Pentax 6x7 67 Metered prism meter

[NDP_2010]

A hail mary to see if anyone may have faced similar issues before I write off this metered prism.

Prism was working fine (needle moving to pretty much correct location) and then after about 6 months of not using (kept in dry environment, similar to how I've kept it for the last 7 years I've had the camera), suddenly the needle responds to max even with no light present.

After having a look inside I cant see anything obvious, the contacts around the chain mechanism and the ISO change dial all look good.
I am thinking, maybe there is a resistor or similar thing on the circuit board that just decided to die out of the blue, thus giving way too much current to the light meter?? (pic of board attached)

Has anyone ever faced such a problem and found a possible solution? Anything I could have missed? I am strongly leaning towards too hard to fix and will need to replace whole prism :'(

Thanks!

 

[campy51]

I would buy an electronic spray and spray everything on the circuit board especially the three circular items which look like potentiometers

 

[NDP_2010]

I would buy an electronic spray and spray everything on the circuit board especially the three circular items which look like potentiometers

Thanks, I will give that a go. If it works it will certainly be cheaper than replacing the whole thing =D

 

[Scott Micciche]

There is a brush resister in the front, attached to the bit that rides with the chain. I found my needle very jumpy until I cleaned it with some Deoxit5 and naptha. You have to remove a bit more on the front section, but it's worth it.