No. 125 - HP 34401A 6.5digit Multimeter Repair - Part 2
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- Опубліковано 26 вер 2024
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In this 2nd video I continue the repair, and stick around to the end of the video.....there's a bit of a twist!
Part 1 here - • No. 124 - HP 34401A 6....
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![Electronic Circuitry Diagnosis And Fault Finding! [Repair]](http://i.ytimg.com/vi/LC7OjuYAOQE/mqdefault.jpg)
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Nice repair sequence.. reminds me of my work @ Airforce lab, ~ 1980, where I repaired a lot of Multavi B / IRU meters from Hartmann & Braun.
They had a 15A DC/AC current range. The big lamella shunt was very often burnt.
It was rumored, that those meters were used by the army comrades to "test" the batteries of their tanks.. under some load.😂
Maybe, they also wanted to get rid of those meters, as we often found a piece of paper inside, reading: "Please scrap it", but we always had enough spare sparts and a fat soldering iron for an easy repair.🤣
BEAUTIFUL repair. I would be very confused if i saw it in the wild, thinking it to be some kind of a factory bodge 😂. Glad you printed your logo & date on it.
NOTE to SELF: After burning one meter out, DON'T connect a 2nd meter till you find out why the 1st one burned out!
I can imagine his boss ".....you did what!!!!"
That goes for a lot of failures. I have made countless repairs to machines where a PCB burned, the in-house tech ordered a replacement PCB and immediately releases the magic smoke from THE NEW PCB. Usually due to fault elsewhere in machine, and/or due to REVERSING & mixing up wire-to-pcb connectors during board swap.
Normally
Interesting repair. Back in the 90s, we did repairs to a controller board that had a few blown bits. We sawed off the charred section, epoxied a bodge pcb matching cut out and bridged the traces across with copper foil. It kept the machine running until we got the replacement few weeks later.
if you want to save solvent fill your ultrasonic with water. Put your part in a small plastic bag and then put your solvent in the bag. Chuck the bag in the ultrasonic and you're good to go. Lets you do a few washes with clean solvent if you want too
That is a very interesting approach. I would love to see a side-by-side comparison. Perhaps get several boards nice and dirty with coffee, soda and/or flux, then clean using one or the other method, REMOVE passives and IC PACKAGES and inspect underneath.
Really great repair Ian!
There's a serial 34401A killer on the loose! 😱
Ian, nice idea. I'd be concerned about leaving all that carbonized black FR4 material, since you might get huge amounts of leakage from traces and relay pins that are still very close , especially at higher voltage/more humid months. My approach would be to cut the blacked burned area altogether with dremel and jump wire your patch PCB with few wires _instead_ of old damaged FR4.
Wonderful work Ian =D
Thank you Ianscott!
Such an interesting repair, great work!!
Hi,
Just found your channel and am very impressed with your thoroughness and attention to detail.
As a keen amateur I find your explanations easy to follow too.
I'm very much looking forward to binge watching all your videos.
Welcome aboard! My background is in training electronics technicians back in the day……I guess my videos hold a similar format!
Your the magic man... Nice job!
Hi Ian, nice work 👍 I see the distance adjusted, the height too, so the aluminum cover doesn't matter. 🤔 what is the probability of creating absolutely identical defects. I don't think it happened gradually, but he was comparing the same connected circuits 🤔 that makes me think - there were really only two 🤪.................. 😂
Nice day 🙂 Tom
Nice proper repair there.
Two units? Somebody had a really BAD day. Yikes.
Great the way you fix nearly everything good video
Thanks
Thanks Ian! Just waiting to receive my HP34401A which is used (in a working condition) but not calibrated. Do you have any video showing how to calibrate this unit using a PVDS?
Skived Teflon might work even better than Kapton tape.
Yes, I need to get a sheet.
That technician is fired! However, fired him right after he/she blew up the first unit.
looks like he either ran out of meters or found the fault in test method. 🙂
It seems to me that you are using a very little amount of IPA in the ultrasonic cleaner. All models I have worked with during my life needs a minimun level of water, otherwise the transducer and / or the PCB would be blown out
My large cleaner I would never dream of running it low, but these small, cheap, low power ones seem to be able to take it.
@@IanScottJohnstoncan you please point me the brand and model? Always good to see your videos, I've learned a lot.
Will you put the repaired units to use?
They are not mine. They will be returned to the owner and probably sold.
Nice one Ian ! Did you drop down a resistor size on the MK2 ?.....cheers.
Yes I did, but same 3W over the original 2W though.
:)@@IanScottJohnston
Cheese!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Squeak !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!@@fredflintstone1
Top notch work I like your mod so much I'm hoping my HP fails this way Cheers from So.Ca.USA 3rd House On the Left
A couple thousand volts at the inputs and your wish will be granted 😂
lol first… I just had to
LOL!......how old are you?....:)
second!
Lol
Don't you start!
@@IanScottJohnston what do you call a group of UA-camrs ? A Gaggle? A Flock? A Tubby? A TeleTubby?
ChatGPT says it's a Content Clan......
Fourth :-)
Second lol
Like Alex at technology connections say "with the magic of buying two.."
Awesome job 😃😃😃
Why did you use SMD resistors again? Through hole resistors could be mounted a cm above the board and can safely dissipate more heat without burning your nice new PCB.
Only if the meter gets back into the same hands as the guy who burnt out these two. Slim chance so no worries.