True Blast II Problem

[EIS]

I have never had any luck adjusting that volume pot shown in a post above.  When I adjusted it on my Williams GG1, it was more like an on/off switch for the horn.  When I tried adjusting it on my Williams F3, I could only get the normal grade crossing sequence in the original pot position.  When I deviated from the original position, all I got was a very short beep.

Earl

[phillyreading]

From what I can tell, the volume switch only works on TB-2 before Bachmann, or the Williams only engines.
Seems like there is TB-2 second edition and now a third edition being offered only in the newest or top of the line WBB engines. Only the second edition TB-2 can be bought from Williams by Bachmann at this time.

The new Amtrak phase V engines have the newest TB-2 horn unit.

Lee F.

[Joe Satnik]

Dear All,

Sometimes simple bare "potentiometers" (aka "pots" or "volume controls" or "variable resistors") are held at a factory determined setting with some kind of glue or wax. 

If you break the wiper free by turning it with a screwdriver, it may lose contact with the conducting surface below because of the residual glue or wax around its original position.   

Left, Right and Center (wiper) terminals of a flattened out circular pot:

L----WWWWWWWWWW----R
         rg    ^  rg  rg         
                l
               C

rg = residual glue
WWW... = uniformly resistive surface

If you want to change the setting, you may have to clean off the glue. 

There are nicer pots available, but they are more expensive, and take up more room.   

If you were out of warranty I suppose you could mount a better pot (of the same, or nearly the same resistance value) off the board and run its three wires to the board...

Hope this helps.

Sincerely,

Joe Satnik

[EIS]

Joe,

Excellent explanation for why the pot was working more like an on/off switch.  I did not realize that the pots were glued to prevent rotation.

Again, thank you for your reply.

Earl