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 Post subject: Problem with Coronet, please help.
PostPosted: Feb Sat 21, 2004 4:50 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2291
Location: Niagara Falls, NY
Hi Guys, Recent purchase of a Coronet C-2. Similar can be seen on Radiophile.com. Replaced all caps and tested all five tubes. Replaced #47 bulb. Plugged set in, bulb lit, than burned out in a second, and set never lit up. No noise, dead set. I might suspect plug but did get juice to #47, if only for a moment. I am Ok with radio repair on hummers, but this set is over my head. Any help on why set would be dead? Tubes are 14Q7, 14A7, 14B6, 50A5, 35Y4. Thanks. Ken <P>------------------<BR>


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 Post subject: Problem with Coronet, please help.
PostPosted: Feb Sat 21, 2004 5:24 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 27410
Location: Detroit, MI USA
Hi Ken, The 35Y4 has a tapped heater and the dial lamp is connected across a portion of it. The common failure on these tubes is for the tapped section to open, thereby causing the lamp to burn out immediately when power is applied. <BR>Depending on the settings of your tube tester, the tube may still check OK if the main section of the heater is still good. Try checking the heater for continuity with an ohmmeter between pins 1 and 4, if it checks open then the 35Y4 is the cause of your problem. Also note that a short in the B+ circuit of the radio or in the wiring to the lamp can cause that portion of the heater to open. Since you mentioned having to replace the lamp before plugging in the set, the tube may have already been bad.<BR>There is also the possibility that if the tube is good, the tube pins are not making good contact with the tube socket.<P>------------------<BR>Dennis


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 Post subject: Problem with Coronet, please help.
PostPosted: Feb Sat 21, 2004 9:55 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2291
Location: Niagara Falls, NY
Mr. Detrola and friends: You may be on to something re. dial lamp. Upon closer examination, the dial lamp wiring is pretty shabby and brittle and its' wires may actually be shorting. It could be the tube is bad or that the dial lamp wiring is shorting out the set. I will disconnect the lamp from the 35Y4 and see what happens. If nothing, then I'll replace the tube.<P>------------------<BR>


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 Post subject: Problem with Coronet, please help.
PostPosted: Feb Sat 21, 2004 9:24 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2291
Location: Niagara Falls, NY
H E L P !<BR>Okay, here's what I have done to date:<BR>1. I cut out the dial lamp at the 35Y4, figuring its poor wiring was shorting out the set.<BR>2. I rechecked the 50 and 35 tubes and replaced both with other good test tubes, even though the originals tested well with no shorts.<BR>3. When set still did not work, I suspected a bad volume control and bridged the two contacts on the back of the switch. STILL NOTHING. Set is dead with no light.<BR>Now what? Was I supposed to bridge the two contacts on the 35Y4 after I cut the dial lamp from it? Look forward to all your thoughts. Ken PS I do not as yet been taught to operate an ohmmeter.<P>------------------<BR>


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 Post subject: Problem with Coronet, please help.
PostPosted: Feb Sun 22, 2004 12:20 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 37248
Location: Livermore, CA
Hi<P> Check continuity between pin #1 and #8 on all your tubes. Any filament open will stop all of them from lighting.<P> If you have a meter select a scale marked RX10. When you short leads together on your meter the needle will move to the right. With this setting connect one lead to pin #1 and the other to pin #8 on each tube. These are pins each side of the keyway. Each tube must make the meter move.<P> <P> <P>------------------<BR>Norm


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 Post subject: Problem with Coronet, please help.
PostPosted: Feb Sun 22, 2004 1:39 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2291
Location: Niagara Falls, NY
Hi Norm Thanks for the advice on dead Coronet. I will try your idea of course. I do have a real nice Simpson meter, have yet to learn how to use it in radio repair. I can perform your suggestion, but is radio on or off during the test? How will needle react when it comes to a shorted tube? A good tube? Regards, Ken<P>------------------<BR>


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 Post subject: Problem with Coronet, please help.
PostPosted: Feb Mon 23, 2004 2:28 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1460
Location: Cambridge MN USA
Radio should be off and preferably unplugged when doing resistance checks. And don't forget to check the filter cap to see if it's shorted.<P>Scott Todd<P>------------------<BR>


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