Why, son, that set ain't old. :D It even uses octal tubes, so it's from about 1936 or so. Many consider that era of '36 to '38 the peak of radio perfection.

Age of radio perfection.... If that's so, what can I use instead of a screwdriver?:D:D

Perfection may be hard to reach but pretty darn good is attainable. Dig right in!

I have this flexible resistor that I can't read on the schematic and I'm not sure how to read the code on it. My meter shows fluctuating readings sometimes 1.2Kohms sometimes 3.4K. It's one of those that looks like a cable with wire winding on the ends. It's brown with 2 painted stripes, green and gray. The gray one is a guess. It could be brown or silver but I have to bet on gray. No color on either end. The schematic is illegible on that particular item and the parts list shows 3 flexibles. I can only find this one on the radio. In the process of elimination, the radical meter readings just don't come close.

If someone could give me an idea how to read this thing, it would be greatly appreciated!

Thanks

You can get 500v caps at justradios A 10uF should do fine for the 8uF cap.

I would assume that flexible resistors use the same color code as carbon resistors. The only one in the parts list that could match based upon the green stripe is R19 which is 450 ohms. I would think it would have yellow-green-brown stripes. Looking at where it is connected in the circuit would be a better way to determine which one it is. R19 is the cathode resistor for the 6F6 so would connect between pin 8 of the 6F6 and ground. R2 is the cathode resistor for the 6A8 and connects between pin 8 and pin 1 (ground) of the 6A8. R5 is the cathode resistor for the 6K7 and connects between pin 5 (5 is tied to 8) and ground.

Thanks Sean. That helps a lot.

I have another question. I'm a little dumbfounded about these dry cap packs with multiple ratings and voltage. How do you replace those? I've never seen this kind of thing before nor do I know what to use in their place. Is there a way to wire in 2 separate caps for each one? Honestly, I don't even know how they work like that.

I would really like to learn about this and take a stab at it.

Thanks!!

I'm working on a few of those right now too. Check out my thread - I put up a bunch of pictures: http://www.videokarma.org/showthread...=246672&page=5

You could just clip the wires going the old ones and solder new ones in.

If you want to try restuffing them, the first step is to unsolder the pack and remove it from the chassis. Then, you need to figure out how to get the old guts out.

The last few I've done had metal tabs I could bend back. A little heat loosen up the tar inside and the old caps slid out. Next, I used some lacquer thinner to clean out any remaining gunk. I soldered new polypropylene caps in place.

Finally, for a couple of them, I refilled them with commercial grade wax. A little foam stuffing or hot glue would work too. Just so the new ones don't flop around inside the box. Bend the tabs back over to reseal the box. Remount it and solder the wires to it.

The worst part is definitely all the tar :yuck:

Good luck
Bob

Thanks Bandersen. The ones I am talking about are in rectagonal silver cardboard boxes one of which is rivited to the chasis. One of them says, for instance, 4mF 450V GEP-5, 3mF 150V DGP-2 on the box which are 2 different caps. Upon opening, there is one large cylindrical clump of wax and tar that is wired green and red on one end and black connected to foil on the other.

Hmm

That makes sense. The black should be a common ground connection. The red and green will be the other end of the 4mF and 3mF capacitors. You'll need to consult the schematic and trace the wiring to determine which is which.

You can clip out that old lump of wax and tar and solder your new caps in there.

If you want to use poly caps, Mouser has some.

3mF @ 200v

4.7mF @ 600v


Alternately, you could use a couple electrolytics.

Thank you so much... You know, I think I have it all figured out now (hope) and when the parts arrive it will be a go! I'll start working on the chassis with the Naval Jelly and get'er all cleaned up for the re-cap.

I'll be back with progress!

Hey guys... I'm back.

I have a problem. I've been pretty lucky in the past with computers and stereo rebuilding considering I am highly inexperienced in electronics. I've recapped many a mother board with success etc, but this!... this advanced tube technology... it's over my head I'm afraid. I am very willing and ready to learn though.

The A-66 is completely recapped. I replaced most of the resistors. I replaced all the wiring that was necessary which was 95% of it. I have stayed away from the coils except to replace absolutely necessary main wires so as to do as little disturbance to them as possible; I only replaced those wires by continuing from the old wiring about an inch off the coil's solder points. I have done the best I can to replicate the capacitors and resistors according to the specifications of the removed part.

With all tubes removed, I plugged into my PMV w/ a 60W bulb. It shows a short; there's no drop in the bulb brightness. Both power plug leads show no continuity with the chassis. With power on, I get 3.4V AC on the chassis.

Like I said before, I've been pretty lucky in the past but I guess here's my chance to learn some troubleshooting electronics. If anyone is willing to help, I would surely appreciate it.

Thanks! :ntwrthy:

I would suggest checking resistances of the windings in the power transformer with the power removed. Make sure they are close to what is shown on the schematic. Also measure resistance from the lead of one winding to one lead of each of the other windings to make sure there are no shorts between windings.

I'm not familiar with the term "PMV" but I would assume that this is what is commonly referred to as a "dim bulb tester"?

PMV = Poor Man's Variac

Yes

Thanks for the tip Sean. I made 2 preliminary readings but I also need to ask if I'm checking it correctly. I followed 2 of the wires that the schematic says are on a particular coil and did the same with another. Both lead to the power rectifier plug. That is where I took the readings. I don't know if that is the correct way to get that or not. On the schematic, one is supposed to be 200 Ohms and reads 380. The other is supposed to be .2 Ohms and reads .6 . I haven't dug around for the other 2 before I find out if I am doing this right.

If this is correct, then the transformer is shot I guess.

Any input? Thanks!