I have a customer's VOX AC15C1 which blows the HT fuse. I have the Inkimodo.Dragon 5 page schematic for reference. There is a 37 ohm short (read on my Fluke 77 meter) from B+ to the 6 volt heater circuit. The ground referencing resistors, R90 and R91 are burnt. I have removed the tube board and also the main board and I am checking everything I can think of with no success.
I temporarily disconnect R90 and R91, add a current meter to the HT fuse slot and read about 350 mA. I measure from the ground connection of the tube board to chassis ground and get 400+ volts. If I attempt to ground the tube board to the chassis as intended with a mounting screw, R11 and R12 start to burn. BTW, I have removed all tubes from the circuit, 3-12AX7 and 2-EL84's. The unintended connection or short between B+ and the grounded side of the 6 volt transformer connection reads 37 ohms. I have checked all diodes and capacitors for proper function. What little hair I have left is slowly dropping to the floor. I could use a real Vox schematic with all the connector numbers, and wire colors. Any help from the seasoned members is much appreciated. Thanks in advance
I temporarily disconnect R90 and R91, add a current meter to the HT fuse slot and read about 350 mA. I measure from the ground connection of the tube board to chassis ground and get 400+ volts. If I attempt to ground the tube board to the chassis as intended with a mounting screw, R11 and R12 start to burn. BTW, I have removed all tubes from the circuit, 3-12AX7 and 2-EL84's. The unintended connection or short between B+ and the grounded side of the 6 volt transformer connection reads 37 ohms. I have checked all diodes and capacitors for proper function. What little hair I have left is slowly dropping to the floor. I could use a real Vox schematic with all the connector numbers, and wire colors. Any help from the seasoned members is much appreciated. Thanks in advance
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