hybridfree/eevblog-posts huggingface dataset:
GW Instek GPC-3020 - Page 1
Forum section: electronics / repair

author: LarryN7LUF
author_rank: Newbie
timestamp: November 25, 2017, 01:10:28 am
content: In a moment of weakness I bought a GW Instek GPC-3020 power supply.It is a Dual Tracking 2 amp with 5V Fixed DC Power Supply.I am looking for a schematic for it.The problem is when I turn on the current of the master side the voltage goes to 44 volts and pegs the volt meter.The voltage control has no effect to the voltage.The slave side seem to be okay as I put a load on it to test it.Thanks for any help!Larry N7LUF

author: cdev
author_rank: Super Contributor
timestamp: November 25, 2017, 01:29:33 am
content: I have a GPC-3020 and its working fine for me (although its fan is noisy) I don't have a schematic but for what its worth, would be happy to test any voltages or current in wires I can get my current clamp around for you so you can tell what its supposed to be.

author: 7SB
author_rank: Newbie
timestamp: November 25, 2017, 01:36:54 am
content: Hi Larry,do you have a circuit or manual please?Karl

author: LarryN7LUF
author_rank: Newbie
timestamp: November 25, 2017, 01:40:29 am
content: The voltage control on the master side does not work at all, but when I turn up the current just a little the voltage goes to 44 volts.I did have to replace the meter back in place.

author: LarryN7LUF
author_rank: Newbie
timestamp: November 25, 2017, 01:42:57 am
content: Hi Karl, I have no manual.

author: xrunner
author_rank: Super Contributor
timestamp: November 25, 2017, 02:00:11 am
content: Quote from: LarryN7LUF on November 25, 2017, 01:10:28 amGood luck getting one. I've personally tried contacting GW Instek about schematics before and they stubbornly refuse to give them out. They are very protective of their designs. I wish you luck though.

author: cdev
author_rank: Super Contributor
timestamp: November 25, 2017, 03:06:31 am
content: When looking for a manual it may be helpful to use their other name "Goodwill Instruments" or similar. I would also be interested in a copy if you find one. Ive looked and havent seen one. Its on my list of service manuals I would like to have.

author: ArthurDent
author_rank: Super Contributor
timestamp: November 25, 2017, 03:48:15 am
content: There is a problem because there are different versions of these almost identical looking supplies that were built over many years so you have many revisions. It is hard to guess which one you have. See if these links are of any help. If one side is working correctly the other side should be a mirror image of it. Check identical points on each side to see the differences. First check that the control pot isn't fried or the pass transistor(s) in/out aren't shorted.http://www.ko4bb.com/manuals/65.175.237.176/Tek_PS280-283_Service_Manual_Schematics.pdfhttp://www10.ujaen.es/sites/default/files/users/ingele/manualfuenteGW-GPC3030D.pdf
Agilent 58455A battery - Page 1
Forum section: electronics / repair

author: Aiy
author_rank: Regular Contributor
timestamp: November 25, 2017, 09:05:31 am
content: Hi,I'm servicing my oscilloscope and found that the Motherboard CMOS battery is lost. The service manual has a simple drawing of the pc-side motherboard which says its 3V, but not the exact type. Can somebody point to a correct replacement buttoncell ? I tried a cr2032 I had on hand, but the scope didn't want to boot with it.Best regards

author: ap
author_rank: Frequent Contributor
timestamp: November 25, 2017, 11:23:16 am
content: The battery replacement causes CMOS RAM data to be lost. You need to configure the BIOS. See page 5-16 of service manual.Keep us posted if you could fix it.

author: Aiy
author_rank: Regular Contributor
timestamp: November 27, 2017, 03:39:29 pm
content: The CR2032 battery worked after all. I needed to do a reset of the bios with the jumper, then it booted
Repairing a Sanwa PS-8 Pocket Multimeter - Now Fixed! - Page 1
Forum section: electronics / repair

author: Dismounted
author_rank: Contributor
timestamp: November 23, 2017, 06:01:47 am
content: Hi all,I know everyone here is a bit of a test equipment nerd, so I thought I'd write up a post as I tried to repair this lovely pocket multimeter! It was bought quite a few years ago and I re-discovered it the other week... lo and behold, it doesn't quite work...Voltage...fail!Continuity...fail!Resistance...fail!(Ignore the LCD screen, it is working fine, but camera caught it in the middle of changing digits)

author: Dismounted
author_rank: Contributor
timestamp: November 23, 2017, 06:03:31 am
content: Let's open it up!WheelTwo screws and we're in (like Flynn). Nice selector wheel with copper (?) contacts - better keep my fingers away!BackLooks like there's going to be a lot of surface mount goodness in here (surprising for the vintage...)FrontWell this is annoying... to release the PCB we need to delicately desolder a few wires - I wonder how they manufactured these en masse.But nothing a soldering iron can't helpLook at all that corrosion from leaky batteries! Better clean that up as a first effort, hopefully we didn't permanently destroy anything. Also look at all that MELF goodness. (Dave would be all over this)This isn't a review, but there looks to be absolutely no input protection? (Expected for the vintage I guess...)

author: Dismounted
author_rank: Contributor
timestamp: November 23, 2017, 10:03:01 am
content: No improvement after cleaning the corrosion off the boardProblem found?Checked the resistance from probe tip to it's PCB solder joint: black seems okay, red is in the megaohms. Could this be it? Replace the red lead with some other wire lying around...Put the necessary bits back together, and... bingo! Got you.Replacing the probesNote to self... check whether the tips are screwed in before freeing them with a soldering iron.(You can see the heat damage on the red probe below haha)I thought it would've been the solder joint coming loose between the wire and tip, but surprisingly, it appears that it's the wires themselves.The red wire appears as if it's (literally) hanging on by a thread. The black at 6 ohms isn't fairing much better to be honest... best to replace them both. A bit tricky to find the right gauge of wire to fit through the probe body, but our donor today is cable from a set of old crappy PC speakers!Alright, everything cut to length and soldered back together (mostly).Everything fits back into the box nicely and yay it works!(Side note: the continuity buzzer on this thing is amazing - absolutely instant with latched tone!)Finally!A beautiful little pocket multimeter, 100% working and now with white probe leads! (I'm actually quite liking the white, it's growing on me)
8656B only fan running - Page 1
Forum section: electronics / repair

author: Daxxin
author_rank: Regular Contributor
timestamp: November 19, 2017, 09:48:52 am
content: cannot hear the relay switch , looking around this circuit i found CR17 (1N4150) open , since the panel is totally off , can be this the cause of trouble?just finish to replace it with 1N4148 ..

author: VK5RC
author_rank: Unknown
timestamp: November 19, 2017, 10:10:24 am
content: Isn't it there to stop "back emf' from the relay when it de-energizes, if you measured it in circuit and it's open , isn't the relay coil also open?

author: Messtechniker
author_rank: Frequent Contributor
timestamp: November 19, 2017, 10:17:56 am
content: To start with, the reverse voltage spec of 50 V for the 1N4150/1N4148seems to me a bit low for this application. I'd use a jelly bean 1N1007with a reverse voltage spec of 1000 V here. But that will not solve theproblem you have.

author: Daxxin
author_rank: Regular Contributor
timestamp: November 19, 2017, 10:36:22 am
content: Relay is working , desoldered and tested all contacts with external psu , just replaced with 1N4007 , outside from the circuit cr17 was openanyway the problem remain , measuring TP about 5V+ rail too weird dont have voltage at the input of regulator , the link is realized with wires and connectors and testedit was OK , the relay i tested before it was working und UNREGULATED +5V is present , what you think if i connect with crocodiles jumper?

author: Daxxin
author_rank: Regular Contributor
timestamp: November 19, 2017, 10:55:37 am
content: With the jumper its working even no output but now dispay is ok ..meaning the relay is gone died, what trouble if i short the traces under the pcb relay contact? ..really not worth 60 euro relay

author: Daxxin
author_rank: Regular Contributor
timestamp: November 22, 2017, 06:55:58 pm
content: This step attenuator was reworked by someone i dont know what they did but this pin marked wirh arrow remained unconnecteddo you have schematic or detailed pic to fix?
Anritsu MZ144A 24V rechargeable battery pack user\service manual source? - Page 1
Forum section: electronics / repair

author: KJ-90
author_rank: Contributor
timestamp: November 22, 2017, 05:58:02 pm
content: I was wondering if anyone knows of a source for the user\service manual for the Anritsu MZ144A rechargeable battery pack. It was made for the Anritsu MS610B series of spectrum analyzers. Some time ago, I found the battery pack ( I don't have the analyzer it was designed for ), but locating any user or service manual seems impossible online. The unit I have is complete, but is missing the batteries inside. I'm not sure what type of batteries it used ( for example- two 12V SLA batteries, or a series of special NiCd cells connected together. Inside the MZ144A is a 24V SMPS, along with some support circuitry as well. Does anyone have any technical data available on this unit?
What is this SMD component? - Page 1
Forum section: electronics / repair

author: illusive
author_rank: Regular Contributor
timestamp: October 28, 2017, 08:30:25 am
content: Can someone identify this component? It looks like a plain and simple diode but i can't find anything specific.Thanks!

author: sleemanj
author_rank: Super Contributor
timestamp: October 28, 2017, 08:34:23 am
content: Looks like a tantalum cap at first glance, have not googled part numbers.

author: sleemanj
author_rank: Super Contributor
timestamp: October 28, 2017, 08:36:29 am
content: http://www.ebay.ie/itm/330NF-0-33-F-0-33-uF-20-20V-Case-D-SMD-Tantalum-Capacitor-Tantal-CONDENSOR-/281959566087?hash=item41a6198b07

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: October 28, 2017, 12:37:30 pm
content: It's not a diode.It is definitely a 33uF 20V tantalum capacitor.

author: illusive
author_rank: Regular Contributor
timestamp: October 28, 2017, 06:26:15 pm
content: Thanks for helping out!

author: chhrisedwards
author_rank: Contributor
timestamp: November 21, 2017, 01:32:22 pm
content: I think it looks like Niobium electrolytic capacitor. This type of capacitor having high capacitance values.
It's never too late to fix something. - Page 1
Forum section: electronics / repair

author: Refrigerator
author_rank: Super Contributor
timestamp: November 19, 2017, 04:57:24 pm
content: At least that's what i found out while practicing GPU reball on a FUBAR board.Yesterday i received a stencil for reballing GPUs and went to my scrap box of dead mobos to practice.Picked a dead probook 4510S mobo with a HD4330 and went at it with my hot air.While removing the GPU i managed to not only rip off two data pads with squiggly traces off the mobo but i also knocked off a bunch of caps off the GPU.That's not all, while wicking the solder off with some copper wire i got the whole thing so hot that the fiberglass substrate warped and i also cracked all the corners off the silicon die as well.I reballed the GPU with some homemade solder balls which were made by cutting up some 0.51mm solder.I then with no magnification soldered two ultra thin wires to fix the two traces that i tore off.The chip then went on the board and with some heat dropped right in, the leaded solder made everything a lot quicker.After everything was done cooling i thought just for the heck of it i'd check to see what the mobo does now.Immediately after i plugged the power in all the lights went on and the fan went full tilt for a few seconds before shutting down."what did i expect" i thought to myself but before i had the time to unplug the power the mobo powered up and an image came unto the screen.This was probably the sloppiest and dodgiest reball ever and it worked.I mean why would it not, after all the cracked silicon die and the warped fiberglass substrate and the missing caps and the eyeballed matched impedance traces are no biggie.I wish stuff worked out as well as this did when i'm actually serious about fixing stuff.Ps: The laptop i'm writing this thread on right now is the very 4510S that i fixed in this tread, and using it i can already say that 720p60 video playback works without a hitch.
HP 3325A OSC FAIL message - Page 1
Forum section: electronics / repair

author: omi
author_rank: Newbie
timestamp: November 19, 2017, 02:37:40 pm
content: I bought a used 3325A, it worked great for about 2 years.I'm now greeted with "OSC FAIL" which I assume is oscillator board.My bord looks exactly like this (rev C)https://www.ebay.com/itm/HP-Agilent-03325-66503-BOARD-FOR-3325A-Generator-FULLY-WORKING/112621791142?hash=item1a38c827a6:g:umUAAOSwo0JWQ15dI've tried to search for a trouble shooting manual, but came up short.I think the Oscillator board seems to be on the bottom side.The crystal that I see there is 30MHZ. What bothers me though is I was expecting to see a big box with 10MHZ or 100MHZ written on it, well like over an inch no a standard size 30MHZ crystal non-ovenized.I've poked around and checked voltages, getting good +/-5V and 15V from power supply down to boards.Just in case, I took out and put back in every RCA cable, I didn't think it would fix it, but you never know.I probed voltages around few transistors that I saw, I didn't see any obvious shorts.There was a large metal shield, I took it apart, there were two compartments. I used a scope to check for any signal going into the shielded boxes, I didn't see any Oscillation. I think the second box is a mixer, I see two small RF transformers with a possibly diode bridge.Cable output 23 (Sine ampl) didn't have any sine wave1MHz jack had a decent looking (with slight overshoot, I guess acceptable for this era equipment) square wave.2MHz jack had a signal too, no overshoot, but is shaped a bit "rounded" that is the wave increases to about 80%, then last 20% looks like a linear function increase to the max, right before the drop.100 KHz jack was different, it had 100khz spikes (instead of the square wave when measured in parallel with 50ohm load). (What I assume is a 74ls74 some hp part # is feeding 100KHZ square wave though a capacitor, which I've checked by soldering it out - is fine) after cap, this feeds into a pnp transistor with 20 ohm resistor between base and emitter (extreme biasing???) point being, for w/e reason, base and emitter are both at +5V.If someone knows more about the unit, please comment what I should further check on the Oscillator board. Or maybe even the problem is on the board that receives the signals. Either way, please help.
Refreshment of rechargeable batteries? - Page 1
Forum section: electronics / repair

author: Physikfan
author_rank: Regular Contributor
timestamp: November 19, 2017, 12:27:06 pm
content: Two rechargeable batteries, one NiCd battery D and one NiMH battery Ccan not be recharged after 2 years of very moderate use:Both batteries were used in two different groups of each four identical batteries of the same type.The three others of each group still work perfectly.Now my question:Please who knows successful refreshment procedures of such batteries from personal experience?

author: BradC
author_rank: Super Contributor
timestamp: November 19, 2017, 01:07:11 pm
content: Quote from: Physikfan on November 19, 2017, 12:27:06 pmIt depends on their failure mode. In all honesty the best "refreshment" is to replace them.You *may* have dendritic growth that can be "remediated" in the short term with a good "zap", but the resulting hole in the insulator will ensure they re-grow so it's really only a short term "fix".Provided you've been looking after them (ie not letting the pack discharge to cell reversal, not overcharging or overstressing the batteries) then you have some failed cells. Any "rejuvenation" you apply will be at best short term and vaguely useful.

author: all_repair
author_rank: Frequent Contributor
timestamp: November 19, 2017, 01:47:39 pm
content: Not worth the time and electricity even you are successful. You need to slow charge and discharge, maybe 3 cycles, and with no guranteed result.
Agilent 35670A A1 board schematic - Page 1
Forum section: electronics / repair

author: rtekal
author_rank: Contributor
timestamp: November 21, 2017, 04:49:56 am
content: Hi,Does anyone have the Schematic for the A1/A2 input board of 35670A 4 channel DSA. The part number is 35670-69502 / 66502. This board fails the A-wt filter self test intermittently. I tried replacing some of the components, but with no success. Any ideas would certainly help.Regards
Parent's Air Purifier - Page 1
Forum section: electronics / repair

author: DDock
author_rank: Contributor
timestamp: November 18, 2017, 08:34:14 pm
content: I would consider myself a newbie/moderate still when it comes to electronics repair. My parents tasked me with figuring out what is wrong with their Ionic type air cleaner. I know what the issue is, but I think it is going to occur elsewhere because it looks like the copper in the PCB is corroding like rust. Any idea how to clean it to stop the decay of the traces? I have attached images. I am going to run a modwire from the button because the trace has completely decayed away.

author: Ian.M
author_rank: Super Contributor
timestamp: November 18, 2017, 10:16:00 pm
content: Most commercial PCB etching uses the Acid Cuprous Chloride process, because the etchant can be cheaply regenerated and the copper recovered, minimising chemical waste production. Unfortunately copper is very seriously affected by chloride corrosion, and once pitting occurs its very difficult to remove or deactivate the chloride ions, so if the PCB was insufficiently rinsed during production, there can be a chemical time-bomb lurking under the solder mask.Seehttps://en.wikipedia.org/wiki/Bronze_diseaseTreating the corrosion is almost certainly uneconomic. You'd have to strip all the soldermask and possibly remove the components as well.

author: DDock
author_rank: Contributor
timestamp: November 19, 2017, 03:59:35 am
content: Thank you for your insight. I ended up just mod wiring all the traces I saw with the corrosion to be on the safe side. It is working again, my parent's will be happy for awhile. I will have to tell them that it may stop working again if the corrosion spreads.
General Radio 1163 decade frequency synthesizer repair. Help needed.  - Page 1
Forum section: electronics / repair

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: June 08, 2015, 09:11:24 pm
content: Dear All,I got this awesome piece of equipment from my favorite dumpster. Its a General Radio 1163 decade frequency synthesizer from the period of 1965-69 probably.I could get this manual,http://bee.mif.pg.gda.pl/ciasteczkowypotwor/General%20Radio/gr_1161_frequency_synthesizer.pdfbut no real schematics for the various modules.The construction is quite impressive as it is build with separate modules that are linked together by banana plugs. So a very modular construction, of good quality, but I am a little blind there.I have started to work on the power supply. Changed a few caps, but still needs to work on it and would love to have the proper schematics. If any one could post it, that would be great.What I would like to do is to test the main frequency oscillator module (AFS) but I need some advice on how to power it.I am puzzled because there is a GROUND banana plug, but not directly connected to the chassis of the module, which on the other side seems to be a ground plane for the circuit. What is the meaning of these two grounds ?Here again, the schematics would help a lot.I must say that although I may be able to reverse engineer the power supply, the frequency module is most probably too hard for me.Before continuing to work on the PSU, I would like to be able to test the frequency unit to see if it is working without any repair.The power supply provides three 18V plugs and two of them are used in the frequency unit.I would like to power it directly from an external PSU. Any advice ?

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: June 08, 2015, 09:14:41 pm
content: Here is the frequency module.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: June 08, 2015, 09:26:30 pm
content: and a higher resolution view of the connections to the frequency module.

author: Vgkid
author_rank: Super Contributor
timestamp: June 09, 2015, 12:00:35 am
content: Try Joining the Genrad Yahoo usergroup, they are very knowledgeable.https://groups.yahoo.com/neo/groups/GenRad/info

author: Vgkid
author_rank: Super Contributor
timestamp: June 11, 2015, 06:30:25 pm
content: I see you popped the question...now to wait

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: June 11, 2015, 10:36:25 pm
content: Yes, I followed your advice...

author: petepdx
author_rank: Newbie
timestamp: November 18, 2017, 07:01:35 pm
content: I know your post was long ago, but did you get what your looking for and a manual ?Although by today's standards the spec s are pretty bad, these synths were quite amazing for their time. I have a few of the and enjoyed fixing them. I love the older transistorized gear and learning how it was designed.-pete
NF ZM2354 LCR meter ERR77? - Page 1
Forum section: electronics / repair

author: mrf245
author_rank: Regular Contributor
timestamp: November 18, 2017, 12:59:04 pm
content: I got a NF model ZM2354 LCR.It worked fine until last time I turned on it, It didn't execute normal boot sequence,but displayed "IL ERR 77".I asked another friend who have some ZM2354, he sadly told me that all of his 2354 also have the same problem----IL ERR 77Most ERR 77 happened after normal use several times. I check manual it only shows ERR77 is "hardware problem". What hardware problem?Anyone know how to solve this problem? Thank you very much...

author: coromonadalix
author_rank: Super Contributor
timestamp: November 18, 2017, 03:10:40 pm
content: Seems your lcr had some beating on the top panel casecould not find a complete manual...Does it have some battery inside ?Maybe some loose part, connector, socketed chip, or even bad/cold solder ?
IFR 2398 spectrum analyzer - Page 1
Forum section: electronics / repair

author: Domrich
author_rank: Newbie
timestamp: November 16, 2017, 07:07:41 pm
content: Hi EverybodyI got a IFR2398 with a curious issue.All tests pass and especially level test.The level show 15dB under the right level whatever is the frequency and the level of the input signal. Excepted this everything is OK and absolutely no error is reported.The input level is verified with other generators and analyzer.I cannot figure out how it is possible. I have checked the input HF block and for me it is OK.Has somebody already seen that? Any idea? I do not know what to check!!Dominique

author: orbanp
author_rank: Regular Contributor
timestamp: November 16, 2017, 11:55:27 pm
content: Hi Dominique,I can not offer real help, but have you seen this thread:https://www.eevblog.com/forum/repair/aeroflex-ifr-2398-calibration-repair-help/They also mentioned there a Yahoo group for that particular SA.Peter

author: Domrich
author_rank: Newbie
timestamp: November 17, 2017, 10:11:36 pm
content: Thanks Peter. I will study this thread carefully.And register to thid yahoo's group.DR
Replacement part searching, help needed! - Page 1
Forum section: electronics / repair

author: Claudiu
author_rank: Newbie
timestamp: November 17, 2017, 02:39:47 pm
content: Hello,I have a Semikron IGBT wich is damaged, the code is SKiiP 32NAC12T42, and I cannot find any datasheet about it, or some other information about some replacing part. As far as I know, the product is discontinued since about 2011, still I have many VFD's with different part code IGBT's, all of them discontinued. Does enyone have better ideea than to write directly to Semikron? Thank's!
GW Instek GOS-653G Display Distortion - Page 1
Forum section: electronics / repair

author: Branqazwsx
author_rank: Unknown
timestamp: January 20, 2017, 04:20:08 am
content: I have a GW Instek GOS-653G analog oscilloscope that was sitting in storage for a few years. I went to use it today, when I discovered there was a problem with the display. The upper right of the display is distorting the traces on the screen. It distorts with or without a probe or signal. It might be operator error, because its been so long since I used it. Does anyone have a thought to what the problem might be. See my video for the problem:User manual:http://www.gwinstek.com/en-global/Download/DownloadFile/DownloadFile/download%23_%2301_Oscilloscope%23_%2304_GOS%23_%2382OS-658G0MG.pdf

author: JXL
author_rank: Regular Contributor
timestamp: January 20, 2017, 05:01:59 am
content: Check for magnetic field near the CRT

author: retired tech
author_rank: Newbie
timestamp: November 12, 2017, 12:43:31 am
content: Like JXL said,might be a magnetic field(around mu-metal shield),or,I hope not,a dropped deflection plate.An old trick is to use a soldering gun(transformer type),turn it on and bring it close to the shield and gradually move it away from it.A foot or so before turning the gun off should do it.This was called degaussing in the old days.

author: 001
author_rank: Super Contributor
timestamp: November 15, 2017, 07:23:50 pm
content: similar problemhow can I fix it?

author: Gyro
author_rank: Super Contributor
timestamp: November 15, 2017, 07:48:15 pm
content: That's trace rotation - there should be a preset scredriver adjustment pot for it (often front panel, sometimes internal).P.S. Your scope probe compensation is incorrectly adjusted too.EDIT: If it is the same scope as the OP's, according to the manual, it is the the control marked 'Trace Rotation' (5) on the front panel!

author: 001
author_rank: Super Contributor
timestamp: November 15, 2017, 07:50:36 pm
content: Fixedhttps://www.eevblog.com/forum/beginners/epic-newbie-scope-problem/

author: Gyro
author_rank: Super Contributor
timestamp: November 15, 2017, 07:57:00 pm
content: @001:It really, really helps to save peoples time IF YOU DON'T KEEP DOUBLE POSTING QUESTIONS!

author: 001
author_rank: Super Contributor
timestamp: November 15, 2017, 10:18:33 pm
content: Ok okThanx

author: oldway
author_rank: Super Contributor
timestamp: November 16, 2017, 11:23:57 am
content: Mu metal offers small coercive force, nominal core losses and small remanence. For this reason, I don't think it is coming from a magnetic field.It seems to be a bad CRT.But you should check first the signals at the vertical and horizontal deflection plates with another oscilloscope to be sure.
Solder that won't melt. - Page 1
Forum section: electronics / repair

author: xavier60
author_rank: Super Contributor
timestamp: November 16, 2017, 06:16:11 am
content: In the photo it can be seen what looks like a solder bridge across a bunch of pins on the micro-controller. It is the motor controller board of Fisher & Paykel washing machine.Whatever it is, I could not remove it with solder wick even after adding fresh solder and also adding chip quik smd removal alloy in an attempt to dissolve it.I eventually scraped most of it out with a sewing needle and lifting 2 pins to clear a stubborn short.The board is one of a bunch that I scored from a Gumtree seller, so I don't know much of its history except that the SMPS transformer had been removed revealing a badly charred LNK624 SMPS IC.I'm really curious about what type of metal it's likely to be and how it got there. Maybe someone has seen the same thing.

author: DaJMasta
author_rank: Super Contributor
timestamp: November 16, 2017, 08:00:32 am
content: It looks like the board is potted, so there's probably a layer of sealant on the pins that's just preventing good metal-to-metal contact. Try chipping it off with a sharp knife (lightly enough not to chip the pins off too) and see if you can make better contact.

author: capt bullshot
author_rank: Super Contributor
timestamp: November 16, 2017, 08:05:58 am
content: Yes, IMO it's the remainders of the conformal coating that interferes with your soldering.

author: Rerouter
author_rank: Super Contributor
timestamp: November 16, 2017, 08:15:18 am
content: Its a common industrial conformal coating, acetone and a toothbrush will clean it off pretty quickly,The solder itself will be lead-free so should melt by 360C, but the coating is somewhat thermally insulating, which prevents you being able to get enough heat into a joint.

author: xavier60
author_rank: Super Contributor
timestamp: November 16, 2017, 08:16:54 am
content: Quote from: DaJMasta on November 16, 2017, 08:00:32 amThere was a light coating of lacquer that I had applied before I knew about the bridged pins.I took the photo after the first 2 attempts of applying a large blob of solder to the group of pins and removing it with solder wick. That remaining metal between the pins was rather tough yet brittle.
UPS Accu leaked - Page 1
Forum section: electronics / repair

author: Lord of nothing
author_rank: Super Contributor
timestamp: November 15, 2017, 04:59:11 pm
content: HeyFrom my good old MGE UPS the 2 of 3 Accu blows up and leak.What is the Main problem Heat or Cold?So whats next? The Cable look not that bad. Put them into an Ultrasonic Bath with Vinegar?How about the UPS? Could there Accid left?Should I open the Electric part?Thanks

author: oldway
author_rank: Super Contributor
timestamp: November 15, 2017, 05:42:39 pm
content: First clean everything with a solution of baking soda to remove sulfuric acid.

author: Lord of nothing
author_rank: Super Contributor
timestamp: November 15, 2017, 05:53:05 pm
content: I rinse the Plastic thing off and the Cable.Tomorrow I will inspect the UPS now its cold and dark on the attic.The UPS is still under Power who 2 Server run behind.

author: Cyberdragon
author_rank: Super Contributor
timestamp: November 15, 2017, 06:49:27 pm
content: Tomarrow might be too late. You need to get the acid out NOW before it corrodes everything. It might even already be ruined if the acid got into the electronics, so definately unplug it until you're sure the acid didn't get into anything else electrical.

author: Lord of nothing
author_rank: Super Contributor
timestamp: November 15, 2017, 07:57:55 pm
content: The UPS Accu leaked for a wile. I was just ordered replace Accu and yesterday I opened it and pull the Tray out.
B&K 2120 calibration  help - Page 1
Forum section: electronics / repair

author: Mikeloiselle
author_rank: Newbie
timestamp: November 15, 2017, 04:58:24 am
content: Good day eevblog,My wonderful wife just bought for our anniversary my first scope. I've twiddle with all the knobs on this wonderful b&k 2120 analog scope and am very pleased however I have on problem. My time base is of by roughly 5% or so. Basicly my waveforms appear about 5 % short of where they should fall. I adjust the time circuit calibration to its maximum to attain this much. I do not see anywhere else on the circuit to compensate this. using the veneer controls only make the waveform shorter from themark. Everything else is great. Any suggestions would be great. I only adjusted vr801 and set the voltages, xy positions and sweep lengthPlease note I am nothing more than a hobbyist who enjoys electronics. I have included a link to the service diagram. I will take a picture tomorrow. .https://elektrotanya.com/b_k_2120_oscilloscope_sch.pdf/download.htmlThanksMike

author: Mikeloiselle
author_rank: Newbie
timestamp: November 15, 2017, 02:35:44 pm
content: Please see atached.First picture is 10k sign wave at 0.1 meSecond picture is 1k sign wave at 1 meThanks

author: Mikeloiselle
author_rank: Newbie
timestamp: November 15, 2017, 02:37:47 pm
content: Second picture

author: oldway
author_rank: Super Contributor
timestamp: November 15, 2017, 05:52:08 pm
content: Hello and welcome to the forumBefore settling anything, you must first know how to use the oscilloscope.This is your first oscilloscope, if it works, use it as it is.I know it's already too late, but stop tweeking all the settings, you're going to do more harm than good.
MLCC flex crack? - Page 1
Forum section: electronics / repair

author: zoltan
author_rank: Contributor
timestamp: November 15, 2017, 11:21:53 am
content: Hello all,After Dave's latest video I've got to do some damage assessment on work. The service guy said that it was a TVS failure after overvoltage condition on the input terminals (green 3-pin on photo), but I am sure that nothing was connected there, never. Not even in error.So here is my conclusion about the damage. Did I missed something important, or concluded wrong?QuoteI'll have a new, working module in a week or two, then I can do the measurements and reverse engineer the schematics. But until then, I would like to know if I am wrong, and if, in what part.Z

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 15, 2017, 11:27:01 am
content: There are MOVs that look like that. Could also be a ferrite bead, and the real short is somewhere else.Tim

author: zoltan
author_rank: Contributor
timestamp: November 15, 2017, 11:46:54 am
content: Quote from: T3sl4co1l on November 15, 2017, 11:27:01 amI focused only on TVS, because the service guy explicitly stated that the TVS died due overvoltage (>14V). I went trough the farnell TVS catalog images and all I found was the familiar terminal design, nothing like this one. I really don't care if it is something inside the main equipment, as the conclusion was that our guys put excess voltage by connecting something to the module and burned out the whole thing (which is not true). The point is to prove the fault is in the module.All I know about the burned part is that it is connected parallel with the two smaller caps on the right side, and they are connected in series across the power supply (probably 5V).
10U 25V Capacitor Ohms reading - Page 1
Forum section: electronics / repair

author: AjA
author_rank: Contributor
timestamp: November 15, 2017, 02:34:46 am
content: I am noobi in soldering and don't have much knowledge to identify components, i have a lot of Capacitors and resisters but not sure which Capacitors and resisters is what size, now i want to know if i need 10U 25V Capacitor from what i have in stocks than how i check and select correct one, if Digital Multi Meter set to 200 Ohms range than what ohms reading it will show if i want 10U 25V? in case if i don't have 10U 25V than what will be alternate, i am trying to fix my laptop motherboard charging section so i need to replace 10U 25V Capacitor, below image is 10U 25V Capacitor which i need to replace from motherboard,any help will be apprenticed,Thanks.

author: jcw0752
author_rank: Contributor
timestamp: November 15, 2017, 05:32:39 am
content: Hi, What makes you think that the 10uF 25 V capacitor is bad? It is very unusual for this capacitor to fail. A good capacitor that isn't in the circuit will show 0 ohms on the scale that you mention. To get an accurate measurement of a capacitor it is best to have a meter that reads capacitance.John

author: AjA
author_rank: Contributor
timestamp: November 15, 2017, 06:19:11 am
content: Hi jcw0752,thanks for reply, actually my laptop can't power on with battery, pls checkThis Threadas per schematics on page 55 on battery section, so i need to replace all cap/zener one by one to check before i put my hands to replace Charging IC so i need 10U 25V Capacitor as per schematics, i have alot of Capacitors/zeners/resistors but all are mixed so i can't figure out which Capacitor is what size, so i asked help, so if it possible to check and try on board?Thanks.

author: AjA
author_rank: Contributor
timestamp: November 15, 2017, 06:47:04 am
content: @blueskull got it, Thanks.
8082A HP Pulse Generator  - Page 1
Forum section: electronics / repair

author: Satbeginner
author_rank: Regular Contributor
timestamp: November 06, 2017, 06:21:10 pm
content: Removed

author: Satbeginner
author_rank: Regular Contributor
timestamp: November 13, 2017, 04:38:40 pm
content: Removed

author: macboy
author_rank: Super Contributor
timestamp: November 13, 2017, 06:06:42 pm
content: There is an equivalent schematic of that IC in the service manual. You could try to reproduce it. Before you make any such attempt, you should read and learn from this:http://www.dasarodesigns.com/projects/reverse-engineering-an-ic-to-fix-an-hp-8007a-pulse-generator/

author: Satbeginner
author_rank: Regular Contributor
timestamp: November 14, 2017, 07:15:53 am
content: Hi MacBoy,I read the article you suggested, and wow, it's seems good news it's (maybe) doable.Based on the size of the 8082A, I would go the ECL route, so no self designed mini boards.Speed will be an issue, the 8082 will go up to 250MHz, but it's worth a try.Problem for now is, that in my pdf that particular page is poorly scanned.There are lines / connections missing, so I am still looking for another scan.However, the scan at Keysight and so far all the others are from the same document.Thanks for that article,Leo (Satbeginner)

author: macboy
author_rank: Super Contributor
timestamp: November 14, 2017, 05:55:50 pm
content: You can buy an original paper manual on ebay.An ebay seller called artekmedia also sells high quality scans of the paper manual, and they claim to be under license by Agilent to do so. Maybe you could try to save on shipping costs and delays by requesting "electronic delivery"? I don't think ebay allows listings which don't promise to deliver a physical item (a CD-ROM with a PDF file on it), but nothing stops you from asking the seller directly.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: November 14, 2017, 06:01:50 pm
content: Artek has manuals for 8007A, 8007B, and 8082A.http://artekmanuals.com/manuals/hp-manuals/I've gotten several manuals on CD. All are very nice, high-resolution scans. You can also buy directly.

author: MadTux
author_rank: Frequent Contributor
timestamp: November 14, 2017, 07:38:50 pm
content: I have butchered a bad HP-8082A a couple of years ago. Looks like my HP-8082A had exactly the same bad 5081-3011 chip , because I saved the working ones in a drawer (3027, 3009, 3012, 3013) and 3011 isn't there ;-)I avoid any HP-8000 series instruments now (8082A, 8112A, 8116A, 8165A...) because these all have unreliable unobtnium ASICs.
Hameg HM1507-3 oscilloscope - Page 1
Forum section: electronics / repair

author: doncia
author_rank: Newbie
timestamp: November 23, 2017, 10:27:27 pm
content: Hi, all of you. I've been working with this scope for a long time now, but lately I noticed that channel one was a bit unstable. Consequently the problem evolved into having ranges of 5V and larger not working at all. The scope internal relay is working as I can hear the click and compared to channel 2 it is switching at the right range change, however the display goes to a flat line at the 5V range. Anyone can help please?

author: oldway
author_rank: Super Contributor
timestamp: November 24, 2017, 03:49:50 am
content: Welcome on the forumIt is probably a problem of bad contacts of the relays.Here is the diagram of the front end of your oscilloscope.
Solid state audio amplifier slight saturation - Page 1
Forum section: electronics / repair

author: Rutherberg
author_rank: Regular Contributor
timestamp: October 26, 2017, 08:14:59 am
content: Hi,I try to fix a bass guitar amplifier with a solid state power amplifier (SWR Workingman's 4004), it have a problem of slight "background" saturation.I isolated the problem to the power amp, the preamp sounds fine.It seems to be load related. When I connect it to a loudspeaker, the problem is present, even with low volume.On the other hand, when I connect only phone output, which is connected at the output of the power amp via 100R resistor, no problem.What could cause a saturation caused by load ? I didn't check the bias yet, is bad bias could be the cause ?Here is the schematic, the power amp is page 5 :https://support.fender.com/hc/en-us/article_attachments/115007682386/Workingman_s_4004__Complete_.pdfThanks in advance

author: frog
author_rank: Contributor
timestamp: October 26, 2017, 09:17:52 am
content: Can you explain what you mean by saturation?

author: Armadillo
author_rank: Super Contributor
timestamp: October 26, 2017, 10:31:24 am
content: Follow the setting up of the bias procedure in page 6/7.To check, short the input and measure the voltage at speaker output at L1 to +vcc, and compare it to voltage of speaker output at L1 to -vcc.Edit: Also check the power supply +15vdc, -15vdc, +75vdc, -75vdc.

author: David Hess
author_rank: Super Contributor
timestamp: October 26, 2017, 01:07:02 pm
content: I am not sure what "background saturation" is.Besides confirming that the bias is adjusted correctly, I would check the output transistors for low gain, check that none of the output emitter resistors are open (and the collector resistors on the drive transistors), and that the supply voltage is not sagging.Does it appear to just have low gain? Maybe C4 dried out. How old is the amplifier?

author: Rutherberg
author_rank: Regular Contributor
timestamp: November 14, 2017, 01:22:10 pm
content: Thanks for all the inputs !I did the procedure to set the bias, it was completely out of range. Since, the saturation disappeared.
Jittery Sinusoidal signal on Tek 2235--power supply issue? - Page 1
Forum section: electronics / repair

author: mstettle
author_rank: Newbie
timestamp: November 15, 2017, 10:10:36 pm
content: Hi Everyone,I just bought a Tek 2235 AN/USM-488 oscilloscope. I've tested it, and is it fully functional, but there are some trace anomalies that make me think the power supply or triggering may have an issue, and I wanted your advice (I looked quickly at the Tek troubleshooting manual, but it didn't seem definitive for the symptoms). Here are the symptoms:- waveforms on both channels "jitter" (bounce back and forth slightly,). This problem is intermittent, sometimes the waveforms are perfectly stable. The jitter appears to happen less after the unit warms up.- Sometimes very small artifacts can be seen on sinusoid waveforms (i.e. extra phosphur dots are lighting up adjacent and just below the trace, like the trace has five o'clock shadow)- there is sometimes a very small ripple on the trace before a signal is applied. I haven't measured it, but it is small and again, intermittent.Is this the "beginning" of a power supply issue?Thank you,Mark
Fluke 87V - no continuity buzzer - Page 1
Forum section: electronics / repair

author: tudorv
author_rank: Newbie
timestamp: November 14, 2017, 09:25:16 pm
content: Hello,i have just bought an Fluke 87V from ebay which works perfectly except the continuity buzzer which works only now and then without having any logic. I opened the case and cleaned the contacts of the buzzer, but still no use. I also used the backpanel from another fluke 87V with a perfectly normal buzzer and it had the same behavior. What could be?Thank you!
Denon Receiver AVR 1912 Troubleshooting - Does not Power on - Page 1
Forum section: electronics / repair

author: eduardo
author_rank: Newbie
timestamp: November 12, 2017, 01:49:51 pm
content: We have a Denon AVR 1912 connected to UPS /Voltage regulator. Suddenly the unit does not power on . We tried unplugging the unit from the UPS and sourcing power from a different outlet and did not power on either. Verified the manual on the troubleshooting section and does not give further ideas to address issue.Any further recommendations?

author: onesixright
author_rank: Frequent Contributor
timestamp: November 12, 2017, 02:57:50 pm
content: Did you checked the fuse?Have a look at the service manual (look at page 61: trouble shooting):https://www.manualslib.com/download/986184/Denon-Avr-1912e3.html

author: oldway
author_rank: Super Contributor
timestamp: November 13, 2017, 03:39:27 pm
content: There are two fuses to check first: F100 and F101.There is an auxiliary SMPS 5.2V...you should then check if you have the auxiliary 5.2V rail.
Help locating relays - Page 1
Forum section: electronics / repair

author: jheatac
author_rank: Regular Contributor
timestamp: November 12, 2017, 03:38:51 pm
content: Hello,I cannot find a source for some Class F Insulated relays for an oven board:Omron G5LE-1-CF 9VDC (or SongChuan 812H-1C-S 9VDC)SongChuan 835NL-1A-F-C 9VDCSongChuan 855AWP-1A-F-S-B 12VDCI can located them, but cannot find a supplier with stock or a minimum less than 100 units.Anyone out there have a source?Thanks!

author: Samogon
author_rank: Frequent Contributor
timestamp: November 12, 2017, 05:26:39 pm
content: https://www.digikey.com/product-detail/en//G5LE-1-CF%20DC12/Z5214-ND

author: jheatac
author_rank: Regular Contributor
timestamp: November 12, 2017, 07:28:54 pm
content: Thanks for the reply. It seems that the 12V options are more popular as I have found stock.The smaller 2 are 9V, and the larger is 12V.I don't have the oven around to see what voltage it is actually operating at, so I was trying to match what was in there.
HP8560A display problem - Page 1
Forum section: electronics / repair

author: thlee
author_rank: Contributor
timestamp: November 12, 2017, 05:12:20 am
content: I brought a second hand HP8560A but there were display problems after power on. The displayed characters were incomplete as shown in Figure 1. I had replaced U207 in A2 control board , trying to fix it. Unfortunately, the problem cannot be fixed. Two resistors R250 (3.16M) and R251 (1.1M) were checked and they were ok.I execute the CRT adjust pattern as shown in Figure 2. All @s and some characters were not displayed fully. Two segments from the upper right corner to lower left corner were dim except at the starting points.Anyone can advice me how to fix it?

author: thlee
author_rank: Contributor
timestamp: November 12, 2017, 12:34:10 pm
content: I have captured line generator output waveform as shown in Figure3 . The figure3a and figure3b are zoomed in waveform. Two signals (z out and blanking) are different from service manual as shown in Figure4 but I am not sure. Anybody can suggest me what is a problem?
Fluke PM2812: broken backlight inverter repair - Page 1
Forum section: electronics / repair

author: Jens01
author_rank: Contributor
timestamp: November 11, 2017, 03:18:25 pm
content: Hi,recently i bought a second hand Fluke PM2812 Power supply, the same as in EEVblog #755. The power supply works great but the backlight of the front display seemed to be broken. I opened it up, and as can be seen in the first attachement it wasn't very hard to find te problemThe transformer in the inverter(schematic: page 57 right bottom)is clearly broken and came loose of the board.The repair shouldn't be hard, but i didn't manage to find a replacement transformer. The package (second attachment) says 'TNB' and '24'. The schematic says 5V Input and 115V AC output. The size between the pins measure 10mm x 9mm.Are there any (Fluke) guru's who can help me finding a suitable replacement part?
Need Schematic or SM for Anritsu Ms611A - Page 1
Forum section: electronics / repair

author: velik_kazakov
author_rank: Regular Contributor
timestamp: November 14, 2017, 06:53:59 am
content: Hi all,I buy Anritsu Spectrum Analyzer Ms611A from ebay/UK and need schematic or SM for it.It work, but maybe have some problems in the power supply (the power rails not the exact value I think) and I try to find some info before to start to repair.Something else, it have NiMH battery in the CPU pcb. I don't know it is used to store only the saved settings in RAM memory or calibration info. Please if someone know this to share with me. If it keep calibration info I will prefer to exchange it with new one.Thank you in advance!