Mysterious (possibly original? Cornell Dubilier Beaver) capacitor not in schematics

[Madeline12]

I apologize for all the questions, but this one has still stumped me… while working on replacing components in this old Stewart-Warner 9121A television, I found an electrolytic capacitor that was connected from pin 8 on a 6W4GT tube socket (horizontal damping) to pin 3 on a 6CD6G tube socket (horizontal scanning output). Note… it may be tough to read on the scan, but pin 8 is marked as ground on 6W4GT. The capacitor is rated at 12uf 150V. I am not seeing this capacitor listed anywhere on the parts list, nor the schematics. I’m curious as to why this was in there… normally I’d assume someone in the past maybe soldered it in for whatever reason and it wasn’t original, but from what I’m learning, this capacitor does possibly seem to match the time that this model was released (1951). Can anyone provide some insight as to why this may be here, or if I should replace it? Or should I just remove it entirely?

Attached are some snippets of the schematics:

[Madeline12]

(Removed and edited original post)

[Alex KL-1]

The pin 8 of damper is ground; the pin 3 of Hout is the cathode (if I read correctly). So, it seems to be the 269 in the schematic. Is 5µF in the schematic, but, for this function, a higher value not hurts.

[Madeline12]

Ok, thank you. I was thinking this, but the 12uf was really throwing me off… thank you for the clarification. I grabbed a 5uf in prep for working on this so I think I’ll stick to what’s listed, even though this one was rated differently.

[Yamamaya42]

Originally Posted by Madeline12

Ok, thank you. I was thinking this, but the 12uf was really throwing me off… thank you for the clarification. I grabbed a 5uf in prep for working on this so I think I’ll stick to what’s listed, even though this one was rated differently.

I can't see that the one you removed is 12uf, the numbers on it really don't make sense.

does it SAY 12uf on the part?

[Madeline12]

Originally Posted by Yamamaya42

I can't see that the one you removed is 12uf, the numbers on it really don't make sense.

does it SAY 12uf on the part?

Yes it does, sorry. What I pictured was the category number of the capacitor from CD BR type capacitors (1215 = 12uf, 150V). It also states the ratings outside of this category number. Photo was mostly for identification purposes and showing age, my apologies.

[Yamamaya42]

Originally Posted by Madeline12

Yes it does, sorry. What I pictured was the category number of the capacitor from CD BR type capacitors (1215 = 12uf, 150V). It also states the ratings outside of this category number. Photo was mostly for identification purposes and showing age, my apologies.

I have never seen a code like that on a electrolytic capacitor before :O

[Madeline12]

Originally Posted by Yamamaya42

I have never seen a code like that on a electrolytic capacitor before :O

Only reason I was able to find it was from this gem circa 1938… maybe that’s why!:

https://ethw.org/w/images/5/55/Dubil...2C_1938-39.pdf

[Yamamaya42]

Originally Posted by Madeline12

Only reason I was able to find it was from this gem circa 1938… maybe that’s why!:

https://ethw.org/w/images/5/55/Dubil...2C_1938-39.pdf

"dry electrolytic" that's why, not come across one yet, from what I hear, they very rarely fail, they can, but not like the normal electrolytic caps.

[Phil]

Actually the only capacitors you will see today are "dry" according to the terminology of the 1940's-50's.
From Wikipedia: He introduced a separated second foil to contact the electrolyte adjacent to the anode foil instead of using the electrolyte-filled container as the capacitor's cathode. The stacked second foil got its own terminal additional to the anode terminal and the container no longer had an electrical function. This type of electrolytic capacitor combined with a liquid or gel-like electrolyte of a non-aqueous nature, which is therefore dry in the sense of having a very low water content, became known as the "dry" type of electrolytic capacitor.[14]

I would definitely replace it. 4.7 mfd would be fine. It is a cathode bypass. It's purpose is to allow the signal to bypass the cathode resistor, which provides at least part of the bias for the horizontal output tube. It's value isn't critical. The 12 mfd may be factory or a later replacement.

[Madeline12]

Originally Posted by Phil

Actually the only capacitors you will see today are "dry" according to the terminology of the 1940's-50's.
From Wikipedia: He introduced a separated second foil to contact the electrolyte adjacent to the anode foil instead of using the electrolyte-filled container as the capacitor's cathode. The stacked second foil got its own terminal additional to the anode terminal and the container no longer had an electrical function. This type of electrolytic capacitor combined with a liquid or gel-like electrolyte of a non-aqueous nature, which is therefore dry in the sense of having a very low water content, became known as the "dry" type of electrolytic capacitor.[14]

I would definitely replace it. 4.7 mfd would be fine. It is a cathode bypass. It's purpose is to allow the signal to bypass the cathode resistor, which provides at least part of the bias for the horizontal output tube. It's value isn't critical. The 12 mfd may be factory or a later replacement.

Sounds great, will do!