I successfully removed the chassis from a Zenith 10S690, and here it is.





Does anything look terribly wrong? On the top of the chassis, there looks to be a tube made out of foil. I am not positive, but I don't think that was standard.


Taking any and all suggestions.

Thanks!
Nicole

Home made shield?

Yes, you do need a Zenith tube shield, although I've seen factory original cardboard shields lined with foil which work fine. That spacious chassis should make changing the paper&foil capacitors, the electrolytic capaciots, and the out-of tolerance resistors fairly easy. Are the power transformer and speaker field good?

Is that old brittle rubber wire insulation I see? If so, the spacious chassis should also make rewiring it easier.

Looks like you are missing the tuning drive belt.

Thanks for all the replies!:)

1. I started cleaning it up after I posted the pictures. I will get a shield and replace the foil one.

2. Yes, that is rubber insulated wire. None of it is crumbling or brittle, but will be replacing it all.... once I figure out how to do that.

3. The tuning belt is broken, so yes, it will be replaced.

I am new to this whole thing, but am not devoid of mechanical ability. I will be picking up a radio repair book today, to begin learning how to do this. Any suggestions would be great.

What is the black box on the lower left corner of the top of the chassis? (top right of first picture. very dirty in the pic)


Thanks!

To make the rewiring job a little easier, you may want to just sleeve the wires. Detach one end and slide an insulating sleeve (heat shrink would work) onto the wire and re-attach. Note the path of the wire and restore it to the original, particularly in the RF section to avoid introducing oscillation. That won’t be possible on the bundled wires feeding through the chassis and they will have to be replaced since the sleeves will increase the size of the bundle. Check the candohm mounted on the side of the chassis for continuity and value. They are frequently open and need replacement. You can make a replacement, if required, by mounting power resistors on a terminal strip with the correct values.
To answer your question about the “big black box”, that is your power transformer.
When it comes time to remove the tubes, note the Loctal (7G7) has a bump on the side. Tilt the tube in the direction of the bump to remove. That will “unlock” the tube. The rest come out by pulling vertically. If they are sticky coming out, you may want to assist them by gently prying with a screwdriver (rotating the blade slowly) while pulling.
This should keep you busy for a while.

Pat

You've already done the first strp, taking photos of the chassis.

Replacing the wires, replacing the capacitors, testing the resistors, and replacing the out of tolerance resistors will all be done at once. When multiple items go to one terminal, it helps to twist one end of the new part or wire to the just disconnected end of the old part or wire.

I've found that #5 desoldering wick works best, but you can try various solder suckers and wick to see what you like.

What is that large square hole in the chassis? Is there an audio output transformer mounted to the speaker? If not, eprhaps one was mounted at that hole.

The hole in the bottom right of the picture is where the push button controls for the radio tuner fit when the chassis is in the console. It was not connected to the chassis, and there are several wires that appear to "plug" into something. I assumed they changed the tuner somehow, but have not yet determined that to be true.

Apart from a soldering iron, solder, and wire cutters, what tools should I acquire?

this is a question for the ages to be sure, what else will i require ????
well, if you have nothing as of yet you will definitely need a volt/ohm meter to test voltages and components within the radio ( also handy for checking continuity of coils and wiring.
also if you can try to find a signal generator at either a swap meet or off flea bay, they are great help in tracking down faults if you plan to do more than one radio once you get the restoration bug that so many of us have here.
of coarse the long needle nosed pliers,side cutters, magnifying glasses, ect..ect..ect.
and not last, you will need patience, the first radio you repair can often be like your first kiss, you will remember it always and it always takes a while to work up the nerve to do it. it will take a bit of time to get the radio back to where it plays well also.
you have picked a nice one to be your first challenge, and you have come to the right place as well. these guys are loads of help and knowledge so ask away with any questions.

buck

You can order the dial belt from Adamsradio.com
Don

In addition to the other tools suggested, add a pad of paper and a pencil ! Make notes on every part you remove, with sketches showing all of its connections. And don't remove a part until you have located it on the schematic diagram and the parts list, so that you know what you are removing. I suggest removing as few parts at one time as possible, replacing them, then going on.

A free copy of "Elements of Radio Servicing", available for download in the Archives section of this website will help you understand the function of the parts you are working with.

With these precautions, you should have a good chance of success on your project.

--Chuck

Thanks, Don! I think you had given me this link in a previous post. I have now written it down, and will order one soon.

This morning, I found the copy of "Elements of Radio Servicing" and have begun to read it. I thought it might be a good idea ...

So, this is how it started when I bought my bug a few years ago ... and I successfully learned how to get it to run like a top now. I think I just might be able to do this ...

Thanks for all the replies and encouragement. I will post progress and questions as I go along.

Cheers!
Nicole

Ok.

I have acquired a multimeter, a soldering iron, and someone to teach me how to use both.

I have printed out the schematic, and have ordered the Carr book on restoring old radios.

Now what? Do I order the replacement capacitors? I am thinking that I should replace these, then test the unit. The wiring looks pretty solid, for its age, and for now. I have noticed the some of the wire is cloth covered, and then some is the dreaded rubber insulated wires. Should all the wiring be replaced? Or just the rubber insulated ones?

I also read a post from a guy who tore everything apart, and then was never heard from again... I do not want that to be me!!

IMO you do not need to replace all the rubber wiring at this point. . If you squeeze the wire with a set of pliers and it crumbles replace it. Leave the pliable ones alone for know. You can replace them after you get all the caps etc replaced. Also take a lot of pictures of the underside of the chassis. Can really be of a great help. Believe me.
Stan Ski

That would be a lot more work. In the process of replacing capacitors and testting a replacing resistors, a restorer will have already desoldered many of the connection points. Why resolder them, then come back later and desolder them again to replace the wires?

Alright. After reading, reading, reading, and watching videos, and staring at schematics until they have begun to make sense, I think I am ready to begin replacing capacitors, out of tolerance resistors and any crumbling wires. I have been working on a smaller radio, so I feel pretty okay with my soldering/desoldering and resleeving abilities.

I will begin with the electrolytic capacitors. I will be leaving the originals on top of the chassis, removing them from the circuit, and putting the replacements underneath. Here are my questions.

1. the positive side of C20 connects to the speaker field, yes or no? So, the positive side of C19 will also? (not at the same point)

2. If that is true, would I connect the negative sides of C19 & C20 together?

3. Would these need to be connected to the chassis somewhere?

EDIT: Forgot the link to the schematic. Sorry!

http://www.nostalgiaair.org/PagesByMode ... 024699.pdf
Nicole

C19 and C20 positive are attached to the start and end of the field coil winding, as per the schematic. The negatives are tied together and go
the center tap of the high voltage winding(B- bus), NOT the chassis. If you note well the connections before you remove the old can you can follow along
easily.

I don't bother to measure small carbon resistors anymore, especially if I have cleared out a terminal or tube pin to rreplace wiring and/or a capacitor.
For the few pennies involved, I just replace them. Makes a huge difference when you finish up and do an alignment.

This set should be a real good player when finished.

Thanks, Codefox.

Can I attach the negatives together on the lug of the twist prong of the original electrolytic cap? That is where the B- from the transformer is currently attached. I mistakenly was thinking that spot would be a chassis ground but it is not, if I am reading the schematic correctly. (am I reading it correctly?)

I will most definitely follow the original wiring. I was confused about the negative side.

Point well taken regarding the resistors.

this radio was working when I purchased it (unlike my Philco 39-7 ), and it did sound great! I am excited to hear not only the radio, but also the 78's ... I have some sweet Benny Goodman that I'm dying to play!

Yes, you can attach there. You must remove all other connections to the can and mount a terminal strip to connect the positive ends of your replacement capacitors.

It's been awhile, but I finally was able to return to my restoration.

I successfully replaced the ecaps as codefox suggested, so THANKS!

I then moved along, replacing caps and resistors, working my way through the power amp section, amp section and inverter. When I tested the radio on Friday, it was AMAZING! Crisp, clear sound, picking up all kinds of stations, where previously, I could barely make out one station, and the volume was very weak, with a bit of a hum. No trace of any of that on Friday ....

... which leads me to today. I then replaced the capacitor connected to volume control, C14, resistor R17, and then the C14 and the C15 in the section that controls the Bass and the Alto ... and I am back to what I had before Friday. Weak volume and a hum.

I have checked, and rechecked and I cannot figure out what I did. Any suggestions on what mistake I have made?

Link to schematic: http://www.nostalgiaair.org/Resources/699/M0024699.htm

Thanks in advance ...