Next, I tackled that frozen HV pot. I cut a slot in the plastic extender to finally free up the inner shaft. Maybe contact cleaner or age melted the plastic ?
I discovered a bad coil in the video amp and had to re-solder one end.
I put a new base on the CRT and replaced the socket. Quite a challenge for me.
Next, I replaced all the wax caps, some mica (I tested them) and out of tolerance resistors (lots of them!)
I replaced all the missing tubes, did some final check, and slowly powered it up.
Nothin'
So, I start testing voltages at various test points - B++, B+ etc. It all checks out. Grrr.
Must be a bad tube or two - right? So I swap out all the tubes from a working set and, viola, audio on channel 6! That one low power OTA station in Chicago broadcasting light jazz.
Which tube was bad?
None of them! I had been referring to a tube placement diagram for the TS-18 chassis instead of the TS-4 chassis
I really shouldn't work on so many projects at the same time!
Still no HV though. I pull the HV cover, turn off all the lights and see a ghostly blue glow coming from the 1B3. I pull it and it's a dud.
That was the only original tube left aside from the CRT.
The only replacements I have is a 1B3/1G3 which is a bit shorter so I need to reposition the feedback coil.
It should be 3/4" from the top of the base.
Bam! I've got a working set
. The vertical and horizonal sync are touchy, but I can work on that.
Here's a short video clip of it
playing.
Next up, tweaking and restoring the cabinet.