[Electrothaumaturgist]

I agree with the above replies about changing the wires. I've tried sleeving them, and outright changing them. Maybe it was just me, but I had a difficult time trying to shove that tubing around tight corners, especially on the pushbutton circuit board of the 42-400. (Before pulling it down). There, I was able to unsolder one side of the wire and attach my new wire to it, (with a touch of solder to tie them together, for the really tight ones), and pull the old out, the new will follow it. Sometimes you have to pull some slack out in sections with a pick, until it all comes. It can go like clockwork, once you "get into the zone". (Don't forget to mark or flag where they connect to!).

[EricS]

Thanks for the input, everyone. I've got some caps, resistors, and wire on order and I'll start working on electrical restoration shortly. Just for kicks, I measured the caps that I removed and found each one read about 50-60% high. Surprisingly, none of them were shorted - though I haven't applied any voltage to them. I'll soften them and restuff the paper sleeves with the new caps to maintain their original appearance.

As I dig further in for cleaning things up, there isn't much left on the top of my chassis. There two rectangular cans sticking up that have some old rubber wires coming from the bottom.

[Image: http://www.facstaff.bucknell.edu/esantan...G_0007.JPG]

According to the schematic, they seem to be coils. There seems to be two nuts that hold each can to the chassis. There is a nut on top which I presume holds the contents in the can, but there are also a few holes in the top with screw heads inside the can. What are these recessed screws for? Are the coils adjustable?

Do I have a correct understanding here, or is there something else that I need to know before I remove these for re-wiring? I am just looking to avoid unnecessary surprises.

Thanks,
Eric

[TA Forbes]

Look at the alignment instructions for your set and reference the diagram. The "adjustments" are trimmer capacitors. The above info will help you understand the what and why..

[37silverstreak]

Hey Eric, those two cans are your Intermediate Frequency coils and the recessed screws are adjustable capacitors for aligning the coils to the 455KC frequency. Don't touch them for now. After you get your set working you can adjust these to peak the sets performance. To access the coils in the cans you remove two nuts underneath the set and the exposed nut on the top. the old wires are soldered to lugs on the coils and are pretty easy to replace. Just be careful with the coil wire itself, the wire is very fine and easy to break.
Kevin

[EricS]

Got it! Thanks, guys!

[jerryhawthorne]

Eric, when removing the top nut watch the "screws" on the top through their holes. You do not want to see those turning. They will if the nut on the top is frozen on its screw. You will then need some penetrating oil on the screw nut to loosen it up. If you don't look down there carefully, you will be turning the whole coil inside and making a real mess out of those little wires. Don't ask me how I know.
Jerry

[EricS]

Thanks for the tip, Jerry. I'm noticing a pattern to some of your posts: "Don't ask me how I know"

[jerryhawthorne]

Yes Eric, I have made more mistakes than most but try to learn from them and help others not to make the same ones. It was a real mess untaggling the fine wires that were wrapped around and broken off.
Jerry

[Radioroslyn]

Don't think you would have that issue with this set as the can is square. Inside you'll find a dual square ceramic trimmer. Some sets mostly older from the early '30's have round ones. That could a problem. And again it's never a bad think to be careful!
Terry

[EricS]

Jerry: I've made my share of problems for myself by not asking enough questions in the past as well. I very much appreciate your willingness to share and help others like me from repeating them.

Terry - good to know about the timing of the shapes. I'll be extra careful as I undo these to make sure the inner elements don't move around while I take them apart.

[fossilexpress]

37Silverstreak:can you say a bit more on how to use the adjustable capacitors to "peak the sets performance"? What steps are involved? Thanks! Roy

[morzh]

You use a generator to tune the filters and the generator to the exact frequencies you need.
usually in Rider's there is the alignment procedure at the end.

[37silverstreak]

Roy, The adjustable capacitors in the IF cans are called "Trimmers" and they are used to adjust the for the 455KC intermediate frequency. this is part of the aligning procedure, which is done to get the best performance out of the set. If you look at a lot of schematics they have a section to tell you how to go about aligning a set. There will be tables telling you how to connect a signal generator to the set and what frequencies to use and what trimmer caps to adjust for each section. In the case of the IF trimmers you usually connect the signal lead to the grid of the RF tube and set the generator to the sets IF frequency which is in many cases 455KC but older sets may use a different one. With the set turned on you will get a tone at the speaker. you would then adjust the trimmer caps in the IF cans to get a maximum volume at the speaker. you can do the same thing just by tuning the radio to a station and then adjusting the caps until you get the loudest signal. It's a little involved but not too difficult. If you want to learn more, there is a DVD made by Bret Menassa of Bret's Old Radios that walks you through aligning old radio's. I bought a copy of it from him on Ebay and I think he does a good job of explaining it.
Kevin

[jerryhawthorne]

Fossil, alignment can often help in a radio's reception but unless you have a signal generator, this is a little premature worry. Get the radio working first and see how it responds to signals in your area. I do like to do a "full" alignment but I have the equipment, often I can get the radio to work a little better if no one else has been in messing with the magic screwdriver. Removing and replacing wires may change alignment a little depending on how you route the wires. Don't worry about that part right now and replace the wires etc. keeping length a routing the same. Take pictures!
Some people with good ears can do alignment without a signal generator, I'm practically deaf.
Jerry

[BrendaAnnD]

I've done literally hundreds of AM (even some FM) alignments by ear, before I finally could afford a scope and signal generator. The primary thing is that one has to assume that the IF's are at least close (a few KC either way isn't super critical). From there, I found a weak station and moved the adjustments just a tiny bit to see if there was an improvement. If there was, I would tweak each stage for max volume. Then I would go back to the tuner, find a weak station around 1400-1500, and adjust the antenna trimmer and the oscillator till I had the station in the proper spot on the dial with maximum volume. Usually, they turned out much more sensitive and selective. It's surprising that even if a stage isn't tuned to the exact frequency in the specs, performance can be significantly improved by simply tuning to all the SAME frequency (IF's).