project 1951 Pontiac Chieftain

[PhilA]

I rode in an elevator that had etched side-lit numbers in a little window for the floor you were on.

 

That's the only time I've ever seen them in use. They have one advantage over nixies, and that's intensity of the digits- neon ionization reaches a maximum useable limit quite quickly.

 

On the other hand, the clock I have has one really neat feature- it uses PWM to change the intensity of each number: net result is each digit can fade into the next. Watching at a slight angle is mesmerizing because the numbers jump back and forth as they change.

 

 

Phil

[Asimo]

I failed a long time ago at repairing a vibrator-supplied car radio The vibrator had extra contacts for synchronously mechanically rectifying the HT. I think I remember it being a Phillips. Very large and heavy, must have cost a fortune to make. Lots of lead and lots of cadmium.

[PhilA]

From what I read, this is a Sylvania design manufactured by Delco.

 

Philips just made some really weird stuff. Including all the way through into the seventies.

 

Phil

[PhilA]

Most excellent. eBay just lightened my wallet again. 12V variant of the radio (Buick fitment) won. Shipping thing reckons it'll be here by the 15th.

 

It's been a long while since I bought a "bid" item, normally I hunt for the BiN items because I abhor bid sniping software.

 

Phil

[PhilA]

That's not too bad. Just do it one component leg at a time and you will be fine.

If the leads are all wrapped as well as soldered I would just snip one leg, solder the new one in, snip the second one, solder replacement in.

Component count is low enough it shouldn't take too long really.

What has helped is sitting down, going through the parts list, identifying each bit and getting a much better idea of where what part of the schematic is on the chassis.

 

The next thing is this one's 7C5's for the AF stage, which are Loctal base and a different pinout to 6V6's.

Why would you want to transpose pins and have it so that if you plug a 6V6 in (like it says is a valid option) that the heater is across the plate and cathode pins on the 6V6?

 

How silly. That would be very very bright for a fraction of a second...

 

 

Phil

[Frogchod]

All this talk of old radios has made me wish I'd stayed awake during electrical and electronic principles at college.

Even if I did stay awake I doubt I'd remember relativly obscure stuff from 1982

I do remember sniggering at "thermionoc emissions" then I glased over, thinking I'd never need or want to know about valves.

I did stay awake long enough to work out v=I x r ,but that's about it....

 

Btw, great thread

[PhilA]

Well, more fun trying to determine what tubes I need to get; 14C5 for the power output stage.

 

Spent a bit of tonight sitting down comparing the two circuits.

 

The 1956 circuit has been economized a little (probably in the name of reliability- a transformer is more reliable than a vacuum tube), the tone circuitry has been minimized down to a capacitor and a variable resistor and the phase inversion circuit has been replaced with a center tap transformer.

 

The tuner potentially looks to be identical, so hopefully if this frame is in better shape it may be able to be transplanted.

 

We shall see!

 

Phil

[Sir Snipes]

All this talk of old radios has made me wish I'd stayed awake during electrical and electronic principles at college.

Even if I did stay awake I doubt I'd remember relativly obscure stuff from 1982

I do remember sniggering at "thermionoc emissions" then I glased over, thinking I'd never need or want to know about valves.

I did stay awake long enough to work out v=I x r ,but that's about it....

 

Btw, great thread

Lol 3 years later and all I can remember is 2πfl. Inductive resstance something something. Oh and 1/ 2πfc, inductive capacitance something something.

[PhilA]

I've found the transmission overhaul manual for this particular gearbox variant.

 

Sitting reading through it, it's quite the complicated contraption. I think best things first will be to hook the engine to the crane, wheel the assembly outside and clean the outside of it thoroughly with degreaser and a toothbrush.

 

The manual repeats over and over and over CLEANLINESS INSIDE THIS GEARBOX IS VITAL.

 

I understand that, but evidently a single particle of dirt can cause havoc.

 

Fun times

 

 

Phil

[tooSavvy]

Don't confuse your bands with your disc pak...

 

 

Rockinn, Bro

[PhilA]

Tonight we are back to the oily bits, if not just for a short while. Weather's a little warm right now compared to how it was Sunday (9c Sunday, 27c today).

This evening was spent making it all a little more clean. I need to get some proper engine degreaser, rather than using carpet shampoo...

Phil

[PhilA]

My radio made a rest stop in Barstow, TX.

 

Maybe it'll be here by the weekend. I can't see it wanting to stay in Barstow, TX.

 

Barstow, TX. From Google Street View...

 

 

There's not much in Barstow, TX. It's Big Sky country.

 

Phil

[PhilA]

Next stop.

[Zelandeth]

When looking for something totally unrelated I stumbled across a photo of the bench meter which lives on my currently buried workstation.

 

 

Simply because Nixie displays make everything better.

[PhilA]

Radio overshot and checked in all the way up in Memphis, TN.

 

Could be worse; that's FedEx's southern hub.

 

Tonight I had a little time so restarted on stripping the engine back down again. Turns out someone actually forked out some money- the starter motor is stamped 12V.

 

Thorough cleaning has begun. Gearbox so it's clean to take apart, engine so it's clean to paint.

 

Phil

[PhilA]

So I check the tracking on the radio and FedEx have had a sudden bout of efficiency. The delivery date had changed from Monday to 2:53am YOUR PACKAGE IS ON A TRUCK FOR DELIVERY TODAY

 

Typically today I have to go to town with the missus to go shopping for upcoming wedding.

 

Oh well. It's due to rain. Hopefully they'll leave it tucked up in the porch out of the weather. I might leave a plastic bag for it with a note.

 

My life, reduced to a scrubbing brush and checking FedEx. Woo.

 

Phil

[hairnet]

Thunderstorms in Texas

 

Moto GP not running not cos rain but thunder and lightning

 

Phil you reckon it's be fun skateboarding down that??

[PhilA]

Depends on what's off to the left of the picture, out of shot. A big pile of pillows, maybe fun.

 

Spectator parking lot not so much

 

 

Phil

[hairnet]

motogp happening after 3 hours

 

unfortunately the pace car isnt a 72 cutlass its a shit modern bmw

[PhilA]

Yeah, they're leaving the classics at home these days.

 

Either that or they do a 22 1/2 mph parade lap

 

Phil

[PhilA]

I arrived home from shopping. There was a box waiting.

 

Fragile fragile fragile! It states.

 

Pop the top of the box open. It's like Christmas.

 

Looks in pretty good shape overall.

 

Popped the back off on the bench. All looks pretty good, but oh, what's this?

 

One of the power output tubes has succumbed to FedEx.

 

Shame, but I hadn't planned on using those tubes anyway. The tuner, as suspected, is the same and is in good shape. Serviceman notes on the top "Pops on and off". Bad capacitors, then. Notes show it was purchased in 1956 by a gentleman by the name of Snyder in Pomona, CA. That would explain the lack of rust then.

 

More to follow!

 

Phil

[PhilA]

Pulled the front off also.

 

Similarities in the design become apparent. Simplification of the design to save on parts, also evident.

 

Looks like it went into the radio shop for repair and never left. It's got all the original Delco Radio capacitors inside.

 

There's a few subtle differences but overall this be good. I think the tuner coil housing will be being transferred also.

 

Phil

[PhilA]

Thermionic glow.

 

Powered it up gently and we do see B+ of 220 Volts so that part of its working. Without this tube though- nada.

 

For those of you who want to see what the inside of a 12V6GT looks like.

 

I also redact the blame of FedEx- there was a spider inside the tube, all crispy and read. That's been broken a while...

 

Phil

[PhilA]

 

Because it didn't go pop or smoke up. It's operating in single ended class B output there with a single tube but that's not bad for being peered up for the first time in probably 40 years.

 

Phil

[PhilA]

Radio scrapyard begins. That's big old tin of spam there is the power transformer. Unfortunately I'm going to have to carefully undo it because there's a big paper capacitor inside that needs to be changed (that particular one is known for going up in smoke, in that position in the circuit because it never gets changed).

 

I looked and I think the two chassis are actually interchangeable in the frame. Must resist putting in the simpler one because it's simpler to work on...

 

 

Phil

[PhilA]

Hmm. Two schools of thought on the design of the circuit. Perhaps the later model isn't such a bad design after all. Lower quiescent current, for sure.

 

Now I'm torn. I may swing the new chassis in there after all. More research to follow. The power transformer had to come out regardless, for that capacitor.

 

Phil

[PhilA]

Okay, doing a little reading and the choice of circuit design makes sense now.

 

The '51 is a higher fidelity design (haha on an AM radio) with a phase splitter circuit driving the output transformer in AB1, which ultimately gives good frequency response, down to the speaker and output transformer choice being the deciding factors on how it sounds.

 

The later version uses a phase splitter transformer. This provides very low input impedance so you can drive the tubes in class AB2 and really push a lot of volume- make it loud at the behest of distortion figures. Which, in the application of car audio doesn't really matter.

 

So

 

Design 1 runs a bit hotter but technically is a a cleaner circuit. Circuit 2 robs a little fidelity to provide punch.

 

I don't need a loud radio. Phase inverter tube circuit it is. Particularly with high quality input such as Bluetooth. I need to check if the loudspeakers are the same impedance because the '56 sounds better than the '51, I think being stored in a drier environment has helped the cardboard cone to stay more supple.

 

Phil

[Sir Snipes]

That whole post could be complete psuedo science nonsense and I literally would have no idea.

I suspect Phil might be well be trolling us by posting nonsense and waiting to see if anyone sports it. I believe this may similar to what cool internet kids call "smurfing"

 

I KNOW YOUR GAME MATE.

 

Edit; LBF or SiC may know but are probably in on the joke. IT'S A CONSPIRACY I TELL YOU.

[tooSavvy]

^^^ ah, Radio Nerd Alert.

 

I'm slightly in awe... During WW2 young lads yomped about carrying 'field radio packs' and being very important for allowing rapid *effective deployment of assets.

Fixing #hit like this, in a wood/in the rain, miles from anywhere was like Voodoo...

 

Came home and promptly sent rockets/aircraft off to blue horizons & built electric guitars/amps.

 

*footsoldiers have their own opinion of High Command.

[LightBulbFun]

all very awesome stuff!

 

I love a good thermionic device restoration

 

although sadly I dont know enough to comment much useful, other then its Awesome! so I just go round liking every post

 

(but luckily I do know enough to know whats going on, for the most part anyway!)