Your experience with the specs of used old Keithley staff

[balage]

Hi,

It is usual that the Ebay seller says that the instrument is "sold as is" mainly because they cannot test the specs. (Or are aware of the fault, but would like you to have hopes.) I have bought a 614 electrometer that is working within the factory specifications. The other staff I have bought, a 237 SMU is performing very bad, it is totally out of specs. Both were sold as is.

I am interested in your experience with the good old used Keithley DMMs, SMUs, electrometers. Have you run into instruments that are perfect? Of course you can find calibrated ones. Also why it can happen that one instrument can be still within the specs and another is not? I would say, that some of them was run over its absolute maximum ratings causing degradation.

Regards,

[MiDi]

A single experience does not give any indication how good or bad the units perform.
At least the components suffer from age, hours of operation and the operating conditions as temperature and humidity - worst parts are mainly electrolytics.
Recommendation is to change at least them to maintain the units for next decade(s).
A good information source are the several repair threads for specific units.
For electrometers there seems also good chance to have leaky reed relays - they are not cheap (for example Keithley 617 thread).

[Conrad Hoffman]

I avoid the older Keithley stuff in the brown block-type cases. Some of the meters had bad thermal design on the power supply and ran terribly hot. IMO, it's more first-generation stuff and later is better.

[balage]

So it depends rather on luck but not on a deterministic thing.

For electrometers there seems also good chance to have leaky reed relays - they are not cheap (for example Keithley 617 thread).

Yes, I have read about the reed relays that they can cause headache. Maybe that is why the reed relay (the shielded ones) matrix cards are always sold fast.

[balage]

I avoid the older Keithley stuff in the brown block-type cases. Some of the meters had bad thermal design on the power supply and ran terribly hot. IMO, it's more first-generation stuff and later is better.

I am sure they are still popular because they have almost the same specifications as the new ones, but has a good price for hobbists. It can be seen that the brown ones are the cheapests, then the grey ones are coming with the same brick case, it is the second generation I guess.

[Fred27]

I'm a bit short sighted, so I find their specs don't really help me at all. They tend not to be to happy about me taking them either.

[rastro]

I would say in general the older keithley electrometers that I have purchased like the 617 arrive unstable at the lowest picoamp setting.  They generally functional at the higher ranges - so if you're NOT looking at femtoamps it will probably be usable.  As noted in other threads the range relays degrade causing leakage currents if it isn't the dual input JFET.  Also shipping dosen't do them any favors since they may see large temperature/humidly swings.  I suspect that this can settle into the PCB/relays.  I had one unstable K617 I had set aside for several months (waiting for troubleshooting) and when I went back it showed significant improvements.  I've had about 5 K617's and can't say any would pass specification at the lowest amp setting upon arrival - two got pretty close.  I imagine the 614 may have similar concerns.

The 19X and 48X series are pretty good.  Most the ones I've encountered will meet specifications even if they first need a repair.  Most failures I've had on these are cleaning the switches and occasionally replacing one of the range setting JFETS.

rastro

[TiN]

Old Keithley stuff is like old exotic cars. Depends if they were cared well, or sat in the rain for 30 years. Mileage may way, but if brought back to life and maintained they deliver nice results. 
I love my Keithley things, but I most of my gear is from 90's+. From older KI stuff only have 182-M nanovoltmeter and Keithley 262 dividers (which are irreplaceable). 

[LapTop006]

It is usual that the Ebay seller says that the instrument is "sold as is" mainly because they cannot test the specs. (Or are aware of the fault, but would like you to have hopes.)

The general way I check is just to see if they sell other test equipment. If not then it's worth taking a chance, if they do it's highly likely BER.

[Gyro]

I'm a bit short sighted, so I find their specs don't really help me at all. They tend not to be to happy about me taking them either.

Especially the old leathery skinned ones! 

[HighVoltage]

I have a few older (brown case) Keithley and instruments and they either come in good working conditions and within specs or you can bring them back in to specs by repairing them.

The newer (White) gear is much better but most often ten fold in price.
All used Keithley gear has gotten unreasonable expensive over the last 3 years.

[rastro]

I haven't found the "brown shoe box" series of equipment problematic.  Even the K617's mentioned before seem functionally reliable.  It's just K617's at the most sensitive amps range they are really finicky - I doesn't take much to impact stability at that level. 

I've also have/had a couple K220's and K230's along with a K196 that have all performed well.  The cases are not pretty - but I do like LED displays which are easy to view and maintainable (unlike LCD's).

I also agree with HighVoltage that the prices have gone up on used Keithley over the last 3 years.

[VintageNut]

1. Meeting specs - The lowest current force/measure ranges drift the most. If the instrument in question has not been calibrated in years, most likely the lowest force/measure range(s) are out of spec.  This happens with the newest Keithley gear. If it has not been calibrated in 10 years, the lowest force/measure ranges will be out of spec.

2. In need of repair - Every piece of electronic gear will eventually need to be repaired. Capacitors fail from age and/or temperature abuse.  Active components fail from operator abuse. Capacitor failures can lead to downstream circuitry failure. This happens in audio equipment, computer equipment, etc. 

I own many old Keithley boxes. Most of them are functional. I sent my model 238 for calibration this year. It arrived at the cal lab out of calibration. It was able to be calibrated and meet spec.

My model 237 died after using it for a few months. It will go under repair when I have time for it. It should be able to be fully restored to original condition. If I needed it, repair would be a priority. I do not need it, so repair will happen when I have time.

I have qty2 of model 147 and they work wonderfully. My model 260 and model 261 both work great. The nanovolt source required replacing the filter capacitors. All of these nanovolt and nanoamp boxes are 40+ years old.

My advice is not be frustrated with the gear. Make a plan to be successful with your gear and work the plan. If you have not read the blogs of TiN's repair work, you should. He is the gold standard for bringing dead test gear to life.

[james_s]

I have an old Keithley DMM with a nixie tube display, I was surprised once I got a voltage reference to find that it is still bang on, it has probably not been calibrated in 30 years or more.

[jpb]

I'm a bit short sighted, so I find their specs don't really help me at all. They tend not to be to happy about me taking them either.

Especially the old leathery skinned ones! 

When I read the title ("old Keithley staff") I too had visions of slightly grumpy tech experts of considerable age!

[balage]

My advice is not be frustrated with the gear. Make a plan to be successful with your gear and work the plan. If you have not read the blogs of TiN's repair work, you should. He is the gold standard for bringing dead test gear to life.

I read often, it is the gold standard, yes. I have also seen Marco Reps' video on upgrading a 236 SMU to a 237 one with making a new high voltage converter PCB.

But I am doing something really wrong. I have a nice 237 with a faulty high voltage converter. Others can upgrade their instruments while I am failing repairing mine...

[balage]

I'm a bit short sighted, so I find their specs don't really help me at all. They tend not to be to happy about me taking them either.

Especially the old leathery skinned ones! 

When I read the title ("old Keithley staff") I too had visions of slightly grumpy tech experts of considerable age!

Okay, I have finally got the joke!!  Sorry, the title has another meaning

Here is a leathery skinned one, though: http://kuzyatech.com/vintage-keithley-130a-teardown

[jpb]

I'm a bit short sighted, so I find their specs don't really help me at all. They tend not to be to happy about me taking them either.

Especially the old leathery skinned ones! 

When I read the title ("old Keithley staff") I too had visions of slightly grumpy tech experts of considerable age!

Okay, I have finally got the joke!!  Sorry, the title has another meaning

Here is a leathery skinned one, though: http://kuzyatech.com/vintage-keithley-130a-teardown

Your English is much better than my Hungarian, and "staff" is very close to "stuff" so I feel a bit guilty highlighting what was a very minor slip but it just happened to paint an amusing picture (Keithley staff = people who work for Keithley). These typos happen easily when both words are in the dictionary so spelling checkers don't highlight the difference. One I remember in a post a few years ago was "lamb" instead of "lamp" - again it was obvious what the post was about but it was fun imagining it applied to a small woolly sheep.
We English have a slightly strange sense of humour, such as illustrated by Monty Python where one of the sketches involves a trial of people who had deliberately provided completely wrong translations for a Hungarian Phrase Book.

[Gyro]

I'm a bit short sighted, so I find their specs don't really help me at all. They tend not to be to happy about me taking them either.

Especially the old leathery skinned ones! 

When I read the title ("old Keithley staff") I too had visions of slightly grumpy tech experts of considerable age!

Okay, I have finally got the joke!!  Sorry, the title has another meaning

Here is a leathery skinned one, though: http://kuzyatech.com/vintage-keithley-130a-teardown

Hopefully you got the whole joke, specs are short for spectacles  (eye glasses). Your title was a perfect storm! 

[BigMark]

A single experience does not give any indication how good or bad the units perform.
At least the components suffer from age, hours of operation and the operating conditions as temperature and humidity - worst parts are mainly electrolytics.
Recommendation is to change at least them to maintain the units for next decade(s).
A good information source are the several repair threads for specific units.
For electrometers there seems also good chance to have leaky reed relays - they are not cheap (for example Keithley 617 thread).

If your prepared to invest the time and money, then the old Keithleys can perform as good as any modern metering. I bought faulty Keithley 617 for around $150 and invested another $100 on parts. I now have a meter which gives good measurements and still cheaper than buying a partly tested Keithley instrument from of these rip off second hand instrument houses.

[coppercone2]

old keithley greybeards are nothing to be paid lightly??

[james_s]

It's remarkable that word play jokes like that are ever picked up on by someone who is not a native speaker of the language used. I'm sure a joke like that in any language other than English would have gone right over my head no matter how long I looked at it.

A former boss of mine was from Germany, for the most part she spoke excellent English but every now and then something came out quite funny and we had a good laugh.

[bitseeker]

I have a bunch of old Keithley gear. Like HP or other aging equipment, they sometimes need attention. Otherwise, they work great. I really like the big alphanumeric LEDs from the Keithley brown era. I concur that all of that stuff has really gone up the past few years. So has the HP 34401A.

[Smokey]

Brown Box Collection:
196
199 x 2
175 x 2
197 x 2
617 (newest addition)

White Box Collection:
2700
2308
2304
7001

Only thing that doesn't work is the ohms range on the 196 for some reason.

[aronake]

Not many instruments have specifications for calibration intervals longer than 2 years. So no specifications to be inside or outside

Generally I am quite impressed how well instruments keep over years of not being calibrated.

Having some capabilities to be able to do some verification and calibration when buying old gear very helpful. And its quite fun! Some signals needed for calibration can be a bit tricky though, but may be for a range that is less used and less critical.