AVO "Two Panel" Valve Tester has arrived.

[Technomaniac]

Hi, All. I bought an AVO two panel (I believe it was their first attempt, so there was no model number allocated) valve tester on eBay from someone in the Netherlands, and it arrived at my place in Australia without any apparent damage a few days ago.
The one panel has most of the controls and meter, and the other has all of the valve sockets and the ten wheel thumbwheel switch which routes the pins of the sockets to the appropriate circuits for the various tests. The switch is made from bakelite and the rotors are accurately positioned by strong leaf springs, the ends of which rest in indents in the bakelite knobs. to ensure accurate location of the switch contacts.
I find that the bakelite thumbwheels offer quite a resistance to rotation, and feel that the assembly may need to be disassembled, cleaned and lubricated.
The reason for posting is to see if anyone has 'been there and done that' and can offer any advice or warnings, regarding stripping, cleaning and lubricating the switch.. I have not yet been inside the main box for a look, I'm hoping that all of the important bits are present, I have a schematic the test data and instructions thanks to the forum. Hopefully I will be able to fit an earthed mains cord before I get to plug it in, assuming tranny leakage is acceptable.

 

[Bluejets]

Most of these old units have open switches so I'd be inclined to stay away from any "stripping down" and simply give each a good dose of crc or wd40 or similar, work back and forth a couple of times and soak up the rubbish which drips out with an old rag.

Any disassembly could be permanent.

 

[Technomaniac]

Thanks, Bluejets. I'm a bit worried about CRC/WD40/Inox type products on bakelite, there's something in the back of my brain putting up a red flag. Maybe I'll do some tests - Shellite/X55/K55 might work for cleaning, and then the Inox carefully applied to the contacts.
"Rudge" had a posting about one of these in October 2007, I wonder if he learned anything that might be useful to me - he was down as a "Guest" so might be hard to track down. I have had situations in the past where I sprayed things onto bakelite and it changed the colour to something much lighter - it may make it less oily and increase the friction between the rotating bits. If the Shellite dissolves or flushes out the oil that might be what I'm trying to avoid.......Proceed with caution. I think.......

 

[Bluejets]

I'm a bit worried about CRC/WD40/Inox type products on bakelite,

Think you'll find those products or kero are actually used to polish bakelite.
It's not like some plastics that might turn up their heels and melt.

 

[Technomaniac]

Yes, I've used CRC or Kero to polish bakelite, but I've come back a day or two later and found the finish had dulled.

 

[Bluejets]

View attachment 49969 View attachment 49968
Yes, I've used CRC or Kero to polish bakelite, but I've come back a day or two later and found the finish had dulled.

In that case polish with Brasso....but that's not the point here.
You were asking about cleaning the switch.

 

[Technomaniac]

which is visible as knobs and housing, all bakelite, outside of the case in a prominent position.

 

[Bluejets]

You asked how to clean the switch contacts and I told you.
If you want to ignore it or argue the point, fine, do it your own way.
Why ask in the first place.