hybridfree/eevblog-posts huggingface dataset:
Nakamichi Delta 20 Operate w/o remote control - Page 1
Forum section: electronics / repair

author: mheruian
author_rank: Contributor
timestamp: November 29, 2018, 06:14:17 am
content: Hi,I am new to the forum and i don't know if this is the right place to ask this since its not actually directly related to fixing electronic boards and such but anyone has a lot of experience about remote control appliances? we don't have techy persons here and i am not yet knowledgeable about remote controls. We have a nakamichi delta 20, an fm radiohttp://nakamichi.com.au/index.php/products/delta/delta-20-detailand we lost its remote control, we can't see anything like button panels on it like any other appliances that has remote controls also. i looked at its manual and hasn't seen anything about operating the fm radio w/o remote control, can i use universal remotes for this? don't i have to program the universal remote? Thanks
HP 34401A Multimeter blowing fuses - Page 1
Forum section: electronics / repair

author: jayceedenton
author_rank: Newbie
timestamp: November 28, 2018, 10:05:36 am
content: I've got a hp 34401a that keeps blowing the power line fuse, there's no visibly bad components. I'm not sure where to start, any help would be appreciated

author: HighVoltage
author_rank: Super Contributor
timestamp: November 28, 2018, 10:48:59 am
content: First make sure the power selector is set to your countries voltage and the right fuse is selected.People have bought a 34401A in the USA with 120V setting and plugged it in to European 230V and the fuse broke right away.Second, unplug the transformer cable to the PCB and hook the power up.If the fuse still breaks, most likely your transformer is bad.

author: jayceedenton
author_rank: Newbie
timestamp: November 28, 2018, 01:37:10 pm
content: Well disconnecting the transformer caused the fuse to violently explode so i guess that answers my question. thanks

author: HighVoltage
author_rank: Super Contributor
timestamp: November 28, 2018, 02:22:40 pm
content: Yes, get a new transformer installed and your 34401A should work again.You can order a new transformer from Keysight or use one from ebay.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 28, 2018, 09:30:45 pm
content: https://www.ebay.com/itm/173561930215https://www.keysight.com/my/faces/partDetail.jspx?partNumber=34401-87901
Try to solder it or bite the bullet? - Page 1
Forum section: electronics / repair

author: Tim88
author_rank: Regular Contributor
timestamp: November 30, 2018, 08:02:58 am
content: Picked up a real clean Tek 2246 for a cool C note. Pic of what is does when powered up from the seller. So, my hunch was at least the battery in it would be toast and it sure was, see the pic. When I got it, something was rattling around inside. Probably during case removal/replacement, someone knocked this precision resistor off. What to do with that resistor? Can get them on the interweb for about $15 plus shipping. For some reason the original had 3 leads and every other I have seen has 5 which the board has slots for. The extra leads I think are just added support mounters. Resolder or not?

author: dzseki
author_rank: Frequent Contributor
timestamp: November 30, 2018, 08:14:42 am
content: If you try you have nothing to lose. It looks doable to me, it still has the leads on the substrate. I repaired the (hybrid) vertical work resistor in my HP scope with conductive glue/paint.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 30, 2018, 08:30:39 am
content: I'd try to solder it, if it doesn't work no big deal just buy a new one.If it does work, you saved yourself $15.Also, I'd suggest looking into replacing that battery with one on flyleads so you can mount it off the PCB somewhere so if it leaks in the future, it doesn't drop it's guts all over the PCB and cause corrosion issues.

author: Tim88
author_rank: Regular Contributor
timestamp: November 30, 2018, 08:35:54 am
content: Quote from: TERRA Operative on November 30, 2018, 08:30:39 amYa, I ordered a plastic mount and gonna figger out a place to put the battery. Amazingly it seems to have done no damage...

author: Tim88
author_rank: Regular Contributor
timestamp: December 07, 2018, 12:41:00 am
content: Well, soldered that resistor back in uneventfully and a new battery. Fired it up and she seems to work. Started going through the checks and adjustments, got to the horizontal timing check and its off by maybe 5%. Ran the diagnostic check, no problems but it shows only that the trigger passed? I think that's the way it runs, just stops on anything that isn't right. Traces seem crisp and clear, ordered a bunch of caps for it just in case. Gonna check the power board voltages and see if they are in the ballpark.

author: Tim88
author_rank: Regular Contributor
timestamp: December 07, 2018, 07:13:12 am
content: Quote from: Tim88 on December 07, 2018, 12:41:00 amWell duh, help if a guy reads the manual correctly. Everything is good after all, even the power supply voltages are good. The +55V one is 57.99 and the range is 58.36-59.84V. Not sure if a guy should be concerned with that...

author: helius
author_rank: Super Contributor
timestamp: December 07, 2018, 08:16:41 am
content: Quote from: TERRA Operative on November 30, 2018, 08:30:39 amLithium-Carbon monofluoride (BR) batteries do not leak. In addition, even if they mechanically rupture, the electrolyte is actually a corrosion inhibitor, so there is no danger of damage.
Sterling Power marine 12V 20A battery charger - blows fuse - Page 1
Forum section: electronics / repair

author: Lomax
author_rank: Frequent Contributor
timestamp: November 28, 2018, 11:43:31 pm
content: I'm trying to repair aSterling Power Products Pro Charge CE1220marine battery charger for a friend of mine. From what I've seen these go for £60+ used, and an equivalent new model would cost over £300, so although it's pretty ugly, and clearly has seen better days, I reckon it's worth a shot. Having overcome my disgust of the horrible exterior, I was pleasantly surprised by the tidy interior, and that the fault was immediately apparent; one of the two main caps had burst fairly violently. So I ordered a new pair of caps, and after a considerable struggle with getting the PCB removed (the mechanical design is incredibly stupid) replaced the caps and re-assembled the unit, thinking this would have fixed it. Alas, what was previously a completely dead charger now instantly blows the 3A mains fuse when plugged in. So I'm going to have to take the damn thing apart again and perform further checks. Since it's such a bastard to disassemble, I thought I'd check with the forum if anyone has any suggestions which parts are likely culprits? I'm thinking the rectifier bridge, possibly one of the MOSFETs? Any suggestions and advice appreciated!
jbc rp 5100 - soldering station pass word reset !!  - Page 1
Forum section: electronics / repair

author: LionelNivelle
author_rank: Newbie
timestamp: November 27, 2018, 02:15:38 pm
content: Hello everyoneI bought in 2005 a station rp5100 of jbc.It still works very well.today I would like to increase the temperature from 325 ° to 350 ° and realize that I need the code.I followed the method of the manual with the code 10000 but it is not the good code.apparently the former owner has changed the code.So I take the procedure to do "reset password" with the method of the manual.but again, the code 10000 is not acceptedI think the 10000 code is not the right one.************************************************** *********I have all the knowledge to carry out this operationI am a former repairer of radio / tv.My questions are:is this the right method?Is 10000 the original code?Thank you for answering me .Lionel Nivelle
Fieldpiece SR2 - Page 1
Forum section: electronics / repair

author: Mukrakiish
author_rank: Contributor
timestamp: November 27, 2018, 02:08:43 am
content: One of the guys at work was asking me if I would have a look at his field scale to see what was going on. It refused to turn on anymore and they are worth a few bucks.It's a surprisingly simple device really, just a big ol load cell in there with a little transmitter board and MCU to transmit to the hand-held remote to read the weight.I pulled it apart and checked the power lines, seems we have power going through the "on" switch and power is getting to the MCU. Nothing seems burned or shorted.So, I'm wondering now since I don't have enough knowledge in this stuff, could it be the crystal not letting the MCU boot up? What else could prevent the system from booting up? It appears to have power going where it needs to and shorting the "start" switch isn't enough. I think the chip is getting a signal but I don't know if it would be the chip or something simple. I'm taking a guess at the crystal since this thing sees some rough use (tossed around a bit, vibration, etc). There is nothing but traces on the back, and the contact switch points.Anyone have some tips for me to narrow down the issue? Hopefully I can save him a few bucks since this seems not terribly trivial. I have a scope and such as well.
Marconi VTVM repair  - Page 1
Forum section: electronics / repair

author: mansaxel
author_rank: Super Contributor
timestamp: November 15, 2018, 02:43:01 pm
content: Hi,(this is my first post here, so bear with me, ladies and gentlemen....)I've recently gotten my fingers on a Marconi ex-MOD VTVM, the TF1041b. I've found the manual, and started to undo the shipping damage. (No, contrary to popular belief, a sturdy plastic bag and some bubble wrap across the front is not appropriate packaging to ship a VTVM.)Themanualis located.I'm trying to verify it and restore working condition. My aim is to have a working instrument that helps me in the workshop. Yes, I have modern meters. And 2 scopes. And more than one cup of T.E.A. Mechanical meters are NICE and ergonomic. Even if they aren't as precise as the Flukes and hp's, I like them and they help me. So, working it is, and it's more important than "vintage" or "pristine". A full re-cap is planned.I have three questions, so far:* The component list (proudly, I might add) lists a bunch ofsemiconductors, of which some are selenium rectifiers. Those will be replaced with 1N4007 and a resistor; if need arises. Some other places in the schematic, in the meter protection circuit (see attached image) have a "S.T.C Unistor Type MQ8/1" which is drawn as a diode. The STC databook I've found lists not that part number, but "Q6/1" which is a miniature selenium ("SenTerCel") rectifier. What to replace with, if need arises?* I'm trying to go through the tests in the manual and am applying a 2V 1KHz sine wave to the AC probe. Regardless of voltage setting on the sensitivity rotary switch, applying the voltage pegs the meter. What should I look for?No more questions. I had one more from the start, but found enough old datasheets to establish the thermistor values I might need. Doing your homework helps./Måns.

author: mansaxel
author_rank: Super Contributor
timestamp: November 26, 2018, 09:20:14 pm
content: So, I once more prove to myself that I have lots to learn. I had my scope connected in parallel to the probe of the VTVM. And a strange 10KHz source. Once I replaced the 10KHz source with the oscillator from my Tek distorsion analyser (which also needs repair, but not the oscillator, it is the analyser part that is weird) and only looked at the waveform with my Scopemeter (which is floating) the VTVM is accurate to within 0,4% to both ScopeMeter and hp 3438a (and they agree to within 0,2%). The clue here is "floating", I think.Did a brief test of DC volts and we're good there too. 13,6V is 13.6V.Tried to volt-nut myself and connect every meter I've got in parallel, but once I got to the Avo 8 it loaded the source causing a voltage drop of ~ 0,1V and did not cope very well with 10KHz. Came to my senses. Obvious conclusion: I need more high-impedance broad bandwidth meters. And a second Avo 8 to check the first.Tomorrow: Assembly and resistance tests.
CM6800 PFC and PWM chip Vgnd point on computer PSU - Page 1
Forum section: electronics / repair

author: lordvader88
author_rank: Frequent Contributor
timestamp: November 25, 2018, 09:12:02 pm
content: On all the computer PSUs I've worked on, they have a PFC boost converter stage, that charges a bulk capacitor. Between the mains FWR neg. terminal and the bulk cap. neg. terminal is/are 1/2/3 fuseable and/or flameproof pink resistors, with sub-ohm resistance.It seems most things on the PCB hotside, are referenced to the neg. terminal of the bulk cap, not the slightly lower voltage of the FWR(-)And for instance the CM6800 PFC/PWM chips seem to always be on a sister PCB, and have their pin10GND on the Cbluk(-)Look at CM6800datasheet and design guidehttp://www.champion-micro.com/datasheet/Analog%20Device/CM6800.pdfhttp://www.bannerspan.com.tw/technical/Champion%20Micro/CM6800%20Design%20Guide.pdfThere's a lot of beyond 1st year EE that IDK to be able to really follow along with these. IDk what internal opamps can sink current, or what hanging a tank circuit on the output really does to pin1 IEAO transconductance error amp, really. And IDK the transfer function eq's they are using to program these.I broke 2 smd caps on a TL431 3.3V regulating circuit. Very soon I better figure out what their values should be, besides checking other similar PCBsSo if the CM6800 is floating slightly over the FWR(-) and yet the current hence voltage across those 1/2/3 resistors is changing all the time, the CM6800 calculations will be WAY HARDER, and none of the datasheets include any amount of formula's (or did I miss them?)And on some of the internal opams like "PFC Current limit", it has -1V as the non-inv. ref, where is that being generated relative to Cblk(-)Is the chip using internal LC circuits to make -1VOr what am I missing/forgetting/not understanding ??

author: lordvader88
author_rank: Frequent Contributor
timestamp: November 25, 2018, 09:32:42 pm
content: I mixed up the pins, I corrected my post. Also the chip is 16pin, and the sister PCB is 10pin, with 1 un-used. The sister PCB is doubled sided, and has about 80 resistors/caps/diodes/transistors, and a LM393 doing something idr-atm, but being powered off only the Vref of the CM6800

author: lordvader88
author_rank: Frequent Contributor
timestamp: November 25, 2018, 11:29:59 pm
content: I mapped out most of it
NEVA 5225 Power Supply - Page 1
Forum section: electronics / repair

author: 09d08
author_rank: Contributor
timestamp: November 24, 2018, 10:52:35 am
content: Hi,I'm trying to fix a rather old power supply. I saw two burned components on one of the two boards, one of them is definitely a resistor but I have no idea about the other axial metal one. The burned axial part is connected to the base and the collector of a BC547. I have just started to draw a schematic of the board so I'll attach the partial schematic and the pictures of the burned components. I hope someone has an idea what that axial one next to the resistor might be.Thanks in advance

author: coromonadalix
author_rank: Super Contributor
timestamp: November 24, 2018, 02:18:24 pm
content: maybe a zenner diode with the orange gold color on the photowould fit the size of the part ?

author: 09d08
author_rank: Contributor
timestamp: November 24, 2018, 05:51:30 pm
content: It's larger than a regular zener diode and every diode on the board. I believe it's a metal axial capacitor but I'm not very sure.

author: madires
author_rank: Super Contributor
timestamp: November 24, 2018, 06:13:30 pm
content: Yep, a capacitor might be possible. BTW, I'd also check the Philips electrolytic caps since they are known to go bad.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 24, 2018, 06:20:39 pm
content: search for the : GPD3303SM service manual there is a similar circuit, mosfet driven serial power supply, or any similar designthis one seems similar in some ways :http://powersupply33.com/transformerless-power-supply-fet.htmlI would say complete your schematic ... it would help to understand the circuit more ?

author: 09d08
author_rank: Contributor
timestamp: November 24, 2018, 06:55:47 pm
content: Quote from: madires on November 24, 2018, 06:13:30 pmTheir values seemed normal but I'll also check their ESR.Quote from: coromonadalix on November 24, 2018, 06:20:39 pmThey indeed seem similar, I'll try to map the feedback portion and other parts involving the tl074.
Gaggenau Service Manuals - Page 1
Forum section: electronics / repair

author: CHexclaim
author_rank: Regular Contributor
timestamp: November 29, 2018, 06:41:42 am
content: Hello everyone.I am looking for some Gaggenau Service Manuals for some appliances. In particular a Type BM271110 Microwave Oven and a Type DF460162 dishwasher.I have searched sites suggested in this forum but coundn't find for these products in particular. Not even in the paid sites, which would be fine if price is fair.Thank you very much,Carlos.
DVI not working on LCD monitor - Page 1
Forum section: electronics / repair

author: lordvader88
author_rank: Frequent Contributor
timestamp: November 23, 2018, 12:09:08 am
content: A while back the DVI input on my monitor stopped working. So VGA and HDMI work fine, idk if DP does.Where would I start after checking that the voltages are all working ? This is my good working 27" 1440p gaming monitor, so IDK if I even want to pull it apart, I sure would like to know why an input stopped working, something else could be about to go from the same problemI've watched videos of some repairs, but IDK the basics of these, past some of the SMPS circuitry.

author: shakalnokturn
author_rank: Super Contributor
timestamp: November 23, 2018, 06:41:21 pm
content: The usual stuff to start with, bulging capacitors, check PSU voltages and ripple.Then move on to the LDO regulators on the other PCB, download datasheets if needed, make sure they are in tight tolerance, I've seen cases where 1.7V instead of 1.8V was causing trouble.It is also a good idea to check ripple on those supplies as sometimes decoupling capacitors age.

author: Rasz
author_rank: Super Contributor
timestamp: November 24, 2018, 04:59:10 am
content: usually its ESD, sometimes bad groundI have couple of monitors with blown HDMI or VGA, all happened when plugging in/out
Leader LBO 508 Oscilloscope, no CRT - Page 1
Forum section: electronics / repair

author: RickEev
author_rank: Newbie
timestamp: November 20, 2018, 08:37:33 am
content: The Leader oscilloscope was a gift from a friend of a friend. I was hoping to use it straight away, but this oscilloscope has become a project unto itself. I have replaced some of the big (non-oil) capacitors and that fixed the problem of the screen slowly dissolving away after being turned on for 20 minutes.I was able to get a 1Khz square wave to display; I then walked away for a while, and when I came back, I had no CRT display. I checked the T1 to T5 connections and T1 to T4 were spot on, but T5 was registering ~300V instead of 1500V. Nothing really stood out (like smoking or smelling parts), but I did notice some cracks in the varistors.I assume this is not a "good thing" and plan to replace them, but with what? The Marcon part numbers are close to the current varistor codes, but they have their differences. From my research (I first thought they were ceramic capacitors), the TNR appears to be a MOV type, 681 is 680 volts, K is 10%, and then things get vague. I assume 015A is some multiple of 1.5 amps, and maybe 70116 is a date.My question is: Can I replace these with another MOV with the correct voltage or is TNR some special type of varistor? Is that really 1.5 amps and is there any other info I need?As you probably have noticed, I am a newbie to the world of oscilloscopes and soldering. This is really meant be a learning experience and if I get a working scope at the end, then so much the better. I haven't lost patience with this scope, yet.My future plans for this oscilloscope is to replace all the electrolytic capacitors, big and small, in the power supply (I am tired of futzing around here). The only other power supply components that have heat issues are a couple of screwed in ?transistors? (see photos) and maybe a resistor or two. Are the transistors easily replaceable or am I wasting my time here?Do you have any suggestions for the various boards (power supply, preamp and trig sweep)? Electrolytic cap replacement always seems popular or should I just deal with them when a specific issue shows up?Thx for any help.

author: petertronics
author_rank: Newbie
timestamp: November 20, 2018, 12:40:42 pm
content: Hello thereI had a simmilar problem with my lbo 508. (https://www.eevblog.com/forum/repair/leader-lbo-580-repair/msg1753652/#msg1753652for further reference like service manual). I would also recomend that you check the HV oil caps and replace them if needed.

author: RickEev
author_rank: Newbie
timestamp: November 21, 2018, 11:05:55 pm
content: I saw your thread and was hoping the hv oil caps weren't the problem. I'll look into them. I think I'll head over to the beginners section for the varistor info and see what they have to say.It looks like you replaced some of the electrolytic caps on your scope, too. On my scope, one had spewd and other others were bulging. I like things that say: Fix me. I also like your fix for the HV oil cap. It's nice to see clean work done on these old tools.Cheers
Rework glue - Page 1
Forum section: electronics / repair

author: jumbodas
author_rank: Newbie
timestamp: November 21, 2018, 01:04:50 am
content: OK years back I had a hot melt glue from Japan that used to be perfect. I can't remember it now. Is there a glue that can do following for PCB rework.a) Safe for copper tracks and Humanb) Instant - Hot melt or other wayc) For wire tacking as well as gap filling to hold / support parts and wires.d) Preferably see thrue) Can be easily removed or soldering rework can be thru. The glue I had from japan could be melted with soldering iron and also I was able to re-solder wires under glue. The glue will simply remelt while I solder and go solid after I finish.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 21, 2018, 03:18:00 am
content: If you have any more specific details, I can look around.

author: jumbodas
author_rank: Newbie
timestamp: November 21, 2018, 03:26:12 am
content: The one I had long back was from japan. It was yellow translucent oval shaped with about 5mm long dia, 6 inches long flexible stick.I know many companies like 3M etc make hotmelt for supporting heavy parts on the PCB. But these can be opaque and not suitable for rework.

author: cdev
author_rank: Super Contributor
timestamp: November 21, 2018, 03:36:58 pm
content: The fumes from some (non-hot melt) glues can be toxic. For example, 'super glue' which is often recommended for Manhattan style prototyping, emits toxic fumes when heated- It is toxic. It really has to be exhausted right outside, just moving it around wont do.Not a good thing to breathe.
What's the soft permanently sticky adhesive used for attaching phone backs? - Page 1
Forum section: electronics / repair

author: e100
author_rank: Frequent Contributor
timestamp: November 21, 2018, 08:24:44 am
content: It looks and behaves like the adhesive used on double sided sticky tape, but I need a liquid version so I can apply a thin bead.The closest I've seen so far is "off'n on craft glue" which goes on white then dries/cures to clear and behaves like the repositionable adhesive used on "post it notes".

author: coromonadalix
author_rank: Super Contributor
timestamp: November 21, 2018, 09:17:51 am
content: i use pritt products, very thin double sided tape, i dont recall the thicknesshttps://www.grandandtoy.com/en/product/442212-0_Pritt_Easy_Stick_Double-Sided_Adhesive_Film_with_Dispenser.aspx

author: helius
author_rank: Super Contributor
timestamp: November 21, 2018, 10:01:45 am
content: https://www.eevblog.com/forum/manufacture/about-the-glue-used-in-layer-laminated-products-and-many-modern-phonestablets/

author: xrunner
author_rank: Super Contributor
timestamp: November 21, 2018, 01:22:35 pm
content: Quote from: coromonadalix on November 21, 2018, 09:17:51 amYea I have the same stuff I've used to put under iPhone batteries after replacement. The tape contains adhesive "dots" that come off individually. Works well enough.
(8FSA) Help me identify this SMD transistor - Page 1
Forum section: electronics / repair

author: rauloliv
author_rank: Contributor
timestamp: November 15, 2018, 09:33:46 am
content: Hello all,i have in hands a inverter welding machine to be repaired (DECASIL-147SIL-417) . I'm not very experienced on this but at first sight it would be just a problem of IGBTs replacement.Looking closer i found one smd transistor (Q3) in s/c.I don't have schematics and the case mark is not giving me any clues.Its a SOT23 case with the inscription 8FSAEdit:::::Just found a similar welder schematic, but no references for the parts. The transistor should be a FET:Can anyone help please?Thanks

author: t1d
author_rank: Super Contributor
timestamp: November 15, 2018, 03:29:07 pm
content: Well, I searched, hard, with all the tricks I know, but came up with nothing. I am sure you have checked the part number, but maybe give it another look.Clean it well. Then, take a little bit of white heat sink grease, or medical zinc cream, and wipe it over the numbers. Sometimes, that helps them to stand out. Use good light, a magnifying glass and younger eyes, if available;-)I will follow, this thread, to continue to try to help. One option is to identify what the part does and try to find a part that will meet the requirements.

author: t1d
author_rank: Super Contributor
timestamp: November 15, 2018, 03:37:12 pm
content: Deca contact info:© DECA s.p.a. Str. dei Censiti, 10 Falciano - Rovereta 47891 Repubblica di San Marino - Tel. 0549 910.711 - Fax 0549 908.360 - deca@decaweld.comIs it SIL-147, or is it SIL-417?

author: rauloliv
author_rank: Contributor
timestamp: November 20, 2018, 03:49:46 pm
content: Hi,Its a SIL-417, thanks for noticing the error. DECA doesn't share schematics or any tech information, i contacted them.I found a similar welder schematic and i am confident that the the component is a BSS123 mosFET.Didn't replace it yet because unfortunately i found other complicated issues issues with this ......Regards,

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 20, 2018, 04:24:36 pm
content: Quote from: rauloliv on November 20, 2018, 03:49:46 pmThat's probably because they don't have that info to start with. It looks like a generic rebadged Chinese machine to me.We never got board level schematics for our house brands when I was in the game, not even for the Flagship rebadged EWM models, let alone the Chinese ones. If even Cigweld and BOC can't get PCB schematics for their exclusive models, I wish you good luck.It was usually a game of swapping boards, and only going to board level repair if things were obvious. (Like the period of time that EWM thought pop-riveting the heat sinks to vregs with the thin tabs was a good idea, then wondered why they all overheated and let the smoke out.....)
464 delayed sweep switch worn-out  - Page 1
Forum section: electronics / repair

author: AnneRanch
author_rank: Contributor
timestamp: November 19, 2018, 04:10:46 am
content: This is one of the weirdest mechanical design by Tek.It operates of "friction" ( pull out to engage ) and it is basically worn-out.I put some paint on the surfaces but have not reinstalled the PCB .I am not sure this will work.I could use some advise how to permanently fix it -super glue is NOT an option - this thing operates like variable clutch ...Thanks

author: tggzzz
author_rank: Super Contributor
timestamp: November 19, 2018, 10:55:25 am
content: A photo would help.Will the paint gradually wear off the switch.Where will any flakes end up? Probably in the contacts of other switches.

author: AnneRanch
author_rank: Contributor
timestamp: November 19, 2018, 07:21:33 pm
content: Your reply indicates that you are NOT familiar with the product.I am looking for an answer from somebody who does not need a picture.Thanks

author: tggzzz
author_rank: Super Contributor
timestamp: November 19, 2018, 08:37:17 pm
content: Quote from: AnneRanch on November 19, 2018, 07:21:33 pmWell, I have renovated more Tek scopes that I would like to admit, including a 464. Forgive me if I forget the details of that particular type, and forgive me if your definition of "surfaces" is less than clear.Good luck.

author: GreyWoolfe
author_rank: Unknown
timestamp: November 19, 2018, 09:10:56 pm
content: Quote from: AnneRanch on November 19, 2018, 07:21:33 pmMethinks you have just shot yourself in the foot. See how many posts tggzzz has? Not a newbie and very well known in the repair and TEA threads for his work on Tek scopes. When you come to a thread and ask for help, be polite and graciously give what information is asked for without. If you keep up with replies like you posted, you are likely to only hear the sound of crickets. Have a wonderful day.

author: AnneRanch
author_rank: Contributor
timestamp: November 20, 2018, 02:11:37 pm
content: Ask and yea shall receive ...I suppose it was naive from me to expect an answer from somebody who actually worked on this problem.But as an unexpected bonus I do appreciate the psychoanalysis of my post.And yes, I am having a great f day.Don't bother (to reply).Irrelevant replies will be cheerfully ignored.

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 20, 2018, 02:31:38 pm
content: Quote from: AnneRanch on November 20, 2018, 02:11:37 pmWelcome to the forums.You have to understand that this is a forum where people voluntarily offer advice and help. Demanding things or generally having an attitude is unlikely to garner fruitful results. One is also expected to contribute, if only by showing people things they didn't know yet. It's definitely a two way street. Ask nicely and yea shall receive.
QNAP TVS-671 Intel B85 Motherboard - Page 1
Forum section: electronics / repair

author: kaz911
author_rank: Super Contributor
timestamp: November 18, 2018, 06:07:00 pm
content: Hi,I could use a bit of adviceon a B85 chipset motherboard from a QNAP TVS-671.Symptom : QNAP does not turn on as it does not enable the standby power circuit to enable the soft power button. A hard ATX power on will turn the QNAP on and all works fine.I first traced high consumption to 5V to 3.3V voltage regulator from the standby power circuit (burning hot regulator).So I tried to manually feed 3.3v in to the standby-circuit bypassing the regulator and now its seems like the main chip-set is absorbing the power/ heat.But randomly the standby circuit will work fine - led comes on fine and uses 87mA. Other times circuit will go into overdrive and consume (max tested/limited) 800mA and the chip-set B85 will slowly heat up (got a heat-sink...)Since QNAP have not responded to my support ticket yet I have not wanted to do anything destructive yet - but has anyone seen similar? And was it the chipset? The randomness could be a cap somewhere but I have not found any that looks/measures cracked or damaged yet.It is random'ish but reproduce-able every time.But when forced On - the QNAP TVS-671 works fine (pull ATX PW-ON to low) - and then voltage regulator will operate within normal specifications. But remove the A/C power for a little bit and problem is back. So I would like to fix it for power out situations..../k

author: Rasz
author_rank: Super Contributor
timestamp: November 20, 2018, 02:21:33 am
content: sounds like similar problem to Asrock motherboardshttps://www.eevblog.com/forum/repair/what-would-cause-failure-of-4-motherboards-in-different-pc_s-within-a-few-months/msg1439544/#msg1439544
tv makes a hissing sound and runs hot (level 6542) - Page 1
Forum section: electronics / repair

author: loordgek
author_rank: Contributor
timestamp: November 15, 2018, 01:14:04 pm
content: i have a tv level 6542, and the inverter for the back light and the main power supply are making a hissing soundthe inverter for the back light is running hota lot of the caps are bad but i dont know if the problem is in the back light it self

author: tpowell1830
author_rank: Frequent Contributor
timestamp: November 15, 2018, 02:28:24 pm
content: Replace the caps...

author: james_s
author_rank: Super Contributor
timestamp: November 18, 2018, 08:16:41 pm
content: If you know the caps are bad why would you even bother to troubleshoot further before replacing them? It's highly likely that is your only problem.

author: perieanuo
author_rank: Frequent Contributor
timestamp: November 19, 2018, 02:21:28 pm
content: Replace the electrolyts.ALL of themEnvoyé de mon iPad en utilisant Tapatalk
fluke 8840a display fading in and out - Page 1
Forum section: electronics / repair

author: mr3141
author_rank: Newbie
timestamp: November 18, 2018, 07:22:33 pm
content: Dear allI have an old Fluke 8840a which is working fine, except the display is going dark from time to time. Not completely off, just fading out... few seconds later coming back on. Until now it helped to gently push on top of the case to make the display come back on.Today, it didn't work at all. I opened the unit and measured voltage rails (all fine). While I had the unit open, it was upside down. I switched it on and noticed that the display was working again. I put it back together and switched it on (in its normal position) and it had the display issue again. It seems to be very reproducible that the display works reliably only if the unit is turned upside down.I guess this is a mechanical issue, but no idea where exactly.Any idea?

author: mzacharias
author_rank: Frequent Contributor
timestamp: November 18, 2018, 09:04:22 pm
content: Solder connections. Main board (around the power transformer), or at the FL tube itself.

author: lowimpedance
author_rank: Super Contributor
timestamp: November 18, 2018, 11:11:44 pm
content: Most certainly re solder the transformer even if they look okay, and for that matter best to re do all connections in the path to the filaments. one other point is IIRC all front PCB connections are via dil headers, give those a wiggle then check for any corrosion on the pins etc. While your at it solder 2 wires to the filament connections right at the VFD to see if the supply is interrupted at any time when the unit is moved/inverted and back. (using a CRO or other DMM etc)The fact that it seems to function then fail repeatably when inverted does sound like an issue in the VFD itself which is not a happy thought, so make triply sure all other possible issues have been eliminated.Good luck.

author: mr3141
author_rank: Newbie
timestamp: November 19, 2018, 11:32:53 am
content: Thanks for your replies!I took a closer look to the power transformer solder connections. There were flux residues, I guess someone has done a reflow before. Under microscope I could see that two of the joints were visibly cracked. I've done reflow of all connections.... considering how heavy that transformer is it seems now quite obvious that this was the issue.I also reconnected the front PCB dil cables. Sockets and pins looked clean.I have it running now in its normal position and the display brightness stableThanks for the tips!
Samsung BN44-00375A mains connector identification - Page 1
Forum section: electronics / repair

author: reubot
author_rank: Contributor
timestamp: November 19, 2018, 06:28:25 am
content: I have a Samsung TV with the SMPS board BN44-00375A, but am missing the mains cable, I am wondering if anyone knows what part/model the connector pictured (CN801) is?
Wavetek 182A 4 MHz function generator - Page 1
Forum section: electronics / repair

author: GregDunn
author_rank: Frequent Contributor
timestamp: November 18, 2018, 08:11:36 pm
content: I thought it might be a good idea to create separate threads for my recent acquisitions rather than clutter up the TEA thread.Yesterday at a hamfest I found a nice Wavetek 182A for $10. The only external issue was that someone had carved an ID into the front panel.For the price, it seemed to be worth picking up.I did a quick check inside and saw nothing broken or burned, though the main filter caps had apparently been replaced. Powered it up, and it did provide a signal, though the range and waveform switches seemed to randomly provide outputs which had no correlation to the values selected. Clearly a problem with switch contacts. I didn't want to disassemble all the switches at this point, so I shot some Deoxit into the little gaps in the switch casings and exercised them for a few minutes. I made sure there was no excess on the board or components, then powered it up again; it worked much better this time. Altogether it took about 15 minutes of back and forth until the unit started working consistently. The wave shapes are off a little bit, which is probably an adjustment issue, but I wanted to be sure the unit was fully working before making any tweaks. PSU voltages look fine, and there really isn't anything else which shouts "replace me" on the board unless for some reason I can't get the adjustments to respond. I'm on to fixing another acquisition at the moment, so I'll update this when I have a few minutes to run through the manual's cal procedures and capture the waveforms.
TDS 500, 600, 700 series NVRAM battery replacement - Page 1
Forum section: electronics / repair

author: Polarue
author_rank: Newbie
timestamp: November 17, 2018, 07:13:18 pm
content: I posted an idea to solve the aging LTC battery issue that all TDS scope owners with the internal battery NVRAM Dallas chips have due to their age.It is simply to put an external battery on the Vcc leg (#32) of the nvram chip. From the datasheet of the ds1486-120, the internal switch does not connect the LTC battery until the voltage on Vcc drops to about 3v. A lithium ion rechargable battery would work if some carefully chosen diodes were to allow the roughly 5v Vcc input to charge the lithium ion when the unit was on to no more than 4.2v and then another diode would only allow about 3.7 or more volts to flow when the unit was turned off. Once in place, the Vcc would never again fall low enough to switch over to the failing LTC battery if the unit was on every three months or so.Does anyone with more knowledge see any fatal flaws with this modification to extend the life of the nvram chip's data?

author: Polarue
author_rank: Newbie
timestamp: November 17, 2018, 09:03:40 pm
content: "As VCC falls below approximately 3.0V, a power switching circuit turns the internal lithium energy source on to maintain theclock and timer data functionality. It is also required to ensure that during this time (battery-backupmode), that the voltage present at INTA and INTB (INTB) never exceeds VBAT. During power-up, whenVCC rises above VBAT, the power-switching circuit connects external VCC and disconnects the internallithium energy source. Normal operation can resume after VCC exceeds 4.5V for a period of 200ms."The above is from the ds1486-120 datasheet. I believe Vcc is normally around 5v so a circuit could be built that allows 4.2v to charge the external battery while the unit is on and then blocks the current to the rest of the board when the unit is off (when the external battery provides 3.7v to the chip). This would require the pin32 (Vcc) to be lifted and integrated with the simple battery circuit.Can anyone say why this would not work?
HP/Tek/Wavetek PH163 mains lead? - Page 1
Forum section: electronics / repair

author: Chris56000
author_rank: Frequent Contributor
timestamp: November 16, 2018, 04:55:16 am
content: Hi!Can anyone tell me where I can find an HP/Tek/Wavetek "Oval" three–pin PH163 type lead or female compatible connector for purchase in the UK?Every listing is either "sold out", " not available" or USA shipping only, the one listing that wasn't wanted over £200 in P & P and import charges!It's for an old Data Precision Multimeter, by the way!Chris Williams

author: alm
author_rank: Super Contributor
timestamp: November 16, 2018, 05:11:01 am
content: I would replace the socket with a modern IEC C6/C13 socket. I believe PH163 is not even rated for 230V operation, and as added complication, there are two different pin-outs with live and neutral swapped. I wouldn't trust equipment from that era to be safe if live and neutral are swapped.

author: factory
author_rank: Super Contributor
timestamp: November 17, 2018, 02:14:51 pm
content: If they weren't suitable for 230V use, then HP wouldn't have fitted these connectors to equipment they either made in the UK or imported during the 1960's.I suspect the power cords were never made in Europe and HP sourced them all from the US, hence they are only marked 110V. They changed to using the IEC connector in the 1970's, if they had carried on using the PH163 connector then I'm sure they would have had all the relevant European approvals & markings.There are some available in Germany (where the mains wall plug is non polarised/reversible) here;https://www.ebay.de/itm/222745856688, their not cheap, but the only other way to find one is to buy something you probably don't want to get one.P.S. You should check the condition of any original power cords & determine they are safe to use, the same as you would for any other cord (including modern ones).David

author: factory
author_rank: Super Contributor
timestamp: November 17, 2018, 02:43:46 pm
content: Quote from: alm on November 16, 2018, 05:11:01 amDon't worry even IEC power cords/leads can have live & neutral swapped, one was found at work about 10 years ago when the portable appliance tester was replaced, the newer machine checked for this.David
Convection oven trips/blows breaker at certain temperature - Page 1
Forum section: electronics / repair

author: attr_writer
author_rank: Newbie
timestamp: November 15, 2018, 07:59:22 am
content: Recently our Sharp R-960N convection/microwave combo oven has started tripping the circuit breaker. This only happens in convection mode when the temperature approaches 140°C. I have tried using it on a different circuit with the same result.Any ideas what might be wrong? I thought possibly the thermostat but I am unsure. Thanks.

author: t1d
author_rank: Super Contributor
timestamp: November 16, 2018, 06:35:22 pm
content: Just to be clear, you mean the house mains ac breaker, correct? Or, the GFIC breaker, on the kitchen counter wall socket? Our, the device has its own breaker?If the first, I would think that your house is old enough to not have GFIC breakers and the device does not have a reset. If so, I would do a visual inspection, of the device.Do not touch anything, inside the compartment, unless you know what you are doing. If you do know what you are doing, here is a reminder, to discharge any caps...Unplug the device, open the control compartment and look for a wire, or component, near the heat source, that is moving, due to the heat, and grounding out. Look for scorching. Pay attention, for a burnt smell.Do a visual inspection of the heating element and fan, if you can see it.Take lots of photos, of everything... Especially, of any observable problem area.Get back to us, with details... Make and model... Which breaker... Photos, etc.Do not use the device, until it is repaired.

author: t1d
author_rank: Super Contributor
timestamp: November 16, 2018, 07:39:37 pm
content: The on-line repair parts suppliers usually have the exploded diagrams, of the device. It can help you see how to get into the device. I am not finding that, for you make/model.There doesn't seem to be anything specific, to your make/model, on YouTube, either.It may be that this model is not sold in the USA? You may have to research things, on your internet.

author: capt bullshot
author_rank: Super Contributor
timestamp: November 16, 2018, 09:57:27 pm
content: You'll probably have to replace the heating element

author: johnkenyon
author_rank: Regular Contributor
timestamp: November 17, 2018, 12:56:36 pm
content: Quote from: capt bullshot on November 16, 2018, 09:57:27 pmBefore forking out for a new element, test the theory by temporarily splicing a marginally rated fuse into the feed to the heating element.By "marginally rated" I mean a fuse which will only just pass the normal current for the element.For example, if the element is rated at 900W, and the nominal mains voltage in SA is 230v (nominal current 3.91A) , then use a quick blow 4A fuse.If the fuse blows when the oven gets up to temperature then you can be a bit more certain that it's worth buying a new element.
Value of current sense Resistor in Korad KA3005D PSU - Page 1
Forum section: electronics / repair

author: Alex42
author_rank: Newbie
timestamp: September 22, 2018, 02:35:13 pm
content: HelloI have a broken KA3005D (5 A) PSU. The current sense resistor and the diode under it is burnt. I am looking for the value of the resistor (wire coil resistor). I an discussion about the KA3003D (3A version) PSU i found a schematic that shows a 50 mOhm resistor. When i replaced the resistor i found out that i need a 500 mOhm resistor. A mutch higher value then i expected. If i take a smaler value the displayed current is much to low. Everything else seems to work.Can someone meausure the value of his KA3005D current sense resistor and post it please.SincerelyAlexander

author: Kleinstein
author_rank: Super Contributor
timestamp: September 22, 2018, 03:44:56 pm
content: 500 mOhms would be much to higher for a 5 A current sense resistor. This would cause 2.5 V drop and 12.5 W of heat. 50 mOhms would make sene and even this is more on the high side. So chances are there is another fault, that somehow reduces the gain for the current reading and maybe also limiting.

author: DaJMasta
author_rank: Super Contributor
timestamp: September 22, 2018, 04:43:42 pm
content: If your current sense resistor is burned, then it wouldn't be surprising that that kind of overcurrent would have damaged the sense amp as well, if not something else. I would try to probe the outputs to some of those parts to check, and probably check anything else connected to those output terminal traces.

author: Alex42
author_rank: Newbie
timestamp: September 23, 2018, 08:19:10 am
content: Thanks Kleinstein and DaJMastaI agree with you that the 500 mOhm ist far to high. After inspecting the sense amp (U6) and the corresponding resistors i assume that it is destroyed and the voltage is not amplifed. Will have to build a mounting so that i can probe the board under power without destroying it.Thanks for your super quick responses.

author: bilibili
author_rank: Newbie
timestamp: November 17, 2018, 03:55:28 am
content: I've measured this resistor with my LCR meter, it shows 95.x mΩ.so the actual value maybe 100 mΩ

author: t1d
author_rank: Super Contributor
timestamp: November 17, 2018, 05:18:37 am
content: Quote from: bilibili on November 17, 2018, 03:55:28 amThat makes sense, is a common value for a sense resistor and sounds about right...

author: Alex42
author_rank: Newbie
timestamp: November 17, 2018, 07:57:15 am
content: Thanks bilibiliFunny this weekend i have borrowed a RND KA3005P (seems to be the same PSU under a differend lable + USB) to measure the resistor.. As mentiond before i have the replacements for the OPs and latches in the current path. At least the OPs are dead. Its difficult to measure on the board because it has a protective coating on it.Thanks for all your help

author: Alex42
author_rank: Newbie
timestamp: November 17, 2018, 12:47:12 pm
content: I measured the RND KA3005P current sense resistor and it is slightly under 100 mΩ. I measured the voltage drop over the resistor with different constant loads.
Searching for a Fluke 7261A manual - Page 1
Forum section: electronics / repair

author: Silveruser
author_rank: Regular Contributor
timestamp: November 17, 2018, 12:59:03 am
content: I have a slightly broken 7261A, it works some times but mostly not. Percussive maintenance works sometimes as well. There seem to lots of manuals on the web missing the last pages - the board layout and schematics. Does anyone have a complete manual or link they can share?