Replacement switches for Keithley 197 - Page 1
Forum section: electronics / repair

author: giosif
author_rank: Frequent Contributor
timestamp: January 29, 2022, 11:49:27 pm
content: Hi,I am trying to restore a Keithley 197 bench meter whose "gang switches" (is that the right name for them?) have suffered quite a bit of abuse: all but 3 switches have had their shaft broken.They all snapped in the same location (indicated with red arrows in the first picture attached).I tried gluing a couple of these back together, but the glued joint didn't hold and easily snapped again.Would anyone have any suggestions for replacing these switches or maybe just the shafts?Thanks!

author: inse
author_rank: Super Contributor
timestamp: January 30, 2022, 06:39:37 am
content: This type of switch has also been very common in audio equipment.Maybe there is a chance to scavenge the shafts from comparable parts.These switching arrays usually have been configured for the application with a combination of common release and single switches.Have you been able to identify the manufacturer?

author: lowimpedance
author_rank: Super Contributor
timestamp: January 30, 2022, 11:11:00 am
content: What about 3D printing ?, do a design in one of the free CAD software's and send to a 3D printing company etc.Otherwise keep a look out for other similar vintage Keithley meters with these push buttons.Fluke gear of this vintage also used this style of push button.

author: giosif
author_rank: Frequent Contributor
timestamp: January 31, 2022, 06:59:32 pm
content: Thank you both for your response!Quote from: inse on January 30, 2022, 06:39:37 amThat's what I was thinking as well, initially.But I suspect I'm not using the correct term for this type of switches (thus my question in the OP), as web searches return everything but what I'm looking for (e.g. regular light switches you mount on the wall).Quote from: inse on January 30, 2022, 06:39:37 amNo sign of a manufacturer marking, but maybe that's because the bottom part of the switches has been potted with some red resin (probably by Keithley).Quote from: lowimpedance on January 30, 2022, 11:11:00 am3D printing has crossed my mind, but I eventually dropped that idea since I find it time consuming and/or possibly expensive and/or not feasible (e.g. usually, the 3D printed items I've seen are rather rough or "wavy").Probably hunting for a parts donor device is the most practical approach.In the meantime, I wanted to make sure the meter is otherwise functional or at least not broken at some fundamental level (e.g. dead voltage reference, dead LCD, etc.), so I soldered jumpers in place of the switches and at least DCV with auto-ranging works and is pretty accurate.

author: free_electron
author_rank: Super Contributor
timestamp: January 31, 2022, 07:59:51 pm
content: those were made by itt cannon. probably long obsolete now

author: tooki
author_rank: Super Contributor
timestamp: January 31, 2022, 08:26:35 pm
content: ITT's switch division was spun off as C&K Switches 15 years ago, and they continue to sell multigang pushbutton switches (the F series). Maybe C&K can help somehow?

author: lowimpedance
author_rank: Super Contributor
timestamp: February 01, 2022, 01:53:31 am
content: Quote from: giosif on January 31, 2022, 06:59:32 pmHad a memory 'spark'Search for "Isostat Push Button"

author: tooki
author_rank: Super Contributor
timestamp: February 01, 2022, 10:28:24 am
content: Quote from: lowimpedance on February 01, 2022, 01:53:31 amIt looks like Isostat was a Polish manufacturer/brand? The chances of Polish-made switches being used by Keithley asymptotically approaches zero. But they do print right on them “licensed”, and it wouldn’t surprise me if they’d licensed it from whatever American manufacturer made the switches Keithley used. For sure, the shaft shape seems to be a perfect match (based on images alone).As an aside, I think someone needs to make a guide of old electronics brands and product lines, specifically with what happened to them as companies merged and divested and sold product lines. And of the second-source agreements. Until this thread, I had no idea that C&K switches was the former ITT switch division, for example.

author: lowimpedance
author_rank: Super Contributor
timestamp: February 01, 2022, 11:53:41 am
content: Most likely there would have been multiple sources of this switch design, but information is rather hard to come by.My suggested search name comes from a box of bits that I have with the Isostat name on it, and a shaft from these bits does indeed visually match the photo of the Keithley switch shaft above. The material quality is excellent and in my opinion would work in the Keithley.

author: SpecialK
author_rank: Regular Contributor
timestamp: February 02, 2022, 01:33:08 am
content: In audio equipment they are often described as 4pdt. Not sure if this is the Keithley arrangement.

author: shakalnokturn
author_rank: Super Contributor
timestamp: February 02, 2022, 02:05:03 am
content: Also "Dialastat".

author: giosif
author_rank: Frequent Contributor
timestamp: February 03, 2022, 08:54:30 pm
content: Thank you all for your input!I found some Dialastat switches on eBay, but they are probably also used in some audio equipment, as they are not cheap.I'll keep looking, but I think my best chance is to find another dead Keithley meter or other equipment from that era.

author: SpecialK
author_rank: Regular Contributor
timestamp: February 04, 2022, 03:59:53 am
content: If it were me, I think I'd replace all ten with a pair of these:https://www.amazon.ca/uxcell%C2%AE-Interlock-Button-Switch-Piano/dp/B07PBMLKQP/ref=sr_1_36?crid=2TXELZ1L5IYYU&keywords=4pdt&qid=1643946912&sprefix=4pdt%2Caps%2C202&sr=8-36