Fleetwood model 4068... Advice?

[VintagePC]

Just finished re-winding the coil (pic below) and I'm waiting for the wax to harden. The CRT yoke had perfectly salvageable wire (and more than enough on just one winding- I nearly filled an 800 yard thread spool!

[VintagePC]

I reinstalled the coil and looked at the circuit diagram- it seems that there are some differences- (or someone has already "serviced" the radio.

Particularly, C25 and C26 are 0.01 µF (vs .03) and one of the filter caps in the can is 100 µF as opposed to 40 on the schematic.

R5 and R31 are completely absent.

Regarding replacements, I take it aluminum caps are fine for the electrolytics, and ceramics to replace the plastic and paper ones?

Also, can someone confirm whether C12,22,16, and 17 are electrolytic? They have the same schematic symbol as the filter caps, but like kinda like the plastic jobbies. (or just leave them alone?)

[electroking]

>Particularly, C25 and C26 are 0.01 µF (vs .03) and one of the filter caps in
>the can is 100 µF as opposed to 40 on the schematic.

Those 2 capacitors bypass the power line to the chassis to filter out some
interference. They are sometimes called 'death caps', because while
they are useful for their stated purpose, they also increase the leakage
between the power line and chassis, and bring up some shock hazard.
The lower value is possibly a production change, you need not worry,
but make sure good capacitors are in those spots. The 100 µF can
is probably fine for C23, but at C24 it may overstress the rectifier tube.
Better limit this one to 40 or 50 µF.

>R5 and R31 are completely absent.

Maybe they were removed by someone who wanted to disable the
radio section; these resistors provide the proper voltage and current
to tubes 6BE6 and 6DC8. The node between R3 and C5 should
definitely not be connected directly to the function switch, or the
tubes may be overloaded. You could replace R5 and R31 by a single
10 kohm, 3 to 5 W resistor. (note added afterwards: maybe the
resistors were moved to the part of the supply line on the other
side of the switch, somewhere to the right of C11)

>Regarding replacements, I take it aluminum caps are fine for the
>electrolytics, and ceramics to replace the plastic and paper ones?

Well electrolytics and aluminum electrolytics are essentially the same
(although there are also tantalum electrolytics, not very often used
in tube gear). Ceramic capacitors don't usually come in large values
(0.1 microF) and reasonably high voltage ratings. But in this radio,
probably anything with correct voltage and capacitance rating will do.

>Also, can someone confirm whether C12,22,16, and 17 are electrolytic?
>They have the same schematic symbol as the filter caps, but like kinda like
>the plastic jobbies. (or just leave them alone?)

Those cathode bypass capacitors are definitely electrolytic, but they
are low voltage units, that is why they are smaller. 6- to 15- volt
units would be fine for C12/C22, and 25-V units for C16/C17. You
can read the cathode voltages on the schematic, respectively 1.1 and
12 volts. These should be replaced, as any leakage will screw up
the bias on the tubes. P.S.: modern plastic units for C12/C22 would
be fine if not too physically big; some audiophiles will even tell you they
will improve the sound!

Good night.