De Vere 504 Uneven Light Output

[Mr Man]

Hi, I have a De Vere 504 with dicromat head, older version cream and brown with a single lamp, that has uneven light output. The light level varies by about 1 stop from the right hand nearest corner to the left hand farthest corner when it is set to a 11” x 14” print from a 5” x 4” neg (it's not my developing because it was measured with no neg in the carrier). The enlarger is all nice and level and square. The lens is a El Nikkor 150mm 5.6 but I don’t think this is the problem as I have tried it in different orientations and the problem remains in the same place. I've cleaned the mixing box and even tried adding new reflective materials but no change. I have tried fiddling with the lamp, as my experiences would lead me to think this was the most likely cause with this type of problem, but it is difficult to adjust a lamp that appears to have no facility for adjustment while its on, and I nearly set light to a towel, and this appeared to make no visible improvement to the problem other than adjusting the overall light output. The only other thing that gives me cause for concern is that the filters appear to encroach on the light path in their off state but there appears to be no way to move them any further out of the light path as they are at the stop point of the control mechanism, they will push a couple of mm further back but they are still in the light path a little and this appears t make no change to the output light level. I don't want to start dissembling the filter unit as I did that once before to another head and it is still in pieces. I have used the enlarger for some time but only on 35mm and 6 x 7 so it's not relay been a problem as I wasn't using that part of the image area but now I want to do some 5” x 4” and it's a real problem. I would gratefully receive any advice or information, any one else ever had this problem?

 

[Mr Man]

Cheers Greg,

I was thinking I may try rebuilding the diffusion chamber tomorrow with new reflective material but I hadn't thought of actualy removing the panel.