Range selector of Metrahit multimeter sticks. WHY? - Page 1
Forum section: electronics / testgear

author: Finderbinder
author_rank: Regular Contributor
timestamp: April 04, 2023, 08:53:50 am
content: It is very hard to turn range selector, but if you have already turn it, it becomes almost normal... until you leave it untouched for some time, then again it is very hard to turn it.Does anyone know the reason?

author: Fungus
author_rank: Super Contributor
timestamp: April 04, 2023, 09:12:57 am
content: You didn't take it apart to look?This is EEVBLOG...(maybe some old internal grease)

author: Finderbinder
author_rank: Regular Contributor
timestamp: April 04, 2023, 09:25:00 am
content: I had took it apart, there weren't any grease (although clean and no signs of wear... at least I didn't notice any). I thought that was the reason so I greased it. It was ok for that day but next day I noticed sticking got backI thought it would be a systematic problem with these range selectors, but google finds 0 problems like this

author: robert.rozee
author_rank: Frequent Contributor
timestamp: April 04, 2023, 12:41:10 pm
content: it could be that the range selector is intended to operate dry. try disassembling again and clean outevery traceof grease or other contaminant, then reassemble and test again over a couple of days. this used to be a problem with garage door openers - customers would grease the pole that the shuttle ran along and then complain that it kept sticking. we would send someone out (this was 20+ years ago) to clean all the grease off and the problem would go away. the shuttle was made out of a plastic that was designed to shed a fine dust that acted as the lubricant.cheers,rob :-)

author: Fungus
author_rank: Super Contributor
timestamp: April 04, 2023, 12:57:50 pm
content: Is the selector part of the PCB OK? Any burn marks? Clean the PCB with Isopropyl Alcohol.Leave the range selector separated from the PCB for a day. Is it the selector that sticks or the PCB contacts?

author: Finderbinder
author_rank: Regular Contributor
timestamp: April 04, 2023, 09:09:05 pm
content: Quote from: Fungus on April 04, 2023, 12:57:50 pmThe PCB under selector and all contacts look very nice, all inside is clean. I think if PCB part or metal contacts were sticking they would be torn off - so hard it is to turn.I'll try to clean grease out as robert.rozee suggests.It looks strange to me that selector turns almost normal when it is in use, but after some idle time it sticks hardly. Have no mind what that could be

author: mqsaharan
author_rank: Regular Contributor
timestamp: April 05, 2023, 06:33:42 am
content: May I suggest to take the pictures of the disassembled switch before and after cleaning the grease, especially the areas that have scuff marks. It will be more helpful for the members to give better suggestions.The area that is sticking could be the centre part of the rotating knob.It could be the bent spring, if it is using springs and metal balls.Or it could be worn out detent spring which is made out of plastic.

author: Finderbinder
author_rank: Regular Contributor
timestamp: April 05, 2023, 04:18:37 pm
content: Quote from: mqsaharan on April 05, 2023, 06:33:42 amThe reason was a sticky substance under the red switch. Really a very little amount of it. Alcohol was unable to dissolve it, but water did, so I assume maybe it was some kind of sugar... or something other.I also cleaned a grease I applied earlier, where springs with balls go (maybe it is not needed as it was dry before my intervention).Now switch turns as new, with clear steps, just tra-ta-ta-ta

author: Finderbinder
author_rank: Regular Contributor
timestamp: April 05, 2023, 04:20:09 pm
content: Some pictures of things of interest:

author: RobinLox
author_rank: Newbie
timestamp: June 12, 2023, 01:57:23 pm
content: Hey there, I have taken A LOT of those meters apart. These marks here are not normal.The springs or the 3mm steel balls used to click the selector in the specific positions might be deformed. Could you provide pictures of the springs?If they are not deformed, try a tiny bit of vaseline at exactly this surface and the edges on the sides. Only a very small amount.

author: Finderbinder
author_rank: Regular Contributor
timestamp: June 13, 2023, 08:06:22 am
content: Quote from: RobinLox on June 12, 2023, 01:57:23 pmThese marks left after incorrect assembly. The second attempt was successful