Restoration Notebook: Model 41-226, also known as "The Sled"

One of Philco's really cool designs, the 41-226 was introduced to the market in June 1940 as one of the company's new 1941 models. The design has become known as "The Sled" in recent years among many collectors.

Not too shabby, eh? This 41-226 photographs rather well.

But what is that on the right side?

Yes, it is a toggle switch. The original off-on switch, which was the first pushbutton on the left in the row of six pushbuttons above the escutcheon, no longer works. Instead of repairing or replacing the switch, someone merely drilled a hole in the side of this nice cabinet and installed a toggle off-on switch! ACK!!!

In this view of the underside of the chassis, you can see that electronic restoration has begun. I have moved the first IF transformer out of the way in an attempt to get to some of the old capacitors and rotten rubber insulation buried inside this small, cramped chassis.

I would eventually remove all three IF transformers to make the chassis easier to service. Of course, I made a number of notes before doing so!

In this photo, you can see that some of the wiring on the right looks very clean compared to the wiring in the center and on the left. The newer-looking insulation is heat shrink tubing. Notice how it looks very much like the old rubber insulation, only newer?

Some more capacitors have been changed in this photo. The 1st IF transformer has been removed and set aside to make the work easier.

Do you notice the old capacitor in the center of the chassis?

Here is a closer look at that capacitor. This was the original AC line capacitor, .04 uF. It was connected directly across the AC line.

This radio was advertised as working. I did something I normally do not do, and tried it out before I began to restore it. Oh yes, it did play, but not very well. After a few minutes, I heard a loud POP! Even though the radio continued to play and no smoke came out of the set, I unplugged it and set it aside until I began to restore it.

You can see that the insides of this capacitor have come out from one side. This was the result of the POP that I had heard.

Moral: Never plug in and turn on an old radio unless the capacitors have been replaced!

You may have noticed two old electrolytic capacitors on the left side of the chassis photo above.

I removed the old electrolytic from the cardboard tube of one of them, saving it to restuff with two brand new 22 uF, 160V electrolytics.

Here, I have the two new electrolytics connected to new wires, ready to stuff into the old cardboard tube.

The two new electrolytics are now inside the old cardboard tube. The ends have been sealed with hot glue.

This part will be one of the last ones to be installed into the radio.

Here is a view of the original off-on switch.

It's too bad that someone did not try to clean the switch before butchering the set by adding the toggle switch on the side of the cabinet.

Someone made sure this switch would never be used again, by clipping the wires nearly flush with the body of the switch.

This is the new switch which I will use. At this writing, it is still available at Lowe's home improvement stores. The package has this number: 1884U.

The actual switch (the black plastic part) appears identical to the original switch.

By drilling the two aluminum rivets on the new switch, it can be easily taken apart. Save that wafer insulator between the metal front part and the black plastic switch - we will be using it later.

Likewise, drilling the heads off the brass rivets will allow the original switch to be removed from the pushbutton assembly.

In the above photo, you can see how the new switch (right) is virtually identical to the original switch (left).

Notice here how I have left the original brass rivets protruding from the pushbutton assembly. I will use these to help assemble the new switch to the pushbutton assembly.

Also notice the original switch actuator, inside a spring, between the two brass rivets. This actuator is what makes the switch click on and click off.

Do not mess around with that actuator and spring! It can easily come off, and is extremely difficult to put back on!

In the photo above, you can see that the new switch has an identical actuator and spring.

The photo above shows the new switch in place.

Before installing the new switch, I removed the old wafer insulator and installed the new insulator in its place. I found that I also had to flatten the rounded end of the switch so that the pushbutton plunger would clear it.

I also found the mounting holes of the new switch were slightly closer together than were the mounting holes of the original switch. Enlarging the mounting holes of the new switch by carefully drilling the holes corrected this problem.

By holding the off-on button down, I was able to keep the left brass rivet post in place so that I could mount the new wafer insulator, and then the new switch, in place.

I used epoxy to hold the wafer and switch onto the pushbutton assembly. I used masking tape to hold the switch in place while the glue dried. A better method would be to remove the brass rivets and use small sheet metal screws to permanently hold the switch in place. Alternatively, the holes left when the rivets were removed could have been tapped for use with 4-40 machine screws. I'll have to try this the next time I have to replace one of these switches.

Here, the new switch is wired into the radio circuit. Notice that I used a double layer of heat shrink tubing on each soldered joint. Perhaps this is a bit of overkill, but I would rather be safe than sorry...

Finally, the chassis is finished! Notice the new capacitors and new heat shrink tubing in place of the old, rotten rubber insulation that was on the wiring. The AC cord is held in the hole in the chassis it passes through with hot glue.

Speaking of the power cord, I used the same cord someone had installed previously, as it is a new cord with a polarized plug. The polarized plug will ensure that B- is always connected to the neutral side of the AC line. (More on this below.)

I tried the set out, and it worked perfectly. Well, almost - the preset station pushbuttons were still dirty and finicky, causing some static when I used them. A later application of Caig DeoxIT D5 on the contacts of the pushbutton assembly cured the trouble and made all five buttons work properly. After using DeoxIT on the pushbutton assembly, I was able to set all five buttons to favorite AM stations. The first button is set to AM 740 (CFZM, formerly CHWO) in Toronto, which comes in strongly on this radio almost every night.

I am fortunate in that I have a few AM stations in my region that play music. So, the other four pushbuttons are now set to WSON (860 - Henderson, KY), WITZ (990 - Jasper, IN), WVJS (1420 - Owensboro, KY), and WBNL (1540 - Boonville, IN).

I did run into one problem during the set's alignment...

...I initially could not find the SW antenna trimmer!

Upon further study, I found that it was located on top of the chassis, next to the tuning capacitor.

The trouble is, you cannot see it unless you remove the 7C6 tube, as I have done in the photos above and below.

If you look inside the red circle, you will (barely) see the SW antenna trimmer.

I decided not to bother aligning the SW band on my 41-226. One reason was because the antenna trimmer is extremely difficult to get to. The other reason is that I found that SW alignment was OK as is; WWV comes in exactly at 10.0 on the SW dial.

So, here it is, sitting on my workbench. It looks nice, and it plays great. The sensitivity of this little set is simply amazing.

There is still the matter of the hole in the right side of the cabinet. I have decided to deal with that later. For now, I am just going to enjoy the radio as is.

A back view of the 41-226.

Important Modification of the Power Switch Wiring in Model 41-226

The power switches on most transformerless (AC/DC) radios were wired so that the neutral side of the line was switched. This is not desirable from a safety standpoint. The hot side of the line is what needs to be switched, so that the hot side of the AC line is disconnected from the radio when it is turned off.

In order to completely accomplish this, we not only need to move the switch to the hot side of the line, but we also need to use a polarized line cord. This is the type of cord with one blade wider than the other.

In the original 41-226 schematic diagram, you can see that the power switch (part 17A in the diagram above) is in series with the B- line of the radio.

An under-chassis view of the 41-226. This shows the original factory wiring of the switch and the power line.

The red lines show the original jumper leads between pins 4 and 7 of the 7B7 2nd IF tube. There is also a jumper from pin 7 of the same 7B7 to pin 8 of the 7C6, and yet another jumper between pins 7 and 6 of the 7C6.

The blue lines show how the AC line cord connects inside the radio chassis. The neutral goes to pin 5 of the 7B7 2nd IF tube, and the hot goes to the right end of resistor (48).

The green lines illustrate the original wiring of the power switch. Notice how the switch is connected between pins 5 and 7 of the 7B7 2nd IF tube.

In the partial schematic above, I have changed the location of power switch (17A) from the neutral side of the line to the hot side.

The pictorial above does a better job at illustrating what needs to be done.

As in the earlier pictorial, the red lines indicate jumpers between pins 4 and 7 of the 7B7, and between pin 7 of the 7B7 and pins 4 and 6 of the 7C6. Note how an additional jumper is added between pins 4 and 5 of the 7B7.

The blue wires again indicate the AC line. The neutral side of the line still connects directly to pin 5 of the 7B7. With the jumpers (shown in red) configured as shown above, the neutral side of the line is now connected direct to B-.

The hot side of the AC line is now connected to the power switch (shown in green). The other side of the switch now connects to resistor (48). This connection can easily be accomplished by conecting the hot side of the line cord directly to the wire going to the power switch. The other wire from the power switch goes to resistor (48).

A final note: Be sure that the ribbed wire in the line cord connects to B-. The ribbed wire is the neutral side of the line. The smooth wire in the line cord is the hot side of the line.

If your line cord does not have a molded-on plug, be sure you attach a polarized AC plug to it! And remember, the ribbed wire connects to the wider prong on the plug. The smooth wire connects to the narrow prong on the plug.