Keithley 190, 5 1/2 digit nixie tube multimeter

[maelli]

Got this beauty cheap from internet, lucky me.
All 74xx TTL, datecode 1973 and 1974.
Two board construction: digital on the top, analog on the bottom.
Five nixie tubes, extra neon bulbs for minux, oxerrange and first 1.
At first glance still within specs... 0.005% on DC volts.
And the manuals are still available, on
http://www.tek.com/manual/keithley-model-190-digital-multimeter-instruction-manual-rev-d

[Dr. Frank]

Just beautiful. 
Just love these old TTL bricks.. date code lets me remember my own first steps with such TTL graves.

Thanks for sharing

Frank

[Vgkid]

That is a neat old keithley. Thanks for tearing it apart.

[Gyro]

Now that's what a meter should look like inside! 

No eeproms, batteries, flash, f/w bugs, or multilayer boards. Easily maintainable with the full component level service manual. There's no reason why it shouldn't give nice, well aged, performance for years to come.

Shame they didn't make the 10V range Hi-Z though.


P.S. You might want to drop a link to it in this thread... https://www.eevblog.com/forum/reviews/lets-see-your-nixie-tube-equipment/

[bitseeker]

Added the link over there for ya.

[TiN]

Sweet box

[maelli]

after a few hours of operation: display shows random numbers...
repair was simple "thou shall check voltages": -15V rail had a huge 100Hz ripple.
Repair was simple, the culprits were the electrolytics, one was leaking current the other one had 5uF instead of 220uF.

43 years old, made in Hong Kong and so close to the heatsink dont go well together ;-)

[Paul Moir]

It's amazing how different this is from the same era Fluke 81xx with it's three digital ICs and two shovelfuls of discrete transistors to get 4 1/2 digits.

[bitseeker]

Yeah, exactly. That 190 is really nice.

[kj7e]

Nice!  I still have an HP 3440a I have owned since I was 9yo in the closet, with a bunch of plugins.