Over the past few weekends, my wife and I have been preparing our garage and making space for a workbench for me to use for radio restoration. I have a good start, but need to get a few other things eventually. Top of my list is a Variac to slowly bring radios up to voltage without stressing them out by applying 120v immediately. (In fact, the first radio I chose to restore was manufactured to use 110v, so I have to have a way to power it without overpowering it). I also need to pick up a Vacuum Tube Volt Meter (VTVM) at some point.
Being relatively new at this, I already made some mistakes.
When I was in the process of removing the chassis from the cabinet, I knew I needed to remove the knobs first, then remove the screws from the bottom of the chassis, but I neglected to notice that the pointer on the dial was friction fit onto the dial shaft of the tuning capacitor. I ALMOST broke the fragile translucent frequency display plate by trying to force the chassis out of the cabinet before I realized it was causing resistance. I then gently wiggled the pointer off the shaft and the chassis came free from the cabinet without further resistance.
First look at the chassis:
Here’s the layout of the tubes on the chassis:
I removed two of the tubes immediately by carefully rocking them back and forth from the base in order to not damage them in the process. The tubes removed were the Type 80 and the Type 42. When I looked at them under sufficient light, I was able to confirm that the Type 42 was marked correctly, but I have questions about the Type 80 tube. Not sure what it is as it is not marked. Someone on Facebook pointed out to me that it didn’t appear to be the correct tube also, so that leaves me questioning whether it is right.
When I removed the top of the can that shields the Type 77 tube in the corner, I attempted to remove the clip from the top connector of the tube and didn’t realize how easy it was to break. This is where I made my second mistake… I pulled too hard and the wire under the metal cap separated from the cap. The clip is still seized to the cap. Mark that up as a learning lesson. Don’t get too impatient. These are fragile devices.
Both Type 77 tubes have loose top connectors. I will have to research how to remove the clip on their caps before going further.
Here’s a photo of the top of the chassis diagrammed above. Note the thick layer of dust that must be cleaned up:
The bottom of the chassis is incredibly dirty… with an amazing amount of cobwebs, silk spider egg pods and dead spiders as you can see below:
Looking at the chassis underside, there’s a little room next to where the cord comes in that I might be able to put a panel mounted fuse on, instead of using a clip.
Using a soft brush and perhaps a vacuum, get as much dirt and debris out of the chassis
Look at the underside of the chassis to determine if any work has been done on it so far or if it has never been in the shop
Safely remove the remaining two tubes without damage
Electrically test the coils to see if they have the dreaded “green disease” (copper wire corrosion), which would mean I need to rewind them with fresh enameled copper wire of a super fine gauge… ugh…
Create the template for the grill cloth insert for the Facebook contact.