Packard Forum Index » Post-War (1946-54)

Thanks to eBay I've manage to acquire 2 radios that could be used in my 1951 Packard 200, which makes for a total of three radios! The existing radio in my 200 has never worked (it hums and the dial light works, but the radio doesn't make any sound through the speaker). Each of the radios is different enough to be interesting:

1. Existing radio with black buttons (probably a model 416387)
2. A radio with chrome buttons and scratched off serial label (beautiful dial and buttons)
3. The 1951 signal seeking radio (model 416394)

My goal is to get the signal seeking radio to work as it has the most attractive dial and I plan to use a 6v MobilMitter device to connect my phone (via bluetooth) to the antena of the radio. This is all for fun and not for high fidelity.

Here's the plan - I welcome your feedback:
1. start by bench test all three radios to sort out which one(s) work.
2. use the working radio to test the bluetooth device
3. if the signal seeking radio doesn't work, start by testing the tubes inside the radio (but how?)
4. replace tubes until the radio works again
5. don't panic if nothing works!

I've also got the service bulletins for these radios which document the replacement tube part numbers. But I am not a qualified service technician so at some point I have to hand this over to someone more qualified to repair a radio from the early 1950s.

My friend Andrew has warned me about the signal seeking radio - that it draws alot of power, enough to dim the lights in his car when he changes stations! But I only need one station, the AM station that the MobileMitter uses as its broadcast frequency.

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On the lack of any sound, it probably is a problem with the radio but if you have the optional rear seat speaker also check that installation and make sure nothing was disconnected or damaged over the years. Instructions start on page 10 in the accessory section of the 51-4 service manual. Make sure everything is intact and connected per the diagram. Pay particular attention to the plug on the terminal board inside the radio. On some models of the radio the terminal board is in a very awkward to reach spot and when disconnecting and making the wire change the terminal can get damaged -- sometimes to the point a wire can be loose or plug can easily fall out. The speaker connection to both speakers is lost or erratic and no sound at all or a lot of static can result if that happens.

On the signal seeking radios, there is a large solenoid that pulls the needle back to the starting position when the sweep across the dial reaches the end. That is what is pulling enough current to dim lights so the radio does need a good solid supply voltage capable of continuously supplying at least the rated fuse amps -- more is better. Bench testing with a small jumper wire or inadequate size battery or power supply can result in the solenoid not getting enough current to work.

My friend, who rebuilds antique radios for a hobby, took on fixing my signal seeking radio, and did a great job. It's been working great for the past 2 1/2 years, and is a super cool feature.

He replaced quite a few resistors & tubes, aligned it, tuned it, etc. All of which is way above my pay grade!

First of all, if you can hear the thing humming along but have absolutely no static out of the speaker then you probably just have a bad tube. Pull the radio out of the car and plug it back into the wire under the dash. Ground the case and turn it on with the cover open to expose the vacuum tubes. Most likely you will see one that does not light up. Be careful to not touch any internal parts when the radio is on as it uses like 200 volts to operate.

Turn off the radio and take it back to the bench, swap the problematic tube for one out of your parts radios, and try it again.

If you can hear crackling out of the speaker but no reception, make sure the antenna is plugged into the radio and the wire isn't messed up somehow. Happens more often than you would think, sometimes it gets damaged from people doing sloppy under hood repairs in the past. And there are a surprising number of people that literally could not care less that they don't have a working radio, so such problems can occur many years in the past.

The 0Z4 cold cathode rectifier tube is a common failure part that will keep the radio from operating

True and you can easily test its operation by checking the output voltage with a 600VDC multimeter, unlike the rest of the circuits which need a scope.

What I was trying to point out with my radio repair, which I see now I didn't make clear, is that even once the radio was powered up and "working", there were several still resistors and other components that were out of spec and needed to be replaced so the radio worked well, and would be reliable.

Resistors used in the 50's are not only old, but not nearly as reliable as modern ones.

Yes the passives can cause issues. Resistors usually not, but the capacitors were made with a wax paper and they can drift like crazy with age.

You can actually buy replica paper caps which are normal ones with a decorative covering, for people doing guitar amps and such that need an authentic retro look with components visible.

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Thanks for the advice about repairing my signal seeking radio - esp about the high voltage waiting for me inside the radio! Will give this a try and let you know what happens.

If you check out my '54 Project Blog you find more details, but here is a video I did on my converted signal-seeking radio:



This will give you AM/FM/Bluetooth, and all the radio controls will work as they should. The cost is not that much more than having someone fully service your AM radio.