1950s RCA B & W TV

[MRX37]

Amazed it still works at all given the age of those caps... Also amazed that anybody outside of a TV collector would be interested in it.

[Captainclock]

Originally Posted by MRX37

Amazed it still works at all given the age of those caps... Also amazed that anybody outside of a TV collector would be interested in it.

Oh trust me, my neighbor is into all kinds of vintage stuff, He has an old Setchell Carlson TV/Radio/Record player combo unit that he had restored by someone in Ohio (I think it was the same person as mentioned on here several times), he has several old radios and he restores antique cars, and he has LOTS of Mid-Century Modern Furnature, and he lives in a perfectly preserved mid-century modern house that was his parents place originally.

[Captainclock]

OK, So, a little update, I started compiling a list of capacitors I need to redo this set and while I was in the process of seperating the chassis from the picture tube I accidentally damaged the original speaker, which just so happens to be a permanant Magnet type speaker similar to what you would find in any modern clock radio, so it looks like I'm gonna have to cannibalize an old clock radio for a speaker for the TV, what's weird though about the original speaker in this TV is that it was being powered by only one wire, the side that would normally be the negative lead had the wire coming off of the voice coil and into the connection terminal block and grounded the negative voicecoil wire lead to the speaker chassis. Has anyone ever seen this done before? I haven't and I find it rather unusual and I don't think its going to be possible to replicate that in a modern speaker because usually the voicecoil wire is snipped off right at the soldering lug for the voicecoil wire on the terminal block for the speaker and so it wouldn't be possible to ground the voicecoil wire to the speaker chassis unless I were to take a wire and jumper it off of the voicecoil wire connection and to the speaker chassis (or in this case the rivet that holds the speaker connection terminal block to the speaker chassis.)
Anyways It seems that the high voltage section of the TV (the back side of the metal portion of the chassis that the High Voltage Rectifier tube, Damper Tube and the Rectifier tubes are attached at) has about 10 wax paper capacitors of which about half of them look a little toasty like they had gotten a little too hot somehow, and showed signs of the wax coating on the outside of the capacitors getting charred or burned somehow, and even some of the resistors near those toasty looking capacitors looked a little toasty as well (but they were only 1/2 watt resistors so the resistors couldn't of gotten too hot themselves unless they shorted.) Any ideas as to how or why these paper capacitors got toasty looking like they did?

[Electronic M]

Small to moderate tears in speaker cones can be fixed with glue.

[Captainclock]

Originally Posted by Electronic M

Small to moderate tears in speaker cones can be fixed with glue.

This isn't speaker cone damage, its the actual terminal strip on the back of the speaker where the electrical connections for the speaker hook to on the back of the speaker that broke and broke the wire coming off of the voice coil with it.

See picture below.

[Eric H]

Well if the wire from the voice coil is still intact you can glue the strip back on and reconnect it.
If it pulled off at the cone of the speaker you may still be able to reconnect it and glue it back in the cone. Otherwise you need a new speaker, shouldn't be too hard to find one.

[Captainclock]

Originally Posted by Eric H

Well if the wire from the voice coil is still intact you can glue the strip back on and reconnect it.
If it pulled off at the cone of the speaker you may still be able to reconnect it and glue it back in the cone. Otherwise you need a new speaker, shouldn't be too hard to find one.

Well I'm gonna just need a new speaker because while the voicecoil wire is still intact in the cone the wire broke off of the terminal strip to the point that I couldn't get it reconnected even if I tried because there's nothing for me to grab onto.

Now as for trying to get a new speaker that's wired for two wires to work in a circuit that only requires one wire for the speaker to work, that's going to be the tricky part.

[Captainclock]

UPDATE: I've got the capacitors for this TV on order and they should arrive by either Monday or Tuesday. Surprisingly enough most of the capacitors in this TV were fairly common values, except for 3 of them, a .39 MFD, a .039 MFD and a .056 MFD capacitor (of which the .056 MFD was one of the bumblebee caps) so I ordered the closest value I could get to those values the .39 MFD I ordered a .33 MFD and the .039 I ordered a .033 MFD and the .056 MFD I ordered a .047 MFD.

So hopefully this TV will work properly once I recap it, seeing as it was already 80% working when I first got it from my neighbor.

Also One thing I found interesting is that the yoke was still in really good shape yet on this TV it wasn't cracked or broken or anything.

[Eric H]

It's a normal speaker, one side is just hooked to chassis ground.

[Captainclock]

Originally Posted by Eric H

It's a normal speaker, one side is just hooked to chassis ground.

The way they did the original speaker was that they took the wire that came off the voicecoil and soldered it to the rivet in the center of the connection terminal strip for the negative connection, and since most of the speakers that are similar to the original one that I'll find in a vintage alarm clock radio from the 1980s will have the wires from the voicecoil just connected to the terminal connector, would it work if I just used a small length of wire and jumper between the negative terminal voicecoil connection and to the terminal strip rivet in the middle of the terminal strip that's holding the terminal strip to the speaker chassis?

[jr_tech]

Yes, or any other convenient point on the metal speaker frame.

jr

[Captainclock]

Originally Posted by jr_tech

Yes, or any other convenient point on the metal speaker frame.

jr

OK, and seeing as I have a stash of about 6 1980s vintage clock radios that use a similar style speaker to what I need, I shouldn't have any issues sourcing a speaker, seeing as 2 of the 6 clock radios have a really bad tuner in them that can barely pick anything up, I may just use one of those.

[Captainclock]

UPDATE: I completely recapped this TV except for 2 capacitors on the PC Board which I couldn't get to because I couldn't figure out how to remove the PC Board completely without damaging anything plus my soldering iron wasn't hot enough to remove the solder off the edges of the PC board to remove it from the back. Anyways the TV still seems to have a vertical problem even with 98% of the capacitors replaced. Any other ideas as to what could be wrong with this TV besides capacitors or tubes? The funny thing is that this TV doesn't seem to have a Height adjustment which is what this TV is acting like its needing an adjustment with.

[Eric H]

It should have a height adjustment, usually one of the controls on the back edge that doesn't have an extender on it.

You don't need (or want) to remove the PC board, just the metal shield that's covering the back of it, that is held on by several screws around the outside edge and several tabs that are soldered to the board.

If the Caps you couldn't replace are in the vertical circuit then they are probably causing the problem. Those sets are difficult to get good vertical adjustment on their best day, anything out of spec will only make it worse.

Some of those odd caps like the .0039 and the .056 are 10% tolerance so if you replaced them with .033 and .047 it could also be affecting it.

Check the resistors in the vertical circuits, they are pretty critical.

If this is the model that uses a 6AQ5 for the Vertical output try swapping it with the 6AQ5 in the Audio and see if it changes anything.

[Eric H]

This chart shows where the vertical controls are, I don't think this is exactly the right schematic but those controls should be the same.

Also make sure you have the picture centered with the centering magnets on the yoke, trying to compensate for an off center picture with the height and linearity will complicate things terribly.