Tektronix TDS320 Division Adjustments Not Working

[darthhideous]

Hi all,

I just got a Tektronix TDS320 from my local university and everything seems to work, including the autoset feature, except both the vertical and horizontal division adjustments don't do anything. Has anyone run into this issue or know how to fix it? Both knobs turn freely, they just don't seem to be doing anything. I've done a factory reset of the scope.

Any help or suggestions appreciated.

Thanks!

[snoopy]

When I bought a TDS784 a few of the controls such as the horizontal shift were very sketchy. After disassembly of the front panel control board I managed to squirt some contact cleaner in a very small gap between the shaft and the rotary control and it managed to seep in and clean the control which fixed the problems on a couple of the controls

[james_s]

I fixed a similar problem on a TDS340 that turned out to be contamination on the PCB that was shorting one of the buttons, the encoders and buttons are multiplexed so a fault with one can cause others to not work. Check for SMT electrolytic capacitors on the front panel board, I know the TDS400's have them, I don't recall whether the 300 series do or not. Those are known to leak and make a mess. Fortunately these are easy to take apart, just don't lose any of the buttons when you remove the front panel bezel. The knobs pull straight out and will come out with the shaft. The front panel PCB snaps on to the back and I think has a couple screws. This is a good time to give the panel and buttons a good scrub, it will look like new.