Back view. Seems to be missing the back cover, but the board with the antenna is there.
Out of the cabinet for a look over.
First check out. Using precautions for both electrocution and to prevent a possible fire if there us a bad short inside.
Let’s put a strong radio frequency signal into it and see if it can hear it.
Also a mud dauber put some junk in here which is one of the main tuning capacitors for the IF section. That has to be addressed.
Bread slicer out.
Tubes removed and chassis cleared off for cleaning.
Main filter electrolytic caps out. Wiring failure of this old rubber insulation.
Needle off and put away to keep it safe.
Speaker protection on.
IF transformer that had the mud packing off the chassis.
Transformer out. Primary and secondary windings are inductors. The capacitors are facing downward. Inductors and capacitors oscillate when connected together. By tuning the resonance frequency using some of the equipment on the bench makes the superheterodyne work. Later they get tuned to 455kHz.
Capacitors which are adjustable using the two screws. They adjust plates separated by sheets of mica.
Close up of capacitor plates separated by mica sheets. Cleaned up ok.
Thinking about placement of new wiring while the tuning condenser relaxes in the hot tub.
Tuner dial cord doesn’t work well so it will need work too.
Rear antenna off.
Tuning condenser before cleaning. The two trimmer capacitors are those two screws under the brass leaves.
Trimmers disassembled with the mica out.
The two mica sheets from the trimmers on the tuner.
Tuning condenser after cleaning.
Chassis after light cleaning. Note the IF can is still off.
Chassis mods beginning for wiring modifications. Center punch.
Fuse block and mounting terminal strip for the surge limiter.
Chassis wiring as received.
After all the caps replaced, a few resisters, and power mods.
Tuner re-lubed and reinstalled.
Run through of the power circuit and review of changes.
First power up test. Hmm 🤔
Thinking it through at 2am. Not at my best I guess.
But, 1) I think I figured out the problem, and 2) had the sense to wait until the morning to fix it.
Ok, so the next day I re- did the wiring and re-ran through the modifications to the power circuitry.
Ok, with the rewire, let’s see if the filaments light up and then if it can hear anything.
Nice to see the tubes glowing. Let’s move to the next step.
Doing the IF alignment. (Will redo it later to correct something I noticed here.)
Next step, getting ready to align the oscillator.
The hassle of dealing with cabinets that hold the dial face. Gotta estimate where 1300Hz will be on the tuner for this first rough oscillator alignment. I will redo this if I get it working and can set it correctly before removing it from the cabinet. I want to re-tweak the IFs anyway.
Working on the oscillator trimmer on the tuning condenser.
Oscillator is running and it is audible.
Without the antenna – it’s trying to hear something.
First trial with the antenna connected.
The tuning cord just doesn’t work well. This one on here is too loose. I’m going to re-string it.
Re-strung and a different spring pulled really tight. Knots super glued to hold.
In order to set the needle, first I set the tuner at half a turn.
Then positioned the needle at near the halfway point along the dial.
Cleaned and buffed the knobs, can you tell which two have been buffed?
The dial glass is really dirty, but need to be careful as there are no replacements available. Cleaned most of the dirt off the face but did not polish it. Did not touch the inside as the printing may come right off.
Inside the cabinet the glass is held in by some very old cardboard. It is about to not to the job any longer. I can’t stand relying on them any longer, especially with an irreplaceable piece of printed glass.
How about some nice oak blocks?
Orbital sander makes quick work of the corners.
Just popped a couple of counter sunk holes in the blocks and mounted a couple of layers of felt to hold the glass.
That’s much better.
Finished chassis ready to go back in the cabinet.
Kilroy was here. 100 yrs from now someone may wonder when the refurb was done.
All reassembled. A run through in my garage with just a short piece of wire stuck out the back as the antenna. About 7” long.
Am doing a burn in to be sure it is ok after a long run, then will set the dial at 1300 and then readjust the oscillator according. Also will re- adjust the IF transformers to the correct frequency. (My mistake.)
Needs to be refinished now. It sounds great. Imagine a better antenna. Ball games, etc.
Link to RCA Victor 56X3 Part 2
See more of Mark’s projects here.