GE 810 oddness

[DaveWM]

http://www.youtube.com/watch?v=SxzEV...CVtyRrqXVtll-g


well its such a mess seems like a mod was done, but not sure if it was correct to the HV, fly does not seem orig nor does it match the riders.

today I cut the lead that feeds b+ to the horz osc plate and the screen of
the CRT and connected back to the boost (this is the way it is in the riders). I left the screen supply for the 6BG6 as is (3 27k resistors in P to the B+). It seems like the set has some changes but not all. The boost is about 450v vs the 370v from the B+. Before this change the HV was about 8kv, width was marginal, and screen brightness required max setting. The CRT bias voltages are correct, just a low G2 due to the use of B+ rather than boost.

anyway that single change (boost to horz osc thru the 82k plate load resistor) resulted in about 9.5kv hv and brighter screen. I figured the improvement in brightness due to the higher CRT G2 but was suprised by the higher HV. the grid drive shot up from -9v to about -13v (did not scope PP just looked at the DC reading with a DMM).

there are so many inconsistenties between the riders, sams and what was done to this set that its hard to tell what is correct.

I am tempted to just re wire the entire HV and Osc to match the later sams that has a fly that seems consistent with what is in there (secondary with 4 leads). figure a fly change was done at some time and maybe not all the fixes were put into play. the riders mentions a newer fly as a production change, but the work does not look very factory, maybe a replacement fly was done by a tech that did some short cuts.