05-27-2017, 07:15 AM
1 uF does seem a bit overkill, but that's one of those questions you would have to ask a dead guy (someone on Philco's engineering team). And dead men tell no tales.
Actually, someone like Mike (morzh) could probably answer that question. What say you, Mike, if you're watching?
Now regarding resistor (69), the dual 70 ohm resistor with the center tap. It is connected between B- and ground, where the potential between high voltage center tap (B-) and ground is low. Low voltage, low resistance (70 + 70 = 140 ohms), low current.
Resistor (51), on the other hand, is connected between B+ and ground. A lot of Philco chassis used a resistor between B+ and ground in this manner, but in other Philcos the wattage of this resistor is much greater. In fact, the others (including 111, early 112, 16, 17, 18, and others) used a very large tubular resistor which was probably at least a 20 or 25 watt resistor. I don't know why Philco used such a small resistor in the late 112, unless the bean counters were trying to cut costs. They should have used something more sturdy than a 2 watt resistor in this position. If that resistor is even still in the ballpark (and it is highly doubtful), it will run red hot in operation. Replacement with a 5, 7 or even 10 watt resistor will result in a resistor that will still generate heat but will last much longer.
Actually, someone like Mike (morzh) could probably answer that question. What say you, Mike, if you're watching?
Now regarding resistor (69), the dual 70 ohm resistor with the center tap. It is connected between B- and ground, where the potential between high voltage center tap (B-) and ground is low. Low voltage, low resistance (70 + 70 = 140 ohms), low current.
Resistor (51), on the other hand, is connected between B+ and ground. A lot of Philco chassis used a resistor between B+ and ground in this manner, but in other Philcos the wattage of this resistor is much greater. In fact, the others (including 111, early 112, 16, 17, 18, and others) used a very large tubular resistor which was probably at least a 20 or 25 watt resistor. I don't know why Philco used such a small resistor in the late 112, unless the bean counters were trying to cut costs. They should have used something more sturdy than a 2 watt resistor in this position. If that resistor is even still in the ballpark (and it is highly doubtful), it will run red hot in operation. Replacement with a 5, 7 or even 10 watt resistor will result in a resistor that will still generate heat but will last much longer.
--
Ron Ramirez
Ferdinand IN
