Update: I revisted the tantalum capacitors and changed them out for a pair of 10uF 50V MLCC caps. The issue with tantalums especially on the output of regulators etc is the large surge current that goes into them on power up (irrespective of voltage), and which can cause 'short outs'. I feel more comfortable now getting rid of the tantalums. Here's a pic of a pair of the MLCC's, so 20uF/50V per replacement: www.ianjohnston.com/images/stories/IanJ/K2001/2001MLCC.png
I have to replace a bunch of older tantalum (mainly bypass and bulk filter) in some 40 year gear, and aluminum polymer looks like a good replacement candidate.
Nice to find a youtube channel where the technician actually knows what he's talking about. Been watching lots of your videos lately, very informative and I feel I can learn some tips and tricks from you. looking forward to your next video.
I think you were being too modest regarding your "luck" finding the cause of the 401 errors. I am reminded of the famous sporting adage: "the more I practice, the luckier I get". You have a bucket-load of experience combined with attention to detail. Great videos.
Good work again, Ian. It does show that you need to keep your eyes and ears open for every little detail and know what is normal and what is not. You were very unlucky/lucky with the failed Tantalum.
Doubt it will help even with the 35V tants I fitted, it's not so much a voltage issue.....tants don't like inrush currents. The later version of the analogue board (this is an early one) doesn't have tants at all. But I thought I would give the 35v ones a go.......till I sort out some other caps to fit. I've become a dab hand at stripping out the analogue board in a matter of seconds...:-)
Update: I revisted the tantalum capacitors and changed them out for a pair of 10uF 50V MLCC caps. The issue with tantalums especially on the output of regulators etc is the large surge current that goes into them on power up (irrespective of voltage), and which if can cause 'short outs'. Here's a pic of a pair of the MLCC's: www.ianjohnston.com/images/stories/IanJ/K2001/2001MLCC.png
Nice job, thanks for spreading the Keithley love. And Ian needs a calibrator now ;) /voltnut_police mode on* You ran thru adjustment procedure, not calibration procedure ;) /mode off*
In our Automotive designs, it's strictly forbidden to connect Tantalums directly to power input ("battery"), or to regulator output. Instead, you need to limit the charging current by a resistor in series. Nowadays, it's recommended to avoid tantalums. That's sometimes mentioned in the capacitor datasheet. I think, that's on the order of a few Ohms. It's a known fact, that tantalums can ignite by inrush currents, due to their technology and low ESR. Therefore, either replace them by high capacity MLCCs, or put that limiting resistor in series. That's a design flaw by KEITHLEY, but other manufacturers did not incorporate a Robust Design. HP6632B power supply is another example.
I think this is the earlier version of the analogue board, my other K2001 has a later version and those caps aren't present. They probably removed them after having a spate of faulty units returned. Give the hardy 7815 reg it's due though, it survived well being shorted at the output for 10+ mins and being cooked almost to destruction......but I didn't re-use it, it deserved to retire.
Update: I revisted the tantalum capacitors and changed them out for a pair of 10uF 50V MLCC caps. The issue with tantalums especially on the output of regulators etc is the large surge current that goes into them on power up (irrespective of voltage), and which if can cause 'short outs'. Here's a pic of a pair of the MLCC's: www.ianjohnston.com/images/stories/IanJ/K2001/2001MLCC.png
Fascinating, Ian. - great video as always. These tantalums throwing tantrums is not uncommon, I have the impression. Are these things always so naughty? Odd.
You get this surge of secondary voltages, have seen 60Vdc on that +BS supply for a second. I dithered with ripping it all out and fixing it at 240VAC like my other 2001 but thought I’d give this one a go. It’s a shame they went with this design decision, it’s hurt a LOT of 2001 and 2002’s (8.5 digit version).
Great video as always! I can't get my head around that auto mains voltage switching business; specifically, why have it in the first place?? That's a lot of design effort and extra components for something that feels like it's just a gimmick. How often is anyone going to want to change the mains input voltage?!
Update: I revisted the tantalum capacitors and changed them out for a pair of 10uF 50V MLCC caps. The issue with tantalums especially on the output of regulators etc is the large surge current that goes into them on power up (irrespective of voltage), and which can cause 'short outs'. I feel more comfortable now getting rid of the tantalums.
Here's a pic of a pair of the MLCC's, so 20uF/50V per replacement:
www.ianjohnston.com/images/stories/IanJ/K2001/2001MLCC.png
Not many reasons to choose tantalum capacitors these days
I have to replace a bunch of older tantalum (mainly bypass and bulk filter) in some 40 year gear, and aluminum polymer looks like a good replacement candidate.
As a hobbyist it's fascinating seeing these high end industrial instruments. Great video.
Nice to find a youtube channel where the technician actually knows what he's talking about. Been watching lots of your videos lately, very informative and I feel I can learn some tips and tricks from you. looking forward to your next video.
Thanks!
I think you were being too modest regarding your "luck" finding the cause of the 401 errors. I am reminded of the famous sporting adage: "the more I practice, the luckier I get". You have a bucket-load of experience combined with attention to detail. Great videos.
Thankyou!
Nice work, lovely to see another Keithley all fixed.
Good work again, Ian. It does show that you need to keep your eyes and ears open for every little detail and know what is normal and what is not. You were very unlucky/lucky with the failed Tantalum.
Yes, it will take some time until I am comfortable with leaving the workshop with it still switched on....LOL!
Excellent! Keithley's are some of the best old equipment out there
Many thanks Ian for another professionally produced repair video, much appriciated.👍
Thanks for another great video Ian. I refer to your videos when I am doing my own repairs.
Keep 'em comin'! 😊👍
16:09 those traces look like they have seen some leaky capacitor goo probably ate away the solder at the pins
The whole board has that "eaten/worn away soldermask" look about it.
Hmm great, another good video follow up repair🙂
Awesome, another one bites the dust
Nice fix, catch and fix! Great video as usual.
@24:15 I would avoid using 25V tantalum on a 15V rail, seen to many failures of 25V tants on 15V rails, 35V is the way to go.
Doubt it will help even with the 35V tants I fitted, it's not so much a voltage issue.....tants don't like inrush currents.
The later version of the analogue board (this is an early one) doesn't have tants at all.
But I thought I would give the 35v ones a go.......till I sort out some other caps to fit. I've become a dab hand at stripping out the analogue board in a matter of seconds...:-)
Update: I revisted the tantalum capacitors and changed them out for a pair of 10uF 50V MLCC caps. The issue with tantalums especially on the output of regulators etc is the large surge current that goes into them on power up (irrespective of voltage), and which if can cause 'short outs'. Here's a pic of a pair of the MLCC's:
www.ianjohnston.com/images/stories/IanJ/K2001/2001MLCC.png
Nice job, thanks for spreading the Keithley love. And Ian needs a calibrator now ;) /voltnut_police mode on* You ran thru adjustment procedure, not calibration procedure ;) /mode off*
Ha ha, I told you I wouldn’t be able to get used to ‘adjustments’…..LOL
Yeah, a calibrator would be nice!
Brilliant job Ian =D Loved that series!
In our Automotive designs, it's strictly forbidden to connect Tantalums directly to power input ("battery"), or to regulator output.
Instead, you need to limit the charging current by a resistor in series.
Nowadays, it's recommended to avoid tantalums.
That's sometimes mentioned in the capacitor datasheet. I think, that's on the order of a few Ohms.
It's a known fact, that tantalums can ignite by inrush currents, due to their technology and low ESR.
Therefore, either replace them by high capacity MLCCs, or put that limiting resistor in series.
That's a design flaw by KEITHLEY, but other manufacturers did not incorporate a Robust Design.
HP6632B power supply is another example.
I think this is the earlier version of the analogue board, my other K2001 has a later version and those caps aren't present. They probably removed them after having a spate of faulty units returned. Give the hardy 7815 reg it's due though, it survived well being shorted at the output for 10+ mins and being cooked almost to destruction......but I didn't re-use it, it deserved to retire.
Update: I revisted the tantalum capacitors and changed them out for a pair of 10uF 50V MLCC caps. The issue with tantalums especially on the output of regulators etc is the large surge current that goes into them on power up (irrespective of voltage), and which if can cause 'short outs'. Here's a pic of a pair of the MLCC's:
www.ianjohnston.com/images/stories/IanJ/K2001/2001MLCC.png
Fascinating, Ian. - great video as always. These tantalums throwing tantrums is not uncommon, I have the impression. Are these things always so naughty? Odd.
nice one Ian...as always
Not sure I like the auto ac input selection. How does it handle brown outs etc?
You get this surge of secondary voltages, have seen 60Vdc on that +BS supply for a second.
I dithered with ripping it all out and fixing it at 240VAC like my other 2001 but thought I’d give this one a go. It’s a shame they went with this design decision, it’s hurt a LOT of 2001 and 2002’s (8.5 digit version).
Great video as always!
I can't get my head around that auto mains voltage switching business; specifically, why have it in the first place??
That's a lot of design effort and extra components for something that feels like it's just a gimmick.
How often is anyone going to want to change the mains input voltage?!
Maybe rear panel 120/240 switches were horrendously expensive back in the day......LOL!
Awesome !
Nice video. but in general you are right..2001 is not stable/good multimeter..personally i don't like it much also..2010 is much much stable..
I wonder if it's a good candidate for an ADR1399...?