Quote:
Originally Posted by zeno
Check the cathodes, they are probably low. Typical K volts on
a console is 125-175 ish depending on design & CRT.
They are run off a 200V supply from a FBT winding. Typ a fusable
resistor, rectifier then a 5-10 mfd filter. Sometimes the supply is
stacked on the main 130V B+ so the filter goes there instead of GND.
To find the 200V each jug has a hefty driver transistor. The collector
goes through a 2-3 watt resistor 18 K ohm plus. That is hooked to the
200V. Look at almost any SS color schematic & it will be near the same set up.
As for the G-2 the low end sounds to high. Typ 800V boost on the high
end & the low end 200-300 V. The wiper goes to G-2.
BTW if you can post some nudies for the group of the chassis.
73 Zeno 
LFOD ! |
Cathodes are actually high, at the top end of that range. About 175. The +200V terminal (marked on board) on the neck board is dead on 200V.
I will look into the bottom end G2 voltages being too high, by tracing out that part of the circuit.
Last night I tried the projector again - things have gone from bad, to worse - the picture now is totally losing contrast and brightness. It's an extremely dim, washed out and blurry picture, but if you turn up brightness the raster itself is quite bright.
I managed to track down a paper copy of the service manual, from
www.stereomanuals.com - once it gets to me, I will be in a much better position to troubleshoot.
I'm starting to wonder if this is an AGC issue, but there's only an RF AGC control on this set, and I'm using the composite video input.
Will take some photos tonight for the forum - it's a very neat set, nice change from the usual.
I have to say that last night, the "audience" of the home theater was starting to lose patience
