Here’s an interesting and detailed teardown and repair of a Keithley 2001 7.5 Digit multimeter that is positively dripping with detail. It’s also not every day that we get to see someone using x-ray imaging to evaluate the extent of PCB damage caused by failed electrolytic capacitors.
Sadly, this particular model is especially subject to that exact vintage electronics issue: electrolytic capacitor failure and leakage. These failures can lead to destroyed traces, and this particular unit had a number of them (in addition to a few destroyed diodes, just for good measure.) That’s where the x-ray machine comes in handy, because some of the damage is hidden inside the multi-layer PCBs.
[Shahriar], perhaps best known as [The Signal Path], narrates the entire process of fixing up the high-quality benchtop multimeter in a video, embedded below (or you can skip directly to the x-ray machine being broken out.) [Shahriar] was able to repair the device, thanks in part to it being in relatively good shape, and having the right tools available. Older electronics are not always so cooperative; the older a device is, the more likely one is to run into physical and logical standards that no longer exist.
Wish there was more shown of the repairs the x-ray identified, but otherwise a really well presented and informative overview of the repair, which it is always nice to see.
Shouldn’t the “MMU” in title be “DMM”? Or is it an acronym I don’t know yet?
I think you’re right. MMU is “memory management unit” which you find in PCs. I can’t imagine why a DMM would need one.
All of Keysight’s current lineup of benchtop DMMs run WinCE… er… Windows Embedded, so they’ve got an MMU somewhere in the box.
Yeah, but the MMU isn’t a discrete part (at last not for 20 years or so I think)
I have been asking myself the same..
Yes–I was disappointed because I wanted to see some fancy microscopic surgical repair on a vintage MMU chip like a Motorola 68851.
Fixed. Thanks.
But how long did he take to repair the xray machine?
10:30ish interesting quick comparison of the repaired instrument with the modern version of the same thing – I’d choose the old one!
I agree with first comment – more details on the xray machine and process and the actual repair would have been informative, but otherwise clearly shot and presented.
This is relevant: we must have 30 of these at work and it’s good to have not only a warning but also a path towards repair.
Start recapping now them before you need an x-ray machine!
Well, to be fair it is a Measure-Measure-Unit :)
2001 is now considered “vintage”?!
Well, I guess that really is over 20 years ago, and that’s actually a pretty decent lifetime for components like electrolytic capacitors.
But damn, way to make me feel old. LoL
Really neat to see there are others working to keep such equipment in working order, and I’m constantly fascinated by the inventive and evolving tools and methods of servicing them.
FWIW the Keithley 2000, the machine this was based on, was released in 1995. I don’t know quite when the 2001 was released but they’re still making them, so this could be anything from brand new to maybe 22 years old.
Alarmed by this article, I went into my workshop to check my beloved 2000 for any signs of leakage.
Mine seems to be from ~’99 and the electrolytics look fine.
I wonder what kind of X-Ray he used. Must have been film because baggage and food X-Ray wouldn’t have that resolution
That meter doesn’t look “vintage” to me. To me, vintage is one with an analog scale.