02-10-2015, 05:46 PM
Today was the day for opening and restuffing electrolytic capacitors.
[Image: http://www.philcoradio.com/images/phorum...770-45.jpg]
Here is cap (78 ), originally 40 uF. Next to the old can is a new Nichicon 39 uF capacitor which will be used inside the original can.
You can see that I've already cut the top of the can off, as it is also shown in the picture above.
[Image: http://www.philcoradio.com/images/phorum...770-46.jpg]
After cutting off the top of the can, I carefully remove the old capacitor's anode. I used a drill to slightly enlarge the insulated hole where the anode came through the bottom of the can. Using a smaller drill bit, I also drilled another hole just below the threads of the can; this is for the negative lead.
I then ran a scrap piece of 10 gauge, solid, insulated electric wire through the anode hole, and a length of 22 gauge wire for the negative lead through the smaller hole.
I soldered the positive wire of the new electroytic to the heavy electric wire, and the negative lead to the thin wire. It is very important that both joints be insulated from each other!
I also added some hot glue where the wires were insulated with heat shrink tubing. You want to be careful and not get the hot glue on the bottom of the electrolytic. Some of them can take the heat; some can't. I learned this the hard way.
But it is good to get a glob of hot glue on the wires, well below the bottom of the electrolytic (and not touching it), for added insulation between the electrolytic and the old aluminum capacitor can.
[Image: http://www.philcoradio.com/images/phorum...770-47.jpg]
The next step is to carefully pull the wires back down so that the new electrolytic goes down into the can.
[Image: http://www.philcoradio.com/images/phorum...770-48.jpg]
Peek-a-boo...
The top of the 39 uF Nichicon can be seen inside the can.
[Image: http://www.philcoradio.com/images/phorum...770-49.jpg]
Now all that remains is to attach it to the radio chassis, and then glue the top of the can back on.
[Image: http://www.philcoradio.com/images/phorum...770-50.jpg]
I rebuilt capacitor (79) in a similar manner. It was originally 18 uF; it is now 22 uF. The only difference with this one is that it had disc insulators on both sides of the chassis, to isolate it from the chassis as its negative side (can) is at B- potential, more negative than chassis ground.
There is a third electrolytic in the 39-770 - part (47), 3 uF. It was in a smaller can that mounts to the chassis with two studs and nuts. It had (and has) wire leads. It was easier to restuff than the others, as it was simply a matter of pulling the original innards out and installing a new capacitor.
In the photo above, all three are now mounted to the chassis and wired into their respective circuits.
[Image: http://www.philcoradio.com/images/phorum...770-51.jpg]
A back view of the chassis showing the newly restuffed electrolytics in place.
[Image: http://www.philcoradio.com/images/phorum...770-52.jpg]
A closer look at the three restuffed electrolytics.
I will glue the caps back on the larger two electrolytic capacitors once I've tried the radio out and know that all is OK with them.
[Image: http://www.philcoradio.com/images/phorum...770-45.jpg]
Here is cap (78 ), originally 40 uF. Next to the old can is a new Nichicon 39 uF capacitor which will be used inside the original can.
You can see that I've already cut the top of the can off, as it is also shown in the picture above.
[Image: http://www.philcoradio.com/images/phorum...770-46.jpg]
After cutting off the top of the can, I carefully remove the old capacitor's anode. I used a drill to slightly enlarge the insulated hole where the anode came through the bottom of the can. Using a smaller drill bit, I also drilled another hole just below the threads of the can; this is for the negative lead.
I then ran a scrap piece of 10 gauge, solid, insulated electric wire through the anode hole, and a length of 22 gauge wire for the negative lead through the smaller hole.
I soldered the positive wire of the new electroytic to the heavy electric wire, and the negative lead to the thin wire. It is very important that both joints be insulated from each other!
I also added some hot glue where the wires were insulated with heat shrink tubing. You want to be careful and not get the hot glue on the bottom of the electrolytic. Some of them can take the heat; some can't. I learned this the hard way.
But it is good to get a glob of hot glue on the wires, well below the bottom of the electrolytic (and not touching it), for added insulation between the electrolytic and the old aluminum capacitor can.[Image: http://www.philcoradio.com/images/phorum...770-47.jpg]
The next step is to carefully pull the wires back down so that the new electrolytic goes down into the can.
[Image: http://www.philcoradio.com/images/phorum...770-48.jpg]
Peek-a-boo...
The top of the 39 uF Nichicon can be seen inside the can.
[Image: http://www.philcoradio.com/images/phorum...770-49.jpg]
Now all that remains is to attach it to the radio chassis, and then glue the top of the can back on.
[Image: http://www.philcoradio.com/images/phorum...770-50.jpg]
I rebuilt capacitor (79) in a similar manner. It was originally 18 uF; it is now 22 uF. The only difference with this one is that it had disc insulators on both sides of the chassis, to isolate it from the chassis as its negative side (can) is at B- potential, more negative than chassis ground.
There is a third electrolytic in the 39-770 - part (47), 3 uF. It was in a smaller can that mounts to the chassis with two studs and nuts. It had (and has) wire leads. It was easier to restuff than the others, as it was simply a matter of pulling the original innards out and installing a new capacitor.
In the photo above, all three are now mounted to the chassis and wired into their respective circuits.
[Image: http://www.philcoradio.com/images/phorum...770-51.jpg]
A back view of the chassis showing the newly restuffed electrolytics in place.
[Image: http://www.philcoradio.com/images/phorum...770-52.jpg]
A closer look at the three restuffed electrolytics.
I will glue the caps back on the larger two electrolytic capacitors once I've tried the radio out and know that all is OK with them.
--
Ron Ramirez
Ferdinand IN
