Repair Keithley 2100

[we]

Several Keithley 2100 showed start-up problems. It figured out, that the three 1000uF/16V electrolytic capacitors beside the transformer, brand "stone", failed. I replaced them with Kemet ESY108M016AH4AA and it works fine.

[alm]

So did replacing the cap fix them? No wonder a cap made out of stone fails 😁

[shakalnokturn]

Several Keithley 2100 showed start-up problems. It figured out, that some 1000uF/16V electrolytic capacitors, brand "stone", failed.

Thanks for the topic.
I have a "Keithley" 2100 that's working for now, would be interested in the replaced capacitor positions for the future, if you noted them.

[tooki]

Several Keithley 2100 showed start-up problems. It figured out, that the three 1000uF/16V electrolytic capacitors beside the transformer, brand "stone", failed. I replaced them with Kemet ESY108M016AH4AA and it works fine.

Honestly, I wonder whether the “stone” caps were original to begin with. I kinda doubt it. I think there’s a chance someone recapped the unit in the past, using cheap caps.

[shakalnokturn]

Hard to say... I'd have to peep in mine and check. The 2100 isn't really a Keithley anyway, I think it's a rebrand of the ARRAY M3500A so who knows how much they spent on electrolytics.

[Kleinstein]

Hard to say... I'd have to peep in mine and check. The 2100 isn't really a Keithley anyway, I think it's a rebrand of the ARRAY M3500A so who knows how much they spent on electrolytics.

The circuit is still very similar to the older Keithley 2000 to a large part. So much that the service manual and plan can help in a repair.

[alm]

It's interesting that the design is so similar if it's not a Keithley design. Did one of the Keithley designers move to Array? Or did Keithley give the design files to Array to design a successor?

[tooki]

It's interesting that the design is so similar if it's not a Keithley design. Did one of the Keithley designers move to Array? Or did Keithley give the design files to Array to design a successor?

I wouldn’t call it a “successor” since it didn’t replace the 2000, but it’s eminently possible that they gave them the 2000 design and said “make a cheaper version”.

[ee1993]

Thanks to this forum, I was able to repair my Keithley 2100.  Replaced the three Stone brand 1000uF 16V electrolytics, but it still failed.  Then checked the 460uF 35V in circuit and one was low (289uF).  Replaced it and now the meter works fine.  I probably should replace all the Stone caps but some are hard to get to.

Thanks again.