.http://imgur.com/a/luHvHSo this thing runs on 12V DC and has a battery compartment with 8 D-cell batteries in it. When I try to power it on I get nothing on the display and key presses seem to do nothing. So I pulled the thing apart and removed the main board from the rest of it. With just powering the main board it was pulling 350mA @12V, which seems like a lot of power for a board doing nothing.I don't have a schematic and I don't have a lot of experience troubleshooting to the component level.So, I start measuring voltages and was getting nowhere, but I noticed the power MOSFETS getting hot. I figure something has shorted out. So I power off the board and start checking different test points to ground, etc. Eventually, I find something odd and I'm not sure how I stumbled across this, but checked a few resistors and all measure open, EXCEPT the 47 ohm resistors, they are all good. This seems very strange to me that all of the resistors would be open. I checked and checked again, thinking I was doing something wrong, but if I am, I haven't figured out what I'm doing differently. I mean, I don't seem to have a problem measuring the 47 ohm resistors, and I'm measuring the others the same way, so I guess I'm doing it right. I suspect these resistors are not the problem, but a symptom of something else, but what do I know. Could they of had a bad batch of resistors? This thing is fairly old, my guess it was made in the '90s as someone wrote in marker that it was updated in '03 and repaired in '08This is turning into a bigger job than I thought.I thought I found a resistor that was shorted, so I removed it and I poorly soldered in a temporary through hole one in it's place, but no apparent change in power use or function. I did try the board without it and when it was missing there was no current draw at all from the PS.The 2 power mosfets get hot pretty quick as well.I guess I'm looking for pointers as how to proceed, or even schematics, but I won't hold my breath.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: April 10, 2017, 06:45:04 pm
content: I have seen MOSFET's blow and take the attached resistors with them. Pull all MOSFETs and suspect resistors and test them out of circuit.
HeathKit Oscilloscope Repair - Page 1
Forum section: electronics / repair

author: CrowdedOuthouse
author_rank: Newbie
timestamp: April 10, 2017, 05:14:25 am
content: I recently came across an old HeathKit Oscilloscope (Model OR-1) from my local university.It works a little bit, but is pretty finicky.I'm pretty new to the whole restoration and repair thing, so I have some questions.1. Recapping is pretty much the first thing to do, right? Should I only replace Electrolytic Caps?2. Is it necessary to replace every electrolytic capacitors? Is there a way for me to know which ones to replace?3. How close in value do I have to keep the power supply caps? Is increasing the value from, say .01uf to .03uf a bad thing to do? And with Voltage Rating should I try and increase it or keep it the same?4. How should I deal with the multi-capacitor towers? There are a few in there.Here is the schematic for referencehttp://www.vintage-radio.info/download.php?id=392Here are some Pictures if they helphttp://s430.photobucket.com/user/mrvicfischer/library/OscilloscopeAny input is greatly appreciated.Thanks!

author: Paul Moir
author_rank: Frequent Contributor
timestamp: April 10, 2017, 06:53:51 am
content: 1. Electrolytic and paper capacitors. Anything with wax on it, or that black plastic one in your picture. The electrolytics contain a liquid which is either dried out or almost dried out by now, while the paper dielectric has absorbed moisture and become leaky. Ceramics and Mica will be fine. Paper can be replaced with superior poly propylene or polyester.2. No, but the few survivors won't have much juice left in them. It's a choice. Know by checking the ESR (equivalent series resistance) or dissipation factor. You can get dedicated ESR meters or use the ESR function on a LCR meter like a DE-5000. Capacitance meters are kind of useless here: the measured capacitance tends to increase as they dry out.3. Not close at all. They can be reasonably bigger or higher voltage. Note that a typical tolerance on an electrolytic capacitor is +80%/-20%. A 0.01uF is not going to be an electrolytic though.4. Depends on your restoration style. Some people gut the cans and stuff them full of new caps, then carefully reassemble them. It helps that new caps are quite a bit smaller. I'm more of a resto-mod guy, so I mount a bunch of new caps to a piece of perfboard cut to the footprint of the can, and replace the can with that. I think the most sensible method is to cut out the can but leave it in place, and mount the new caps under the chassis.And 5:5. Those carbon composition resistors drift badly. Some people will replace them wholesale, but I just test and replace the bad ones. Either way you'll want to address them. Almost all the time you can replace them with a metal film capacitor, but beware of the standard carbon film resistor since they do not withstand high voltages and tend to have high inductance making them unsuitable for high frequencies. Metal film resistors can be unsuitable for high voltages too so make sure you check the datasheet before ordering.Check out Jordan Rubin's restore of a Heathkit O-12 for some ideas:or Paul Carlson's O-11: