Does anyone have recommendations for locking these pots in place after they are set? We have noticed they shift with vibration from shipping/handling and we are currently stuck with them unless we do a full board redesign (which is not in the cards right now).
Manufacturer: Bourns Inc.
Part Number: 3312J-1-103E
Description: TRIMMER 10K OHM 0.1W J LEAD TOP|
Link to part: 3312J-1-103E Bourns Inc. | Potentiometers, Variable Resistors | DigiKey
Hello,
Thank you for your inquiry.
I do not see anything in the manufacturer’s documentation that mention anything about keeping these locked in place.
At work the classic product we used in the 70s early 80s was Red Insulating Varnish (Glyptal)
Then we switched to Organic Products tamperproof lacquer so each tech could use a different color, but that company went under.
So now we use Dykem Cross Check Torque Seal
The old stuff
https://www.gcelectronics.com/product/10-9002-a
Thanks! Any suggestions on how to best apply? Looks like the Glyptal comes in a quart container, but the cross-check comes in a tube - can that be applied directly from the tube?
Also - have you run into a situation where you would want to remove it for investigation later? If so, do you know if either are removable?
From what I see of it, the cross check stuff would be something that can be used straight from the tube. I would not think that it would take much to lock the pot.
As for removal, I am not seeing that there is anything specific listed.
a suggestion I saw was to use a tool to help scrape the sealer off.
However if it is anything like the thread locker I had seen in some hard drives a firm grip on a tool and a steady turn of the knob can work.
Which is why it is important to not use too much when locking these.
The GC Electronics Red varnish (generic Glyptal) in a 2 oz. bottle for ~ $30USD, I think does 1000’s of trimpots.
IIRC there is a brush mounted in the cap. We used small cheap artists paint brushes to apply it more precisely.
We just apply from the tube for the torque seal types.
For any sealer we apply a tiny amount that overlaps the housing and wiper trying not to get it in the adjustment slot.
All the time, because our products usually are in service for 10 to 20 years so at least a 3rd of them come in for service and re-calibration at some point.
The sealer breaks off easily just by turning the adjustment slot. (use a tiny pick to get it out of the slot if needed)
I turn the adjust from end to end a few times to make sure the sealer has completely let go before making the final re-adjustment.
Found MG Chemicals version the old style product @ DigiKey
