10-14-2018, 06:08 PM
Dear RadioAbby
Call me confused.
I have been working on stuffing the electrolytic caps #49 & #50. 49 went smoothly using the same process as I used in the Philco 60MB.
The #50 shows in the schematic as two separate 8uF caps and the actual Philco capacitor part #30-2028 does indeed have two lugs on it as you would expect.
[Image: https://www.dropbox.com/s/2m60cf1nzl7vxt....jpg?raw=1]
The common negative connection is made with the usual small metal lug physically held next to the outside of the capacitor can by the cardboard sleeve that insulates the common negative (which connects to the power transformer center tap) from the chassis. When I pulled the cardboard sleeve off of the can I found some stamped markings that list the cap as a 16uF cap. What the heck…?
[Image: https://www.dropbox.com/s/ga3448755352ks....jpg?raw=1]
Then after a little internet searching I found a restoration done on retrovoltage.com that says the schematic had an error and that there was a connecting dot missing that makes the two 8uF electrolytics into a parallel configuration and in effect a 16uF cap. I've included the link to the retrovoltage.com article and here is the relevant image showing the correction [image from retrovoltage.com site]
[Image: https://www.dropbox.com/s/vprkxatomf0vwn....jpg?raw=1]
When I measured the capacitance, each lug displayed 17 or 18uF. If I wired the two lugs together and measured the capacitance, it still only showed 18uF which says to me that it is indeed a single 16uF cap it just has two lug (but for some reason there is no continuity between those two lugs when checked with an ohm meter).
The wires in the radio connected to the “red” lug go to the 1st IF compensator cap #17 and to one end of resistor #28.
The wires in the radio connected to the other "plain" lug go to the filament of the 80 rectifier and to the green/white wire leading to the field coil.
While tracing these all out it became apparent that there was another connecting dot missing from the schematic because there is continuity between the end of the #28 resistor, the #17 compensator AND the White wire connecting to the field coil. Here is a portion of the original schematic and my addition of the correction from retrovoltage.com (RED dot) and my correction (BLUE dot).
[Image: https://www.dropbox.com/s/k9cn1sdj0e3dv5....jpg?raw=1]
[Image: https://www.dropbox.com/s/b17utigao0dyk7....jpg?raw=1]
This lead me to thinking you would not connect the positive of a single 16uF cap to both sides of the field coil (assuming the retrovoltage.com correction is actually correct)…
I was all set to stuff in two 8uF solen caps each wired separately to one of the two lugs like its shown in the schematic but now I’m totally confused…
Call me confused.
I have been working on stuffing the electrolytic caps #49 & #50. 49 went smoothly using the same process as I used in the Philco 60MB.
The #50 shows in the schematic as two separate 8uF caps and the actual Philco capacitor part #30-2028 does indeed have two lugs on it as you would expect.
[Image: https://www.dropbox.com/s/2m60cf1nzl7vxt....jpg?raw=1]
The common negative connection is made with the usual small metal lug physically held next to the outside of the capacitor can by the cardboard sleeve that insulates the common negative (which connects to the power transformer center tap) from the chassis. When I pulled the cardboard sleeve off of the can I found some stamped markings that list the cap as a 16uF cap. What the heck…?
[Image: https://www.dropbox.com/s/ga3448755352ks....jpg?raw=1]
Then after a little internet searching I found a restoration done on retrovoltage.com that says the schematic had an error and that there was a connecting dot missing that makes the two 8uF electrolytics into a parallel configuration and in effect a 16uF cap. I've included the link to the retrovoltage.com article and here is the relevant image showing the correction [image from retrovoltage.com site]
[Image: https://www.dropbox.com/s/vprkxatomf0vwn....jpg?raw=1]
When I measured the capacitance, each lug displayed 17 or 18uF. If I wired the two lugs together and measured the capacitance, it still only showed 18uF which says to me that it is indeed a single 16uF cap it just has two lug (but for some reason there is no continuity between those two lugs when checked with an ohm meter).
The wires in the radio connected to the “red” lug go to the 1st IF compensator cap #17 and to one end of resistor #28.
The wires in the radio connected to the other "plain" lug go to the filament of the 80 rectifier and to the green/white wire leading to the field coil.
While tracing these all out it became apparent that there was another connecting dot missing from the schematic because there is continuity between the end of the #28 resistor, the #17 compensator AND the White wire connecting to the field coil. Here is a portion of the original schematic and my addition of the correction from retrovoltage.com (RED dot) and my correction (BLUE dot).
[Image: https://www.dropbox.com/s/k9cn1sdj0e3dv5....jpg?raw=1]
[Image: https://www.dropbox.com/s/b17utigao0dyk7....jpg?raw=1]
This lead me to thinking you would not connect the positive of a single 16uF cap to both sides of the field coil (assuming the retrovoltage.com correction is actually correct)…
I was all set to stuff in two 8uF solen caps each wired separately to one of the two lugs like its shown in the schematic but now I’m totally confused…
