[Test-Equipment] Tektronix T935A Scope - seized knobs

[Barry]

> I have a similar problem with the band indicator on 
> a -hp- 606A. This is a pointer hinged on a shaft and 
> operated by a cam and returned by a spring. When I got the 
> generator the pointer wouldn't move. I applied Liquid Wrench 
> to the end of the shaft and after several days it loosened 
> up. Now its sluggish again. The problem is that to get to it 
> for a proper cleaning requires removing the front panel. I 
> will eventually have to do this. The problem with Liquid 
> Wrench, WD-40, Deoxit, etc., is that they are not real 
> lubricants and are pretty volitile. While they may soften 
> old grease temporarily they don't really replace it with 
> anything and the grease will harden up again when the 
> solvent evaporates. Sometimes there is no easy way to do a 
> job and trying to save trouble just makes it harder.
> As far as the sticky pots go it depends on whether its 
> the shafts sticking in the journal or if its the wiper 
> sticking to the resistance element. If the shaft then 
> running a little very light silicon oil into it may fix it 
> permanently. If the wiper you need to open the pot and get 
> some cleaner into it. Sometimes a light grease like 
> Tuner-Lub will work on old pots but most were intended to 
> run dry.
> 
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickbu
> rk at ix.netcom.com 

Same problem with my 606A.  I disassembled some of the mechanisms (the entire job is a lot of disassembly and wasn't completely necessary), cleaned and lubed everything, and it started working again.  There are lubrication holes in the large bearings that help more than anything but the detents need their lubrication as well.

Barry - N4BUQ