hybridfree/eevblog-posts huggingface dataset:
Replacing the internal fuse of a Fluke 8842A DMM - Page 1
Forum section: electronics / repair

author: jafasi
author_rank: Newbie
timestamp: January 12, 2019, 01:15:54 pm
content: Hi,I got myself a Fluke 8842A on ebay and it seems to work fine except for the current measurement. So it turned out that the internal fuse is blown (not the one directly accessible from the 2Amps connector). The service manual says it should be "600 V / 3 A slow-blow", but the blown fuse itself reads "BUSS BBS3" (and looks similar tohttps://xdevs.com/fix/f8842a/). However, the data sheet says it is a fast-acting fuse.Since these fuses are expensive and not so easy to get, I wonder which is the correct choice?I appreciate your help...

author: Nusa
author_rank: Super Contributor
timestamp: January 12, 2019, 02:44:00 pm
content: If the factory spec is 600V/3A slow, that's presumably correct by definition.What you find in the meter may not be original, but the only difference is that 600V/3A fast will blow faster.In this case, I'm going to say either choice is acceptable to protect the meter. Availability and/or cost may decide the matter for you.Fuses last forever, until you screw up. Then you're glad you had one.

author: jafasi
author_rank: Newbie
timestamp: January 12, 2019, 05:14:23 pm
content: Sure. I actually preferred the slow fuse and assumed it to be okay (it is in series with the fast fuse directly at the input connector anyway) but got confused by the fact that both my meter and the one in the blog post to which I linked had the fast fuse...Thanks for your advise!

author: t1d
author_rank: Super Contributor
timestamp: January 13, 2019, 07:46:41 am
content: Please know that the special fuses used in better multimeters are counterfeited at a very high rate. And, their prices are marked up, to boot. So, you can just about forget about ordering them off Ebay, Amazon, etc... You need to buy from a vendor that is an authorized distributor of the fuse... Check their website for the list. This is not necessarily the maker of the multimeter... The big component houses, Mouser, Digikey, etc., should be alright, but their prices are high, on these fuses. I found a greatly better price, from my local parts house, that also sells multimeters... I had to really search for the best price, but I saved 2/3rds.
HP 3468A  no zero on resistance - Page 1
Forum section: electronics / repair

author: truser
author_rank: Newbie
timestamp: January 12, 2019, 08:12:57 am
content: HP 3468A no zero on resistanceWhere problem ?https://www.youtube.com/watch?v=-GOzBPub7cU&feature=youtu.beThank's for help.

author: say
author_rank: Contributor
timestamp: January 12, 2019, 03:13:32 pm
content: This may help. The manual is available here:https://elektrotanya.com/hp_agilent-technologies_3468a_b_digital_multimeter.pdf/download.html

author: Specmaster
author_rank: Super Contributor
timestamp: January 12, 2019, 04:32:04 pm
content: The thing with these meter is that they can only be calibrated in either 2 wire or 4 wire mode, usually which ever is the most likely to be used. I have a 3468A that was calibrated in 4 wire mode, in 4 wire mode I can get a reading of .001and .236in 2 wire.

author: truser
author_rank: Newbie
timestamp: January 12, 2019, 05:10:39 pm
content: it's all cool but anybody viewed my video, for start ?

author: Specmaster
author_rank: Super Contributor
timestamp: January 12, 2019, 05:50:02 pm
content: Quote from: truser on January 12, 2019, 05:10:39 pmYes I did, that's how I knew you was using the 4wire mode, and hence my reply. It looks like I said, yours has been calibrated for 2wire mode. Download a service manual for it and it will explain that it can only be optitimised in 1 mode only, the other mode be an approximate only in the low values.
Jabra 9470 PRO base unit power jack replacement... - Page 1
Forum section: electronics / repair

author: hemi
author_rank: Newbie
timestamp: January 12, 2019, 07:07:48 am
content: Hello! First post at EEVblog, and I've ended up here cause I'm at my wits' end trying to find a replacement power jack for this Jabra 9470 PRO. A friend dropped it off with me cause I occasionally do minor electronics repair, and have done small board-level fixes for him before. This unit has a bad power jack. The unit would only receive power when the plug was inserted and pulled up. Since the jack itself is too small to get tools in and straighten out the fingers inside, I decided to remove and replace the jack. No problem, right? Well, the removal went fine, but I can not find a replacement jack anywhere that resembles the original one.https://photos.app.goo.gl/p3pD85rtpyC2h2vV9is the underside of the PCB showing the three solder holes, plus the odd retention holes near the top edge of the board. Odd, cause everything I've found at Mouser/Digikey/Newark all have board-retention holes similar to the reset button next to the empty jack location.https://photos.app.goo.gl/kQQvPxz3EfK5YPWn8is a pic of the empty jack location in the case. Size is roughly 8mm x 4mm. I don't have my calipers handy, so that's about as close as I could get by eye.The jack looks to accept a standard 2.35mm outer, 0.7mm inner coaxial plug. I'm hoping that someone can point me to a part that will work. If push comes to shove I'll just pigtail a different jack off the board, but I'd really rather not do that if I can avoid it.I'm pretty unhappy with Jabra. Their customer support was unwilling to help in the first place, then decided their policy wasn't to help at all...And we only got to that point after I cajoled them into contacting their product engineers. It bothers me that a $120 piece of kit may get binned cause of what will probably be a $0.76 component (at individual price).
Moto G 1st Gen XT1039 Display – Blue Patches & Smears on Display? - Page 1
Forum section: electronics / repair

author: Chris56000
author_rank: Frequent Contributor
timestamp: January 11, 2019, 08:02:10 pm
content: Hi!I bought a replacement Moto G 1st Gen LTE (XT1039) to replace my previous one which I dropped once too often resulting in nothing but a trelliswork of lines on the screen, but this replacement phone has it's own annoying display fault – when I try to read pdfs with any bold text or blocks of blue colour, I get smeary blue bars that run across or down the screen whose width is that of the bold colour or lettering – the fault looks just like you used to get on old CRT based colour TVs with "colour–difference drive" when the grid clamping on the blue gun went faulty!Has any other Member seen this fault on this series of Moto phones, and is there a quick resolution, or am I looking at a physical LCD or motherboard fault?Chris Williams

author: amyk
author_rank: Super Contributor
timestamp: January 11, 2019, 10:16:10 pm
content: Pictures please?
Tektronix 464 - Horizontal Deflection Switch - Page 1
Forum section: electronics / repair

author: mldevw
author_rank: Contributor
timestamp: January 09, 2019, 05:40:15 pm
content: Hello,I recently bought a Tektronix 464 Oscilloscope and I think it makes a rather good screen for my computer, as you can see in the image attached.But there is one serious issue: The horizontal time deflection switch does not work properly in every position. Especially on the slow setting (high time per division that is) it only works when the knob is pushed to the right of the instrument.Suspecting the switch contacts, i disassembled it, as depicted by an illustration of fellow member xtoffer below, and cleaned each contact with isopropanol. Still the issue persists though the switches visually seem to make contact. Do you have an idea what I could check next or is this fault common to you?Assembling the knob on the shaft was a kind of trial and error... do you have a hint how to do this properly?Thank you in advance.Cheers,mldevw

author: bd139
author_rank: Super Contributor
timestamp: January 09, 2019, 06:16:54 pm
content: Got a 475 here with same trouble I haven't got around to yet and have fixed a 465 with the trouble before.This usually happens because either the bearings are worn on the shaft, the cam shaft is worn or the contacts are bent or the plastic ends worn. In this case as it's consistent with lowest speed settings, probably the cam shaft or plastic ends. You will have to hook up a continuity tester in situ (before removing it!) and work out which contacts are problematic. This should be done with the assembly fully assembled. Then you will need to very carefully inspec the switch and possibly bend the offending switch hinge up at the soldered end and then down again at the other end without breaking them. This will give more positive cam push on the switch and should resolve the issue. Also look for broken fingers on the switches.If fingers are broken or damaged the timebase is a write off and you'll need a donor one.Close up from a 465 I did here:

author: mldevw
author_rank: Contributor
timestamp: January 10, 2019, 05:33:18 am
content: Hi,thank you for your input. Iwill try to fix it this weekend and give subsequent report.Cheers,mldevw

author: mldevw
author_rank: Contributor
timestamp: January 11, 2019, 09:15:00 pm
content: Hi again,thanks to bd139 for giving me the hint on rebending the contact spings. As my camshaft seems to have a bit of wear I decided that I have to bend them two ways (up in the back near their attachment and down at the finger side) to give them just a little bit more travel.Now everything works again nicely, even surfing on eevblogCheersmldevw

author: bd139
author_rank: Super Contributor
timestamp: January 11, 2019, 09:15:51 pm
content: Glad to hear it works againYou have motivated me to fix my 475A now
How do I test a LM3886 ? - Page 1
Forum section: electronics / repair

author: Hextejas
author_rank: Frequent Contributor
timestamp: January 11, 2019, 07:07:13 pm
content: I took this one out of a board that I am trying to make work. As you can see it is pretty beat up.So, how can I test it to see if it is any good ?

author: rsjsouza
author_rank: Super Contributor
timestamp: January 11, 2019, 07:19:38 pm
content: IMHO the best way to test this is simply to assemble its circuit on a breadboard or, if you live in the US, spend about $10 and get one oftheseto test it.
Atlas Peak repair - Page 1
Forum section: electronics / repair

author: salviador
author_rank: Regular Contributor
timestamp: January 11, 2019, 09:25:14 am
content: Hi,My Peak SCR is broke,I identified the component but the acronym is unknown, can you tell me what component is it?Thanks

author: Armadillo
author_rank: Super Contributor
timestamp: January 11, 2019, 09:49:03 am
content: Its a MCP1623/24

author: salviador
author_rank: Regular Contributor
timestamp: January 11, 2019, 10:49:15 am
content: thank you very much!!!! Friend!!!
Philips N2225 - Page 1
Forum section: electronics / repair

author: ensoniq
author_rank: Newbie
timestamp: January 11, 2019, 07:40:24 am
content: Hello guys,I tried to repair an old cassette recorder made by Philips in the '70, model N2225.This thing is not starting. Replaced the belts and everything and still no fun.Then i got serious and started to meassure some things.This particular recorder has an automatic stop feature (which, when it works, it cuts power to the motor by means of a rotating switch which keeps closing and opening while the cassette wheels turn. No problem whatsoever with the switch tough.The sound signal is hearable in the speaker so the sound generator circuit is engaged which makes me think the problem is related to the automatic stop circuit beeing stuck.Emiter of TS462 - 0 V.TS460 is always open. Emiter of TS460 11.7V which is normal.Points A, B, C all meassure 0V always. What are theese points anyway? Power rails? If so, the whole thing powers via TS460?!?Power supply seems to be ok - that is i do get 11.7 V.I don't get it.Any help / ideas will be much appreciated.Thanks

author: Armadillo
author_rank: Super Contributor
timestamp: January 11, 2019, 09:22:03 am
content: I suspect C777.Change C777 capacitor.

author: ensoniq
author_rank: Newbie
timestamp: January 11, 2019, 09:32:59 am
content: Yeah. BUT.. A,B,C -> why is all dead there ? Are these power rails?C777 will unblock autostop which can be bypassed all together by shorting TS480 and still no power.

author: Armadillo
author_rank: Super Contributor
timestamp: January 11, 2019, 09:38:18 am
content: Easy Elimination;Take out TS462Take out C755Short emitter and collector TS460.

author: ensoniq
author_rank: Newbie
timestamp: January 11, 2019, 09:45:35 am
content: Did that. TS462 is ok. emiter of TS462 -> 0 Voltshorted TS460 -> emiter of TS462 -> 0 volt,so now, i wonder where power comes to points A,B,C -> are these power rails or ? if so, the whole thing powers thru TS460. If so, that is absurd. And if not, how power get to amplifiers and to the rest of circuit ?Forget the motor, autostop and all that circuitry at the bottom. Suppose I only want to power the amplifiers at the top of the circuit. How power gets to these circuits? According to schematic, from A, B, C which are simple resistor dividers if they had something to divide. But at that point of emiter of TS462, we get 0 Volts.) Messed my head mate.

author: Armadillo
author_rank: Super Contributor
timestamp: January 11, 2019, 09:59:00 am
content: Relax;

author: ensoniq
author_rank: Newbie
timestamp: January 11, 2019, 10:02:16 am
content: yeah. and ?)) We now only powered autostop which is great. Further down the road, TS460 needs to open. We shorted it and bypassed autostop. Still no joy. I'l try C755 and C777.
Repairing a Hameg HM1008 oscilloscope - Page 1
Forum section: electronics / repair

author: Yamin
author_rank: Frequent Contributor
timestamp: January 08, 2019, 07:24:08 pm
content: Hi, I have done some recapping on the power supply on couple of HM1008 scopes. There is this one unit which when powered up all the lights on the front panel flashes and there is nothing displayed on the screen. What could be thepossible cause for this, I haven't done any intensive troubleshooting yet. But I did check supply voltages at the other boards and it showed the correct voltages. I was able to get the service manual today but I couldn't find this error stated.I have attached some pictures and I was hoping that you could help me identify the circled parts.1. Photo 12. Photo 2 - there are two wires which one end of it doesn't seem to be connected to anything, what could these be? Referring to the manual the board is MB board, and the function of the board is to generate sweep(sawtooth)signals.I also have a calibration question, I checked all the units (both channels) using a 1kHz square wave from a function generator. One unit displayed a trace similar to the picture attached (photo 3). Whats the name of the calibration which corrects this issue? For the probe I used a one with a bnc connector and alligator clips on the other end.

author: shakalnokturn
author_rank: Super Contributor
timestamp: January 11, 2019, 01:43:38 am
content: PSU hiccuping could be due to an overload condition (scope), internal fault (secondary diode), remaining bad caps (primary side near PWM IC).Photo 1: Thick film precision resistor. Could be on H.V. section but going by situation and markings it could be on one of the X/Y output stages. Sorry need more photos.Photo 2: The yellow wires leading nowhere serve as cheap adjustable capacitors. Bend them away or towards resistor below to adjust a couple of pF. (Here appear to be in frequency response for one of the CRT output amplifiers.)Photo 3: Incorrect frequency response but that could come from many places. Better know where you're going before working on that.
WiThings Scales: Fat/Body Composition etc: ITO Coating - Page 1
Forum section: electronics / repair

author: NivagSwerdna
author_rank: Super Contributor
timestamp: January 10, 2019, 02:50:06 pm
content: I have some WiThings scales... which are a few years old now... which displays "Fat x" which is either a personal insult or an indication that it cannot read the body resistances etc...Looks like this...Now I presume the quadrants must be somewhat conductive and that by over zealous cleaning I might have changed the surface properties???What should the resistances read? e.g. If I put a multimeter probe at two locations in a quandrant should it appear low resistance?Can the ITO () coating be re-vitalised?Thanks in advance

author: Armadillo
author_rank: Super Contributor
timestamp: January 10, 2019, 06:11:33 pm
content: You can use a multimeter in high ohms mode to verify the top surfaces if you want.Teardown and Repair Video here;https://youtu.be/npYzjEaxCW8?t=4

author: tsman
author_rank: Frequent Contributor
timestamp: January 10, 2019, 06:25:54 pm
content: Quote from: NivagSwerdna on January 10, 2019, 02:50:06 pmIf you've damaged or badly scratched the ITO coating then it is complicated to repair it. The industrial process needs a high vacuum and high voltages. The "easy" process for home ishttps://simplifier.neocities.org/optglass.htmlbut that still isn't very easy due to the chemicals and high temperatures needed. Your coating will have different electrical properties from the original coating so it'll probably give you weird readings unless there is some way of calibrating it.If you have damaged the coating then getting a replacement scale is probably going to be your only realistic option.

author: Armadillo
author_rank: Super Contributor
timestamp: January 10, 2019, 06:30:26 pm
content: You can still improvise with 4 aluminum tiles/plates if you want, connected to the 4 clips [see video].That's if you can accept it, but chances are, you buy a new one for style.
Repair Fluke 77 series I - Strange Capacitor not in SM schematics! - Page 1
Forum section: electronics / repair

author: ElecSeb
author_rank: Regular Contributor
timestamp: January 10, 2019, 08:32:02 am
content: Momentarily I am restoring an Fluke 77 I which was having a leaking 9V.Stripped the board and gave it a good ultra wash.Board is clean and all components checked on peak component checkers (I am aware it does not fully test C).Board is build-up again, however I cannot find the location of an 20.4pF C (Ceramic) in the schematics:https://www.eevblog.com/forum/testgear/fluke-77-strange-demise/msg503021/#msg503021If I search this forum I see different layouts, and also bottom sides with 2 C, both not in the schematics:https://www.eevblog.com/forum/testgear/fluke-77-strange-demise/msg502863/#msg502863Anyone who can clarify where these C should belong and why they are not in the SM?

author: mzacharias
author_rank: Frequent Contributor
timestamp: January 10, 2019, 12:51:30 pm
content: Pardon me, but why do you care? Is there some problem with the meter's operation?

author: lowimpedance
author_rank: Super Contributor
timestamp: January 10, 2019, 01:05:50 pm
content: Just to be sure , did you say you stripped the PCB of its components to clean it or you removed it from the case to clean the assembly !?.If you stripped the board did the clean then reaasmbled but had a ceramic cap left over ??.The photo you show (of another 77 I asume ?) clearly shows a bodge cap that was found to be needed AFTER the design was committed to production for that rev at least.Use that photo to trace where its connected and that will give you some idea of why its there.Post production bodges are common place if it gets a cct working without scrapping costly assemblies.After all whos gonna see it when the covers are on.

author: ElecSeb
author_rank: Regular Contributor
timestamp: January 10, 2019, 05:38:02 pm
content: Quote from: mzacharias on January 10, 2019, 12:51:30 pmThere was battery guts over the place. So I did want to tidy it up.Furthermore since it was not working I wanted to disassembly to test the individual components. Following rebuilding following the pictures I had taken and the SM.So basically it is now rebuild as it was, except 2 C's (C12 & C13) which broke while disassembling (probably due to the battery guts).The picture is of my 77. The links are to an other topic just as a reference to show that that one has 2 C.But lowimpedance made clear that this C should be installed and I understand its reason. So tomorrow it will be placed back.When the 2 new C's come in I can finally test the meter and hopefully
My EEVBLOG BRYMAN 235 is faulty - Page 1
Forum section: electronics / repair

author: Manorris
author_rank: Newbie
timestamp: January 10, 2019, 03:48:04 am
content: Dave, I think I have your 2nd faulty meter. I just bought it but the current readings dont work. They either show 0000's or start out with a value and then drop out.Can I send to you for help with repair, or exchange?Mike Norris1007 S Mitchell stBloomington, IN 47401Love the shows!Bit of a newb

author: ataradov
author_rank: Super Contributor
timestamp: January 10, 2019, 03:56:36 am
content: Sounds like a blown fuse. What and how did you measure?

author: Manorris
author_rank: Newbie
timestamp: January 10, 2019, 04:00:11 am
content: Measured micropic explorer 8bit prototype board - 5v, less than one amp

author: Manorris
author_rank: Newbie
timestamp: January 10, 2019, 04:01:42 am
content: I also used an alternate meter, 2nd meter. It read correctly

author: ataradov
author_rank: Super Contributor
timestamp: January 10, 2019, 04:05:17 am
content: In any case, fuse is a user-replaceable part. Check that it is good.Also, what range does not work? The mA range is 600 mA max, and startup transient may have blown the fuse.Blowing 10 A fuse is harder.

author: Manorris
author_rank: Newbie
timestamp: January 10, 2019, 04:14:55 am
content: The 1000v fuse shows no resistance 0000s,However the 400mA fuze shows a 1. Which is the same as open - correct? If I dont connect my leads to anything I get a reading of 1. also.

author: Manorris
author_rank: Newbie
timestamp: January 10, 2019, 04:16:26 am
content: The mA and uA ranges dont work

author: ataradov
author_rank: Super Contributor
timestamp: January 10, 2019, 04:16:32 am
content: Well, the fuse is blown. Replace it, and don't exceed maximum current. It is strange that is it 400 mA. The front face of the meter seems to say 600 mA.QuoteThe fuse is blown, so they don't work.

author: Manorris
author_rank: Newbie
timestamp: January 10, 2019, 04:17:59 am
content: Should I replace with a 600 mA?

author: ataradov
author_rank: Super Contributor
timestamp: January 10, 2019, 04:19:20 am
content: Quote from: Manorris on January 10, 2019, 04:17:59 amThat I don't know. I would replace with a fuse recommended in the manual. But also try to figure out why it is 400 mA.I don't have that meter, so may be owners will chime in.

author: Manorris
author_rank: Newbie
timestamp: January 10, 2019, 04:20:14 am
content: Dave,Disregard - User error, I blew a fuse.Thanks to ataradov for your help.
Using an RF signal for circuit tracing on boards with BGA devices? - Page 1
Forum section: electronics / repair

author: rhb
author_rank: Super Contributor
timestamp: January 10, 2019, 03:49:32 am
content: I'm trying to sort out the header pins on a BGA Zynq based system which is not working. In particular I want to identify the Zynq JTAG pins.Obviously I can't do a normal continuity test. But in considering the problem, I got to wondering if perhaps an RF signal injected at the header pins could be detected with a capacitive probe at the BGA.The scheme I'm considering building is a 1-5 Hz pulsed 0.5 Vpp RF signal from an xtal oscillator and a synchronized pulse detector with an adjustable gain to help localize the other endpoint of the line, an electronic technician's version of an electrician's circuit breaker tracer.The goal is to not turn on any transistor junctions so that the strongest signal is from a direct board trace and I don't cause any damage.Obviously there are lots of complications due to coupling. The concept of circuit tracing at RF is so nuanced that I don't even want to look at what google would suggest. But it seems like something that might have been routine for a member of this forum.
Help identifying a burnt chip - Page 1
Forum section: electronics / repair

author: imperyal
author_rank: Newbie
timestamp: January 08, 2019, 04:48:54 pm
content: Hello everyone!I'm struggling to identify this component for replacement. Can't find the thing anywhere!Brand seems to be PTC, I don't know the logo or the company.Text in the component:PT2N50S1 or PT2N5081 / CCN02A / 1AG302I attached pictures...Thank you all for your help.

author: tsman
author_rank: Frequent Contributor
timestamp: January 08, 2019, 04:59:22 pm
content: Looks like some kind of complementary pair MOSFET. It is aPT2N50by "Princeton Technology Corp".

author: imperyal
author_rank: Newbie
timestamp: January 08, 2019, 05:22:50 pm
content: Thank you very much! Fantastic
Delta DPSN-525AP Power Supply worth repairing? - Page 1
Forum section: electronics / repair

author: jayjr1105
author_rank: Regular Contributor
timestamp: January 11, 2019, 06:02:09 pm
content: This is a power supply for a Cisco POE switch. It appears to be putting out 50v on it's POE rail but the 12v rail seems shot. The switch was part of a network that went down to a power outage and a surge when the power came back up killed it. Can't find a schematic or pinout for that 14pin connector. Not sure where to start.https://prnt.sc/m5m6uhhttps://prnt.sc/m5lwqq
Yamaha TX81Z Power Supply - Page 1
Forum section: electronics / repair

author: RJDog
author_rank: Contributor
timestamp: January 07, 2019, 01:47:18 am
content: I have a Yamaha TX81Z, circa 1987 -- to save a Google, it is a 1980s MIDI sound module; that is, MIDI in, FM synthesized audio out, so it has both analog and digital circuitry. Anyway, it works fine, but the transformer in the internal power supply is starting to make a godawful hum. I haven't really looked but I'm guessing finding a replacement transformer is going to be nigh impossible, so I'd like to replace it with a DC-DC converter with an external power brick, or similar approach. So, a couple of questions:- The original power supply outputs +5V, +15V, and -15V (7805, 7815, and 7915 in the original power supply). The +/-15V is for the analog output circuitry -- is there a problem if I use a power supply which outputs +5, and +/-12V? I have a DC-DC converter with these outputs already...- The original power supply seems to maintain different/separate grounds for "digital" (0V, +5V) and for analog (-15V, 0V, +15V) -- is this critical to keep separate or can "digital" 0V == "analog" 0V as would be the case for probably any power supply I might replace it with?Any insight would be greatly appreciated!

author: GregDunn
author_rank: Frequent Contributor
timestamp: January 07, 2019, 03:08:34 am
content: Have you verified that the transformer secondary isn't being loaded by a failing cap or part of the regulator circuit? You usually don't see low power transformers like those failing without some kind of external cause. Is the power supply still within spec?I would expect that the analog portion is being run at ±15V to maximize S/N and voltage swing out of the unit - taking it too low might compromise the performance of the op amps, but without knowing more about the circuitry it's just a guess.You definitely want the analog and digital grounds kept separate throughout the unit to avoid crosstalk and possible digital noise in the outputs. They should be joined at exactly one location inside the module (a star ground to the power supply common if it was designed right) and separate everywhere else.
need help identifying a diode package - Page 1
Forum section: electronics / repair

author: vega_radio
author_rank: Newbie
timestamp: January 06, 2019, 11:02:02 pm
content: Hey all,I've got this 6 pin diode surface mount component that I've blown up. It has the lettering "KL6C8" on it written both ways up. I can't seem to get any results for it in my google searches. I was wondering if anyone knows what these digits mean so I can find an equivalent. Any help would be much appreciated. Thanks in advance.

author: fzabkar
author_rank: Super Contributor
timestamp: January 07, 2019, 12:30:07 am
content: BAT54ADW:https://www.diodes.com/assets/Datasheets/ds30152.pdf

author: vega_radio
author_rank: Newbie
timestamp: January 07, 2019, 01:51:58 am
content: Quote from: fzabkar on January 07, 2019, 12:30:07 amGreat thank you. I see the KL6 refers to BAT54ADW and C8 means it was made in Aug, 2015. How did you find that out?

author: fzabkar
author_rank: Super Contributor
timestamp: January 07, 2019, 02:36:53 am
content: http://www.smdmark.com/en-US/search/code?id=kl6
lith-ion battery charging wire placement - Page 1
Forum section: electronics / repair

author: billrabinowitz
author_rank: Newbie
timestamp: January 06, 2019, 04:46:53 pm
content: I have a wheel chair with a lith-ion battery. it does not take a charge . I opened it and found the charging port black wire has come off. the red is still attached. problem is there are 3 leads , 2 on the outer edge, 1 in the center, to which lead does the black wire attach.thanksI have pictures if I can load them

author: Simon
author_rank: Unknown
timestamp: January 06, 2019, 06:36:11 pm
content: Please do not double post the same question as it causes a lot of confusion.
lith-ion battery charging wire placement - Page 1
Forum section: electronics / repair

author: billrabinowitz
author_rank: Newbie
timestamp: January 06, 2019, 04:23:28 pm
content: I have a wheel chair with a lith-ion battery that would not take a charge. after opening it I found that the black wire has come off, red wire is still attached. problem is there are 3 leads- 2 outer one in center, to which lead does the wire get attachedthanks
Rigol 1102E next page softkey does not work. - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: January 03, 2019, 09:53:33 pm
content: I just bought a junked Rigol DS1102E.I got it now to function almost correctly. An only thing that does not work is the bottom soft key that is usually assigned to NEXT PAGE. Tried cleaning with alcohol, nothing..... Tried using another keypad rubber membrane, and nothing.Is there anything known about this? Is there such thing as service manual on these things?

author: tkamiya
author_rank: Super Contributor
timestamp: January 04, 2019, 01:21:19 am
content: Found a corroded PC board trace on back. Used a small jumper wire to fix. Glad to report it works correctly now.

author: tautech
author_rank: Super Contributor
timestamp: January 04, 2019, 01:47:34 am
content: Quote from: tkamiya on January 04, 2019, 01:21:19 amPics ?

author: tkamiya
author_rank: Super Contributor
timestamp: January 04, 2019, 02:35:12 am
content: I'm sorry, I didn't take pictures. It is unlikely it will show up anyway.On back of keyboard PC board, there was a very thin trace that didn't quite look right. It was probably 0.25mm or so wide. Upon close inspection, it looked as if trace was actually broken. The copper was so thin I couldn't solder anything to it. So I did the jumpering on the other side. (keyboard side) A bit unconventional but it worked. To me, it looked like it could be a manufacturing defect.

author: tautech
author_rank: Super Contributor
timestamp: January 04, 2019, 04:16:26 am
content: Quote from: tkamiya on January 04, 2019, 02:35:12 amDid it have a conformal coating on the trace or was it bare copper ?

author: tkamiya
author_rank: Super Contributor
timestamp: January 05, 2019, 01:29:59 pm
content: It had a green solder mask and some type of coating. But I'm guessing it wasn't applied evenly as there was an obvious corrosion.
software to build repair flowchart ? - Page 1
Forum section: electronics / repair

author: kripton2035
author_rank: Super Contributor
timestamp: January 04, 2019, 08:59:12 pm
content: do you use one ?to build something like : measure voltage at pin 4 of ic102 and 2 buttons "more than 1V" " less than 1V"and that brings you in a repair process.I don't want something very polished and like publishing software, but something more dedicated for electronic repair.any hints ?thanks.

author: Armadillo
author_rank: Super Contributor
timestamp: January 04, 2019, 09:45:49 pm
content: Microsoft Visioorunder Microsoft office - flowchart

author: Berni
author_rank: Super Contributor
timestamp: January 04, 2019, 10:12:35 pm
content: A free alternative ishttps://www.draw.io/It runs both in the browser or downloadable as a windows program. Works a lot like Visio and makes for reasonably fast drawing of flow charts.Here are some examples of what it can do:https://about.draw.io/features/examples/
TS80 low-volt issue - Page 1
Forum section: electronics / repair

author: vnv
author_rank: Contributor
timestamp: January 04, 2019, 06:00:28 pm
content: Hello everyone,just got TS80 and having issue.As I connect it and press A (short) it starts up and it seems to work, because I can solder (for now), but trying to put it to standby shows LOW-VOLT.Seems that someone has posted on their forum same issue:http://www.minidso.com/forum.php?mod=viewthread&tid=3262&extra=page%3D1but no solutions has been provided.Can anyone propose what to do? Maybe someone with similar situation?Thanks in advance!

author: vnv
author_rank: Contributor
timestamp: January 04, 2019, 06:13:59 pm
content: SOLVED!Just to help out others here is what I've done.Found the firmware with TS80APP1.06s on this link:http://www.minidso.com/forum.php?mod=viewthread&tid=3225&extra=page%3D1Also there is source and firmware on this link:https://github.com/xjtuecho/MiniDSO/tree/master/TS80Procedure:1. Press A button and hold it2. Plug in the USB3. Screen should write DFU mode4. Open disk drive which was created by soldering iron5. Unpack zip file and add the file in the drive (I have added zip file to attachment)6. After copy it will do it's job... and after some time it will be NAME.rdy (NAME - name of the firmware)7. Restart - any happy soldering
Tektronix TDS7104 No Waveform on screen - Page 1
Forum section: electronics / repair

author: ssysm
author_rank: Newbie
timestamp: November 22, 2018, 08:39:54 pm
content: Just got my self a tds7104 off from ebay. Came in with a dead NVRAM battery, I replaced and set the vxworks boot parameters. The scope application is now able to start but there are no waveform on screen(just a black screen), but it pass self calibration and self diagnostics, snapshot seem to be working and I can calibrate my probe with it.Does anyone know what kinds of issue is related with my scope? Perhaps it's something wrong with the video card driver?thanks in advanceI attached some image of the scope applications.

author: STDio
author_rank: Newbie
timestamp: January 06, 2019, 11:51:27 pm
content: Had the same problem using win 2000pro,upgraded to XPpro and updated to tecscope2.5.5and it's fixedStandardio

author: Johnny10
author_rank: Frequent Contributor
timestamp: January 07, 2019, 12:35:47 am
content: Does it work with external monitor?

author: Jwalling
author_rank: Unknown
timestamp: January 07, 2019, 11:07:42 am
content: I'll bet it's the video driver for the Chips and Technology video chip.Make sure that the driver is owned by Asiliant and not MicrosoftThe correct driver is in \Tektronix\video.

author: TiN
author_rank: Super Contributor
timestamp: January 07, 2019, 02:58:35 pm
content: Yup, wrong video driver, must use one from Tektronix.They way these scopes work - PPC acq board writes waveform "data" into videocard frame buffer memory , and then PC side will use that memory to plot to image "overlay".
Help. Identification of part. FA265K - Page 1
Forum section: electronics / repair

author: SlurmMcKenzie
author_rank: Newbie
timestamp: October 06, 2017, 10:46:31 am
content: Hello,i could use some help with identifiying a part on a failed device.The device is an active USB3 hub.It does not work anymore, so i opend it up.There is one part that is burned.the device has 6 usb ports (and one port for charging only and one ethernet chip).the internal design looks like they used one usb controller chip as master for the first three ports and for the communication with the pc.and a second, identical controller as slave for the other three ports and the ethernet chip.the failed part seems to be power supply related for the first chip and the first three ports.which would match the symptoms, that the thing does not communicate with the pc and that the status LEDs of the first three ports are now always on.luckily, there is an almost identical power layout for the second chip, and the parts there are all ok.The markings on the part in question readFA265Kand some dots and slashes on the second line.i can't find anything on that specific number, but i may be searching wrong.do the dots and slashes have any meaning ?the closest thing i could find is the"Ti TLV6256x 1.5-A High Efficiency Step-Down Converters in SOT-23 5-Pin Package"Because the pinout matches and the layout example in the datasheet is basically identical.but if my part is a step-down converter too, then what are its ratings ?attached is a photo of the good part and the layout example from ti, which matches my part in question.i hope that someone can help me.best regards

author: SlurmMcKenzie
author_rank: Newbie
timestamp: October 06, 2017, 10:56:57 am
content: This is the damaged parts.The chip is burned and the case is damaged where the "K" of the marking is (should be the input pin, top right of the chip).

author: blip555
author_rank: Newbie
timestamp: January 03, 2019, 11:23:28 pm
content: I have the same USB hub by Aukey and the same part failed.

author: fzabkar
author_rank: Super Contributor
timestamp: January 04, 2019, 05:45:27 am
content: What are the values of feedback resistors R2 and R4? Do you know what the output voltage of the regulator should be? If you know these parameters, then you will be able to calculate the feedback voltage, which would then help to narrow down suitable candidates. For example, the TLV6256x has a feedback reference voltage of 0.6V.

author: SlurmMcKenzie
author_rank: Newbie
timestamp: January 04, 2019, 09:57:41 am
content: Thank you for your reply.However, for me this case is closed.My original post was over a year ago. Then i had this board then sitting on my desk for over half a year.Then i decided that it is not worth the space, time and energy trying to repair this.My Hub has been thrown out a while ago.
Winsun WS50–3BAC +5V and ±15V power supply component values? - Page 1
Forum section: electronics / repair

author: Chris56000
author_rank: Frequent Contributor
timestamp: January 04, 2019, 12:01:47 am
content: Hi!My friend's got stuck with a Winsun WS50–3BAC–01 Chinese 50W power supply from another piece of gear because it had gone bang and rendered a number of small parts indicipherable!One was a 2W metal film resistor that had burnt up the PCB, R8, which we managed to identify as 4K3 2W from a pic on Aventrepairs' website, but there's a surface mount resistor R7 burnt up underneath, which seemed to measure about 400 ohms over a quarter of what was left and I could make out the first figure '2' but the rest had gone!Also there's a 500mW zener–diode across the MOSFET current sense resistor (ZD3) burnt black and I can't make out it's marked voltage and it's s/c!!!!The circuit is UC3842 based, but before anybody tells me to "look in the datasheet!!" I have ALREADY spent four hours this evening searching for another '3842 based circuit example with a zaner directly across the c.s. resistor and I cannot find one!!Has anyone got or come across one of these Chinese Winsun WS50 psus and can tell me the value of R7 and ZD3's nominal voltage?Chris WilliamsPS!Why would Winsum add a zener–diode directly across a MOSFET Source Current Sensing Resistor when a search of over two hundred assorted examples using the same '3842 pwm controller totally fails to turn up another PSU with this?
Need help to identify the decorative outfit accessory - Page 1
Forum section: electronics / repair

author: 17_29bis
author_rank: Regular Contributor
timestamp: January 03, 2019, 07:46:48 pm
content: Hello,I think this is mostly the question for guys who still remember 1980s.My friend asked me to help him with moving the small train (it stuck in the tunnel, I know it sounds weird by just check the picture below) a bit by supplying some voltage to a vintage "decorative outfit accessory" which is a fact is a replacement of a bulb from an indoor string lights.The stamp on the toy says "1988", search in the internet did not return any results. The friend does not remember if this particular string lights was directly connected to the mains or there was a dedicated power adapter.Looking at the adapter which does not have any marking or a key I think that this is an AC powered device, the question is how many volts should be applied.So may be someone knows anything about those vintage toys and can provide some useful info?PS: Disassembling the item is not the option.

author: ElecSeb
author_rank: Regular Contributor
timestamp: January 03, 2019, 07:56:42 pm
content: Hallmark Village Express Magic Light and Motion Ornament 1986

author: tsman
author_rank: Frequent Contributor
timestamp: January 03, 2019, 08:00:23 pm
content: https://www.ebay.com/itm/HALLMARK-Magic-Light-And-Motion-Ornament-Childrens-Express-Linda-Sickman-Train-/183616362179?oid=113401074245Quote

author: 17_29bis
author_rank: Regular Contributor
timestamp: January 03, 2019, 10:23:54 pm
content: Hello guys,Thank you very much for your help, I really appreciate that!
Fluke 97 backlight inverter - Page 1
Forum section: electronics / repair

author: mlefe
author_rank: Regular Contributor
timestamp: December 29, 2018, 05:08:43 pm
content: Hi guys, merry Christmas!I’ve bought a Fluke 97 scopemeter and replaced the 4 aluminum caps as one of them was leaking. I thought that this would also increase the light coming from the backlight.Instead of more brightness, now I can hear a low volume, high pitch sound from the inverter when I turn on the backlight... is this normal? Should the inverter make this noise or something else is wrong?Thanks

author: mlefe
author_rank: Regular Contributor
timestamp: January 02, 2019, 01:05:45 pm
content: To be brief, for those of you that have a fluke 97: do they buzz a little when you turn on the backlight?

author: willb
author_rank: Regular Contributor
timestamp: January 03, 2019, 12:23:07 am
content: Yes, my Fluke 97 does the same. I wouldn't describe it as a buzz but more of a high pitched whine. I replaced the 4 caps as well on my unit (all were leaking, back light was dead).

author: joeqsmith
author_rank: Super Contributor
timestamp: January 03, 2019, 02:15:13 am
content: There are a few threads on this site about the 97 and back light repairs. I have a couple of them and ended up replacing the EL on both, plus one cap had failed on them. After replacing the cap with the old EL, one was pretty loud. With the new ELs I can hear them if I place my ear on the units.Link shows the ELs I used.https://www.eevblog.com/forum/testgear/old-philips-fluke-97/100/

author: mlefe
author_rank: Regular Contributor
timestamp: January 03, 2019, 07:08:47 pm
content: Excellent, thanks for the info!
Weir SMM300 Switching PSU Not Starting - Page 1
Forum section: electronics / repair

author: dexters_lab
author_rank: Unknown
timestamp: December 02, 2018, 10:50:13 am
content: i have a uk made Weir SMM300SW power supply (a 300 watt chassis psu with multiple otuputs) here which is refusing to start up when powered, i have checked all the output rails and there are no shorts on the host circuits and all the sense lines are connected.I am going to guess there is an ageing capacitor issue on the switching controller section in the PSU but if anyone has first hand experience of these PSUs that would help if you know what the issue might be? The SMM300 seems to be a very popular PSU from the 90s and used in arcade cabs so hoping someone can help.interestingly i have had two other of these PSUs do a similar thing, but power cycling them always fixed it so there could be an inherent issue with them that causes them to do this

author: fourtytwo42
author_rank: Super Contributor
timestamp: December 02, 2018, 07:33:12 pm
content: I have history with this psu, we (CASE) were probably there largest customer by far, I think I have some schematics somewhere and plenty of people I know have rejuvenated them without trouble. I have contacts who might sell you a refurb unit if that suits ?BTW make sure you have an amp or five load on the 5V

author: dexters_lab
author_rank: Unknown
timestamp: December 03, 2018, 07:09:39 am
content: thanks, if you do have schematics available they would be handy to have!i read on another forum that some of the caps on the control side can be problematic, so on my issue 16 board i pulled caps C7, C11, C18, C33, C5 & C6 all located around the primary / control sideC18, C33, C5 & C6 were all serviceable, but C11 was marginal and C7 was leaking and utterly dead, this is also right next to the TDA1060 controller IC too so i suspect this is the issue, i'll know once my replacement caps arrive

author: dexters_lab
author_rank: Unknown
timestamp: December 04, 2018, 12:18:11 pm
content: in case anyone is referencing this thread in the future, the PSU is now working again after replacing the caps detailed above.

author: fourtytwo42
author_rank: Super Contributor
timestamp: December 19, 2018, 01:27:46 pm
content: Sorry for the delay I had to find some ancient files but here is the SMM300 schematic, I have a higher resolution version 1600x1200 but cannot post it here.

author: dexters_lab
author_rank: Unknown
timestamp: December 19, 2018, 02:49:09 pm
content: thanks, i'll pm you a link so you can upload the higher rez file to me if you don't mind, i don't think there is really enough detail there to be of any use...

author: dexters_lab
author_rank: Unknown
timestamp: January 03, 2019, 09:28:32 am
content: here is a slightly better version of the schematic in case anyone is looking for it...
Help me identifying the diode - Page 1
Forum section: electronics / repair

author: josipk
author_rank: Newbie
timestamp: January 02, 2019, 09:22:07 am
content: Does anybody recognize the characteristics of schottky diode 34 30 on the picture (red arrow)? How could I test it?May be this diode is the solution of reversed polarity problem on Minolta DiMAGE Scan Elite 5400 (production year 2004)?RgdsJosip

author: Armadillo
author_rank: Super Contributor
timestamp: January 02, 2019, 10:43:22 am
content: This is a small scanner.Hence; I suspect this is a SS34Is a 3A diode hence 34 3.0amp

author: Armadillo
author_rank: Super Contributor
timestamp: January 02, 2019, 10:48:58 am
content: It may be a short circuit elsewhere.Hence if you want to test it, best would be to unsolder it from the circuit board and use a multimeter in diode mode, just like any diode, conduct in one way only.But like I said, it's more likely a short circuit elsewhere.

author: josipk
author_rank: Newbie
timestamp: January 02, 2019, 11:04:11 am
content: Thanks for suggestion.Yes, I accidentally connected reverse polarity to scanner and after that there is no chance to switch it on.

author: Armadillo
author_rank: Super Contributor
timestamp: January 02, 2019, 11:11:43 am
content: Then you should check continuity of fuse instead.Like on the circuit board, should be many fuses like marking FB31 for example.

author: djQUAN
author_rank: Frequent Contributor
timestamp: January 02, 2019, 12:49:14 pm
content: From my list of components, 34 is RB160L-40 40V 1A schottky diode by Rohm. "30" is the date/batch code.https://www.rohm.co.jp/datasheet/RB160L-40/rb160l-40te25-eFB31 is a ferrite bead, not a fuse.

author: Armadillo
author_rank: Super Contributor
timestamp: January 02, 2019, 01:32:53 pm
content: Oh hahahahaha, these miniature creatures, mA rated, no idea if it will sustain a direct reverse short circuit?

author: josipk
author_rank: Newbie
timestamp: January 03, 2019, 07:56:18 am
content: Question after reading the datasheet: reverse polarity could cause thermal destruction of diode?