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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Wed 11, 2004 4:43 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3298
Location: Cedarville OH USA
Have had this for a while, I am fixing for someone. I was on this 4 hours last night. Won't oscillate. I have chekced and rechecked wiring till I am blue in the face. On thing I notice is B+ voltage is way high, like 270 volts where it should be 180. Voltage on screen grids though (around 78 volts), seems to be right on. After a lot of messing around I determined the oscillator coil (BC portion) was open between the ground side and center tap. I unwound the coil, fixed the break (right at the tap) and carefully rewound it as it was. Ohmed out in proportion to the lengths of the windings. Radio loads pretty badly on a strong local (700) and you get it all over the dial--won't tune anything else. Radio has had the paper caps replaced. The 220 uF mica cap.measures around that, can't really measure the 33 pF one. IFs ohm out in the 20-something ohm range. Tried different 6SA7--no change. Oscillator circuit looks very simple on this one, can't see anything else that could be off. Any suggestions--anyone else work on one of these Crosley "Victory" sets? I've been on a radio fixing roll lately and this one brought the cutain down on me.<P>Thanks<P>------------------<BR>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Wed 11, 2004 6:31 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1999
Location: Mt. Prospect, IL USA
Hi Bob,<BR> I have a Philco 48-475 that uses a much higher oscillator plate voltage for FM than for AM. During troubleshooting, I happened to try AM at the higher voltage- wouldn't oscillate. Perhaps the problem giving you too much B+ voltage is making the oscillator quit. (Something not drawing plate current like it should, power supply miswiring by previous person). Maybe something shorted in the past, putting too much current in the osc. coil and making it fail. Just my hunches...<P>------------------<BR>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Wed 11, 2004 7:06 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 37514
Location: Livermore, CA
Hi Bob<P> Could portion of the oscillator coil be wound in the wrong direction? An oscillator requires positive feedback. Coil polarity needs to be correct.<P> A strong local station may be heard, not tunable, with a dead oscillator.<P>------------------<BR>Norm


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Wed 11, 2004 7:56 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3184
Location: California
I had one with the same problem. It was a cold solder joint on the ground end of the coil. I used two soldering irons to get the solder to flow onto the chassis and it woke right up.<P>------------------<BR>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Wed 11, 2004 8:23 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3298
Location: Cedarville OH USA
Hi All,<P>Am at work and thought I'd look back here at lunch time. Thanks for all the replies. This radio appears to have had some previous work and I will admit some of the solder joints look suspicious, although continuity seems to be fine. I do see that to draw plate current, the 6SA7 cathode circuit does go through the oscillator coil. I rewound the oscillator coil exactly as it had been--appeared to be factory orginal and not touched before. Broadcast section of the oscillator coil is a single coil with a tap--all wound in same direction (Clockwise looking from the top as I recall). I'll double check continuity to ground on the ground side of the oscillator coil. Power supply looks to be orginial except the power transformer is sort of loose on the chassis--it seems to fit the chassis slot OK. I am getting about 315 VAC out of the tranny where the schematic says it should be 270.<P>------------------<BR>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Thu 12, 2004 5:57 am 
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Location: Earth
Hi Bob,<P>Another thing to look out for, although maybe un-related, I think it would be a good proactive step to prevent further problems. I've seen Crosleys that use "MICAMOLD" capacitors. The little square ones that look like throat-logenzes that have the domino dots on them. Most people think these are Mica caps due to the fact they look like them and they have the "Micamold" name. Couldn't be further from the truth. These are actually junky paper-caps. Even if they don't appear to leak they are pretty much garbage as far as a reliability factor. If you're under there, change 'em out as these little values are often used for tank/oscillator circuitry.<P>Joe<P>------------------<BR><I>Clock-radios, the original form of multi-tasking!</I>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Thu 12, 2004 8:04 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3298
Location: Cedarville OH USA
Still dead for the most part. I tried a 1K wirewound in series with the output of the 5Y3 tube. Got B+ right at 180 but screen voltage down to about 55 but would be enough to power up all the radio circuits.. Radio still dead and no oscillation. IFs do work and was able to peak the IF transformes at the IF frequency (forget exactly waht it is). Shooting signal into the antenna from a signal generator gave nothing on the SW band. On AM it acted like it was tuning a station but I think it may have been a strong local coupling in with the signal generator. That came in very weak. Can't pick up anything else from the signal generator excpet the IF frequency. That oscillator is just plain not working. I am thinking it could be the caps (33 and 220 pF). Joe, will conside what you said, I think one IS a Micamold. Only thing I know to do is replace oscillator components one by one. It's a simple oscillator circuit, don't know what else could be wrong. Continuity seems to be fine everywhere. Frustratng--spent way too much time on it last night--still tired <IMG SRC="http://antiqueradios.com/forums/smile.gif">.<P>------------------<BR>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Mon 23, 2004 9:28 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Cedarville OH USA
IT'S FIXED!!!!!!!!!! I tried everything I knew of--new caps and double checked that coil I rewound. I took the tuning cap off and found the oscillator section had about 420K ohms resistance from rotor to stator. Apparently the wire from the bandswitch to it had been soldered with acid core solder. I cleaned the cap with Lime Away, dried it with a blow dryer and lubed the shaft at each end. Cap showed varying capacitance and I hooked it back up in radio--fired right up. I had put it away for a week or so--it was haunting me!<P>------------------<BR>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Mon 23, 2004 10:49 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: California
Great job! You are the man!!<P>------------------<BR>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Mon 23, 2004 4:55 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3298
Location: Cedarville OH USA
Only way I can get to see the later replies is to reply myself--any idea why?<P>Bob<P>------------------<BR>


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 Post subject: Crosley 63-TA, Won't Oscillate
PostPosted: Feb Mon 23, 2004 5:53 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1218
Location: Charlotte,NC
Sounds like your server is using stored "proxy" pages instead of the real ones. AOL is especially notorious for this, although I think they all do it to some degree. Hitting the "refresh" button should take care of it. When you reply to a post, it pretty much does the same thing (reloads the page). <P>------------------<BR>


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