I used my 8YP4 test CRT and powered it up. After carefully checking B+ and filament string voltages, I powered it up to full voltage. I noticed that when the tubes heated up, the B+ would drop from around 270V to 140V. After some troubleshooting I found that L17 was open and not allowing B+ to get to pin 5 of V11 a 12AX4GTA Damper tube. I pulled the coil and sure enough one of the fine wires were broke off the main lead. An easy fix. Once done, B+ came up and stayed at 271V. Sams list it at 265V.
Here is what I was greeted to:
I know the picture is bad, but I also have some tubes that tested bad that I haven't replaced yet till the weekend.
All the controls did something so that's good. The filament string dropping resistor R59 was a 41 ohm 20W is now a 60 ohm 25W resistor that runs very hot. My spit sizzled when applied with a craft stick. Do they always run that hot? Do I need to go with a larger wattage? I went to 60 ohms because my line voltage is 122vac.
Another thing I need some help with. I have no audio. The volume pot does increase and decrease the "hash" so I know downstream of the volume pot is working. I did some troubleshooting and found L14 the 1st IF coil is open.
It's a simple coil and I have to pull the main board to either fix it (fingers crossed) or replace it. the Philco part number is 32-4644-12 with no other manufacturer listed as a substitute.
I did try jumpering across the 2 terminals to short it out to see if that was the problem of no audio. Jumpering didn't help. I even heated up both terminals and re-flowed the solder, still no joy. I hoping that when I get some of the tubes replaced the picture and audio will be improved.
As a long shot, does anybody have one of those coils?