01-22-2019, 02:15 PM
Good afternoon guys and gals, I have this VTVM that I obtained on eBay a few weeks ago. It looked decent on the outside, but the inside was another story. Not only was the original kit build terrible, someone else decided to make some of their own modifications, like an extra phone jack with a slide switch.
Anyway with some web searchs I found the original construction manual and decided to tear it completely down, check the major components and install new everything else. I used the step by step build instructions and it came together very nicely.
Ok, so I fired it up through the variac and at least got the tubed and power light to light. But when checking the voltages from the manual they are way high. On the 6SN7 AMPL. Tube it says pins 2 & 5 each should be about 90 volts. Mine are about 250. Pin 3 should be 3-4 volts, mine is 2.5 and pin 6 should be 3-4 volts and mine is 2.5 volts.
I double checked my connections and also the 33k resistor across the C2 filter (15mfd), also the 10k and 20k resistors between the 6X5 power rec and the 6SN7 tube and all are good. I have no idea if the 15 mfd electrolytic is correct value, because it just calls it the C2 filter everywhere in the manual and schematic. It had a 16mfd in it, but I have no idea if it was correct or not, since the whole thing was a mess. Any help would be appreciated. Thank you!
Anyway with some web searchs I found the original construction manual and decided to tear it completely down, check the major components and install new everything else. I used the step by step build instructions and it came together very nicely.
Ok, so I fired it up through the variac and at least got the tubed and power light to light. But when checking the voltages from the manual they are way high. On the 6SN7 AMPL. Tube it says pins 2 & 5 each should be about 90 volts. Mine are about 250. Pin 3 should be 3-4 volts, mine is 2.5 and pin 6 should be 3-4 volts and mine is 2.5 volts.
I double checked my connections and also the 33k resistor across the C2 filter (15mfd), also the 10k and 20k resistors between the 6X5 power rec and the 6SN7 tube and all are good. I have no idea if the 15 mfd electrolytic is correct value, because it just calls it the C2 filter everywhere in the manual and schematic. It had a 16mfd in it, but I have no idea if it was correct or not, since the whole thing was a mess. Any help would be appreciated. Thank you!
1929 Victor R-32, 1933 60L, Phil 40-158, Phil 42-400X, Phil 47-1230 Radio/Phono,, 1950 Phil TV t-1104, Air King 4000, Philco 41-105, Philco 37-675, RCA Victor 9K2, PT-50, Phil 54C, PT-44 Cabinet, Phil 118X Cabinet
Gregg
