[morzh]

I found that, at least in mine, a 6U5 did not give much action.  It stayed perpetually bright and would not open and close.  I replaced it with a 6E5 with no circuit modifications and it worked perfectly.

[Image: http://cdn.instructables.com/FBC/CF9O/HF...MEDIUM.gif]

Which could also mean there is something wrong with the circuit.

[thirtiesradio]

Ron,
I found two unrestored chassis and underneath, this is the best of the two. It has had some capacitor replacements, and the local/distance switch has been partially removed but hopefully it helps. If not I have a restored one in a Walton cabinet I can pull out and get photos of this weekend.

[sam]

here`s shot of one 
http://www.flickr.com/photos/24503719@N0.../lightbox/
not mine

[Geoff]

I found that, at least in mine, a 6U5 did not give much action.  It stayed perpetually bright and would not open and close.  I replaced it with a 6E5 with no circuit modifications and it worked perfectly.

[Image: http://cdn.instructables.com/FBC/CF9O/HF...MEDIUM.gif]

Which could also mean there is something wrong with the circuit.

I replaced every single capacitor and resistor, testing them before installation, including the 1MEG in the eye tube socket.

[thirtiesradio]

That 1 meg in the eye tube socket almost always needs replacement if you want the eye tube to work correctly. Zenith should have put the resistor in the chassis, or at least made the socket less breakable.

[Geoff]

Ron,

Here are some shots of the underside of my chassis as found. I only have one shot from after I did a complete rewire (82 MB ZIP file):

https://drive.google.com/file/d/0B-05OmK...sp=sharing

- Geoff

[Geoff]

That 1 meg in the eye tube socket almost always needs replacement if you want the eye tube to work correctly. Zenith should have put the resistor in the chassis, or at least made the socket less breakable.

You are right.  Not much forethought by the Zenith engineers on that one.  I cracked mine trying to get at it but was able to glue it back together.

[Ron Ramirez]

Did Philco create under chassis drawings?

Yes! Not for every model (I recall some of the little Transitone home radios not having these), but most Philcos did have these.

From 1928 to early 1930, up to the model 111, Philco factory service info included a photo of the underneath of the chassis. The photos did not always reproduce well or clearly show details, so beginning with model 46, Philco switched to under-chassis drawings. These did not show all of the wiring, but do show placement and position of capacitors, resistors and other parts...which helps when you are in unfamiliar territory.

[Ron Ramirez]

Many thanks to Geoff, thirtiesradio, and Sam for the photos - those do help a lot! Merry Christmas!

[Geoff]

Did Philco create under chassis drawings?

Yes! Not for every model (I recall some of the little Transitone home radios not having these), but most Philcos did have these.

From 1928 to early 1930, up to the model 111, Philco factory service info included a photo of the underneath of the chassis. The photos did not always reproduce well or clearly show details, so beginning with model 46, Philco switched to under-chassis drawings. These did not show all of the wiring, but do show placement and position of capacitors, resistors and other parts...which helps when you are in unfamiliar territory.

Ron, you are right.  I forgot about the partial under chassis drawings Philco did that point out positions of parts.

[thirtiesradio]

RCA made great, detailed drawings for many of their sets to go along with the schematics and other info. It would be nice if others would have done that

[Arran]

That 1 meg in the eye tube socket almost always needs replacement if you want the eye tube to work correctly. Zenith should have put the resistor in the chassis, or at least made the socket less breakable.

It looks like the 1938 brand Z models used the infamous Eby magic eye sockets, so their role in this had little to do with designing the socket so much as selecting and acquiring a poor product. Those sockets are weird, rather then using a normal six pin socket and putting a cover on the back, the main body of the socket is a cap with cavities for each tube pin, the wire is threaded into each hole, the contact soldered onto each wire, and then a phenolic wafer snapped into the front to hold the mess together. The reason I know about these is that Canadian RCA and G.E sets from the early 40s used to use them, like a JK-70 or an A-22, which stupidly have the rectifier tube mounted right next to the magic eye cable roasting the wires to death. The 1 meg resistor can be dealt with without opening the sock, but a flaking cable cannot.
Regards
Arran

[Ron Ramirez]

Moving right along...

A warning. Do not purchase the 1/4" aluminum rod from Home Depot. It is ever so slightly larger than 1/4" in diameter...just enough that it will not fit in a 1/4" shaft coupling.

So I had to fall back to Plan B...

Two of the controls in my junkbox had to be sacrificed in order that I could have shafts for the volume control and the power-sensitivity switch.

Once I cut two shafts to fit, these were installed in the couplings...

[Image: http://www.philcoradio.com/images/phorum...62_012.jpg]

Here is the volume control now:

[Image: http://www.philcoradio.com/images/phorum...62_013.jpg]

and the power-sensitivity control:

[Image: http://www.philcoradio.com/images/phorum...62_014.jpg]

Notice that both couplings are far enough out of the way that they will not interfere with the indicators which display amount of volume and whether the radio is set to Off, On Local, or On Distance.

[Ron Ramirez]

Today I removed the Candohm...

[Image: http://www.philcoradio.com/images/phorum...62_015.jpg]

...and installed two terminal strips in its place:

[Image: http://www.philcoradio.com/images/phorum...62_016.jpg]

Like the volume control now in this Zenith, the terminal strips were salvaged from Philco sets.

[Ron Ramirez]

I think I have gone as far as I can go with this Zenith until the new parts arrive.

[Image: http://www.philcoradio.com/images/phorum...62_017.jpg]

Waiting for resistors to replace the Candohm...plus a few electrolytics...

I think that once I started digging into the set, it wasn't as bad as I thought it would be. However, I have to take some issue with that deep chassis that people seem to love; the depth of the chassis made it difficult for me to replace the .002 uF cap that connects from the 6F6G plate to its cathode.