Philco 49-500-121

[fujifrontier]

Originally Posted by Chad Hauris

I think those needle nose are too big for this job...you need a type like an Xcelite which is made for electronic work.

I knew there was a "special" type of pliers I had to wait for :P

Now... the problem of the loose green wire remains. I tried looking at the schematic but it didn't make much sense... i know it's referred to as C101 but I couldn't get any further..

[Keefla]

honestly man, from the pics so far youve posted, things dont look too bad from my house. Youre taking your time and you care to do it right.

[fujifrontier]

if only I knew what the green wire had been connected to

[blue_lateral]

Well, to figure out where the green wire goes, you need a schematic diagram. All the ones from the Rider service manuals are posted on Nostalgia Air.

http://www.nostalgiaair.org/Resources/

That cardboard tube had electrolytic capacitors in it. Judging from your pics, there must have been three of them, because there are four wires. They would have had a common ground wire, probably the black one. The other leads will be for the positive connection of each cap. If you read the cardboard tube, it will tell you which lead goes to which cap.

In an AA5 set like that, electrolytic caps are generally used for power supply filtering, and occasionally for a cathode bypass on the audio output tube. The most common setup only has two caps, both PS filters. Since yours has three, you're gonna have to look at a schematic diagram to figure it out. I found one for the 49-500 here:

http://www.nostalgiaair.org/Resource...=\M0013657.pdf

The schematic diagram is on page 5 and 6 of that PDF. Since the most likely use for these caps is power supply filtering, start looking near the rectifier tube. In this case it's a 35z5. I found it at the lower right corner of page 6. Sure enough, all three caps are right there. c101a is 30mfd, c101b is 25mfd, and c101c is 20mfd. All are power supply filters. To find out where the missing cap connects, you need to trace a little wiring. Start at the 35z5 cathode. It's pin 8 according to the schematic.

The 35z5 is an octal tube. Heres how to find pin numbers on an octal tube. Looking at the socket from the bottom, find the keyway. Turn the chassis so the keyway is at the bottom. Pin 1 is just to the left of the keyway. Going clockwise, the next pin will be 2, then 3, and so on up to 8. Pin 8 (the one we are looking for) will be on the other side of the keyway.

Found pin 8? Good. One of the capacitors should be connected there, the 30mfd one. Look at the schematic again, and you'll see it. It's the component that looks like one straight line and one curved line. Look at your old cap to see which color wire went with the 30mfd cap.

There is also a 220 ohm resistor connected to pin 8. Look at the schematic. It's the component that looks like a zigzagging line. Find it in the radio, and follow it to the other end. Look back at the schematic. The 25mfd cap connects here. The paper tube will tell you which color.

Look back at the schematic. In addition to the 25mfd cap, there is also a 1200 ohm resistor connected here, and a wire going to the output transformer. Follow the 1200 ohm resistor to the other end. Look back at the schematic. The 20mfd capacitor connects here. Thats all three.

Good luck.

John

[fujifrontier]

The cardboard cap actually had one giant cap in it, not separate ones. It broke apart when i was trying to peel off the cardboard while determining how many capacitors were in it.

Thank you for your help. I'll trace it tomorrow when I have a little more patience. Would just using two 50mfd 150v caps like i have in the picture be sufficient, with all 3 leads going to the other end of the capacitor?

[blue_lateral]

No. According to the schematic there were three capacitors in there. What does it say on the outside?. The negative wires of all three capacitors go to the wire that was marked "common". Its probably the black one, but you'd have to look on the paper tube to be sure.

The positive lead of each new capacitor goes where an old lead was. Start at the cathode, as in my post above.

Maybe you could get away leaving the third one out, but I probably wouldn't.

John

[fujifrontier]

It had a giant one in there!!!

I broke it in half and there were 3 leads of differing lengths in the middle of it. Maybe I'm wrong. I'll play around with it soon.