The old crazy Tektronix TD 210 rotary encoder problem - solution - Page 1
Forum section: electronics / repair

author: Paulusthewoodgnome
author_rank: Newbie
timestamp: October 21, 2018, 10:58:26 pm
content: These scopes are often flogged off cheap due to their dicky rotary encoders and the annoying trait of timebase/voltage div. settings jumping around when trying to adjust them.Similar forums have suggested trying to source replacement encoders from sacrificial units bought cheap but then there's the hassle of completing the transplant without causing further problems.My old TDS 210 had a timebase encoder in this jumpy state so I ended up drilling two 2mm holes very carefully in the bottom edge of the encoder and opposite top edge using a pin vice and sharp 2mm bit. The holes went through to empty space (see pic) and attention was paid to ensure no swarf went in.I then jetted in plenty of contact cleaner and exercised the encoder for a minute or so before sending in some compressed air in each hole to make sure things had evaporated off.After this cleaning things are back to normal and I can reliably make my adjustments without relying on the lottery draw of turns that I was having to make before cleaning.

author: xrunner
author_rank: Super Contributor
timestamp: October 21, 2018, 11:06:31 pm
content: Interesting solution. What type of contact cleaner did you use?

author: Paulusthewoodgnome
author_rank: Newbie
timestamp: October 22, 2018, 12:05:48 am
content: Hi Xrunner, the contact cleaner is a WD-40 product - 3 in 1 contact cleaner. I should add that when drilling the holes, I only just allowed the drill bit to form the hole and kept it's intrusion into the inner workings to a minimum.I guess there's always a risk of doing damage to a component when drilling into it but the scope's behaviour was a risk to itself and I saved it from being kicked across the room in frustration so I felt like there was nothing to lose.

author: Specmaster
author_rank: Super Contributor
timestamp: October 22, 2018, 12:16:52 am
content: Quote from: Paulusthewoodgnome on October 21, 2018, 10:58:26 pmThanks for the handy tip.

author: xrunner
author_rank: Super Contributor
timestamp: October 22, 2018, 12:29:42 am
content: Quote from: Paulusthewoodgnome on October 21, 2018, 10:58:26 pmMan you need to post a lot more - you joined in 2014!

author: xavier60
author_rank: Super Contributor
timestamp: October 22, 2018, 01:53:25 am
content: I find that Pots, mechanical rotary encoders and tactile switches are less likely to fail again after a suitable lubricant is used.I have good results with synthetic PAO oil.It is commonly available as compressor oil.

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 22, 2018, 04:24:15 am
content: Deoxit fader could be good for this application.A bit of tape ove the holes could be good to keep dust out in the future too.

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 23, 2018, 07:56:58 am
content: Nice trick, I've used contact cleaner before on one of my Lecroy 9300's, that uses similar Bourns rotary encoders.In my case there was enough play in the axis to let the spray flow down it.A couple of side notes:Protect your eyes when spraying into small holes, I once sprayed into a small DC motor at the brush holes with contact cleaner, quie a proportion flew back at me and cleaned my eye. That was painful and stressful for several hoursOn cheaper rotary encoders and potentiometers as found in much (Wun Hung) Lo-Fi audio equipment where the grease just turns to stiff goo, white-spirit before contact cleaner works wonders to ease the rotation.

author: rf+tech
author_rank: Frequent Contributor
timestamp: October 23, 2018, 01:03:49 pm
content: A non-invasive technique that I use successfully, gets Deoxit into such places, by putting physics to good use.Preload a small amount of Deoxit into a syringe.Warm the component body to expand internal air.Using the syringe, apply a few drops of Deoxit to the shaft bushing.Deoxit will be observed to flow into the bushing/body, as internal air contracts.Place part in freezer for a few minutes to accelerate the process.Two or three cycles has proven sufficient.RF+ Tech

author: Specmaster
author_rank: Super Contributor
timestamp: October 23, 2018, 02:24:28 pm
content: Thats a real crafty and neat solution that leaves zero evidence behind that you've in there as well, neat.

author: nouserid
author_rank: Contributor
timestamp: April 25, 2020, 02:49:25 pm
content: I too have my TDS2014's encoders fixed with CRC contact cleaner (a no residue solvent). Instead of drilling a whole on the encoder body, I noticed that there is a tiny gap between encoder casing and PCB. Spraying directly to the gap with the supplied red nozzle/tubing drove the cleaning solvent into the internal contacts quite effectively. Be sure to clean the PCB before spraying so that dust won't get into the contacts along with the solvent.