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Dragging out an old nemisis-Philco 66 cathedral-SUCCESS
#5

Good catch, morzh. My old man eyes failed to notice the tiny little m in front of the V. I ran major resistances, and R44=254.5, R27+R29=140K, both coils gave good numbers for primaries and secondaries, choke is 2400, field coil=1200, output transformer is good, and both IFs have good windings. Used a dim bulb and variac to bring the set up with no tubes in, and the bulb stayed dark. While under load, the bulb has a dim glow going on. All heaters run about 2.3v.
voltages:

80:filaments=4v, plates=300 different and lower.
42: plate=205, screen=209, grid=-6.4, cathode=0
6A7:plate=213, screen=76, anode grid=136, control grid=1.9 (positive voltage) and grid cap= +1.9
78: plate=212, screen=75, suppressor and cathode (pins 4 & 5 are connected)=1.6, grid=1.6 grid cap= -82mv
75: triode plate=148, diode plate=-96mv, cathode=.1, grid=0 grid cap= -.5

Still gets buzzing where it did before. I need to get the heater voltage higher and the 6A7 grid in the negative, right? I still wonder about the grounding for several components, so I will look there (especially the ones that have their grounded sides connected together on the daughterboard (are all 66s done that way?). I also have the service note components i this set (the 20K resistor off the bandswitch, the 70 ohm resistor in the oscillator coil.

That's it for tonight. I'll think about it tomorrow as Scarlet says.


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RE: Dragging out an old nemisis-Philco 66 cathedral - by ccomer1955 - 08-11-2014, 12:52 AM



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