No.089 - Keithley 2001 7.5 digit Multimeter Repair - Part 3
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- เผยแพร่เมื่อ 6 เม.ย. 2022
- This is Part 3 of the repair of my Keithley 2001 7.5 digit Multimeter. Picked up quite cheap I was hoping for an in-depth repair.....and it certainly hasn't disappointed so far!
In this video I work on the Display Board, the aim to get it up and running with the main digital board.
Part 1:
• No.086 - Keithley 2001...
Part 2:
• No.087 - Keithley 2001...
Part 3:
• No.089 - Keithley 2001...
Part 4:
• No.090 - Keithley 2001...
Part 5:
• No.091 - Keithley 2001...
Part 6:
• No.092 - Keithley 2001...
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'horrendous repair' as mentioned in the video title clearly was an understatement. The damage is incredible. The only thing not damaged perhaps is some flatcable. Good thing you enjoy a (horrendous) challenge. Very impressive work - and what a nice donation of that viewer. Looking forward to the next rescue episode of this instrument.
This has got to be the hardest repair I've ever seen!
Big thumbs up to the viewer who donated the other keithly!!!
Very generous viewer, excellent progress as a result.
Your pain has been our gain. It's been very interesting to follow. As I stated before - when you get a short on the VCC line it's never very easy and this project has not proved to be an exception. With multiple component failure it seems that everything on the 5v line has failed. I can't wait for the next episode.
Wow, so many faulty ICs! I thought that Master System was bad lol! As always, looking forward to the next part =D
Wow ! what a result, super kind viewer and it was great when that display sprang into life great series...cheers
I was expecting a trilogy, and your delivering ore... nice, I am about 99.99% sure you will crack this one too, waiting for next epesode :)
Incredible damage to repair, but a great video learning experience. Thanks for the great videos.
Only 5V regulators that need extra capacitance are the LDO versions, the regular ones, that need 3V across them to operate, are perfectly fine running with no output capacitance at all, like the original LM7805, and are stable. But yes unknown ones could be a LDO version with nothing other than a tiny bit in the datasheet about input output differential being 1V, which means they have a PNP pass device, or a small note about ground pin current being higher at full load as against no load, as the PNP base current has to go somewhere. The NPN versions simply get it from the input side.
In some of my designs I include an SCR clamp in case of overvoltage, if something happens it can definitely save a lot of ICs.
I'd guess those SN75160's and every other IC are also dead if they share that same supply rail. I think I'll add some additional protection to future designs if there are expensive parts used! Are you able to backup the firmware from the display MCU with the Dataman? Did you approach Keithley to see if they can supply spares?
I haven't backed up the display board firmware, not sure I want to go to the trouble of removing it just incase I damage it, and knowing my luck it would be locked anyways!
The GPIB buffers are available via Ebay new old stock, I bought some to repair a 3458A a few years ago, 75160, 161 & 162, still available to buy now.
I haven't tried contacting Tektronix (Keithley), but interestingly I did contact Tekmos about getting the firmware for their IO controller or replacement but they said it was proprietary to Tektronix so no luck.
Do you maybe want to add a crowbar circuit to the 5V rail? After all it seems like the fault may well occur again.
You're my favorite repair channel.
is it Sunday yet?
Nice repair! BTW the Keithley 7001 have the same VFD and processor, they tend to be cheaper than a 2001
I await Part 4 I hope all ends up okay Ian🙂
Nice to see another impressively competent repair of a 2001. I tried my luck on one some years ago but got stuck at the broken VFD inverter brick ERG E705-E905VF which is not in stock anymore. May I ask if you still need the one from your donor device?😊
First view LOL! Nice job mate!!
In the last power up at 16:40 the GPIB error didn't seem to get displayed, was that expected? Wonderful series, love the detail and explanations!
Is the GPIB address lost not related to the EEPROM memory, just saying that it has lost the stored value rather than any connection fault? Potentially disables GPIB until a valid address is configured?
More than likely thinking about it......and why I can't connect to my network, i.e. there is a null or corrupt GPIB address configured currently. GPIB can wait until I get the DMM up and running.
In one of the videos in this series you were checking for shorts on the board and mentioned that you showed how to do that in one of your videos. Which one would that be? I'd like to learn how to do that properly.
Video Blog 035 - Locating a PCB short.
I've desoldered the MC68HC705C8A from my 7001 just to realize that I don't have the right programmer/reader :( Do you have a reader Ian?
Also, the VFD inverter brick seems to be identical aswell.
I need one of those donated for parts .
Strange that if you're unit is more recent, that it has trough hole memory chip and the other has more SMD.... You would expect that a more recent model has more SMD parts.....
I think back then, you really had a choice in relatively equal proportions for the use of TH or SMD. Neither was termed "old school" back then.
Pcb rev dates:-
Donated digital board = 1990
My original = 1992
you stil have the GPIB bus drivers that might be bad.
I think it's pretty much guaranteed - absolute max in the datasheet is 5.5V, same as all the other parts that died
Major Dog
Wow, so many faulty ICs! I thought that Master System was bad lol! As always, looking forward to the next part =D