[jrblasde]

Thank you, Richard! I am using KiCAD for the schematic and PCB design.

[jrblasde]

I started to consider a PCB for the new C100 A/B bakelite capacitor, but then I had an idea. What if I were to get a three-lug terminal strip with a common central lug, such as this?

   

I could mount it to the chassis where the old bakelite capacitor has been removed, and then solder the two new safety capacitors to it. Schematically, here's what I need to do.

   

This would be very simple with a terminal strip. Additionally, I don't feel that I need to over-engineer this one with a PCB. The entire system is mounted to the underside of the chassis, and there is only one screw to connect the grounded connection to the chassis.

[morzh]

Well, my personal opinion:

If you miss the backelite, it is OK
If you do have the existing backelite, it is a waste of effort.

[jrblasde]

Are the bakelite capacitors allowed to stay in place? I suppose that's my only concern.

[morzh]

A popular practice is to restuff them with new capacitors.

This is a thread I wrote, it is in "Shop talk" here.

https://philcoradio.com/library/index.ph...soldering/

[GarySP]

The simple answer is "no, they can't remain in place". These are stuffed with paper caps and resistor wire in some cases, and need to be refurbished. It's not a difficult procedure, and there are tutorials on this site to guide you. Lots of help here if you ask for it. Gary

[jrblasde]

That’s what I had thought. I know that we can reuse the mica capacitors when they are within tolerance, but I didn’t think so regarding the Bakelite capacitors.

Thank you for the link, Mike! I think I’ll restuff this one. It does look quite simple.

[morzh]

It is simple.

As for "can they remain in place" - well, if this means "can I simply parallel new caps to the old one, using it as a solder post" - no, you cannot. The old cap, first of, retain some capacitance, often it goes up; what's worse, it develops leakage (which is the reason it gets replaced) and this leakage will be in parallel to the new cap. So you will end up with not cured leakage problem and wrong capacitance value.

However, if you use it purely as solder post, making sure the old capacitor does not become part of the circuit, then yes, ir can stay. I see little reason if any to do this, it is wasteful and, to me, simply counterproductive, but I've seen this (and invariably would do away with it).

[jrblasde]

Understood. Yes, I will remove the internals of the Bakelite casing and install the new capacitors inside.

Initially (when you first suggested that I keep the Bakelite) I had thought you meant that we could keep the original unit intact, but now I understand what you had in mind.

[radiorich]

Hello Joseph,
Very nice I will have to remember that KiCAD
I personally restuff the bakelite blocks not just they look right but the factory wiring stays the same and makes it just that much easier to work on and to trouble shoot .

Sincerely Richard
P.S. the Philco 38-10T that I am working on right now had only one bakelite block and it was also the safety capacitors one .

[jrblasde]

I believe that the 48-482 sitting in my attic has some bakelite capacitors, but I haven't restored that radio yet. The 49-906 I restored didn't have any in it, so this here is the first bakelite cap that I will be restuffing. I agree that it will keep the wiring nice and neat. I liked the look of it from the link that Mike shared.

[morzh]

I doubt a 1948 radio will have backelite caps in it.

[jrblasde]

You had me second-guessing myself, but then I remembered that I took this photo of the underside of the chassis (bottom left, line-to-ground caps on the AC mains).

   

But I’m sure that this was a rarity. I know that the 1949 parts catalog didn’t even list Bakelite capacitors. Probably all replaced with ceramic ones.

[jrblasde]

Oh, this is interesting. The listed part number for that capacitor in the 48-482 is a 61-0120. I looked that up in the parts catalog, and they are actually supposed to be 600V tubular capacitors. I wonder if this Bakelite capacitor in my 48-482 was an instance of Philco using up their old inventory.

[radiorich]

Hello Joseph,
I would not put it past them to do just that !!

once you do one or two you will get the hang of it just like on my Philco 38-10T.

I even restuffed the electrolytic capacitors and the coupling capacitors I used film capacitors instead electrolytic capacitors the radio should last another 80 years .

Sincerely Richard