Years ago I began work on my very own 47-1230 and got it to a point where most of stages 1 and 2 of the schematics are essentially recapped, fuses and ground has been installed, essentials changed to get the radio safer, and cabinet refinished, as the finish was Sun damaged and veneer was missing.
At that time I also shipped (gifted) the D-10A changer to another 1230 owner.
Sadly life happened and the radio remained untouched and un powered for years as my life changed.
Last year I got a likely "aftermarket update" in the form of a Voice of Music changer from 53, that has 45s & 33s (and 16s but who cares?)
Soooo, 1230 now sees lot more air time, and I realize I never finished with its restauration... While AM is good, nothing plays on AM here.
FM and Phono are low. And a bit gritty.
They share the same tubes. In stage 3.
I think it's time I attack this part of restauration, at last.
Soooo.... Here's what the guts currently looks like.
I have a resistor I want to change, some safety caps that are waiting to be installed, and several caps to continue my quest.
-Mars
(This post was last modified: 12-13-2020, 04:21 PM by Marsupial.)
I go with the philosophy that I want the next tech inside to know what's been done and what's original. So the caps have schematics numbers directly on them.
This evening I was trying to fix the limit switch that turns the phono light on.
After much contact cleaner, opening the switch and cleaning, I came to the conclusion that it was just too damaged and that's what was causing it to not fully retract to off position when in use. So I added a return spring (green arrow)
Then, upon reinstalling, the hole for the pull spring teared out. (circled orange)
... I don't really want to pierce another hole. The whole design was strange at best.
I guess I'll just install a modern switch like I was trying to avoid.
-Mars
(This post was last modified: 12-08-2020, 04:54 PM by Marsupial.)
So for my first step, I've followed some helpful hints.
I've changed c100 and c101 (installed safety caps). This was suggested long ago by Ron Ramirez, thanks a lot.
And @criageek hinted that r100 was problematic, I've had a similar value to his... It's replaced now and I'm certain my FM and Phono are less gritty and more loud than before the change. Plus, I had a bad soldering spot, so it was twice worth it.
Phono still not as loud as AM, and hummy. Hoping the current recap of section 3 will help with that.
-Mars
(This post was last modified: 12-08-2020, 08:44 PM by Marsupial.)
The radio is clearer but FM and Phono are still lower volume than AM.
As a result, I need to crank the volume up.
At that high volume, noise is also amplified (slight hum?)
This can be filtered out by turning the tone knob clockwise, but it sounds less good and reduce volume on some of the frequency range, soooo...
AM is crystal clear and loud. But besides traffic report there's not much.
So, there's still something to change if I am to get the same quality out of my Phono & FM than my AM.
If you have physical access to some of the cap see if you can spin it off the wires. Leaky screen bypass caps cause a lot of trouble. Generally, hot screen resistors.
You can try removing the nut holding the band switch, move it left or right to get better access. I was going to suggest poking or pushing it off the wire but if that is unsuccessful then you would create a new problem.
From what I've seen, the bandswitch is held on the knob side by the mechanism connecting it to the knob, and on the other side by a bracket that is bolted to the top of the chassis.
I tried removing this bolt, but the whole switch assembly didn't move much. Not enough for me to access the cap.
I don't know that I want to dismount the mechanism between the shafts and the knob. Anyone ever tried?
I don't have any other ideas. It's worth pursuing because it's an 80 year old paper wax cap. Maybe keep it in mind for now and when something comes up attack it.
