Fw: HX-20 HELP!!!!!

[talen]

Hi Sandy,

I happen to have a schematic for that one from the "old days".

I would say the smoked R76 is an indication, looks like that is a
dropping resistor in the plate of V9. I'd make sure V9 has 275V
on the plate, 100V on the screen and 1.5V on the cathode. Then
check the same points on V10 270V/135V/3.25V and V11
600V/200V/(cathode grounded).

If the screen voltages are low, check the bypass cap for leakge.
If the grid bias (relative to the cathode) is high check the coupling
capacitor to the previous stage for leakage. If there is no plate
voltage on V9 on some band positions, the associated coil is
probably open for that band. Also check to make sure C81 isn't
leaky to where it "cooked" R76....doesn't take much current at
1K and 275V to cook one.

I doubt that a resistor value change of 10%-20% is going to do
anything in those circuits...... Ref: R81, R82. The OA2 will still
provide 150V to the VFO (important for stability)..but measure it.

73s  Kees K5BCQ



----------
From: Sandy Gerli <angerli at HOME.COM>

I've discovered a smoked R76 which I replaced.
Also, R81 and R82, the two 7W resistors in the 150V LV line,  have
increased in value beyond 10% so I'm going to change them, but I
doubt that they're at the root of the problem.

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