MJLorton Solar Power and Electronic Measurement Equipment Forum

General Category => General Discussion => Topic started by: Mr Eastwood on December 04, 2013, 08:42:17 AM

Title: Bad Trimmer Pot
Post by: Mr Eastwood on December 04, 2013, 08:42:17 AM
The other day I was setting up one of my new controller boards; and part of that process involves turning the trimmers to their maximum anti-clockwise position;  once the board was powered up, this one particular trimmer which was used to trim the LCD contrast didn't seem to make any difference when adjusted; So I knew instantly the trimmer was at fault so I just replaced it with another and it worked perfectly.

The problem seemed to be that when I initially quickly adjusted it to it's maximum anti-clockwise position, the wheel gear cog must have gone too far, and then wouldn't re-engage.

I've never experienced this before but might be something to bear in mind.  Luckily the LCD contrast made the screen visible; but had it failed in the clock-wise direction of turn, the LCD would have been blank;  and I would have certainly had to fire-up the scope to find out what was going on.

(http://3.bp.blogspot.com/-tubZFX0m9GU/Up8rU-LRI_I/AAAAAAAABqE/9X_Br5pIaXk/s1600/DSC02925_small.png)

(http://1.bp.blogspot.com/-8gveQHnzTNA/Up8rYMI8VdI/AAAAAAAABqQ/l2rueYkcJAE/s1600/DSC02924_small.png)

(http://4.bp.blogspot.com/-Paf1kLcilj4/Up8rXlY3AVI/AAAAAAAABqU/IaFEuxfgrh4/s1600/DSC02923_small.png)
Title: Re: Bad Trimmer Pot
Post by: SeanB on December 04, 2013, 02:35:36 PM
Nice to know, I normally turn them until they click and stop there, as then you can turn it back and it will engage.
Title: Re: Bad Trimmer Pot
Post by: TechJunkie on December 06, 2013, 06:50:19 PM
I believe I remember having one do something like that many years ago. I think it re-engaged finally, and I was able to save it.