Marconi moisture meter tf 933 b

[Rap94]

My Marconi tf 933b will not zero, the dial is unresponsive on the scale after initially zooming from one side to the other. Any ideas as to what the problem may be ?

 

[davidroberts30]

@Lodekka

 

[Brisel]

I had that trouble with mine. @Lodekka is the main person who will tell you why. Normally a power circuit failure. Is it mains run or battery powered?

 

[Rap94]

It’s fitted with a mains unit

 

[ewald]

My Marconi does this if it is damp - try putting it in the airing cupboard for a day. Works fine if dry, has been doing this for ten years or so, have never bothered to find out why. (Battery powered 933b)