| Author |
Message |
    
R_a_feldman
Tinkerer
Username: R_a_feldman
Post Number: 2
Registered: 11-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 19, 2008 - 11:36 am: | 
|
Does anyone know voltage the selenium cell in a Weston Master light meter is rated for (any or all models from I through V)? I have a Master II that is a bit eratic and a Master V where the photo cell is dead. I would like to try replacing the cell, but need some idea of what voltage to look for. |
M_currie
Tinkerer
Username: M_currie
Post Number: 118
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 20, 2008 - 09:45 am: |
|
I am away from home for the week. I have a Master IV and V, and might be able to test one of them next week, if I remember. Would volts to full scale be appropriate? |
R_a_feldman
Tinkerer
Username: R_a_feldman
Post Number: 3
Registered: 11-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 21, 2008 - 12:08 pm: |
|
Yes, measuring the voltage needed to bring the needle to the top of the scale would be fine.
Thanks. |
M_currie
Tinkerer
Username: M_currie
Post Number: 123
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 31, 2008 - 09:07 am: |
|
I'm home, but kind of busy, will try to test a Weston soon. I haven't forgotten (yet), but please nag me if you don't hear back in a week or so! |
M_currie
Tinkerer
Username: M_currie
Post Number: 124
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, April 06, 2008 - 09:50 pm: |
|
Ok, here it is to the best of my ability. I opened up a Master IV which has been reading a little low but still has life in it. I gained access to the connections for the meter by removing the back plate and the hinged door over the photocell. The body of the meter is negative, and the zero adjust tab of the movement is positive. I found a light source that put the meter to full scale, then measured the voltage with that source hitting the cell. It came to about 150 millivolts. I cannot guarantee that reading to the last millivolt, but it was pretty close.
I did not try to find a variable voltage source and actually run the meter with it, because the connections here are pretty delicate, but I hope this helps.
OK, now I am going to try to put my Master IV back together. |
