hybridfree/eevblog-posts huggingface dataset:
New polypropylene capacitors damaged?  - Page 1
Forum section: electronics / repair

author: Rickpercy87
author_rank: Contributor
timestamp: March 21, 2016, 09:51:13 pm
content: I've bought some polypropylene capacitors from eBay. They are 4.7uf rated for 400v. They are Chinese so I didn't pay an awful lot.The dipped case looks peculiar. Some of them have very slightly sharp edges in the case and you can make out bare metal where is has not been covered properly.Could this be dangerous?ThanksSent from my SM-N9005 using Tapatalk

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 21, 2016, 10:06:10 pm
content: Answer is same as always... what were you expecting...I'd be curious if a hi-pot shows them even handling the rated voltage without breakdown.Are they at least a reasonable size (maybe 32mm long, 13mm wide)?Tim

author: station240
author_rank: Unknown
timestamp: March 21, 2016, 10:17:12 pm
content: Quote from: Rickpercy87 on March 21, 2016, 09:51:13 pmDanger is relative, what voltage are you actually applying ?If the polypropylene sticks out further than the foil, it should be too much of an issue.Pictures would help, but sounds like they didn't pour enough epoxy on the ends to seal it.Pick the worst one and send it to Photonic Induction, or some other local nut ball with a huge variac.ps: You might want to disable Tapatalk's eWank feature.

author: Rickpercy87
author_rank: Contributor
timestamp: March 22, 2016, 12:18:57 pm
content: Cheers for the reply, I will be using them with 230v AC led bulbs using the reactance to step down the voltage. I've not calculated the exact current I'll get but it will be around 200mA I suppose.I'll get some pictures later, would the metal be the conductive plates of the capacitor? If it is won't it arc? Also is could potentially short.I'll probably end up applying power to it and poking it with my multimeterSent from my SM-N9005 using Tapatalk

author: wraper
author_rank: Unknown
timestamp: March 22, 2016, 12:59:20 pm
content: Quote from: Rickpercy87 on March 22, 2016, 12:18:57 pmFirst of all, sooner or later 400V capacitors will fail if you use them at 230V AC.Secondly, what you are going to do, don't sound to be smart. The result might be not what you expect.

author: Seekonk
author_rank: Super Contributor
timestamp: March 22, 2016, 01:32:58 pm
content: Metal, those were the days. You have a flash metalization of the insulator which is self healing. A short would likely clear itself with enough power.
TDA8920 TDA8920B TDA8920TH TDA8922 Understanding Faulting troubleshooting Repair - Page 1
Forum section: electronics / repair

author: nerdalert
author_rank: Newbie
timestamp: March 22, 2016, 11:41:33 am
content: From The Datasheet..2. Features\\\\\\The TDA8920B is a high efficiency class-D audio power amplifier with very low dissipation....From Datasheet alsoThe audio input signal is converted into a digital pulse width modulated signal via an analog input stage and Pulse Width Modulation (PWM) modulator.SO AFAIKThe audio input signal is turned into a 'digital' carrier?.. and then amplified and the carrier? is then filtered off with HPF and you are left with HIGH power output.Trying to understand the tda8920 operation better to assist in repairing amplifier.i.e. what signal should we see at output pin21also post filter ?whats with the push pull thing ?and the 90% efficiency that is really impressive...and where is the bias is that now the boot pin15&22 job ?what is the difference in the PSU pins..VSSP VDDP VDDA VSSA. what do those abbreviations mean ?SO questions comments..http://www.farnell.com/datasheets/1503711.pdfhttp://www.farnell.com/datasheets/1503711.pdfcircuit page 21TDA8920 circuit diagram from data sheet Att.
Keithley 2000 - Page 1
Forum section: electronics / repair

author: klaus11
author_rank: Unknown
timestamp: March 21, 2016, 11:07:43 am
content: I'm trying to repair a K2000, fault 600.1, 600.2, 601.1, 601.2. I have replaced all the transistors marked with 6G mmbf4393 but I find with 3 transistors 132 marked:2 transistors, pins 2 and 3 in short and third transistor Pins 2 and 3 not short.Like, you can be a double diode NXP.Someone help me with device 132.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: March 21, 2016, 01:31:10 pm
content: Have you looked at the schematic?https://dev.xdevs.com/projects/kei2000/repository/raw/schematics/K2000_bbs_38hot_net.pdf

author: klaus11
author_rank: Unknown
timestamp: March 21, 2016, 01:40:31 pm
content: Yes, the scheme marking all snj132199. But all device 6G, exception 3 device marked 132.I have replaced 3 mmbf4393 device 132, and have general error in DCV

author: klaus11
author_rank: Unknown
timestamp: March 21, 2016, 04:55:15 pm
content: I cleaned device 132, now 3 same measures. Become welded in place.Surprise all bugs fixed 60X.X. 6G also replaced all transistor.30X.X. errors appearBefore they were not. You can mistake buffer masked by Q109, Q106, Q105 ...
DSE Q1760 Box of bits - Page 1
Forum section: electronics / repair

author: electrogeek
author_rank: Contributor
timestamp: March 20, 2016, 04:55:25 am
content: Well, as tails of woe can go I find myself with a freshly thrown out DSE Q1760 Bench top power supply. What could possible be so wrong I thinks to myself, here will be the catalog of just what I find. and with some luck, acquire a useful little power supply.it arrived in my hands in the condition shown, so I am expecting a bit of a challenge. I have found a schematicQuote from: wilfred on August 07, 2013, 11:30:49 pmalready.Any thoughts where I should start looking? usually I would start by plugging it in a verifying there is in fact a fault, but I suspect this one is a bit past that. it looks like from the bits that came with it someone has already replaced the bridge which makes me a bit nervous about what is lurking.Cheers

author: electrogeek
author_rank: Contributor
timestamp: March 20, 2016, 05:30:20 am
content: I guess this isn't factory fresh...

author: electrogeek
author_rank: Contributor
timestamp: March 20, 2016, 06:16:45 am
content: Doubt that had anything to do with it's failure, but I guess it'll need replacing, and probably if one is bad, they all are....

author: electrogeek
author_rank: Contributor
timestamp: March 20, 2016, 06:29:19 am
content: The bodge is strong with this one. I guess you have to power the fan from somewhere...

author: electrogeek
author_rank: Contributor
timestamp: March 21, 2016, 05:08:33 am
content: Its alive! now to put it all back together and see if it regulates. for those playing at home the fault(s) were as follows:1x short bridge rectifier (DA1) (I'd love people thoughts on how that might come to fail)4x tracks burnt off pcb, V1-RLY1, V2-RLY1, not well labeled, but what appears to be V3-C33 and lastly RLY1-C24.

author: iampoor
author_rank: Frequent Contributor
timestamp: March 21, 2016, 08:26:16 am
content: How hot does the Bridge Rectifier get?Is the PCB made from the same material that is use in cheap consumer electronics? (FR1?)

author: electrogeek
author_rank: Contributor
timestamp: March 21, 2016, 10:14:04 am
content: They may have been running the bridge a bit hot, the fan kicks on when the heat sink the bridge is on hits 60 degrees. And regarding board material, yes it appears to be fr1.

author: Shock
author_rank: Super Contributor
timestamp: March 21, 2016, 12:47:09 pm
content: Quote from: electrogeek on March 21, 2016, 05:08:33 amFilter capacitor.
Weller VP800/801 desoldering station, how many filters are needed? - Page 1
Forum section: electronics / repair

author: AndersJ
author_rank: Frequent Contributor
timestamp: March 20, 2016, 01:23:54 pm
content: The station has filter cans on the input, on the front panel,and on the exhaust, on the rear.The cans have plenty of space for many filters,and the cap has a spring that implies that a handful of filters could/should be used.Q1: Is one filter enough, and if so, why is the spring there?Q2: Or, are many filters needed, stacked one after another?Q3: Does anyone have a operators and/or service manual?Grateful for all commentsAnders J

author: SeanB
author_rank: Super Contributor
timestamp: March 20, 2016, 01:34:06 pm
content: One filter on the case itself, and in the actual solder station 2 filters stacked. The reason for 2 is that when the first is dirty the one behind will be only mildly contaminated, so you discard the innermost unit and put the slightly used on in the firing line, and put a new one behind it to keep the suction lines and pump clean. Maximises filter life, as they cam be quite expensive. To improve life of the filter in the suction head get a plain stainless steel pot scourer ( check with a magnet it is not steel, and immerse a sample in some slightly salt water for a day to see it does not rust. Beware of plated plastic scourers though, they melt) and cut a small plug out of it to fit ahead of the filter, to catch the molten solder. Small plug, and you can easily toss it along with the solder when it clogs up, saving the filter.
KORAD KA3005P Repair - Page 1
Forum section: electronics / repair

author: Morgoroth
author_rank: Regular Contributor
timestamp: March 20, 2016, 06:43:58 am
content: I received a regulated power supply Korad KA3005D, and as soon I turn it on the transformer sound very ugly and after a second... nothing.... then after 2 mins I realize that the power supply was set up to 110V (I have 220V here), so I replace the fuse, fix the voltage set up and powered, but not working...Seems like the display control is dead.brand new...any idea ??, someone ?
Fubared mosfet in induction heater - Page 1
Forum section: electronics / repair

author: wkb
author_rank: Super Contributor
timestamp: March 30, 2016, 01:49:44 pm
content: Last week I received an induction heater toy from Banggood. This onehttp://www.banggood.com/5V-12V-ZVS-Induction-Heating-Power-Supply-Module-With-Coil-p-1015637.htmlUnfortunately it was a DOA (BG is sending a refund), it emitted the magical smoke on first powerup (dead short between the power input terminals).Doing some investigation and it looks one (or maybe both) of the mosfets (?) is/are dead.Sofar I have not found the magical Google search string to identify it. Someone who has a clue based on attached picture?

author: MK14
author_rank: Super Contributor
timestamp: March 30, 2016, 01:59:51 pm
content: I'm NOT 100% sure, but my best guess so far is...ON Semiconductor NTB30N06Ghttp://www.digikey.com/product-detail/en/NTB30N06G/NTB30N06G-ND/1484676

author: Miyuki
author_rank: Frequent Contributor
timestamp: March 30, 2016, 02:40:49 pm
content: Any of many Chinese 30A 60V mosfetThey use local manufactured parts mostly copy of any big brand with similar labellingbut it is "current"n"voltage" system
Wonky BK Precision 1743B power supply - Page 1
Forum section: electronics / repair

author: Debunque
author_rank: Newbie
timestamp: March 20, 2016, 01:12:09 am
content: Hello - question from a newby here.I have a BK Precision 1743B power supply (CC and CV, 0-35V, 0-6.5A) that mostly works, but has glitches. This is an analog supply that makes loud clicks, suggesting it uses a relay to switch between transformer coils.First problem: it takes a while to stabilize after turning on. The voltage and current dance around.Second problem: Now it won't to go the top of the 35V voltage range. Turning the coarse and fine voltage adjustments all the way up takes it to about 25V, and then it crawls up slowly. Because of the crawl-up (now at 28V) this suggests that it isn't a problem of the final transformer coil not being activated.The voltage and current readings are basically correct, agreeing with a BK multimeter to a couple of percent.The unit is a bit rough with the casing a somewhat rusty from humidity. So a bad contact is a possibility.So my question is ... is this this behavior (lack of stability, can't reach highest V) characteristic of some known problem, like a bad electrolytic cap? If it's just a cap, it's worth repairing. If it involves more digging around, then maybe a new supply is in order.Jonedit- there's one big old-fashioned electrolytic cap rated at 50V that is at 42V when running, but dips down to 20V at heavy current draw. The other caps are small.

author: mojoe
author_rank: Frequent Contributor
timestamp: March 20, 2016, 02:38:44 am
content: I don't know the history on your unit, but if it is rusty, then I'd certainly open it up and poke around inside. First, I'd spray some DeOxit on the adjustment pots. If you don't find any physical damage inside, do at least check the filter caps (discharge them first). If none of that works, then a little more work will be required. See if you can find a schematic.The fact that it mostly works is reason to keep it. New linear bench supplies are expensive.

author: Debunque
author_rank: Newbie
timestamp: March 20, 2016, 04:09:47 am
content: So there's only one big cap as I noted in my edit. It seems OK. It sparks violently when shorted after turning the unit off.Yes, linear PSs are expensive, especially at high amps. This one goes for $475 new. However, Amazon is selling the smaller 30V,3A version at a discount for just $113. So I'd give up half the amperage, but replace a very rough unit with shiny new unit at a decent price.I thought it might be the coarse voltage pot, but I ran it back and forth, and it didn't get better. The lower end of the range seems a little above zero, which suggests the pot could be the problem (too much R, too little V). Arguing against the pot hypothesis is the fact that the problem partly fixes itself slowly -I turned it on again, and it is at 16 volts at the highest setting, and it will eventually crawl to 30 volts by itself.I wonder if self-generated heat could be fixing it.
Nikon MH-23 quick charger doesn't work. - Page 1
Forum section: electronics / repair

author: Gerardo
author_rank: Newbie
timestamp: March 19, 2016, 10:38:09 pm
content: Hello,I have a Nikon MH-23 quick charger. Some months ago, it suddenly stop charging the battery. Even the LED indicator doesn't turn on. I checked the fuse and it's ok. The voltage after the diode bridge is correct. The control IC also has voltage to feed it (5Vdc). In the output of the the flyback secondary side the voltage is also present (8Vdc). I tested the LED individually and it's fine, in fact I notice that the control IC don't send voltage to it.Apparently neither component looks like broken or burned. Ofcourse, I know it doesn't assure the correct operation of each component. I believe maybe some protection is already activated. Some one have an idea of what's happening or how I must proceed to check it?.Thanks.

author: IanB
author_rank: Super Contributor
timestamp: March 19, 2016, 11:02:37 pm
content: Have you tested the battery with a different charger? It could be the battery that is not working rather than the charger.If the battery has failed the charger may refuse to charge it.
Schematic and troubleshooting of LD 4000 FL ballast - Page 1
Forum section: electronics / repair

author: krzychb
author_rank: Contributor
timestamp: March 20, 2016, 09:59:25 am
content: Hello everybody and here is my first postThanks togreat blog by Pavel RuzickaI have managed to repair two faulty electronic ballasts of LD 4000 fluorescent lamps by a German company Elektra. I have seven of them used every day since more than 12 years. Two failed out of seven over 12 years seemed to me a reasonable reliability to invest some time for repair.You will find schematic of ballast and description of repair in myrepository.Below is a nice waveform of ballast starting up. I consider it as an EKG of FL brought back to lifeIf you have such lamp and it happens to be faulty, do not throw it away because it is robust, nicely designed and therefore fun to fix.Krzysztof
Lambda LPD-423A-FM manual wanted - Page 1
Forum section: electronics / repair

author: Cloud
author_rank: Regular Contributor
timestamp: March 18, 2016, 07:41:25 pm
content: I have lambda LPD-433A-FM PSU, but one channel isnt working. I have tried replacing one capacitor, but it works some times and sometimes not. So I am looking for a manual.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 18, 2016, 08:03:58 pm
content: http://www.davmar.org/pdf/LambdaLPD.pdf

author: Vgkid
author_rank: Super Contributor
timestamp: March 18, 2016, 08:18:20 pm
content: The good thing about lambda, is that tey are responsive to emails. Unfortunately some have schematics, some do not.
My home lab's Rigol MSO 1104Z Logic Analyzer is failing calibration? - Page 1
Forum section: electronics / repair

author: matrixofdynamism
author_rank: Regular Contributor
timestamp: March 20, 2016, 08:31:43 pm
content: I have only used the scope's logic analyzer part once with my PS2 dual shock controller more than 6 months ago. I used it again today but it would give wrong result. I tried a "probe calibration" twice and it failed both times. This scope was bought in mid of 2014. I don't even know where to start to get this problem fixed.

author: JFJ
author_rank: Regular Contributor
timestamp: March 21, 2016, 12:54:57 pm
content: Quote from: matrixofdynamism on March 20, 2016, 08:31:43 pmYou might try a factory reset:http://beyondmeasure.rigoltech.com/acton/attachment/1579/f-02f4/1/-/-/-/-/file.pdfFailing that, I believe that your scope comes with a 3-year manufacturer's warranty (excluding probes and accessories). So, contacting Rigol Support could be a good place to start.
Interfacing to a CCD sensor - Page 1
Forum section: electronics / repair

author: Alex
author_rank: Regular Contributor
timestamp: March 17, 2016, 05:07:17 pm
content: I have a machine vision camera that uses a CCD array, the CCD47-10 AIMO from e2vhttp://www.ccd.com/pdf/ccd_47.pdfAlthough the camera appears faulty, the sensor does push out analogue 'video' data. I therefore suspect the sensor is OK and there is something wrong with the readout/processing circuit.Is there a simple way of getting an image from a standard CCD sensor to some display device?Alex
Tektronix 2201 Repair and Calibration video - fixed :) - Page 1
Forum section: electronics / repair

author: ManCave
author_rank: Regular Contributor
timestamp: March 18, 2016, 01:23:26 pm
content: Finally got to finishing this - done! The last issue was just a silly cable backwardsDone a video calibrating it. Can now take it off my bench finally.Video if you are interested...https://youtu.be/W9KBPU19rZcHope to do some more videos on some different content now.
old ega repair - Page 1
Forum section: electronics / repair

author: alwayslearning
author_rank: Contributor
timestamp: March 17, 2016, 10:47:00 am
content: hi im restoring an old pc and the monitor had the cables cut so im putting a 9 pin female plug on the back of the monitor but have run into a roadblock ,have worked out thegreen,red,blue,ground but dont know how to figure out the v-sync,h-sync and the intensity wires.1-ground-black2-not sure3-red-red wire4-green-green wire5-blue-blue wire6-intensity-not sure wire7-not sure8-H sync-not sure wire9-V sync-not sure wireWire colors i have left isBrown ,purple ,white ,yellowIts a THOMSON 4470D chassis ICM 2

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 17, 2016, 12:35:22 pm
content: Colors are usually by resistor color code, or with some offset. So1 = Black2 = Brown3 = Redetc.EGA is six bit, and TTL not analog RGB, so I wouldn't expect them to have used RGB colors for those lines.http://www.allpinouts.org/index.php/EGAIf you actually have CGA not EGA, then you will have an intensity pin and some NC/GNDs.Tim

author: mmagin
author_rank: Frequent Contributor
timestamp: March 17, 2016, 08:52:26 pm
content: Assuming you have a raster but it's not synced, you should be able to figure out the RGB and intensity by feeding them TTL high and low levels one at a time and noticing the change in the video raster.

author: alwayslearning
author_rank: Contributor
timestamp: March 18, 2016, 10:29:36 am
content: im just winging it basicly .im trying to find wiring schematics but its hard
Wanted: PicoScope 3425 schematic/service manual - Page 1
Forum section: electronics / repair

author: Helix70
author_rank: Unknown
timestamp: March 17, 2016, 08:13:52 pm
content: Does anyone have a schematic or service manual for a PicoScope 3425? We have 2 of these with broken channels, and before I start working up the signal path, I would love to have the schematic.Cheers,Josh

author: German_EE
author_rank: Super Contributor
timestamp: March 17, 2016, 10:52:11 pm
content: Good luck! I have an earlier model to yours (3206) and even after offering to sign an NDA they still would not part with any information.
Littelfuse age fatigue/failure(Bird 4421 RF meter repair)? - Page 1
Forum section: electronics / repair

author: TheSteve
author_rank: Unknown
timestamp: March 17, 2016, 03:33:06 am
content: I recently purchased a Bird 4421 electronic RF watt/SWR meter with a 4022(25 to 1000 MHz 1 KW) sampler head. The 4421 powered up fine but indicated it could not communicate with the sampler head. I opened things up and found two 2 amp fuses going to the head, one was blown. I did the simple fix and replaced the blown fuse(with the proper value). I then gave it another try and the second fuse blew. At this point I figured I had better investigate instead of just swapping another fuse. I couldn't find anything that seemed like a problem. I eventually connected the sampler head up to an Agilent supply set to 15 volts and 0.2 amps max. There was no drama and the head drew a reasonable 50 mAh. Not able to find a problem with anything including the cable that connects the two units I replaced the second fuse and powered it up. It has been working fine ever since. I have wiggled cables and moved things around with no issues.So that said, has anyone seen an age related failure to a Littelfuse style fuse? The fuse is the standard green one that is the same size as a normal 1/4 watt through-hole resistor. The unit was built in the 80's so they were likely 30 years old.Pics of the unit measuring a radio with a rated 50 watt output(all looks good!) and of course a blown fuse attached.

author: mojoe
author_rank: Frequent Contributor
timestamp: March 17, 2016, 02:47:43 pm
content: My guess is that the sensor got abused in the past, which blew the one fuse. This probably stressed the other fuse, also. Those look like polyfuses to me.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 17, 2016, 02:58:27 pm
content: +1I guess the old second fuse got a good beating when the first one blew, and you just ended his misery.
Keithley 2400 spark followed by smoke... - Page 1
Forum section: electronics / repair

author: Joe e19
author_rank: Newbie
timestamp: March 10, 2016, 03:48:45 pm
content: HelloI have a Keithley 2400 SMU that produced a spark from a probe and now doesn’t read anything sensible, reading 23v without anything connected. The probes were not currently measuring or under any load at the time, just being moved to connect to a photovoltaic device. It seems something has blown inside the unit however it still turns on fine without displaying any error message. I'd like to repair the unit as it still seems to function. Any ideas what I could try next for troubleshooting?

author: plesa
author_rank: Frequent Contributor
timestamp: March 13, 2016, 05:17:22 pm
content: Check all FET and BJT mounted on heatsink. I assume one of them is dead at least. Check the current sources and zener diodes around.In one of the user manual is simplified shematic. Or look for H class amplifier.http://www.google.com/patents/US20130265110Complete self test passed?

author: Joe e19
author_rank: Newbie
timestamp: March 17, 2016, 08:36:49 am
content: Thanks for the replies. The unit passed it's self tests fine, it's currently in someone else's hands will update if they fix it
Need help with an lg os-5020 it stopped working(fixed) - Page 1
Forum section: electronics / repair

author: little_carlos
author_rank: Regular Contributor
timestamp: March 14, 2016, 05:47:08 pm
content: Hello, so i was using the scope and it was working well, then i switched it off and disconnected the probes, after a while i turned it on, with no probes, and when i hit the switch i heard a pop and now the controls dont work at allhere's a picture of how the screen looks likei tested the fuse and its allrighti opened the scope and i cant find any burnt componentwhat can i do?

author: little_carlos
author_rank: Regular Contributor
timestamp: March 14, 2016, 06:50:45 pm
content: Solved! new recordits the resistor r353, its 2.2 ohm, it was burned, just replace it in case you have the same problem

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: March 14, 2016, 07:24:12 pm
content: But you didn't see if the new resistor isn't too hot? It can do the same problem...

author: little_carlos
author_rank: Regular Contributor
timestamp: March 14, 2016, 07:46:01 pm
content: Quote from: SAUL BRITTO on March 14, 2016, 07:24:12 pmno, i leaved it working for an hour and nothing, keeps cold, the new resistor is 2w the old one was 1/2 a watt

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: March 16, 2016, 07:00:50 pm
content: Ok but, look at the function of this resistor,maybe a big resistor can't be so good as you think,put 1/2 watt as the original.
HP1740A Horizontal gain adjustment - Page 1
Forum section: electronics / repair

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: March 16, 2016, 03:54:41 pm
content: I did exactly as in manual but I can't see a dot but, some cycles when it says:b: Adjust horizontal POSITION control until intensified "dot" is exactly on second vertical graticule line.What dot is this?
scopemeter 123 keyboard inibited... - Page 1
Forum section: electronics / repair

author: elias-rgb
author_rank: Newbie
timestamp: March 16, 2016, 11:22:25 am
content: buon giorno a tutti,desideravo una consulenza per riparare il mio Scopemeter 123.dopo qualche minuto di funzionamento la tastiera si inibisce,come se ci fosse un blocco dei tasti. per avere il ripristino delle funzioni dei tasti devo attendere quanche giorno con batteria staccata.vi ringrazio scusate il mio pessimo ingleseattendo che qualcuno mi dia un consigliogood morning to all,I wanted a consultation to repair my ScopeMeter 123.After several minutes of operation the keyboard is inhibited, as if there is a keypad lock. for the restoration of key functions have to wait quanche day with disconnected battery.thank you excuse my bad EnglishI wait for someone to give me advice
Nixie tube failure? - Page 1
Forum section: electronics / repair

author: ITman496
author_rank: Regular Contributor
timestamp: March 15, 2016, 10:22:18 pm
content: So I made a clock a while back, and it's been working great, except that one of the digits seems to be acting weird..I am ignoring that my drive system could be causing it since if it was, surely the other digits would also be doing this?It appears to look like cathode poisoning, but I'm not so sure. It happened pretty suddenly (over the course of a few weeks) across all the digits of the display (and it was on the seconds display which is the most constantly changing display in the clock)I'm very confused. Is it just a defect?

author: lowimpedance
author_rank: Super Contributor
timestamp: March 16, 2016, 02:22:51 am
content: I does look to be a dud tube rather than the drive. Next question is do you have a replacement and is it easy to remove ?.Substitution is the quickest way to test both the driver and if the previous tube was a dud.

author: Gyro
author_rank: Super Contributor
timestamp: March 16, 2016, 10:10:22 am
content: If it's cathode poisoning then it's sometimes possible to recover it using brief application of higher than spec current to sputter the surface clean. Try googling it. eg.http://www.tube-tester.com/sites/nixie/different/cathode%20poisoning/cathode-poisoning.htmThe other possibility is that some Soviet (can tell it is by the upside down '2' for the '5') Nixies can suffer from physical cathode erosion due to absence of mercury in the fill mix. It's worth checking the affected cathode with a magnifier, and look up the exact part number for that problem.Edit: The paragraph above the photo:http://danyk.cz/digitrony_en.html
Tektronix 2456B after 10 mins - looses focus -   - Page 1
Forum section: electronics / repair

author: jlp1167
author_rank: Newbie
timestamp: March 16, 2016, 05:39:19 am
content: The scope looses focus after running 10 mins. Anyone have this problem ?

author: tautech
author_rank: Super Contributor
timestamp: March 16, 2016, 05:46:35 am
content: Quote from: jlp1167 on March 16, 2016, 05:39:19 amWelcome to the forum.Can focus be recovered with adjustment?From the Repair docs and links thread in the Repair board:http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

author: amine
author_rank: Newbie
timestamp: March 16, 2016, 09:54:12 am
content: Here is a link to the service manualhttp://www.atecorp.com/atecorp/media/pdfs/data-sheets/tektronix-2465b-2467b_manual.pdfPage 79 describes the Focus AmplifierPage 87 describes the Focus circuitsThe Diagram on page 536 ( last page..) shows the Focus Amplifier circuitry..Hope this will help you tracing the problem ..
HMO1002 Osciloscope  - Page 1
Forum section: electronics / repair

author: chivu
author_rank: Newbie
timestamp: March 16, 2016, 09:44:22 am
content: Hi, pls excuse my poor English, i had bought a new R&S HMO1002 oscilloscope, I used it only for 30 min. and suddenly stopped (no power supply). I tried to restart it but nothing, is lighting up the power button for short time (it should be lit when power is aviable) and a closing/opening relay contact is hearing. It could be from psu ?. It is still in warranty so I cannot open it for the moment.

author: tautech
author_rank: Super Contributor
timestamp: March 16, 2016, 09:47:27 am
content: Quote from: chivu on March 16, 2016, 09:44:22 amWelcome to the forum.You must return it to your supplier ASAP.
HP 3312A RF generator repair help - Page 1
Forum section: electronics / repair

author: Ron1973
author_rank: Newbie
timestamp: March 14, 2016, 04:07:57 pm
content: Hey Folks,Just acquired a 3321A function/sweep generator in really nice shape. I noticed the set frequency starts falling immediately after I set it. I have let it warm up for hours, and still the freq continues to fall lower and lower. I searched online for hours, and I can't find anything to lead me where to start. Any ideas would be appreciated.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 14, 2016, 04:15:23 pm
content: Here is the service manual:http://literature.cdn.keysight.com/litweb/pdf/03312-90004.pdf?id=734381Start by checking the power supply.Can you give us an idea about the frequency falling, like what frequency you set it and how fast it is falling?Since this is not a digital generator it will always be a bit unstable.

author: Ron1973
author_rank: Newbie
timestamp: March 14, 2016, 05:52:49 pm
content: Thank you for the reply. I'm trying to align an old am shortwave radio. I set the freq at 455.00 kc. The freq pot is very jumpy. It bounces up and down slightly at initial set, then just starts slowly dropping. It goes to 454.75 within 10-15mins, and then just keeps going down slowly. Is this normal? Am I asking too much from this aged machine. It looks very clean inside, and nothing looks like it was tampered with.The service manuals online are pretty rough, and barely legible on the fine print schematics. Anyone have a clean copy of the power supply portion of the schematic?Thanks

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 14, 2016, 08:25:04 pm
content: Considering the drift I think this is about what you can expect from a unit like this, 250 Hz drift in 10-15 minutes is quite nice.I can't even find the drift mentioned in the specifications, there must be a reason for that...If the frequency pot is very jumpy you could try to clean it with some contact cleaner, but overall there's not much else you can do.Note: 454.75 KHz is well within the IF bandwidth of the radio (I don't expect it to have a 100 Hz CW filter), so don't worry, just make your alignment in 10 minutes
HTC Desire 310 boot loop - Page 1
Forum section: electronics / repair

author: GuilTy
author_rank: Contributor
timestamp: March 04, 2016, 11:10:09 am
content: Hello,I have a problem with my HTC Desire 310.When I try to open it, it enters into a boot loop, and the screen remains blocked with the HTC logo. I tried hard reset and it did not solved the problem.Any suggestions? PleaseGuilTy

author: poot36
author_rank: Frequent Contributor
timestamp: March 05, 2016, 04:29:52 am
content: Can you enter the firmware recovery mode (if your device has this mode)? This is usually accessed by a key combination at start-up.

author: GuilTy
author_rank: Contributor
timestamp: March 05, 2016, 09:02:02 am
content: Yes. It is possible to enter recovery mode.

author: poot36
author_rank: Frequent Contributor
timestamp: March 14, 2016, 05:47:54 am
content: Sorry for the late response. Have you tried clearing the various temp file caches from the recovery menu? If that does not work try a full reset on the phone (note this will erase anything on the phone and set it back to factory settings). If that does not work try the firmware upgrade as a last resort. Good luck.

author: Wilksey
author_rank: Super Contributor
timestamp: March 14, 2016, 04:15:02 pm
content: I have a HTC Desire that suddenly started going into a reboot loop, did a full factory reset, upgraded the firmware etc, in the end I gave up and tossed it in a pile of other crap I have, apparently the motherboards on the HTC Desire phones have hardware issues that can cause this reboot loop, one I heard of was a faulty temperature sensor, haven't been arsed to look into it and probably never will, but might be a hardware issue like mine is.Mine gets to the white HTC logo and then reboots, and occasionally (like 1 in 25 / 30 tries) it gets to the main screen then reboots again.
Schematics of Wavetec/Fluke 9510/9530 active head for 9500 calibrator? - Page 1
Forum section: electronics / repair

author: e-doc
author_rank: Contributor
timestamp: March 14, 2016, 03:59:28 pm
content: Can anybody help me to find schematics for a Wavetec/Fluke 9510/9530 active head?Anybody repaired with success?
How best to remove glued down capacitors without damaging the board?  - Page 1
Forum section: electronics / repair

author: hydrogen maser
author_rank: Regular Contributor
timestamp: March 18, 2016, 12:31:24 am
content: Subject says it all - "How best to remove glued down capacitors without damaging the board?" These are the typical larger elctros in a power supply glued down to the circuit board. This device is at least 15 to 20 years old and the glue appears to be just that - some type of glue - semi-transparent, light brown and hard and not: the white soft but tough stuff often seen - "silastic". Hot air? Solvents? Acetone? I really don't want to damage the board on this one.

author: nidlaX
author_rank: Frequent Contributor
timestamp: March 18, 2016, 01:51:17 am
content: Quote from: hydrogen maser on March 18, 2016, 12:31:24 amI puzzled over this while repairing my Keithley 193. My solution: cut around it with a knife, try to scrape some off the PCB as best as I can, then replace the caps and forget about it.

author: Shock
author_rank: Super Contributor
timestamp: March 18, 2016, 03:36:08 pm
content: The heat and the IPA is probably more effective if the glue isn't baked hard. But I just tried it on a super hard dried out glue on a SMPS I have in front of me.Aim to get it off the PCB board (not the component) as once the component can be removed you can clean it up easier.I soaked a cotton bud/swab and dabbed around the edges in a controlled manner periodically for about 20 mins going between the different spots.After you have done that and only if you can (for smaller components) gently push the component in the direction away from the bonded seal which can make a tiny gap on the seals edge to apply more IPA into, just do that while applying more IPA. A very small movement will start to release it without effort.Once the IPA has had plenty of time to settle in, with your tool of choosing (fine tipped pliers) now try to squeeze the glue and crush it up slowly on itself while giving the component extra support with your fingers, it should break apart and instead of messing up the component or pcb hopefully the IPA got in there and it comes away cleanly.Another way of long soaking is to make a tissue ball or cotton ball and use a syringe to keep it moist with IPA. I think this method breaks up the bond only, a mineral or citrus solvent may eventually make it goo like.When you get some glue off you can test it in the solvent of your choice.

author: hydrogen maser
author_rank: Regular Contributor
timestamp: March 18, 2016, 04:14:33 pm
content: Thank you very much for the info Shock, will definitely go that route next time. It turned out that for this project all I had to do was wiggle the caps a little after desoldering and it broke the glue bond (and took off some of the solder mask in a few places but no major harm done).
Samsung TV spares - where to get in Australia? - Page 1
Forum section: electronics / repair

author: Brumby
author_rank: Unknown
timestamp: March 14, 2016, 11:53:44 am
content: This seems like a stupid question - and I feel a bit embarrassed to ask, but I have been trying to get a spare part for a Samsung TV and I'm not making any progress here in Australia - yet there are at least a dozen places in Asia and the US that advertise the part on eBay.I called Samsung to ask them where I could get a spare part - and from their reaction, the call centre person seemed to find it a bizarre question. They then asked me what the problem was - as if there were going to help me diagnose the fault. So I told them in very clear detail. He clearly did not know what I was talking about, but he knewIknew and was not about to challenge that. They then asked for details so they could create an 'account' ...When I asked why, they said so they could have a record of the problem in case further calls were made. I told them I knew what the problem was - I just wanted the part to fix it! Eventually I was given the contact details for a couple of their authorised service centres. Great. Now I'm going to try to get parts of a business who makes money doing what I was trying to do.So, I called the service centres. Gave them every detail they could possibly want and asked for price and availability. Never heard back from any of them.Then I tried online parts places in Australia. Couldn't find the exact model in any of them and those that had similar models, didn't show the part ... so I shoot off an inquiry or two. I only got one response and that was 'Sorry - can't find it' and they pointed me to a PDF that supposedly had a parts list for me to choose from. It was a single page with a line drawing of part of the TV. It had 9 parts mentioned - labelled 1, 2, 3, 4, 5, 6, 7, 8 and 9 - none of which were the part I needed. Don't like my chances that those are the manufacturer's part numbers .... and no, there was no legend.Can anyone suggest someone in Australia I can approach who might have the parts - or do I just give up on a local supplier and hit out on eBay?Alternatively, does anybody know of a 32" Samsung LED TV carcass that I might be able to cannibalize?All I need is one LED baclight strip.
Schematic for Anritsu 37347A - 20GHz Network Analyzer - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 10, 2016, 05:31:51 pm
content: Do any of you nice people have the schematic of the Anritsu 37347A available? I can get the service manual, but no luck with the schematics.

author: kanuk
author_rank: Contributor
timestamp: March 12, 2016, 11:49:01 pm
content: Hi, Look here:https://testworld.com/wp-content/uploads/Anritsu-37369A-Vector-Network-Analyzer-Maintenance-Manual.pdf
ASUS N56VZ motherboard video connectoe - Page 1
Forum section: electronics / repair

author: james3
author_rank: Newbie
timestamp: March 12, 2016, 09:20:11 pm
content: Hello everybody and thanks for the attention. I have a laptop motherboard (ASUS N56VZ) with damaged Video connector and I't like to try to replace it before throw everything into the garbage The problem is that I don't know how to identify the connector and I can't find any scheme about how is welded and if it's possible to attempt the repair with a hobby equipment (welding station + hot air etc.)anyway here is the picture of the connector and thank who whom will try to help me !!
How to open a Fluke 1507 - Page 1
Forum section: electronics / repair

author: michael2
author_rank: Contributor
timestamp: March 12, 2016, 10:56:49 am
content: I bought a Fluke 1507 on ebay. It works fine, however it has a loose contact on the sockets for the remote test button.So I removed the four screws, and:There is some snapping mechanism or something and I'm not able to remove the back cover. I don't would like to pull indefinitely and risk to crack something. So my question: Is anybody out there who knows how to open this puppy?

author: kripton2035
author_rank: Super Contributor
timestamp: March 12, 2016, 02:25:05 pm
content: everything explained in the pdf here :http://www.docdatabase.net/more-150x-series-fluke-1158185.html

author: michael2
author_rank: Contributor
timestamp: March 12, 2016, 04:20:31 pm
content: Thanks. I managed to fix this puppy. You have just to pull the back cover firmly.The problem was not a solder joint as I first thought (I reflowed the joints anyway), but the inner diameter of the sockets for the remote button were (maybe) out of tolerance or maybe the plugs from the test lead are out of tolerance. The plastic housing was manufactured so precisely that the plugs were sometimes not touching the socket walls because they sat exactly concentrically.After some fiddling with this issue I decided to wrap the back cover in aluminum foil, made holes at the proper place and by using hot air I made the plastic where the sockets were mounted kneadable and pressed the two sockets a little bit together. After cooling down I reassembled this puppy and now: It works! No loose contact anymore!
Bench PSU Repair Help please - Page 1
Forum section: electronics / repair

author: Aerobyrd93
author_rank: Contributor
timestamp: March 12, 2016, 10:59:12 am
content: Hi,So my uncle has (had?) a power supply, which is quite similar to this onehttp://www.ebay.com/itm/Mastech-HY5003-2-300-Watt-Digital-Benchtop-Power-Supply50VDC-3A-Dual-Output-/121675579358?hash=item1c546dffde:g:qLEAAOSwpdpVefgDThat is, until I tried the incorrect way to try and use it as a +/- supply to power a +/-15v op amp (I'm sure there's a way to do this, but I still don't know for sure how). I shorted the +side of one channel to the - side of the other, then pressed only the right button (there are two buttons on the front controlling whether the supplies are in series/parallel. The diagram on the front indicates press only the left to put the sides in series, but for some reason I pushed only the right.) Pop, Fizz, Smoke, Smell.The fallout is thus: If you turn the power supply on currently, the left side appears to be working just fine with no damage, while the right side is stuck at 49.9v (on a 30v unit) This causes several resistors to quickly heat up and begin to smoke, making it hard to test the system better while it is on. If anyone can provide a possible solution, it would be greatly appreciated. I've offered to buy him a new one if I can't repair it, but I REALLY don't want to do that.

author: voltz
author_rank: Frequent Contributor
timestamp: March 12, 2016, 11:10:47 am
content: Hi,Have you located a schematic for the PSU yet? if not, that would be the first step."while the right side is stuck at 49.9v (on a 30v unit) "This sounds like output transistors E-C shorting. You are seeing the full supply voltage, none regulated, at the output terminals. Check those. ( usually something like 2n3055's or 2n3773's etc).. If not, then go further back to the regulator circuit itself.Presumably, the PSU has no 'crow bar' protection to clamp over voltage.Hope that helps.

author: Aerobyrd93
author_rank: Contributor
timestamp: March 12, 2016, 11:18:03 am
content: Thank you, I will try and take a look at those transistors. Unfortunately, I have not had any luck whatsoever finding a schematic as of yet. It's kind of a generic Ebay power supply, and even the name doesn't yield much in the way of useful results. It's an Arksen 305-2d.

author: voltz
author_rank: Frequent Contributor
timestamp: March 12, 2016, 11:27:23 am
content: You're welcome.This thread talks about the 305-D single version:https://www.eevblog.com/forum/reviews/beware-yihua-yh-305d-bench-psu/Might help.Its common for a single device to be released under many brand names. Its a case of working out what is really is and then getting the diagram.
Rigol DS1054z offset problem - Page 1
Forum section: electronics / repair

author: martin.s
author_rank: Newbie
timestamp: March 10, 2016, 06:21:36 pm
content: Hello there,I have a problem with my Rigol DS1054Z.When I measure DC signal with CH2 I found problem with offset.You can see it in print-screen and photos.I tried to change probes, re-calibration in setup menu.. everything else.. and phenomenon still persist.Without any signal there is without any offset.Do you have some solution for it?

author: Bud
author_rank: Super Contributor
timestamp: March 11, 2016, 03:25:45 am
content: You may get a clue from Part 4 of my thread here once I post it:https://www.eevblog.com/forum/projects/project-yaigol-fixing-rigol-scope-design-problems/But you have to wait a bit for it.

author: JFJ
author_rank: Regular Contributor
timestamp: March 11, 2016, 01:16:48 pm
content: Quote from: martin.s on March 10, 2016, 06:21:36 pmHave you tried re-calibrating with the channel inputs shorted to ground? Also, don't forget to let the oscilloscope warm-up for 30-minutes before re-calibrating.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 12, 2016, 04:57:40 am
content: overdriven input..https://www.eevblog.com/forum/testgear/mechatrommer's-rigol-bug-report-space/msg883553/#msg883553http://cp.literature.agilent.com/litweb/pdf/5989-0068EN.pdf
HP 8002A  - Page 1
Forum section: electronics / repair

author: BFX
author_rank: Frequent Contributor
timestamp: March 10, 2016, 08:04:15 pm
content: I bought broken HP 8002A and I need a service manual.Have somebody link or copy?

author: MK14
author_rank: Super Contributor
timestamp: March 10, 2016, 09:00:32 pm
content: http://cp.literature.agilent.com/litweb/pdf/08002-90001.pdf

author: BFX
author_rank: Frequent Contributor
timestamp: March 11, 2016, 05:37:35 am
content: I found that but there is no schema

author: Joule Thief
author_rank: Regular Contributor
timestamp: March 11, 2016, 06:34:31 am
content: I just recapped an 8003a model. The Agilent website has full schematics for the 8003a. Those documents may get you close.

author: BFX
author_rank: Frequent Contributor
timestamp: March 11, 2016, 08:57:56 am
content: ThxI hope there couldn't be a big difference.

author: Joule Thief
author_rank: Regular Contributor
timestamp: March 12, 2016, 04:30:12 am
content: I believe the 8002 has variable rise and fall time and the 8003 has two outputs. They should be quite close in construction.
scope burped... - Page 1
Forum section: electronics / repair

author: femtohertz15
author_rank: Contributor
timestamp: March 11, 2016, 07:50:47 am
content: Hi all!My HP54510 froze today. Just stopped responding to keyboard or updating waveform. Video DMA was still churning away though - it took a few seconds to realize what had happened. First power cycle, no happy little "Chirp" , no screen. Second power cycle, up and running! Whatzit mean? It passes all POST's, and its fan is blowing air fine.

author: wkb
author_rank: Super Contributor
timestamp: March 11, 2016, 08:15:58 pm
content: Quote from: blueskull on March 11, 2016, 04:13:33 pmSatan itself is the dodgy PSU imho

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: March 11, 2016, 08:36:51 pm
content: Quote from: blueskull on March 11, 2016, 04:13:33 pmI agree.It can be memory.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: March 11, 2016, 08:59:58 pm
content: But first of all see the PS.

author: femtohertz15
author_rank: Contributor
timestamp: March 12, 2016, 02:20:09 am
content: Ok, thanks for the suggestions all!