Gary Schafer wrote:
Check at the center tap of the mod driver transformer with your scope and
see if you see anything there. Could be a bad or missing bypass cap there.
It's brand new but I didn't have a 15mf so I used a 47mf.. ditto for C59A.
Check the jumpers on the plug in the back to be sure that the proper taps on
the mod transformer are selected.
All ok.
Check the clamp tube circuit. Could be holding the screen slightly low on
the 6146 and clipping the modulation peaks to the screen.
Screen voltage is 150 and the nom is 190.
However, R35, the Modulator Screen Voltage Adjustment resistor seems to
go to the clamp circuit and it is not at all clear what is going on
here. It seems to me that diddling with it changes the screen voltage
on the 6146.
So does diddling with the modulator current effect the 6146 screen
voltage or do I have a screen voltage problem?
Check modulator screen voltage.
It is the nominal 250V... but again, why is it nominal if that resistor
is there to diddle with the current?
js
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