No.092 - Keithley 2001 7.5 digit Multimeter Repair - Part 6 

Ian, brilliant work, and a very nice instrument at the end of all your effort. You would not bore us with the calibration run through!! Would be very interesting to see how the accuracy fares given the number of issues, donor board etc. Thank you for sharing your work.

I wish one day I would be as careful, thorough, and patient as you Ian!

Best repair I've ever seen, totally epic and really interesting. Thanks for sharing this... and yes, I echo the other comments in saying the calibration video would be awesome...lets see this one through from soup to nuts....

I knew you would get there, congrats on a job well done, look forward to the calibration video

Great series. I enjoiyed it as much you did I think. Please complete the series with the calibration.

I really enjoyed this masterclass video series. Thanks fot putting in the effort

Ian, brilliant series of this fix, I’ve only just found your channel, and wow, you went all out on the repairs, keep up the great work mate, your friend from Australia… 🤙🏼🇦🇺

Awesome series and end result Ian, especially as I was able to binge watch all of it in the one sitting!

Discovered your channel after seeing your chat with Dave on The Amp Hour podcast. Love this series! What an epic repair! I'm really surprised at how poorly designed that 110/220V selection feature is on the preregulator circuit. For a meter this expensive you'd think they would include a bare minimum of protection circuitry to cut power in the case that the relay fails and puts 220V on the 110V primary winding. So many ICs could have been saved from untimely death!

Nice job Ian. Enjoyed the series.

well done! what a great repair series and exellent fault finding reasoned approach all along the way. very glad to see after TSP's video which made this thing look a lot more daunting. it has added to the the body of expertise in fixing these keithleys. much appreciated

Thanks for all the work getting this up & running , and thanks to whoever donated the other unit ;)

Put a note on the board to say why parts are missing. Love the videos thanks for sharing

Ian, very well done! Like to see how you test and calibrate this unit.

great to see the readings are not too far off even with no cal.

That was some heavy duty repair, congrats!!!

Absolutely brilliant job Ian. I too love the series of videos to 1 repair. Thanks for sharing.

Outstanding work, Ian! It is always interesting to see the thought process of others when troubleshooting and repairing a piece of gear. As others have said, I would like to see the calibration process especially in light of Xdev's comment on the complexity of calibrating this model! Regards, David.

Great job Ian. This was an awesome series to follow 👍

This episode takes me back to memory lane. I don't miss those 2001 :) Sounds like fan need replacement. You left us hanging with no self-test result. That's when real repair starts ;-).

A brilliant series!!! I very much enjoyed and looked forward to each part =D And a fantastic end result for all of the hard work!

Well done Ian, brilliant work. Well worth the toil.

Smashing stuff ! Dont think the calibration would be boring but what a result !...cheers.

Wow, what a journey! Top work there diagnosing all those faults!

For someone without any of these high end equipments, seeing what the calibration process is, even abbreviated, would be very interesting to me.

Excellent job Ian, I have enjoyed watching all parts. I would also like to see a video on the calibration, as several others have requested, please.

Great result. You must be a happy man.

What a repair!!! Thank you.

Well done sir! That was a fun ride!

cool repair vid,thumbs up!

Hello, absolutely first-class demonstration of the repair of such a complex device, I watched the whole series, I played some passages several times. I am always very happy when the repair is successful and congratulations on getting a new multimeter. Unfortunately, I cannot fulfill your request to send the defective equipment for repair, I have collected quite a lot in my life, but my workshop was stolen and I lost everything. I start from the beginning and this is not a cheap affair in the Czech Republic. I wish you a lot of success and look forward to more interesting videos, I don't know about the others, but I am improving in the field of electronics in this way. T.H. Edisson wishes everyone a beautiful day

You did it, realy great and top work.

I would love to see the calibration process. Thanks for these videos, they are great.

Hi Ian, I wonder how many Keithley Technicians watched your video. Maybe you will get a new flash unit in the post 😁 Cheers Dave.

Excellent repair 🤓👍

A great series Ian, very much enjoyed it. Thank you! I hope you'll get your wish for more Titanic repair projects requiring Herculean efforts ;-)

Love the videos. I always learn something new to add to my knowledge base. Regarding the AC power supply, seems to me that circuit was designed to take out the entire board! I certainly hope Keithley is better than that, but I now have my doubts about their ethics.

at last the wait is over a great series for this repair, shame the original was so knackered though 🙂

Wow, that was a great repair job. And now we know the secrets how these meter can fail. Quite catastrophic how the pre-regulator/voltage selector circuit can end up destroying every chip on the board.

Good work.

epic repair

Great job!!

Hello Ian. It looks good now. I would suggest to let it stay on for about week(so it get baked to correct temperature for some time and to remove some humidity from board..that will take some time) and after that start re-calibration. It does looks good. I wasn't able to do full calibration(too many things..)..but i was able do that calibration with two voltage sources and two resistors..That should be easy to do for you as well. Nice video.

I abandoned the side swipe DIP sockets a long time ago, except if they were on board already when I received the item. Then I just pulled and re-plugged the chip. But when designing the board or installing sockets myself, I changed to the 4-side contact types. Much more expensive, but never any problem. Well, not quite true, once I had to troubleshoot a solder bridge under the socket. That solder job was not mine, though. The fact is the fatter metal on the underside can increase the chance of excessive solder forming a bridge despite of board solder mask.

Please show calibration! Love the videos, thanks.

Would really like to see the calibration and self test process! 😀

Great repair, you succeeded the impossible. Btw. did you notice the read DC value from voltage source was *changing* while you varied the AC supply. Like something is still not regulated or exactly right

Do I have new competition for the mammoth repair series genre ? LOL

I new those 4 DVM bench meters would come in handy - You enjoyed the repair wow you enjoy punishment LOL. I know I guy that has two Solarton 7075s that dont work?

👏👏👏👏👏👏👏👏👏👏👏👏👏👏👏👏 Great, Ian!

Great efforts Ian….thorough as always in working through all those faults. Can you tell me what was the part number for the power mosfet in the the pre-regulator….?

I for one would've loved to see it being calibrated.

Do you already have a video out on calibrating one of these Keithley meters? Cheers,

Excellent repair journey, thanks for sharing! Looking forward to seeing the calibration vid. One question: why did the (uncalibrated) reading vary so much when you slowly changed the line voltage? Is the 230V line voltage directly controlling the unregulated +/-8V supply?

I had no doubt you would get it working, just how many Parts 6,7,8,9 ... would it take. *_Cheers_*

Shame about the original board, because one of the other vids with the finding and replacing of lots of failed ICs was pretty interesting.

So how do you calibrate this so that you have 6.5 digit accuracy? The needed calibrator costs more than a used working meter. Awesome repair in any case.

Ian did you remove the auto voltage select circuit to prevent the unit self destructing in the future? Brilliant repair and very entertaining.

Epic repair, not many would try with such so much damage with a massive voltage overload which takes out fixed regulators, well done. Any idea what the root cause of the over-voltage was? i.e what failed in the voltage selection circuit or theories?

and PLEASE show us the calibration

Please show us the calibration...

Dude , how are your lucky charms?

lesson learned...don't buy one of these LOL, what a nightmare