TSP

[@brainslay3r]

You could attempt a firmware update over the serial port, as long as the unit is still going into the bootloader. www.fluke.com/en-us/support/software-downloads/fluke-744-final-release-firmware-upgrade . The update wizard extracts a .bin firmware image for the main application into your windows temp directory, along with the "segload32.exe" flashing utility, if you run segload from the command line it looks like there are some diagnostic options that could be helpful.

[@Chriva]

This is even better than my idea. Let's help and bump this comment

[@video99couk]

Absolutely worth posting this video. Not everything can be fixed, or not always straight away. I used to worry about posting failures but the journey is sometimes just as important as the destination.

[@electronicengineer]

The journey is always as important as the destination, in my opinion. Fred

[@video99couk]

@@electronicengineer I've just had a bit of journey to somewhere but not where I wanted to be, myself: kzbin.info/www/bejne/jX68ZKaNmqiYfJI

[@jimomertz]

It’s not a failure until you give up!

[@helamzampier3575]

And thank you very much, because without your video I would never have achieved this repair.

[@redtails]

A 6ghz oscilloscope to troubleshoot this handheld device. Hats off.

[@MIsam-fv9kb]

High-quality content as usual

[@largepimping]

Shahriar, thank you for the morale-boosting video... if YOU fail once in a while, it makes me feel better about the stacks (yes, plural) of stuff in my house that I was never able to fix!

[@electronicengineer]

Keep filling your brain and revisit each one of the items in your stacks. Persistence is a powerful tool. Fred

[@colin7406]

It's so fun watching you blast through the troubleshooting process

[@christianmiller3345]

I had a similar issue with a 744 where the screen would flash and the relay would click I tracked it down to the LCD ribbon cable had broken conductors where the blue bonded support ended the ribbon was folded back on itself due to the side port board. I trimmed the cable back and processed it reinstalled into the connector for the win. Your issue looks to be more than that. Good luck.

[@Switchxxi]

I guess you checked the voltage of the lithium battery or the output of IC U114. From what I see in the diagram, this voltage is used as a pull-up for the chip select signals from both the RTC and the RAM (R109, R110). Maybe in the 744 they used the same circuit and if the voltage is low it may not activate the ICs. That is if U114 does not switch from vbat to vcc. Anyway, if you can't repair it, it's a very interesting video. I'm looking at the schematic and I find the voltage / resistance generation part interesting. Thanks for sharing.

[@TeslaTales59]

I would ask Pooch his opinion. Cats will know the best course to take. Great video as usual. After an event like that get a cold beer.

[@SeanBZA]

Possible that the battery backed memory is corrupt, and that simply removing the battery and shorting out the SRAM power for a few minutes to get the cells back to a power on state might get the CPU to run the system setup again, as likely then any magic bits it has set are going to be wrong, thus allowing it to do a cold start. Probably worth seeing if you can connect via JTAG first and read out the SRAM contents first, so you have a record of the calibration constants to put back in afterwards, or you will have to send it in for cal as well.

[@Thesignalpath]

I tried that too. But no luck.

[@-yeme-]

thanks for posting even though you couldn't fix it. its always nice to see the patient revived but its the process we're really interested in anyway, so still plenty of value here

[@helamzampier3575]

Friends, I was on a 741B and had the same symptoms. I simply noticed that the RTC had pin 12 glued to pin 11. After re-soldering pin 12 in the correct track, it started working again.

[@dalmolima8862]

Dear Dr. Shahriar, I feel bad for you. Sometimes we do all right and best we can and still loose it, nothing wrong, it is just life. If I may suggest, an desperate attempt would be brushing the board with IPA. Sometimes the solder flux + dirt over long time create a "low impedance" between track of very low current disrupting the way it works. Thank you for all those excellent video. May the force be with you.

[@DannyBokma]

Thanks for posting this although there is no full repair. A few times I was successful with the repair of these "old" architectures by replacing the RAM chips ( if they can be found at all ).

[@MiracleMAX]

Thanks Mate for posting this video. You have successfully shown us how to diagnose at this point in time. Hopefully someone can help you out with the firmware. I also used to worry about posting videos of components that I wasn't able to repair due to my personal limitations at the time or customer request. Now, with a little more confidence and experience under my belt, I can more often take the advice of Thomas Edison who is quoted as saying ' In fact, I have a video to put up soon with a multimeter I couldn't repair as it has a failed COB. Thanks again for your videos, skills and hard work. MiracleMAX

[@Scuba_Bro]

He’s getting closer to 100k!!! 👍

[@ttkoh123]

I think the single flick backlight gave a important hint. It must be a protection or power supply protection fault since there are active signal being send to the LCD screen module. I would firstly troubleshoot the screen since it would provide any further visual fault indication onto the screen once it is repaired. The TFT driver IC would give further measurement points, hopefully maybe ST7789 or ST7735?

[@Chriva]

if it's a 6833x etc based processor (ie CPU32) it has a interface called BDM. I have some diy code running on a stm32f103 capable of interfacing them.

[@Chriva]

I should've looked closer on your schematic. 306 is not a cpu32 but a ec000 based processor. (Same family but less capable more or less) I have absolutely no experience with their debug port but I suspect it's not bdm. Sorry for the confusion

[@malgailany]

Have you tried providing the 1 Hz from a signal generator to see if you can turn the unit off? Nice video, thanks.

[@gwyllymsuter4551]

Perhaps reaching out to Fluke may help? Given your popularity perhaps it will work. Wonderfully informative, as usual.

[@BruceNitroxpro]

Gwyllym Suter , I was thinking exactly the same way. Perhaps they need a GOOD kick in the brains to revive their line.

[@NikiBretschneider]

I am not sure if this is firmware issue, it could be SRAM issue, especially if the SRAM is battery backed up. This often leads to state similar to firmware issue on m68k systems, but in fact is not. If the SRAM is battery backed up, then remove the CRxx battery, give it time to lost its content (15 minutes should be enough) and try to turn it on again and check voltage on all SRAM chips.

[@TheDefpom]

What about trying to provide your own 1Hz and IRQ signals to see if you can at least get it to come alive ? Maybe check all the data lines in case one of the lines isn't working, did you check for shorted caps yet?

[@worroSfOretsevraH]

That R&S scope tho.

[@heri4284]

Where do you look for schematics?

[@simontay4851]

22:38 To get the firmware how about buying/borrowing another working fluke 744, unsoldering the flash chip, reading it in a TL866 programmer then reflashing the firmware back onto this non-working unit. Then re-sell the other working fluke 744. Maybe someone who has a working fluke 744 will kindly read the flash for you and send you the file.

[@thefatmoop]

16:00 is agilent now re-badging lambda power supplies? They're nice but the sure have loud fans.

[@verihendrayawan]

You have video tutorial for fluke 754?

[@MegaVolt_ex]

Can you share the schematic?

[@hellelectronics3792]

I have a Fluke 744 the same, which does not turn on. Can you help me with the service manual?,,,please!

[@foxtrot1724]

I bought a replacement battery and I can’t get it to go. The old one works but doesn’t hold a change long… any ideas?

[@bfx8185]

Finally you also failed ;) But thx to share this video. One hint from my site : try to check pull-up resistors around flash memories if there is separate memory for boot loader and firmware open pull-up on FW flash could cause similar problem when CPU is stuck in boot loading.

[@DustanWebb]

This is probably a longshot but I have a 744 also. It seems to be doing the exact same thing as yours was. I tried the firmware but it never could connect...I was using the battery to power it (battery is good) then I swapped to a bench power supply it tried to power on but blinked and shut down. I then upped the voltage to 9volt and it powered on and boots. It still says battery low unless I increase the voltage to 9.25volt. Do you know what I should be looking for that may be dragging down the voltage? Edit: I am now able to power it thru the battery eliminator at 7.5v and it is fine with it. So it just doesnt like the battery voltage unless its 9v or higher.

[@MsGale.]

I have a fluke 741 it only powers on when the ac adapter is plugged in outlet. I bought a new battery for it and a new fluke charger to charge the battery and it still seems to not work, when I put the battery in it beeps and the battery saver annunciator icon is on in the top right corner and then it turn off so I keep the battery in and connect the adapter and it comes on....it only works when it's plugged in... Not just on the battery... Any suggestions on what to do? I'm thinking the annunciator?

[@supriono7964]

Hallo sir , ask batarai elimintaor center negativ or positv

[@electronic7979]

👍

[@cncdavenz]

Don't let it beat you :-). It needs a CAT scan.

[@PaulHigginbothamSr]

I never saw you inspect all the different voltages out of the power board. Since it is a 90's board and the power button and brightness button react differently, a thorough cleaning with alcohol or even naphtha might rejuvenate the button press board. I feel the Motorola chip and the special glue chip made by Fluke are still functioning correctly and the turn on process has not yet reached the 68k chip. Probably a fault in the firmware and maybe the non-volatile memory or battery has a fault since it has a Motorola chip it must have firmware.

[@jeremiahweger5332]

Any chance you can tell me what that internal battery is? Mine is dead and needs replaced

[@Thesignalpath]

Do a quick search on Amazon or eBay for the model number of the instrument and you’ll find it. It is a NiMH battery. Keep in mind that the instrument cannot charge the battery!

[@jeremiahweger5332]

@The Signal Path no the circuit board battery. Its a cr2032 now i got my 741b tore apart. Thanks anyways

[@Thesignalpath]

Oh I see. :)

[@aqib2000]

Who can dump the firmware for us?

[@devil2005iscool]

Hopefully you can find a working 744 and then reflow the chips over and see if it works to confirm the dead chip. you could also desolder the chip and to hopefully dump the existing firmware from it dependant if the chip is listed in the library of your universal programmer? since you have older schematics; they probably used the same manufactuer for you to deduce which chip it is if it is a proprietary IC. I like your X-ray :p what is the model ?

[@ciropena3289]

Buen día, no parece buena práctica... Al autor del video gracias por el mismo...

[@dipakbhalodia7155]

Frome name of website youre circuit diagram download give me pleaz

[@jakp8777]

I kinda think this may be a Philips product and not fluke designed

[@singhpk99]

desolder flash copy flash from working scope. replace flash

[@paulpaulzadeh6172]

can we have some Chinese wooden chopsticks , I get nervous when you come with sharp nail to keithley display , they cost penny compare to keithley

[@Pieh0]

1st :)

[@jrf2112swbellnet]

2nd

[@giacomo1191]

@@jrf2112swbellnet 11