TV recapping advice needed.
 

I'm getting ready to replace around 20 or so old wax-paper/plastic style tubular capacitors in a '50s Raytheon TV, and have a few questions. I've done plenty of electrolytics before, so I don't need help regarding those or the wafer-ceramic types, as I'm leaving those in place. Due to the cramped chassis design, I've separated the CRT from the chassis, so I'll be shotgunning the caps.

I'm a little puzzled about "coupling" caps. I understand the function of coupling caps, what I don't understand is how to locate them in my schematic. I take it they are usually in series before and after various tubes in the circuit. Is that correct?

Do coupling caps have to be a different type than the remaining tubular caps I'll be replacing? Or, can I do these 20 or so caps with one type/style (for example: polyester, polypropylene etc)?

If any of you have advice (or pics) regarding your recapped TVs, I'd appreciate your help.

One of the uses for paper caps is coupling, there were many other uses like cathode bypass, RC time constants etc. Replace all paper dielectric caps with film caps like those made by Panasonic or Illinois capacitor.

Coupling caps pass the AC while blocking DC.
Best example is an audio out tube.
USUALLY the plate of the audio amp or detector tube goes to a cap going
to the 1st grid of the output tube. If it opens little or no sound.
If it shorts the output tube goes into full conduction & will overheat &
in some cases actually melt the tube. Tubes are forgiving so you do
have a little time to trouble shoot.
Decoupling caps are much like the big 'lytic caps. They ground out unwanted
signals to keep them out of the rest of the set & keep the voltage
fairly constant. You often see them on the G-2 or G-3 of a tube.

For a recap I always recommend doing a few then check the set so it is
a good idea to add extensions or a test tube to your arsenal. Nothing
harder than finding a self induced problem.

73 Zeno:smoke:
LFOD !

I've decided to start with the electrolytics (which includes 3 can/capacitor units) and other general repairs before I tackle the non-polarized caps. That will buy me a little more time to get a better understanding of the circuitry in this thing before I start replacing those (the non-polarized caps). The CRT feeds though the chassis, so the two have to be separated to do these repairs. Hopefully, in a month or two I'll be able to fire it up again (or watch it go up in flames?). Thanks for the info folks.