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.

The back is held on by clips that fasten to the back and held to the case by friction.

I have found the schematic for a Philco model 48-460 which uses a PM speaker and the same case as yours.

The filter network in this radio is a 30ufd on pin 7 of the 35Y4, a 220 ohm resistor, a 25 ufd cap, then a 1200 ohm resistor, and finally another 30 ufd cap.

The speaker output transformer is tapped into the center 25 ufd cap. The rest of the radio is powered from following the 1200 ohm. See below.

***************** --------------- to audio out transfromer.
*****************|
***********220***|****1200
35Y4 -------\/\/\/\/------\/\/\/\/-----to rest of radio
******|***********|*******|
******----*30*****----- 25 *----*30
******----********----- ***----
******|************|*******|
******---------------------------
******************|
****************------
*****************----
******************--

The tube lineup is 14AF7, 7B7, 7B7, 7C6, 50L6, 35Y4. Please excuse the *s, for some reason when I posted, my spaces in the picture were wiped out so I replaced them with *.. Probably related to crappy Microsoft software.

Thanks!
That's exactly how my filter network is wired except I have 7C7, 7A8, 7B7, 7C6, 50B5, 35Z5 . So it is original after all :)

Good luck with your restoration. I like the sound and the excelent reception of this type of late 1940s Philco radio.

I am near Austin, Texas and the nearest AM station that plays music that I like is in San Antonio, 60 miles away. These receive the station fine. Other radios that I have without a RF stage or two IF stages, have a hard time.

Sister set arrives from Boulder
 

My buddy in Boulder, CO just sent me this set with a big chip missing.
Exactly the same 46-420 variation - PM speaker, 50B5 audio output, etc. How crazy is that!

http://www.bobandersen.com/images/ph.../hippo-201.JPG http://www.bobandersen.com/images/ph.../hippo-202.JPG

Best of all - it has the original back :banana:
http://www.bobandersen.com/images/ph.../hippo-203.JPG

It's a little warped, but maybe I can steam and flatten it out? :scratch2:
http://www.bobandersen.com/images/ph.../hippo-204.JPG http://www.bobandersen.com/images/ph.../hippo-205.JPG

I've started recapping the other set and hope to power it up tonight or tomorrow.

As mentioned before, I have a couple of empty cases for these. Do you want to have two restored radios?

Well, I had been just focusing on getting one working, but I supposed it would be silly not to restore both!

PM sent.

Looks like all the tubes are the originals Philcos and they test real strong :banana:

Maybe this set did see much use. I'm gonna try powering it up later tonight for the first time.

I finished recapping and replacing out of spec resistors. I powered it up but only get a loud hum - the tuning and volume controls have no effect :(

I'll double-check all my work - I hope it's nothing serious like an open coil.

As to that back, spritz it good with water on the side towards the inside of the radio, flatten between weighted boards, leave for a few days to a week.

Reece

Just use a signal generator to inject signal along the line, you'll find the fault. You can also just apply a soldering gun to the center terminal of the volume control, which should give you a hum if the audio amp is working okay.

Maybe you'll get lucky like I did with mine and find that the grid cap on the audio output is shorted to a pin on the rectifier socket. That is a pretty cramped chassis under there!

It sure is cramped.
I pulled out my second chassis (the one that just arrived from Boulder) and quickly tacked some new electrolytics in. Bam! Works just fine :music:

Great sensitivity and a lot louder than I expected. That skinny 50B5 output tube runs pretty darn hot though.
I wonder if that's normal or it's biasing is off a bit? Some of the resistors have drifted a bit and I haven't swapped them out yet.

I'll do some more checking tomorrow.

Thanks for the tip. I'll give it a try.

Re-stuffing electrolytics
 

I'm just about done restoring one of these 'hippos'. It's playing great with excellent reception. I decided to re-stuff the one electrolytic for a final touch. I've restuffed a few metal can types, but never a paper/wax one.

Here's how it went.

First I pulled the old caps. out of both radios. 3 new caps need to go into each one.
http://www.bobandersen.com/images/ph.../hippo-301.JPG

I tried heating up the caps to free up the innards. After a few minutes I gave up :yuck: The tubes were starting to fall apart which is the only part I cared about salvaging.
http://www.bobandersen.com/images/ph.../hippo-302.JPG

Why not roll my own?
http://www.bobandersen.com/images/ph.../hippo-303.JPG

I painted them yellow with some kids paint.
http://www.bobandersen.com/images/ph.../hippo-304.JPG

Then I made some water-slide decals using paper left over from another project.
http://www.bobandersen.com/images/ph.../hippo-305.JPG

I also 'dirtied' them up a little using a light spray of flat black paint. I don't want them to look brand new. The original is in the middle.
http://www.bobandersen.com/images/ph.../hippo-308.JPG

Next, I soldered the 3 caps together and reused the original wires.
http://www.bobandersen.com/images/ph.../hippo-310.JPG

Finally, I inserted the caps and filled up the tube with wax. First, I stuffed up one end and filled it 3/4 with wax. Then removed the plug and filled the other end.
http://www.bobandersen.com/images/ph.../hippo-312.JPG

One down, one to go :D
http://www.bobandersen.com/images/ph.../hippo-315.JPG

Thanks- that shot of those caps puking their guts out is just what I wanted to see before sitting down to Thanksgiving dinner. Have a great holiday!

ps- where did you get your waterslide decal paper from? Is it inkjet printer friendly?

I never thought about using water slide for caps. I bet that would work with a scan of a paper cap tube that was unwound also.

I normaly don't care to go to that much effort for originality, but I have an Arvin what I'm found of.

John

Neat re-stuffing! Very "fulfilling" on turkey day.

LOL - maybe I should have waited a day to post those pics :D Hope you had a good dinner.

I got my paper from this place. It works fine with an inkjet printer. Use it like you would glossy photo paper.

I've used it before to make decals for TV controls like this. They recommend using clear acrylic for the decal backing but I used lacquer. Works just fine.

I normally wouldn't bother either, but I was curious to give it a try.

I've got them both running
 

The turkey must have jogged a few brain cells, because I finally found the problem in the first set.
When I recapped it, I inadvertently broke a crucial ground connection :o Those two tube pins should be shorted together!
http://www.bobandersen.com/images/ph.../hippo-401.JPG

Here's one of the radios all done with the rebuilt cap in place. I added a safety cap across the AC line and added a fuse.
http://www.bobandersen.com/images/ph.../hippo-402.JPG

I found a faucet washer that works well as a cushion between the cord and chassis.
http://www.bobandersen.com/images/ph.../hippo-403.JPG http://www.bobandersen.com/images/ph.../hippo-404.JPG

I took Reece's suggestion and spritzed the back with some water and placed it between two metal plates with a little weight for a few days.
It came out real nice :banana: Just a little stain when there was already a break in the board. I'm going to try making a copy with some masonite.
http://www.bobandersen.com/images/ph.../hippo-405.JPG http://www.bobandersen.com/images/ph.../hippo-406.JPG http://www.bobandersen.com/images/ph.../hippo-407.JPG

I cleaned all the contacts and oiled up the tuning capacitor. They're both playing really well now :hdphones:
I hope Jody's white case makes it in one piece :scratch2:
http://www.bobandersen.com/images/ph.../hippo-410.JPG http://www.bobandersen.com/images/ph.../hippo-411.JPG

Replacement case has arrived
 

peverett (Jody) sent me this case to replace that broken brown one. It's in great condition aside from the flaking paint.

Any suggestions for stripping it off? I'll be repainting it white.

http://farm3.static.flickr.com/2519/...7042bd2819.jpg

http://farm3.static.flickr.com/2612/...b9d3b908_b.jpg

I have used various kinds of paint stripper on Bakelite, from gel types to old-fashioned zip strip. Some people also use oven cleaner. None of that stuff will faze Bakelite a bit, so use whatever you like.

Resist the temptation to scrape. Repeat: no scraping. If you're lucky, the original Bakelite will have been protected by paint all these years, and may still have that gorgeous shiny-new surface. If the old paint doesn't turn to mush and wipe off, be patient, apply more stripper, and come back later.

I have stripped a couple of sets that looked so nice after stripping, I couldn't bring myself to paint them again. Here's one.

http://www.antiqueradio.org/art/farn021.jpg

Phil Nelson

Thanks Phil, I give my favorite strippers a go. It does look pretty good where the paint already has flaked off which is going to leave me with your dilemma. Do I paint it ?

I've seen some wild color combinations online. I thought the only productions colors were bare bakelite and painted white ?

Pay no attention to the loons who paint old radios glitter green, popsicle purple, etc. They are going straight to Hell without passing Go.

Phil

Why don't you tell us how you really feel? :D

Seriously though, I've been searching for example photos of several radios I picked up recently and have seen some really horrible restorations. Horribly overpriced too.
Like this Philco 38-10 with it's photo-finish completely gone :wtf: On sale for only $350 :rolleyes:

Anyway, the stripping has begun :yuck: