05-31-2013, 11:21 AM
I recapped "all caps except micas" and changed resistors as needed. I had to put on shelf for 3 months till I found a correct speaker which I did and ordered an ot8se universal output transformer. I got the transformer and hooked it up tp speaker.
I brought the radio up on variac and had no sound. So I touched grid cap of 75 tube and got some static with volume all way up. Then I noticed the 42 output tube glowing blue,very blue so I turned off.
Pulled the 42 and started checking voltages The 80 has 384 V. Plate to cathode. 6A7 P to K =346 , 75 P to K=201, 78-1st. IF=344 PtoK
78 2nd. IF=260 P to K. And the 42 P to K =456 with tube out.
Could mis- wiring output trans cause the high voltage on the 42?
I hooked the blue 7K OHM wire to the 42plate pin out. The 80 to field coil plus the B+ from the OT. and the 42 grid to the other field coil wire. On secondary black wire (0 ohm)to one voice coil wire and grn wire (3.2ohm) to other voice coil wire. I realize all the voltages are high. How should I procede to trouble shoot this problem? It took about 20 minutes to ck the tube volts and the power transformer just got warm to touch, not hot at all. I hope thats a good sign. Thanks. Mike
I brought the radio up on variac and had no sound. So I touched grid cap of 75 tube and got some static with volume all way up. Then I noticed the 42 output tube glowing blue,very blue so I turned off.
Pulled the 42 and started checking voltages The 80 has 384 V. Plate to cathode. 6A7 P to K =346 , 75 P to K=201, 78-1st. IF=344 PtoK
78 2nd. IF=260 P to K. And the 42 P to K =456 with tube out.
Could mis- wiring output trans cause the high voltage on the 42?
I hooked the blue 7K OHM wire to the 42plate pin out. The 80 to field coil plus the B+ from the OT. and the 42 grid to the other field coil wire. On secondary black wire (0 ohm)to one voice coil wire and grn wire (3.2ohm) to other voice coil wire. I realize all the voltages are high. How should I procede to trouble shoot this problem? It took about 20 minutes to ck the tube volts and the power transformer just got warm to touch, not hot at all. I hope thats a good sign. Thanks. Mike
