Philco 46-420 restoration
 

I was wandering around my neighborhood today and went into a new vintage resale shop. They have lots of cool stuff - furniture, albums, jewelry, and nick-nacks. A few early Polaroids too. Way up on top of a bookshelf I spied this Philco 46-420 "hippo". The price was right so I picked it up. http://www.bobandersen.com/images/smileys/fruit.gif

The cabinet is in fantastic shape. No cracks - just needs a good cleaning. The inside look pretty clean too. The back is missing, but I think someone out there makes reproduction backs :scratch2:

I hope to get it working real soon :)

http://www.bobandersen.com/images/ph...0/hippo-01.JPG http://www.bobandersen.com/images/ph...0/hippo-02.JPG http://www.bobandersen.com/images/ph...0/hippo-03.JPG http://www.bobandersen.com/images/ph...0/hippo-04.JPG

Retro-Tronics has a back for this model. I don't see any screw holes. Maybe friction keeps it in place?

Yep, 50B5.

Awesome! You have the service bulletins for almost all my other Philcos too :D 15DX, 37-60, 38-10 and 39-30.

Now I just need to find one for a 37-10 & 643.

Thanks! Here ya go - enjoy :)

I found a nice label on the bottom.
http://www.bobandersen.com/images/ph.../hippo-101.JPG

I used a little windex followed by Novus #2 to clean it.
There's still a little gunk on the knobs. I've been using a toothpick to clean out all those grooves, but my hands are pooped. :drool:
http://www.bobandersen.com/images/ph.../hippo-102.JPG http://www.bobandersen.com/images/ph.../hippo-103.JPG

There's a little crazing in the clear plastic, but I don't think it's worth messing with.
http://www.bobandersen.com/images/ph.../hippo-104.JPG

Next up - the chassis. The audio transformer has broken off the speaker but looks intact. Other than that it looks pretty easy.

Octal, loktal and miniature tubes in the same radio. Weird!

I have a similar one with two octal tubes (rectifier and audio output) and three
loktals, but I have never seen one like this.

Interesting indeed. Philco's TVs have a weird lineup too including loktals.
Here's what Reece had to say before my thread was "purged":

I started working on the electronics last night and ran into a few issues. First, someone has replaced the original field coil speaker with a PM one.
Now instead of a 500 ohm coil, there's a 220 ohm resistor feeding the audio output tube and output transformer and a 1.2 K resistor feeding the other tubes.

Wouldn't a single 500 ohm resistor be more appropriate? Were they trying to boost the output power?

http://www.bobandersen.com/images/ph...420/sch-01.jpg

The other issue is with what is labeled C14 and L1 on the schematic connecting the chassis ground to earth.
The existing parts are a 0.02 uF cap with a few turns of plastic insulated wire. Does anyone know the purpose of this? Maybe a noise filter ?

My modern 0.022 uF caps are a lot smaller and a rewound coil won't have the same inductance.
Any thoughts on how to replace it?
Here's the old one behind that big yellow cap.

http://www.bobandersen.com/images/ph...-420/01-01.jpg

I had the same cap wrapped in wire in my Philco Bing Crosby phono radio, and I just inserted the much smaller modern cap through it, and just left it that way. My radio doesn't seem any more prone to interference than any of the others in my house. Perhaps this was to cut down on noise from car generators?

Thanks, I'll give that a try.

Must be my lucky day.
I have a friend in Boulder, CO who's picking up this Philco 46-420 for me tonight. It's exactly the same even - has the little audio output tube and a good back! It has a cracked case, but I should have no problem making one complete working radio now :D

Backs are available from Radiobacks.com. Also, I have a couple spare cases for these.

I have several of the late 1940s Philco radios that use this case. Some have all loctal tubes, some have a mixture of octal and loctal, and some have a mixture of all three types-lockal, octal and minature. The have a nice sound and have good reception when restored. All of mine came with orignal PM speakers.

That's odd - the schematic shows a speaker field coil that doubles as a filter choke. How is the power supply wired in yours that have a PM speaker?

I will need to find a schematic, but have the following information. I do have a 46-420 and it does have a speaker with a field coil winding-not PM. Philco made radios using this case until 1949(49-XXXX) at least. I looked at one of my 1949 models and it has a PM speaker. Once I look at a schematic, I will re-post.

Banderson-I the case of postwar Philcos, I have never found two chassis that were exactly alike, different tube lineups, pm and electrodynamic speakers, "anything goes" values for noncritical caps and resistors, etc. These guys were almost built on a case by case basis. I'm sure it drove everyone at the factory nuts.

In the case of my Philco, the Rider's consists of two pages of info, and I have the Philco memo that consists of about fifteen pages of design changes!

Ugh - no wonder I'm a little confused :headscrat.