12-23-2019, 09:34 PM
Thanks Ed. A lot of work, yes indeed!
Tonight I did a bit of troubleshooting.
First, I tried injecting a signal in the SW range. Result: Nothing.
It appeared that the oscillator was not running on bands B, C, or D.
So I did not remove the Magic Brain, but I did remove the top and bottom shields so I could merely flip the entire chassis over and have access to the bottom of the Magic Brain unit. I wanted to specifically examine the area around the oscillator tube and its associated coils, capacitors, and wiring.
Take a good look at the photo below. There will be a test later.
[attachment=21102]
Now carefully examine the partial under-chassis wiring diagram of the oscillator portion of the Magic Brain. Again, take a good look, keeping in mind that this diagram is upside down in relation to the photo above.
[attachment=21103]
Do you see the mistake I made?
Give up? Well...I accidentally switched the red and green wires at the band switch.
After unsoldering, switching and resoldering, it looked like this:
[attachment=21104]
Now it matches the RCA diagram.
Did the wire swap fix the "No SW" issue?
You be the judge...
You will notice in this video that I'm still having difficulty switching from band B to band C.
I think that tomorrow morning, I will remove the Magic Brain top and bottom shields again, hit the band switch contacts with DeoxIT as carefully as I can, and then leave it alone until tomorrow evening or Christmas Day, at which time I will attempt an alignment.
Tonight I did a bit of troubleshooting.
First, I tried injecting a signal in the SW range. Result: Nothing.
It appeared that the oscillator was not running on bands B, C, or D.
So I did not remove the Magic Brain, but I did remove the top and bottom shields so I could merely flip the entire chassis over and have access to the bottom of the Magic Brain unit. I wanted to specifically examine the area around the oscillator tube and its associated coils, capacitors, and wiring.
Take a good look at the photo below. There will be a test later.
[attachment=21102]
Now carefully examine the partial under-chassis wiring diagram of the oscillator portion of the Magic Brain. Again, take a good look, keeping in mind that this diagram is upside down in relation to the photo above.
[attachment=21103]
Do you see the mistake I made?
Give up? Well...I accidentally switched the red and green wires at the band switch.
After unsoldering, switching and resoldering, it looked like this:
[attachment=21104]
Now it matches the RCA diagram.
Did the wire swap fix the "No SW" issue?
You be the judge...
You will notice in this video that I'm still having difficulty switching from band B to band C.
I think that tomorrow morning, I will remove the Magic Brain top and bottom shields again, hit the band switch contacts with DeoxIT as carefully as I can, and then leave it alone until tomorrow evening or Christmas Day, at which time I will attempt an alignment.