Rogers Junior control unit resistor values?

[jmedley]

I have a Rogers Junior amp with a separate control unit.
In the control unit quite a few of the resistors are more than 10% out of spec. and will be replaced,
However I have a problem with 2 resistors mounted on the back of the selector switch for the pick-up.
Looking at the attached pictures, the rotary "selector" switch is to the right of the valve holder.
The first image is of my own unit
The second image is of the same type of control unit that was shown in a post from Pamphonica
The 3rd image of the fron panel is also from Pamphonica
In the first image there are two identical resistors directly on the rotary switch.
Colours BROWN (could be purple) YELLOW, GREEN, YELLOW (rest of body)
I think they are previous replacements and read O/C on my Fluke 77
In Pamphonica's image these two resistors are
Colours :- GREEN, BLACK, BLUE, ?
Well that looks like 50M.ohm !!!!!
They are connected to switch position 1 (78rpm) and Pos.3 (DECCA LP)
Problem is what value should they be, I certainly have'nt seen any 50M.ohm resistors before
Please let me know what you think
Jim

[Edward Huggins]

These switched equalisation settings are quite accuracy dependant. Best to get the circuit and check?

[jmedley]

Thanks Edward,
I haven't found a circuit yet, if there is one out there I would be grateful to have a copy.

[Pamphonica]

Jim,
I just checked inside both of my Rogers preamps of this type. The brown-front (older?) one has 2x 50Mohm (green/black/blue) and the cream-front one has 2x 10Mohm (brown/black/blue). But the latter has the resistors wired slightly differently. The layout you have is the same as my brown-front one. So possibly very high value grid-leaks. You might try 4.7Mohm as yours might be yellow/violet/green in body/tip/spot format.
I hope this helps
Jeremy

[jmedley]

Thanks Jeremy