Jump to content

1951 Pontiac Chieftain


PhilA

Recommended Posts

(also I will require a picture of all the tubes glowing in operation when you do get the radio :) )

Going over the schematic, they're all metal can tubes apart from the two in the power output section (V6GT). Not much will glow in this case.

 

A few of them are loctal though.

 

Phil

Link to comment
Share on other sites

very interesting how the Radio uses a vibrator to generate crude AC for the power tranny

 

im guessing the tranny also has high voltage windings for the grid voltages n stuff?

 

a vibrator+Ballast is how some early DC fluorescent fixtures worked :) as seen here https://www.lighting-gallery.net/gallery/displayimage.php?pos=-102721

 

im really curious what RTC1 used http://www.countrybus.org/RT/RTC1.htm its said to have used fluorescent lighting, in 1947!

Link to comment
Share on other sites

I was asked by someone else if the exhaust hotspot on my manifold works still.

 

post-5454-0-11302100-1553557007_thumb.jpg

Up inside the exhaust is a spring loaded plate, whose purpose is to deflect some of the exhaust gases upwards onto the base of the intake manifold directly below the carburetor.

 

This is to try and prevent liquid fuel from pooling below the carb as the manifolds are still cold enough for this to happen. When fuel ignites in the manifold it causes pops and bangs backwards out of the carburetor. This is undesirable and a fire risk.

 

post-5454-0-81645300-1553557152_thumb.jpg

On one end of the spindle is an excentric mounted weight, the other a bimetallic coil spring. The coil spring holds the weight up and the flap closed until there's enough heat in the exhaust to allow it to open fully and not impede exhaust flow.

 

post-5454-0-94238700-1553557290_thumb.jpg

Heating the bimetallic spring allowed the weight to fall and the flap to open. Simple but sturdy engineering.

 

Phil

Link to comment
Share on other sites

I showed the kids the picture of the radio I ordered; question was provided.

 

Was it in black and white back then?

 

 

What, black and white radio?

 

 

Yeah.

 

 

 

 

 

 

.....

 

 

 

 

 

 

At least I can say I didn't spawn these children.

 

Phil

 

ahh nothing like a bit of good old American and millennial stereotype mixing :)

 

you should of said "No it was Black and green!" and whipped out a Magic eye tuning tube  :mrgreen:

Link to comment
Share on other sites

So, there's still no radio. Last checkpoint was in Minnesota.

 

I hope it's not what happened to my friend's wedding ring. He sent it addressed to Luenberg in Canada to be resized. It ended up in Luxembourg. Not entirely sure how it ended up not only in the wrong country, but entirely the wrong continent...

 

I hold out hope that it'll arrive tomorrow. Maybe.

 

Phil

Link to comment
Share on other sites

post-5454-0-42153500-1553651103_thumb.jpg

 

Sat down and drew out the circuit diagram for the audio amplifier of the radio. I needed to get a better understanding of the circuit and how it functions.

It's a class AB phase inverted "push-pull". Standard common cathode arrangement as used by Marshall, Fender etc in their guitar amplifiers.

 

I can definitely add auxiliary in. Just trying to figure the least hacky way to do it, and have it correctly squelch the radio too.

 

Phil

Link to comment
Share on other sites

post-5454-0-43921100-1553725134_thumb.jpg

There is radio.

 

post-5454-0-29994700-1553725164_thumb.jpg

It's actually pretty clean inside, though. Looks like the original Delco branded tubes, though the output tubes are an approximate substitute, again Delco branded so probably a repair.

 

The tuner is twisted and cracked. I hope the coils aren't junk- if I can straighten it out hopefully it'll be good. It's moving slug tuned could rather than variable plate. Better for a moving vehicle and allows for the preset buttons.

 

Complete take-apart shall occur!

 

Phil

Link to comment
Share on other sites

That looks quite pleasant to work on compared to some car radios from the era. I repaired one for a friend from the late 50s (Zenith branded I *think*) which was without doubt the most maddening bit of equipment from the valve era I had ever had the misfortune to work on. The whole experience could be summed up by comparing it to a car where you had to remove both axles and diamante the entire gearbox (without removing it from the car) to change a spark plug.

 

The fact that the thing was horiffically unstable unless the case was fully assembled and screwed on made testing a real chore too.

 

I did eventually get the cursed thing going, but made it absolutely clear that while I considered them a friend that any further work on that particular set would need farmed out to a specialist as I didn't ever want to touch it again!

Link to comment
Share on other sites

I have a feeling this one will be a bit fiddly to get right.

 

I just freed the tuner up. The casting that holds the tuning coils at the back is suffering from the same metal degradation that toy car collectors fear. It's not too bad right now but it's slowly falling apart.

 

post-5454-0-50893100-1553743162_thumb.jpg

The front comes off, the speaker is connected with a bullet connector to the output transformer.

Whoever designed this (Sylvania) definitely got it right.

 

The circuit itself isn't bad; 7 wax paper capacitors. One big can capacitor for input smoothing (that's gone really funny and leaked) and a bunch of high value carbon comp resistors that be replaced for high stability versions.

 

Phil

Link to comment
Share on other sites

post-5454-0-78391200-1553744996_thumb.jpg

Zinc pest in action. The casting has swollen in size, forcing everything out of line.

I may have to attempt to remanufacture an alternative if that one falls apart completely. It's not far off doing that.

 

post-5454-0-15961300-1553745114_thumb.jpg

Preset mechanism now works properly.

 

post-5454-0-54529100-1553745160_thumb.jpg

Q-tips and tape machine oil. Nice high viscosity stuff that clings well. Cleaned up the face a little- the screen print on the glass is going a little funny but it's still there for now. Shame it was just printed and not etched.

 

The buttons should come off. Just need to figure out how. They're designed to be pulled on so it's not a case of just pull on them...

 

Phil

Link to comment
Share on other sites

The same as a number of people on here, I'm going to say "It's only another mechanical device".

 

Broken down into constituent parts, an AM tube radio is a moderately simple device. Make sure that each individual section does what it's meant to do and as a whole it'll come together.

 

The car will never make Pebble Beach. Pebble Mill, maybe.

 

Phil

Link to comment
Share on other sites

thoroughly enjoying the Valve radio restoration so far :)

 

especially as iv spent far too much time watching https://www.youtube.com/channel/UCJ6nWQ7UO-Lve9ji2FUNYwg restore his valve Radio and TV sets  :mrgreen:

 

(I have an old 1950s Philips Valve radio here U131, https://www.doctsf.com/documents/schematheques/radio_anglais/PHILIPS/131U.PDF thats in good cosmetic shape, but somethings shorting the mains, verified via a dim bulb tester and a variac, only problem is iv not been able to figure out how the damn thing opens up, normally the chassis just slides out the back, but in this case theres some elaborate string mechanism for the tuner dial i guess, tying the chassis to the body, and im worried about snapping the string/breaking the mechanism)

Link to comment
Share on other sites

thoroughly enjoying the Valve radio restoration so far :)

 

especially as iv spent far too much time watching https://www.youtube.com/channel/UCJ6nWQ7UO-Lve9ji2FUNYwg restore his valve Radio and TV sets :mrgreen:

 

(I have an old 1950s Philips Valve radio here U131, https://www.doctsf.com/documents/schematheques/radio_anglais/PHILIPS/131U.PDF thats in good cosmetic shape, but somethings shorting the mains, verified via a dim bulb tester and a variac, only problem is iv not been able to figure out how the damn thing opens up, normally the chassis just slides out the back, but in this case theres some elaborate string mechanism for the tuner dial i guess, tying the chassis to the body, and im worried about snapping the string/breaking the mechanism)

Ah, the dreaded word...Philips.

 

There's the way everyone in the industry does everything, then there's the way Philips do it.

 

There's always at least one really odd aspect to any set they've made, and the tuning cord setup is often guilty. I did have a look to see if it's one I have the service data for on file, but sadly not.

 

 

Phil, is the zinc section of the tuner bracket electrically/magnetically involved in the operation, or does it just hold those (ferrite?) sleeves in place? If it is just a bracket, I reckon 3D printing may well be a sensible way to get a new one made up. If it *does* need to be metal...yeah, that gets more tricky!

Link to comment
Share on other sites

The casting appears to do both; shielding for the center and holding the ferrites. It doesn't support the coils, that's done by rubber bungies mounted to the circuit board. The cores are free to wiggle a little.

 

Making another would be fairly easy. Block of aluminum, drilled 3 times. Steel cap screwed on the back, drilled to accept cores.

Top of block fitted with spacers for the circuit board and long screws to hold it in place. Frame screwed to the sides of the block.

 

Possibly sawn down to separate the 3 bores to reduce eddy current.

 

Phil

Link to comment
Share on other sites

The same as a number of people on here, I'm going to say "It's only another mechanical device".

 

Broken down into constituent parts, an AM tube radio is a moderately simple device. Make sure that each individual section does what it's meant to do and as a whole it'll come together.

 

The car will never make Pebble Beach. Pebble Mill, maybe.

 

Phil

 

 

there maybe a problem there :unsure:

 

post-17711-0-99440900-1553813695_thumb.jpg

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...