[osanders0311]

Can anyone help me figure out a capacitor that has 3 wires coming out of it red and green on one side and a black wire on the other. I seem to only find ones with 2 wires and not sure about the difference. It's a Philco 400V, 4-4 MFD. I will try and include a photo.
Thanks,
Guys    

[RodB]

That's a dual 4 MFD, red and green are both 4mfd and black is common negative. You should be able to see them in the power supply circuit of the schematic diagram.

[Vlad95]

Regarding picture 5 on page 1 of this thread this capacitor is #40 on scematics diagram - 4mF+4mF. Black wire is "-" (grount), red and green "+".
But it look like this capacitor was dead and as parralel was soldered two another, in blu and metal.

My advice - foud two new capacitors 4mF x 400V. It may be very small. And restore old as I present in my message here:

https://philcoradio.com/phorum/showthrea...#pid206311

[Image: https://philcoradio.com/phorum/attachment.php?aid=32368]

[osanders0311]

Thanks, RodB and Vlad95,

I was mainly trying to figure out this capacitor to locate a replacement, Vlad thank you for reminding me of the blue capacitor which I almost forgot about being that I couldn't find it on the schematic. I was so busy trying to get the other unsoldered and forgetting the 2 were soldered to the same contacts. Seeing the blue capacitor and some taped wires and missing antenna tells me someone worked on it in the past. I do wonder if they started on it and gave up.

Vlad thank you for the link for restoring the old capacitor, I'm really not concerned about returning to original and wonder if I can just install the 2 capacitors separately. Which brings me to another question in regard to the blue capacitor it's 450V 8MFD, is having a capacitor with more MFD's bad for the radio? If the blue capacitor is ok to use, I can keep it connected and get another for where the green wire is connected from the old capacitor. Hopefully I am testing it correctly, but I have tried testing the old capacitor and not getting any reading.

[Vlad95]

The more the better. (Within reasonable limits.)
2-5 times more is no problem in this case.

[osanders0311]

Looks like if I am reading it correctly it looks like the silver capacitor#57 that appears to be a replacement is of a lower voltage than the original. I am currently working on the wiring and in the process of ordering resistors and caps as well. This radio will probably cost me more than what I'll be paid but it's interesting working on it. I am attaching some pictures if anyone can let me know if I am correct about the silver cap. The schematic is very difficult trying to read the printed numbers.            

[RodB]

Yes, 57 is an electrolytic cap that should be 12 mfd 400 volts according to the parts list from the Phorum library schematic. Someone replaced it with the duo 20 mfd 150 volts and it looks like they used only one section. You can use 12 to 16 mfd 400 volts and the negative lead is not grounded. BTW the schematic I used is very clear.

[osanders0311]

I have ordered and received new caps for this radio and hope I've ordered the correct ones. I tried matching them to the schematic as best as I could but matching the voltage was difficult, so I ordered ones with slightly higher voltages. They are also smaller in size based on the ones installed but I read that this is normal. I am attaching pictures and not sure about the big silver cap and a 400V cap in the picture. Does the silver cap need to be replaced with a large cap of the correct voltage (400V) as in the picture? also the dual 400V 4-4MFD tan paper cap which earlier was pointed out as possibly dead. The tan cap has a replacement blue 450V cap in parallel with it but probably the 2nd 400V is still needed            

I am confused about the differences in Electrolytic condenser/capacitors and the metal vs paper material and the sizes.

[RodB]

Hi, there's a lot to consider when designing these circuits so you shouldn't have a lot of concern when replacing caps. A lot of people concentrate on replacing them with exact values but remember that these circuits are 60-80 years old and when they were designed components had a 20 percent tolerance. Standard values for caps are different today than 60 years, or more, ago. So, a 0.05 mfd cap in your chassis is now a 0.047 mfd and 0.02 mfd is 0.022 mfd. These are all within tolerance of circuit design. You'll pay more for exact values than getting replacement values.

Electrolytic caps are manufactured for low frequency applications thus have higher capacity. In the old days they were made of paper impregnated with an electrolyte which apparently increases the capacity.

When you buy poly film caps you can get them all at 630 volts and you'll save some money because that is the most common voltage and manufacturers see this and give a price break when they can make them in bulk quantities. Also, if you have to buy 6 or more of a certain value you might as well get ten and pay less.

Quite often you will find that someone has either substituted a cap with a different value or wired in the new cap across the old one. In this case stick with the schematic. Either practice does not fix the problem and causes confusion. If a circuit calls for a 400 volt electrolytic then that voltage would be the same or higher for the replacement. Remember, the higher the voltage, the greater the size.

Hope this shreds some light on capacitors.