hybridfree/eevblog-posts huggingface dataset:
Fluke 375 clamp meter with large DC current offset - Page 1
Forum section: electronics / repair

author: radioFlash
author_rank: Regular Contributor
timestamp: September 23, 2016, 12:16:08 am
content: I have a Fluke 375 which is showing a large offset in the DC current mode without any wire or current (see image). The photo was taken while the meter was on a metal chair, but the negative reading doesn't change much if I move it around. I just received this meter so I'm not familiar with how it should normally operate.Turning it off and on has no effect. The batteries in the meter measure fine. The zero button does nothing when I press it except chirp. The DC V and Ohms mode seem to work correctly. If I do put a DC current (say 1 A), the reading does change to reflect the current, so the meter is detecting a change (the reading changes by 1A). Is this a case of user error and there's a simple way to zero it out, or does it need to be re-calibrated, or is it broken and needs to be fixed?Thanks for any suggestions.

author: MarkL
author_rank: Unknown
timestamp: September 23, 2016, 02:13:07 am
content: It looks broken to me.I have the 376 and it starts up with DC offset of 0.4A to 0.5A but goes to 0.0A once the Zero button is pressed. Yours should do the same.

author: retiredcaps
author_rank: Super Contributor
timestamp: September 23, 2016, 04:50:00 am
content: This recall notice shouldn't be the cause of your readings (26A offset), but you should check anyway.http://www.fluke.com/fluke/caen/about/press/digital-clamp-meter-recall

author: radioFlash
author_rank: Regular Contributor
timestamp: September 23, 2016, 09:18:05 pm
content: Quote from: MarkL on September 23, 2016, 02:13:07 amThanks for the confirmation, that's what I expected.

author: radioFlash
author_rank: Regular Contributor
timestamp: September 23, 2016, 09:21:06 pm
content: Quote from: retiredcaps on September 23, 2016, 04:50:00 amThanks for the info, interesting to know. And thanks for all the other answers you've given to others when they asked for help too!

author: walter.aranda
author_rank: Contributor
timestamp: August 21, 2024, 06:46:30 pm
content: Hello, I have a Fluke 376 FC with the same problem of a 1.3A DC offset in its default setting. Since I don't have a Fluke warranty because I live in a third-world country, I decided to fix it on my own. Maybe this will help you solve your problem as I did:1. Turn off the multimeter.2. Open the battery cover; it's not necessary to remove the batteries.3. Remove the two Phillips-type screws.4. The circuit has a single surface-mounted metallic potentiometer. You should carefully adjust it clockwise or counterclockwise in very small increments (take a photo beforehand to remember its original position).5. With each slight adjustment, cover the clamp and check the new offset. Repeat these steps until the offset is zeroed out.NOTE: It's recommended to use Loctite 243 after finishing, as it seems the manufacturer overlooked protecting this single potentiometer from mechanical movement due to use.In my case, it worked with a very slight movement.I am not responsible for improper procedures.Good luck!
Fluke 435 II Repair / SMD identification - Page 1
Forum section: electronics / repair

author: lthrelfall
author_rank: Newbie
timestamp: June 07, 2022, 05:24:11 pm
content: Can anyone help identify the component in the photo?I think it could be a SOT-23, MMBT404A but thats only if I assume it was marked 2n. (Sorry I might be misunderstanding the marking convention)I can’t seem to find any PCB schematics for Fluke 435 II on the Web?Any help is appreciated.Lee

author: gamalot
author_rank: Super Contributor
timestamp: June 07, 2022, 05:38:44 pm
content: They are dual schottky diodes BAT54S.https://assets.nexperia.com/documents/data-sheet/BAT54_SER.pdf

author: fzabkar
author_rank: Super Contributor
timestamp: June 07, 2022, 06:21:24 pm
content: http://www.smdmark.com/en-US/search/code?id=wv4
Fluke 435 Power Quality Analyzer - Page 1
Forum section: electronics / repair

author: Steamdonkey
author_rank: Newbie
timestamp: February 05, 2022, 06:13:36 pm
content: I have a Fluke 435 with a suspected internal power supply problem. Fluke won't repair it since it's obsolete so I'm trying to fix it myself. Does anyone know where I might find Fluke 435 diagnostic / troubleshooting / repair information? Also is there a good resource, other than Google searches, for identifying components by their markings? The components in the attached image are pretty well marked and should be easy to find information for but I'm striking out big time. Any help would be greatly appreciated.
Fluke 43B Display - Page 1
Forum section: electronics / repair

author: eduaqa
author_rank: Contributor
timestamp: March 23, 2025, 11:27:10 am
content: I'm trying to repair a fluke 43B display.The device turn on, I hear the beep, I can use the computer software and connect, capture the screen, capture measure etcThe display backlight turns onBut the display is completely blank, not a single dot comesI hard to believe the a display goes on this condition and not signal of mechanical problem (the seems like new), so I'm focus on other point.While reading the service manual on page 7-7 7-8 about testing the signals I saw these notation that I'm NOT familiar with, example:FRAME, for 250 ns pules, ≅66Hz or ≅ 50 mV or ≅ 15 ms ... what that symbol with --~ (2 straight and 1 curved lines) in the top of each other means?

author: benj38
author_rank: Frequent Contributor
timestamp: March 27, 2025, 01:54:43 pm
content: It means "approximately equal to".

author: TimFox
author_rank: Super Contributor
timestamp: March 27, 2025, 04:26:08 pm
content: Yes, in this context it means “approximately equal to”, sometimes written with two curved lines without a straight line.There can be confusion with the normal notations in geometry, where one squiggle over the two-line equals sign means “congruent”, and one squiggle means “similar” (comparing two shapes).

author: eduaqa
author_rank: Contributor
timestamp: March 27, 2025, 06:46:32 pm
content: Thanks, clear.I advanced a little more in my repair and discovered that no reference voltage is been generated by the T-ASIC session, (not of those 3.3 1.2, etc)I tested the outgoing test point from the P-ASIC session ant they are ok.Looking the circuit diagram for the T-ASIC seems that there are 3 inbound connection for the powerLooking the picture (attached) for the T-ASIC session the resistor for the inbound power are noted 0E 1E 10EWhat type of note are those? I saw 3 digits 4 digits and EIA-96 , but none of those is like that
Fluke 45 IEEE option problem. - Page 1
Forum section: electronics / repair

author: Paceguy
author_rank: Regular Contributor
timestamp: November 12, 2021, 12:49:37 pm
content: I picked up a non working Fluke 45 with the IEEE option installed. It was marked as defective, when powered up it stayed hung up on the start up display and would proceed to self test. I found an open electro cap 10uf 63 volts, replaced the cap and still no go. I disconnected the IEEE board and viola it works! I conducted a visual inspection of the IEEE board, but all looks well. Is there a common problem with these IEEE boards and is a repair possible?

author: commongrounder
author_rank: Frequent Contributor
timestamp: November 12, 2021, 04:05:54 pm
content: First thing I would check is to see if the IEEE board loads down any of the power supply rails in the 45 when it’s installed. Could be a bad local filter cap on the board. Check with a scope for clock signals. If it’s locked up, it could be preventing the boot process from completing. I have two of these meters, but neither came with the IEEE option installed, so I’m sorry that I can’t give you specific signal info.
Fluke 45 looking for a front panel with bad display - Page 1
Forum section: electronics / repair

author: Tango1668
author_rank: Newbie
timestamp: February 26, 2022, 11:16:40 am
content: By accident the VCC was shorted to the +30V. All ICs in the digital kernel were fired, including those on the front panel. Analog kernel is intact because it is isolated by the inverter.Use hot air gun to remove all ICs. Put a socket for the main digital processor and the switching IC. Also replaced a few diodes in the power supply section. Could source all ICs from China and Element14.All voltages are within specifications. Can hear the relay clicking when powering on. E clock gives a 1.085 uS square wave. SWR1 to SWR5 status are normal. The problem is the FIP IC. The display looks like that. The beeper beeps continuously.Would like to ask if any member have a front panel with broken or non usable VFD, but a working FIP IC? The VFD is in a good condition, not dim and no uneven digit. If I can get a front panel with working FIP I can swap the VFD and bring the meter back to life for another 10 years of service, of course a calibration is required.Otherwise need to look at the option of using a OLED display with a processor to decode the messages from the main processor. Had tried capture a few packets. They are SPI but the data stream decoding is not straight forward.Thanks in advance.
fluke 45 no display symptom - Page 1
Forum section: electronics / repair

author: ant17
author_rank: Regular Contributor
timestamp: April 22, 2020, 11:38:49 pm
content: hi guys i am trying to fix a fluke 45. i am pretty sure the cal is ok. but it just started when i turned it on it would beep but no display. i got the fluke 45 service manual which seems to be the generic one on the internet .but in the schematic it doesn't show what some of the ics are and the ones it does are not the same part numbers can anybody help.
FLUKE 5100A Display issue - Page 1
Forum section: electronics / repair

author: Crambone
author_rank: Frequent Contributor
timestamp: November 28, 2023, 01:06:55 am
content: I have a 5100A that when powered on nothing lites up on the front display but when you power off it blinks for a split second. I can’t find any info as far as service manual, schematic….I’m wondering if the 5100a and 5100b share any similarities?I would like to find some voltage specs especially for the power rails….If anyone has any inside or info (document) to share it would be greatly appreciated.Drew

author: bdunham7
author_rank: Super Contributor
timestamp: November 28, 2023, 01:16:37 am
content: They're very similar and AFAIK the modules interchange, but IDK what specific differences there are. IIRC userRunco990had one of these with a similar problem and the issue was that there is a 555-based oscillator on the PSU board that drives the display multiplexer and his had stopped oscillating. Just use the 5100B service manual until you manage to locate the 5100A version.

author: Runco990
author_rank: Frequent Contributor
timestamp: November 28, 2023, 10:36:21 pm
content: Yep, my 5100 damn near killed me trying to figure THAT one out. Check the 555 on the bottom right corner of the power supply board first. It is the clock for the display. I soldered a wire to the output so I could get a probe on it without an extender. Of course, check all fuses and voltages on the Power supply board before digging in deeper. As far as I know, most of the 5100A and B are interchangeable. I have swapped most boards and all work.
Fluke 5100B drifting - Page 1
Forum section: electronics / repair

author: broketest
author_rank: Newbie
timestamp: December 15, 2023, 11:27:55 am
content: Hello,I have 5100B, who works perfectly, with action on pots on Ranging board etc. The Power supplies are stable. But the +10V from A14 is drifting after 5mn after power on. then the pots seems inactive, nothing moves.I suspected U10 reference on A14 'SZA263), which i borrowed from a broke 8840A, unfortunately the restults are the same.Does anyone have an hint?
FLUKE 5101B any known issues? - Page 1
Forum section: electronics / repair

author: Crambone
author_rank: Frequent Contributor
timestamp: September 15, 2023, 03:03:09 pm
content: I came into possession of a 5101B with no panel lites so that’s my first task. After screen is opposable does anyone know of any common issues/ problems that may need looking at, tantalum’s, electrolytic, IC,s……Thanks for any suggestions.Drew

author: bdunham7
author_rank: Super Contributor
timestamp: September 15, 2023, 04:33:27 pm
content: Quote from: Crambone on September 15, 2023, 03:03:09 pm?Those 5100-series monsters have so many issues I don't know where to start. Wait, I do--the power supply board. You have to start there. Sort of...First, I'd pull all of the modules out except the CPU, isolator and ranging assembly. Inspect them all for burnt traces or blown up things. Then pull the power supply board and inspect it as well for burnt things. If none, then reinstall it and check all of your power supply voltages. If all the voltages are OK and you still get absolutely nothing on the display, then you have a problem somewhere in the CPU, motherboard, display or display clock circuitry. The display clock is actually a 555 on the PSU board, something userRunco990discovered after quite a bit of searching. You can find plenty of old EEVBlog threads on the 5100-series.If you do find burned up PSU sections, you need to check all those tall modules for shorts. The tantalum caps that are sprinkled all over like to develop little black holes that can seemingly sink almost infinite current, burning up traces and PSU components like wildfire. The two on the bottom of the HV module are notorious for this, but there are others.There are a large number of revision levels for the PSU board as well, so it probably won't match up to your schematics perfectly. There are some zeners used as voltage drops for regulators that like to self-toast, I use new 5W parts and stand them off the board. It's a crappy design, IMO, but if you try redesigning all of the issues out of these you'll be at it for decades, like Fluke was.
Fluke 5101B output fault. - Page 1
Forum section: electronics / repair

author: mzspring
author_rank: Contributor
timestamp: October 01, 2024, 12:43:09 am
content: Fluke 5101B directly outputs 18V when it is turned on, which is uncontrollable and all functions are unavailable. where can I start the maintenance?

author: squadchannel
author_rank: Frequent Contributor
timestamp: October 01, 2024, 12:53:43 am
content: Get the service manualCheck the power supply voltageClean card connectorsImprove contact of switchesIt's in the electrician Bible.
Fluke 52 II PCB missing passive component - Page 1
Forum section: electronics / repair

author: Blynski
author_rank: Newbie
timestamp: March 17, 2023, 07:24:16 pm
content: I am trying to fix my dad's Fluke 52 II and it appears to have multiple issues. Firstly, half of the header contacts had broken solder joins which I repaired. Secondly, it appears to have some damage and a missing passive component (probably a capacitor based on how it is acting). Attached is a picture I found of a good board with the missing component circled. Does anyone know the correct value of this component so I can order one and replace it (or someone with a schematic)?

author: fzabkar
author_rank: Super Contributor
timestamp: March 17, 2023, 07:59:34 pm
content: The colour is reminiscent of a precision resistor. What resistance do you measure for the "2742" part and for the other unmarked part?

author: Blynski
author_rank: Newbie
timestamp: March 18, 2023, 02:42:14 am
content: Thanks for the hint on it being a resistor. I’ll take some measurements tomorrow and report back.Assuming you are correct I would still need someone with a good board or a schematic to help me out on the needed value.

author: fzabkar
author_rank: Super Contributor
timestamp: March 18, 2023, 03:10:57 am
content: The Linear part is a dual precision reference:https://www.analog.com/media/en/technical-documentation/data-sheets/1034fe.pdfThat would lend support to the precision resistor idea.

author: Blynski
author_rank: Newbie
timestamp: March 19, 2023, 01:34:43 am
content: Based on taking measurements on my board, I would agree that they are in fact resistors. Picture attached of the measured values. Essentially two 27.4k ohm and one 5k ohm resistor. So at least I know I'm looking for a precision resistor, but still need the correct value...

author: fzabkar
author_rank: Super Contributor
timestamp: March 19, 2023, 05:37:58 am
content: Just in case you don't have it, here is the service manual (but no circuits):https://elektrotanya.com/fluke_51_52_53_54_series_ii_thermometer.pdf/download.html#dlYour board is the "isothermal PCA". I suspect it provides cold junction compensation for the thermocouple.

author: coppercone2
author_rank: Super Contributor
timestamp: October 04, 2024, 06:36:50 am
content: Ah I fixed mine after dropping it, I was very confused.YOu see, that board has pins on it that are SMD! I thought they were through hole and figured there is no way that could break.
Fluke 5500A repair - Page 1
Forum section: electronics / repair

author: Reee
author_rank: Newbie
timestamp: April 20, 2024, 09:16:38 am
content: So recently I disassemble it to repair broken plug, and when it's done, it look like in the picture, I think I broke something else, anyone seem know the problem? no text at all just blank square

author: alm
author_rank: Super Contributor
timestamp: April 20, 2024, 10:05:50 am
content: I haven't worked on this instrument, but this looks like an LCD screen that's not initialized. So I would expect either a problem between front panel controller or LCD, or a problem preventing the front panel controller to start up.What did you repair and what did you disassemble? Internal pictures clearly showing the relevant parts could be helpful. The first place I'd look is the connection between front panel and the rest of the unit. Particularly if you have unplugged it.
FLUKE 5500A -- Seeking bodge compare to other units; PCNs - Page 1
Forum section: electronics / repair

author: gwideman
author_rank: Contributor
timestamp: February 16, 2023, 06:21:38 am
content: Fluke 5500A aficionados: I'm looking at a partly non-functioning 5500A and making some progress, but I'd appreciate info you might have on PCNs ("updates"), and the likelihood that one thing I'm looking at is such a PCN, or at least a factory mod.1. Does anyone have a list of PCNs? The unit I have has a sticker which suggests PCNs 4776 and 5072 were installed, and possibly 19422. Any info on those?2. On the A6 DDS board, I see the following bodge:The resistor is added and a trace is cut, with the net effect of adding a 390 ohm in series with C63. That is a plausible revision, but the actual implementation is poor -- tearing up a track, and the "hot iron trimming" of nearby C63 0.47uF leaves something to be desired. Regardless, I wonder if this mod is present on other units?Thanks!

author: Jetecnet
author_rank: Contributor
timestamp: February 16, 2023, 04:36:15 pm
content: I don't have that mod on my A6, it looks to be a resistor in series with TP7 (Current error out)Interesting photo, must be a late version, weird chip numbers.As regards getting any parts / boards for this from Fluke, pretty much noJC

author: gwideman
author_rank: Contributor
timestamp: February 17, 2023, 01:31:50 am
content: Quote from: Jetecnet on February 16, 2023, 04:36:15 pmThanks for your reply. From the photo it might look like the resistor is in series with TP7, which in a sense it is. However the trace from TP7 that runs under U33 is cut. The net effect is like in the schematic attached. On the schematic I've relocated TP7 to where I think it actually connects on the board.And yes, all the ICs that the schematic calls out as DG444DY appear on the board as 92944L1 L018FLA. I'm inclined to think the former is a date code and the latter a part number, though google finds me neither, and the "44" in 92944 does somewhat match the 4's in DG444DY.
Fluke 62 MAX+ infrared thermometer vs Battery Leakage: how to open?  - Page 1
Forum section: electronics / repair

author: Electro Detective
author_rank: Super Contributor
timestamp: March 30, 2018, 01:00:47 am
content: You guessed it, I recently got a used dual laser Fluke 62 MAX+ infrared thermometer on the cheap to keep my single laser Fluke 62 MAX company,and two meters are always the way to go to verify readings and operationIt had battery leakage from the single AA fitted, brown goo stuck on everywhere and suspect has gone inside tooThe meter works perfect but I want to get in there asap and check and or clean upI got as far as removing all the battery compartment 'miniature' screws (obvious and hidden.. and stubborn) but the meter body half will not lift off completely (stops halfway past the battery section)and I don't want to force it like you would say a Fluke 114 / 117 series multimeter which sort of 'crack' open at the top without actually breaking anythingIs there a trick to it, or designed that way so user can't stuff up the calibrated innards and laser alignment thingies?This is the first Fluke I haven't been able to get intoAny suggestions or 'leave it be' recommendations are appreciated

author: Skroob
author_rank: Newbie
timestamp: November 14, 2020, 10:45:58 pm
content: I'm necroing this thread because it's one of the few hits on the webbernets that even hints at a possibility of this thing being opened.The second secret location to find the screws is behind the Fluke label above the display. Carefully peel it back (the IP54 rating sadly depends on that label) and you will find two screws.Cheers!

author: derrickito
author_rank: Newbie
timestamp: June 30, 2021, 08:25:38 pm
content: i also found this as the only hit on some web searches. had a damn hard time getting this thing open. found the 2 screws behind the label thanks to Skroob. i ended up hulking the hell out of it because i still couldn't get it open, it turns out there is another secret screw behind the label in the bottom of the battery compartment.pic:https://photos.google.com/share/AF1QipPaK7zzIQi3ml2LL9a6k64nyqkpcw5RYYVeZCIKJWmdBgTXtwnhN-q3LGIH8jeOYw?key=c2h3YmFqUE14ZEp0S29oM3FEN0dPSVVKQXhyamJRso it goes. this was already broken so no harm no foul. but just in case any other wayward souls find this thread in the future days... be mindfuland damn these screws are in there solid. these fluke tools are wonderfully constructed.

author: mcinque
author_rank: Unknown
timestamp: June 30, 2021, 09:29:17 pm
content: yep, a good advice is to double, triple check every label because under them there are often hidden screws. I'm really sorry for your unit.

author: najrao
author_rank: Regular Contributor
timestamp: August 23, 2021, 03:02:42 pm
content: A small but strong neodymium magnet will detect hidden screws as under a label, by feel alone. No need to peel and mutilate. Screw must be steel, most are.
Fluke 6500 Calibration procedure? - Page 1
Forum section: electronics / repair

author: gamerpaddy
author_rank: Regular Contributor
timestamp: December 23, 2024, 08:46:19 am
content: Fluke is hiding its secrets when it comes to calibrating a 6500 appliance tester.theres probably still many thousands out there that have to be Cal'd every 12 months for a lot of money.This is obviously something they wont share with anyone outside the yellow circle.does anyone know the deep dark secrets of this mystery? like a hidden key combination to access a secret menu, rs232 commands to enter this mode etc etc. ? there are no pots on the inside.Those devices are popping up everywhere on ebay the last few years as their displays are failing.its a 50$ part, easily replaced but of course fluke wants you to buy the new 6500-2 by telling people it costs millions to repair by a certified® fluke Sensei with golden hands.I know, a uncertified self cal causes problems when making a insurance claim that something blew up that tested fine with a device like this.they are there to ensure electrical safety in the first place. but the heck its just a fancy multimeter that measures the basics with like 3 digits of resolution, any 20$ aneng can do better.
Fluke 70 Series replacement LCDs - Page 1
Forum section: electronics / repair

author: Axtman
author_rank: Regular Contributor
timestamp: October 08, 2022, 07:03:52 pm
content: I wish someone would manufacturer new replacement LCDs for Fluke series multi-meters. Since these meters are several decades old, Fluke will not service them nor are OEM parts available.I have two Fluke 77 meters that have faded screens. (Not the faded partial digits/zebra strip issue.) I believe the fading is due to long term exposure to UV light. Both are hard to read, but one is almost impossible to read. I will probably end up selling it on Ebay for parts. It's too bad because they are both in great working condition (other than the screens).I am sure there are many other people in my position that want to keep their old Fluke meters alive and running for many more decades!

author: modz786
author_rank: Regular Contributor
timestamp: October 10, 2022, 05:47:14 pm
content: no incentive for manufactures to make lasting equipment or supply parts in agebut i still say older gear is far better made than current gear with more use of copper and gold everywheretodays china copper is stranded aluminum copper plated or so it looks then try passing a few amps and see some sparkles

author: robert.rozee
author_rank: Frequent Contributor
timestamp: October 11, 2022, 12:56:14 pm
content: have you looked at replacing the polarizing filter that is attached to the front of the LCD? i can't guarantee this will fix it, but worth a try.averygood source of polarizing film is from the front of a discarded or broken colour LCD monitor. this requires extracting the panel from the monitor, then very carefully stripping out the front polarizing film using whatever solvents you have to hand to dissolve the adhesive. i did a 22" monitor recently, and after a couple of hours ended up with a 19" x 10" sheet - enough to last a lifetime! btw, i found the rear film was too thin to extract.thankfully, removing the polarizing filter from the front of a small LCD like used in the fluke 77 meter is far easier, it can generally just be peeled off with due care and patience. once you have it removed, you can check if a replacement will help by viewing through a scrap of polarizing film held by hand.cheers,rob :-)
Fluke 705 detailed pictures and/or schematics - Page 1
Forum section: electronics / repair

author: ja4
author_rank: Newbie
timestamp: November 30, 2016, 11:53:17 pm
content: Hi, could someone help me getting a detailed PCB picture and/or the schematics for the Fluke 705.I've blown transistor Q6 and would like to know the value for the replacement part.Thanks.---- A month later and I know now that it is a PNP transistor, replaced it and it works fine again.

author: giacomo
author_rank: Regular Contributor
timestamp: March 17, 2021, 03:37:47 pm
content: Hi, i just got a brooken fluke 705, it turns on but no output, after the teardown i saw that the relay was destroyed as well as the fuse.For the relay i can still read the part number, but not for the fuse F1 close to the com portIf you still have it could you kindly take a look for me ?
Fluke 707 repair - information request - Page 1
Forum section: electronics / repair

author: tfm
author_rank: Contributor
timestamp: July 22, 2024, 11:41:31 pm
content: Hi,I have a faulty Fluke 707 laying around for quite a while, and after a closer inspection, I realized this unit has seen better days.Someone has been here before, and they weren't exactly kind. A few ICs have been removed, and the pads along with them:Many blobs of solder, poor technique, twisted components, flux all around, bodge wires.C86, below the encoder, is missing. They soldered an upsized cap on the bottom:I have not found any teardown so far. I need a couple of things to give this a try.First, I need to check if the components are right, including the values of the passives. So I kindly ask if someone could share high-quality pictures of their board, with the IC markings visible, as well as the passives.Also, if by any chance a good soul could measure the values of the caps, I'd appreciate it. The reason being, with all these blobs of solder around, I don't trust these are the right values, despite probably not being critical.Of course, the best option would be a BOM and schematics, but we know we don't get that from Fluke. Maybe someone here did a reverse engineering?

author: tfm
author_rank: Contributor
timestamp: July 24, 2024, 01:47:41 am
content: Guys, I know this is not a super common equipment, but no one has a working Fluke 707?
Fluke 725 not turning on - Page 1
Forum section: electronics / repair

author: RYcal
author_rank: Contributor
timestamp: October 26, 2021, 06:59:43 pm
content: Hey all I have a Fluke 725 that's not turning onI have checked all the usual things like batteries and where those paths go. And have taken off the touchpad PCB and cleaned it etc. with no luck. Is there anything obvious I should also be checking.Cheers
Fluke 725 repair - Page 1
Forum section: electronics / repair

author: kingsolmn
author_rank: Contributor
timestamp: June 29, 2021, 05:13:52 pm
content: Greetings StarFighters.I've been tasked with repairing a Fluke 725 that appears to have been grabbed by a sparky and used on a mains voltage line. Anyway, the input protection seems to have done its job but I'm having trouble finding what the "proper" replacement fuse is supposed to be. I have attached pics of the full back of the mainboard, a close-up of the blown part (quite a spectacular failure, the pics don't do it justice!), and the board details. Btw, the board is a Martel (of course) Rev D board.It would be really awesome if someone in the know can enlighten me with the correct fuse type/rating that's supposed to be there (4 places), or even a way to convert this board so that it has user servicable fuses like the manuals show. Considering the difference between what's on my bench and what has been shown by @somlioy's teardown photos, and @PA4TIM dealings in trying to find/produce schematics leave me with little hope of finding an official source of documentation.Thanks in advance for reading and maybe having something to contribute!Also, do you all want to see better pics of the failure?

author: kingsolmn
author_rank: Contributor
timestamp: June 30, 2021, 05:35:41 pm
content: So, I've accepted that I'm not going to find an "official" designation of the fuse used. With that said, how would I go about determining an acceptable replacement for the failed fuse? The front of the case has the max ratings of 30V and 24mA but it doesn't give much in the way of other ratings I find in the parametric search. Does it even matter significantly about the other attributes of the replacement parts? For reference, here is ahttps://www.digikey.com/en/products/filter/ptc-resettable-fuses/150?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALGGABxwDsIAuoQA4AuUIAyuwE4BLAHYBzEAF9CAVgAMNRCBSQMOAsTLgAzPSrM2nSD37CxkkDBqaFSlXkIlI5AEwUABAFsAgnpAcuAVSEBdgB5VABZXHRsAFc%2BXAlxcSA]link (https://www.digikey.com/en/products/filter/ptc-resettable-fuses/150?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALGGABxwDsIAuoQA4AuUIAyuwE4BLAHYBzEAF9CAVgAMNRCBSQMOAsTLgAzPSrM2nSD37CxkkDBqaFSlXkIlI5AEwUABAFsAgnpAcuAVSEBdgB5VABZXHRsAFc%2BXAlxcSA) to some of the parts I'm considering. Which metrics are the most important and which ones aren't that important when selecting a replacement component in this case?Thanks in advance!
Fluke 725 Seriously damaged (HELP!!) - Page 1
Forum section: electronics / repair

author: oldmansinger
author_rank: Newbie
timestamp: October 21, 2019, 09:23:15 pm
content: Good evening friends,I am repairing a Process Calibrator that has been damaged at the MEASURE input, they have injected a voltage of 220VAC.The equipment is very damaged but I need to repair it, it is a commitment to my boss.Anyone have and want to share electronic diagrams with me?I would also like to collaborate, I have some service manuals and also some knowledge of electronics (not comparable to yours).Greetings from Spain.Alexander

author: m3vuv
author_rank: Super Contributor
timestamp: October 22, 2019, 07:09:47 pm
content: dont you think mentioning the make and model may help,or do we look into our crystal balls?!!

author: mikerj
author_rank: Super Contributor
timestamp: October 22, 2019, 07:16:12 pm
content: Quote from: m3vuv on October 22, 2019, 07:09:47 pmIt does say Fluke 725 in the title. There are other people withblown up unitsbut no sign of a service manual or schematic.

author: edpalmer42
author_rank: Super Contributor
timestamp: October 22, 2019, 07:17:17 pm
content: Quote from: m3vuv on October 22, 2019, 07:09:47 pmSo the "Fluke 725" part of the subject line isn't enough? What's missing?
Fluke 726 handheld calibrator repair - Page 1
Forum section: electronics / repair

author: Krampmeier
author_rank: Regular Contributor
timestamp: June 08, 2019, 12:12:06 pm
content: I recently got a defective Fluke 726 handheld calibrator. Lucky me!The reported problem was that the resistance measurement was not working right in 3-wire mode. The instrument had already been adjusted by using the calibration menu via RS-232. In fact, it measured more or less correctly in 4-wire and 2-wire mode, and 1.47 times too high in 3-wire mode. Like with a constant gain error, which varied slightly over time.I noticed that in 4-wire and 2-wire mode, the test current from the 726 was 135 µA, while it was 200 µA in 3-wire mode. Some internet search showed that the correct current is 200 µA.As the unit is adjusted in 4-wire mode only, a wrong current in 4-wire mode would break measurement modes where the current is correct.The circuit board looked alright, so I had to dig deeper. Without a service manual, I had to figure out how the ohms measurement circuit works in order to find the error.I buzzed out the attached schematic of the ohms measurement circuit, which may still be partly wrong and incomplete. See attached fluke_726.pdf. I also checked the analog mux settings for the various resistance measurement modes, and verified that all muxes worked fine.The constant current source built with U7 and Q4 seemed to stop working properly in all cases where no current was sourced from the "3W" terminal (marked "1" in the attached overview).It turned out that the zener diode D25 got very hot in those cases, and the voltage drop at D25 got much higher than the nominal 18 V: up to 21 V. This reduced the negative supply voltage for U7 so much that it could not deliver enough current.But why was U7 sourcing so much current (>20 mA) into negative supply rail (which should have been at 24V-18V = 6V below the positive supply)?I removed D21 and it suddenly behaved correctly. Very, very strange.In the end, I replaced U7, and everything was fine. I could adjust the instrument without any problems and it is now working fine in all resistance measurement modesIt seems like U7 was partly defective, and started to overstress the negative supply when U11D was inactive and Q3 should have been completely off.I hope someone finds this interesting, or has a use for the attached information!U112W3W4WPin1HHHPin10LHHPin11LLHPin20LHLU112W3W4WConnecting pins2-32-32-3Connecting pins7-88-98-9Connecting pins13-1413-1412-13Connecting pins17-1818-1917-18U92W3W4WPin1LLLPin10LLLPin11LLLPin20HHHEdit: Added reference to attached schematic fluke_726.pdf
Fluke 726 PTC help - Page 1
Forum section: electronics / repair

author: kleblanc
author_rank: Unknown
timestamp: July 23, 2017, 06:02:06 pm
content: I have a Fluke 726 process calibrator that will not measure or source milliamps. I am curious is the PTC is an issue. One is read 110kohm and the other is 300kohm. I am attaching pictures, and I just measured without removing them. The "square fuses" are around 8 ohms each.Any help would be greatly appreciated.

author: retiredcaps
author_rank: Super Contributor
timestamp: July 23, 2017, 06:26:50 pm
content: Quote from: kleblanc on July 23, 2017, 06:02:06 pmI'm not familiar with the 726 and I haven't searched for a service manual/schematics (I doubt one exists for the newer Flukes ), but in Fluke's handheld multimeters, the PTC is used for input protection on the volts/ohm input jack and is usually in the 1.0 to 1.1k ohm ballpark.If this meter is not under warranty, you could, for test purposes only, remove the two PTCs and temporarily use two normal 1.0k ohm resistors to see if that corrects the issue?

author: retiredcaps
author_rank: Super Contributor
timestamp: July 23, 2017, 06:28:19 pm
content: Quote from: kleblanc on July 23, 2017, 06:02:06 pmI think you meant "without" removing them as your picture shows them being measured in-circuit.

author: Gyro
author_rank: Super Contributor
timestamp: July 23, 2017, 06:30:41 pm
content: If it helps, I think those are Raychem parts.Edit: Now Tyco.

author: kleblanc
author_rank: Unknown
timestamp: July 23, 2017, 06:47:31 pm
content: Thank you Retired caps, yes I meant without. Mistyping from my phone...I have not been able to find a schematic either.It is out of warranty so I must try that.I am also hoping someone might have this Meter and be able to check theirs.Gyro, the raychem lead is more than I had earlier.

author: lowimpedance
author_rank: Super Contributor
timestamp: July 24, 2017, 03:19:49 am
content: Quote from: kleblanc on July 23, 2017, 06:02:06 pmQuick check on that 34401 reading which is some what hard to see, but is that not a decimal point before the 110 as in ' 0.110,97 Kohm ' or nearly 111??.

author: kleblanc
author_rank: Unknown
timestamp: July 27, 2017, 11:03:27 am
content: I didn't even notice the decimal. I'll have to recheck to see if the other one is 300 ohms or 300kohms.

author: JerryV
author_rank: Newbie
timestamp: October 30, 2020, 07:10:03 pm
content: was this ever corrected? i have a Fluke that is doing the same thing

author: kleblanc
author_rank: Unknown
timestamp: October 30, 2020, 07:14:16 pm
content: Unfortunately no, I sold it on eBay as parts
fluke 726 repair help - Page 1
Forum section: electronics / repair

author: janosky
author_rank: Newbie
timestamp: June 14, 2022, 05:22:49 pm
content: Hello good day, I have a problem with a fluke model 726 process calibrator, the instrument had a fault in the integrated LT1373(250kHz Low Supply Current High Efficiency 1.5A Switching Regulator) which was changed, however the equipment turns on but shows a battery icon which marks that it is low and turns off the instrument, clearly the batteries are good and also perform the tests with a power source to rule this out and the fault is the same, if any user of this forum has experience in repairing this equipment or any notion of where the revision should continue, I would greatly appreciate it since it is a very expensive equipment to dispose of and I need it for daily use , Thanks a lot

author: Ugur
author_rank: Regular Contributor
timestamp: June 16, 2022, 11:37:38 am
content: Hello,Can you check these parts?D5-D7-D4-D10-D37-D11Q5-Q9U2-U23
Fluke 73 Series III service manual - Page 1
Forum section: electronics / repair

author: LateyMatey
author_rank: Newbie
timestamp: August 16, 2020, 07:34:19 pm
content: Hi GuysI have a Fluke 73 Series 3 which does not read DCV correctly (actually, it's an eBay purchase which I've not received yet). Just wondered if anyone has the correct service manual I may obtain before it arrives. The series 2 one seems readily available, but not 3. Is this because its still repaired by Fluke perhaps?I work as a Calibration Engineer here in the UK, having previously been a production and service engineer so will probably be OK without, but they do make life so much easier, don't they?Many thanks in advance.Leighton

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 16, 2020, 09:45:43 pm
content: I think the 23 II service manual is very close.

author: retiredcaps
author_rank: Super Contributor
timestamp: August 17, 2020, 03:45:01 am
content: When you get the meter, come back and post the problem. We can help.A non Fluke resource that you might find helpful.http://mrmodemhead.com/

author: LateyMatey
author_rank: Newbie
timestamp: August 20, 2020, 07:17:57 am
content: Thanks for your replies guys.Just as an update. The meter has arrived, its actually a Fluke 75 series III. When it came, I checked it over with the supplied fused probes and nothing, but the meter powered on OK. Swapped the leads from another meter and it seemed to work fine so I took it into work yesterday and gave it a full calibration. Everything was inside specification apart from the 32 Meg range so a bargain meter for the bench.Thanks anyway

author: jgustavoam
author_rank: Regular Contributor
timestamp: June 01, 2025, 01:20:44 pm
content: Fluke 73 Series II - service manual. (oldest series)Manual Source = xdev
Fluke 741B & BE9005 Battery Eliminator - Page 1
Forum section: electronics / repair

author: Alvin Purple
author_rank: Newbie
timestamp: November 12, 2021, 05:15:28 pm
content: Hi,Does anyone know the polarity of the Fluke 741B or BE9005 Battery Eliminator - power connector? I think I've killed a Fluke 741B Documenting Process Calibrator by trying to power it with a generic 7.5 DC power supply with the polarity reversed. As you may know most electronics equipment with a barrel type power connector has polarity of inner +ve and outer -ve. I have a (sinking) feeling the Fluke 741B external power (BE9005 Battery Eliminator) is -ve inner and +ve outer on the power connector. Please confirm. If I'm correct then can I repair this 741B?Thanks!

author: Tj138waterboy
author_rank: Regular Contributor
timestamp: November 13, 2021, 12:55:48 am
content: I stumbled across 1 photo of the wall wart that showed center positive marking on the plastic. It seems that that info has been blurred out or erased from most photos I came across.

author: dew
author_rank: Contributor
timestamp: April 15, 2024, 04:14:22 pm
content: Port for BE9005 Battery Eliminator is center negative at least on Fluke 744. I guess BE9005 should be too. I've just tested my 744 with center positive voltage from a lab supply.It does not conduct in that polarity. At least, no current was shown on the supply down to mA. I haven't tested above 7.5 V though... 744 still works after this test.

author: mairo
author_rank: Unknown
timestamp: December 17, 2024, 11:24:35 pm
content: Also confirmed on 743B, center is negative, I repeat center is negative.Why Fluke is not specifying this!? It is not marked on the unit (even voltage is not given), not mentioned in the manual apart of only to use BE9005 Battery Eliminator, and its datasheet also does not show or mention about itInitially I tried with center positive with 7.5V and it did no work, but also did not get damaged. The reason I tried it with center positive is because after some search with no result I saw a third-party adapter in eBay that was advertised as center positive and apparently an alternative for Fluke's BE9005 Battery Eliminator
Fluke 741B Process Calibrator Firmware Issue  - Page 1
Forum section: electronics / repair

author: sprit
author_rank: Regular Contributor
timestamp: April 21, 2023, 04:05:03 pm
content: Hi everybody. Have a good day. I have a Fluke 741B Process Calibrator that is experiencing software failures. After trying to adjust the reset pin state, I finally managed to connect it to the computer via rs232. I am looking for software update for this model. i can't load 744 program in my 741B because it only has 2 sram while 744 has 4 (probably the problem is not enough memory). I need your help. Thank you very much everyone.Sincerely,Feng
Fluke 744 Display - Page 1
Forum section: electronics / repair

author: Tommy_T
author_rank: Newbie
timestamp: December 23, 2021, 12:14:55 am
content: Hi folksI recently got my hands on a Fluke 744 but the display Contrast isn't working correctly.It fades after a few seconds the device is still working.So im looking for the schematics to check if some voltagerails is breaking down.It makes no difference if i power the device from batteries or external power source.LC displays are not my special field so i hope for some clues from the forum.I also made a video of the behavior:https://youtu.be/-CaztCxyu7IPics:https://imgur.com/a/vczUywIThe lcd PCB gets driven from an Epson S1D13305F00B1The Display gets driven of 6 samsung s6b2086x01Thanks Thomas

author: byte
author_rank: Contributor
timestamp: December 24, 2021, 01:35:57 pm
content: You haven't mentioned whether you have probed anything yet. I would work backwards probing from the LC display until I find out where the drop in display voltage/current is coming from. Could be the driver ICs, could be a voltage regulator feeding the IC, or something else. I didn't look at the datasheets on these ICs, but one of the ICs/regulators may have thermal or overcurrent protection built-in. If so, then once you isolate the device you can check for downstream from it for unexpected low impedances and start probing back to the LCD. Assuming excessive current draw, it could be coming from anything such as an electrolytic cap that is aging or something as simple as a barely bridging solder joint and/or excessive flux that after enough time has started to cause excessive current leakage.I'm no expert with LC displays either, just my 2 cents.
Fluke 744 display - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: November 09, 2019, 10:01:59 am
content: hilooking for the commercial part number for fluke LCD Display and service manualpicture attachedthanks in advanceAnand

author: Black Phoenix
author_rank: Super Contributor
timestamp: November 09, 2019, 01:19:44 pm
content: Directly from Fluke's calibration manual - LCD MODULE, 240X200 GRAPH TRANSMISSIVE - 602430.https://dam-assets.fluke.com/s3fs-public/74x_____cmeng0200.pdfhttps://www.ebay.com/itm/for-multimeter-F-744-FLUKE744-FLUKE-744-LCD-screen/123686026086?hash=item1ccc42fb66:g:LLwAAOSw0dFchhuW

author: rvalente
author_rank: Frequent Contributor
timestamp: November 09, 2019, 03:32:57 pm
content: The polarizer film went bad, its a characteristic of some vintagem LCDs from 90s, just replace both (easily found online).Carefully disassemble the display, peel of the old polarizersClean the glue residue, try rubbing alcohol, then acetone and last gasolineMake sure the screen is totally residue free, no oils or dirtPlay with the film to find the best contrast angle. Use a scalpel to cut the film, not a scissor (they crack the film)That was my THS720P before:And after replacing the polarizer. You can see I missed cleaning the backlight diffuser.

author: hitecelec
author_rank: Regular Contributor
timestamp: November 11, 2019, 06:20:32 am
content: hithanks for all the hints. Will try out and let you know
Fluke 744 Process Calibrator Schematic - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: September 02, 2020, 01:01:59 am
content: Friends,I am looking for the schematic of the Fluke 744. If you have it, I would very much appreciate it if you could share it with me.I am also happy to pay for a copy. I am working on a repair video.Thanks!

author: rvalente
author_rank: Frequent Contributor
timestamp: September 02, 2020, 01:31:01 pm
content: I sure do not have your schematics, but I like your videos, keep it up!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: September 03, 2020, 03:06:30 am
content: Thanks!
Fluke 75 iii rotary switch cleaning and lubricating advice - Page 1
Forum section: electronics / repair

author: bborisov567
author_rank: Regular Contributor
timestamp: May 20, 2025, 10:48:08 am
content: Recently i bought a used Fluke 75 iii. I would like to service the rotary switch. What methods do you recommend for cleaning, especially the area on the bottom side of the switch. Also what lubricant should i use? Some place on the internet suggest using lithium grease. And lastly, does anybody know what is the life expectancy of these switches?

author: Paceguy
author_rank: Regular Contributor
timestamp: May 20, 2025, 11:01:46 am
content: On my 73III I used Deoxit D5 to clean off the oxidation, and followed that up by flushing it with IPA to remove any residue that could effect readings. I did not lub the switch. My meter worked well afterwards.

author: J-R
author_rank: Super Contributor
timestamp: May 22, 2025, 12:45:43 am
content: This has been debated a bit before. I'm of the opinion I'd rather clean and service a selector every decade or so rather than have to deal with contacts that are worn down permanently.So I would suggest some kind of electronics lubricant, such as CRC 2-26.I've also used a PTFE lubricant, such as Super-Lube (with Syncolon).Use tiny amounts, just enough to prevent further wear of the metal contacts.