Any AM radio experts here?

[50Champ]

I got my radio back today from the guy I sent it to in New York about 7 weeks ago. I talked to him on Thursday and he said it works great. He replaced several things and did some other work to it including replacing the speaker. Anyway, after installing it in my car today I can't get it to work. I took it out and put in on the car's floor and I know it's getting power because I can see some of the tubes lighting up. I plugged in the antenna but nothing happens. I ran a ground wire from the top of it to a bolt under the dash by the glove box but that didn't help. Does anyone have any suggestions on how I can get it working?



1950 Champion 2 Dr. Sedan

[countryboy]

Dave, you are at the end of your problem determination as you have already done everything that a novice would be able to do other than shot gun the thing. If the tubes light up then the ground is OK going to the radio. Since the speaker is internally attached to the radio, there is nothing for you do do in that regard. You can't listen for the vibrator to hum as the repair person you got to work on your radio probably replaced the vibrator with a solid state vibrator, and they don't buzz. Since the antenna is plugged in you have all of the requirements for the thing to make noise of some sort.
Wish I could be of futher assistance, but you need to get the person who worked on the radio to take it back and fix the thing assuming it got damaged in shipping back to you, and that could happen you know.
I am an Electronics Technician so your description of what you have ran into is the reason for my gloomy diagnosis. I am assuming the radio is for your 50 Champion, and you didn't mention if you provided 6 volts to the radio and not 12 volts, and make sure you have the polarities correct, with +6 volts going to the frame of the radio and negative side of the battery going to the voltage wire. You do have a positive ground car you know.

[50Champ]

Yes, I'm talking about my '50 Champion and I am well aware that it has a 6 volt positive ground system. There's no way the radio could have been damaged during shipping. It was well protected with bubble wrap and big pieces of foam, and there was no damage to the box whatsoever. I forgot to mention that when I removed the radio from the car last month I damaged the antenna wire. The end came off of it and a thin wire several feet long came out of the thicker black antenna wire. I bought a new antenna and cut off the wire part and spliced it into the old antenna wire because I wanted to keep the original crank up antenna on the car. Could that be the cause of my problem, or should I still get some noise out of it even if the antenna isn't hooked up right?



1950 Champion 2 Dr. Sedan

[gordr]

Even if the antenna is not hooked up right, you should hear some "hash" from the vibrator, even an electronic one. "hash" being maybe a bit of a hum or a whine, or just a rushing sound. Dead silence indicates there is probably no B+ to the tubes, given that they are lit.

Are you sure your radio repair guy knows that the radio came out of a positive-ground car? If he is used to doing GM car radios, he might have wired the vibrator to use negative ground, which could very well toast the vibrator instantly once the radio is installed as it was intended to be.

Please note that the radio's INTERNAL wiring, for the tubes, etc. IS negative ground; that is everything on the high-voltage side of the power transformer. Everything on the low-voltage side should be positive ground.

My best suggestion at this point would be to remove a cover so you can access the chassis wiring, and measure the voltage at the point the lead from the output transformer connects to the socket for the audio output tube. That transformer should be pretty easy to recognize, as it will have at least one lead (probably two) connected directly to the speaker. Either of the other two leads on the transformer should read ABOUT 200 volts (+) relative to chassis, if the radio's vibrator supply and rectifier are in working order. Anywhere from 100 to 300 volts should give you some sound. Well under 100 volts, and you either have a short to ground on the B+ line, or else the vibrator and/or associated components are bad.

If you feel confident doing it, check the voltage, and then post back here, and also contact your radio guy.

Warning: that 200-odd volts is enough to give you a nasty shock. Be careful, and try not to have both hands in or on the radio while probing with your test lead.

Gord Richmond, within Weasel range of the Alberta Badlands

[50Champ]

Thanks for all the info but I have no idea how to do any of those things you mentioned and I also don't have the device needed to measure the volts. I emailed the guy in New York and included a link to this thread so he can read your comments and decide if he fixed my radio correctly for a 6 volt positive ground system. I'm positive I mentioned to him when I sent it to him that it's a 6 volt positive ground but he didn't start working on it for about 6 weeks so he may have forgotten. When I hear from him I'll let you guys know. Thanks again for the help....



1950 Champion 2 Dr. Sedan

[barnlark]

That may be the same guy that fixed mine. It's a 1960 12V, but didn't make a sound until I got it on an actual station. No hash noise on mine at all and nothing until I got my antenna splitter hooked up from my roll up. Pretty low volume, too. But...it works. Let us know what you find out. I still like the hidden am-fm conversions for stock radios. Anyone get a 6V pos ground conversion to work yet?

[mdelapp]

I had what I thought were problems with my radio from a 53. It had been converted to solid state. It was removed for dash replacement. the fellow who helped me indicated the radio would not work. Even when bench testing it. I sent it back to the place where it had been converted. They said it worked fine. I reinstalled it. It was dead silent, so I thought. I had to one, crank up the volume knob and make sure it was exactly on a station. It works fine. there is just no static in between. this may not be the case on a tube re-buld but I would carefully move the tuning knob and have the volume on full.

[50Champ]

I emailed the guy (Robert Pacini of New Hartford, NY) who fixed it and told him it wouldn't work. He said he knew that it was from a 6V positive ground car. He told me to rev up the engine for 3-5 minutes and then turn the radio on and off several times because the vibrator might be stuck. I revved it up for 15 minutes and turned it on and off at least 50 times but still couldn't get it working. I then decided to take the back off the radio and take a look inside. I noticed that 2 or 3 of the tubes were not seated securely so I made sure all 8 tubes were down nice and snug. I put the radio back in the car and revved up the engine for a few seconds and then turned the radio on and off 3-4 times and it started working. I'm not sure if it was a loose tube or the vibrator was stuck but I don't really care as long as it's working now. It sounds great with the new speaker and has plenty of volume. Thanks to all of you who offered advice....



1950 Champion 2 Dr. Sedan

[countryboy]

Way to go there Dave. It is nice to suggest things to people wanting to make progress as you have done. BTW: I like the wing guards on your Champion front bumpers. Sets it off real good, and creates a 2nd or third look. Another BTW: Now you can look for a 45 rpm record player and install it on your car since you have a tube radio working in your car. I'm gonna put one in my Champion. Found out that solid state radios would not drive a 45 rpm record player, as a solid state model gives feedback and whistles when you turn the volumn up to a listening level.

[50Champ]

I'll pass on the record player, but I would like to know how to set the buttons for different radio stations. They won't pull out like on most cars and there's nothing in either the owner's manual or shop manual telling me how to set them. I think there's a separate manual for the radio which of course I don't have. Can someone please tell me the secret?



1950 Champion 2 Dr. Sedan

[BobGlasscock]

Yea! Radio noise!!

Now you can hear those Golden Oldies again![8D] Don't let any of that new-fangled stuff get in those tubes.



'50 Champion, 1 family owner

[Tom Bredehoft]

The delux (8 tube) '50 radio was tuned by turning the ends of the buttons to tune in a station. once tuned in, the push button recalled the station. I don't know if this would work on a 5 tube radio.

[img=left]http://www.alink.com/personal/tbredehoft/Avatar1.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe (since 1959)
'55 President (6H Y6) State Sedan
(Under Construction 494 hrs.)
'05 Legacy Ltd Wagon
All Indiana built cars

[50Champ]

I have an 8 tube radio but I don't understand what you're talking about regarding turning the buttons. I'll try turning them tomorrow and see what happens....



1950 Champion 2 Dr. Sedan

[mdelapp]

As I recall some of those early radio button sets were done by turning the tuning knob to the desired station and then depressing the button FULLY in. This would set it. Usually the tuning with the button took only a slight push. Of course recollection could be foggy but it is worth a try

[Chucks Stude]

Don't you miss the simplicity of tube radios? I remember taking the eary tv's and radios apart, marking where the tubes went, walking to the little corner grocery, and going to the tube tester. All in a days work.