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  #16  
Old 06-12-2018, 10:40 AM
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Ok so it's all recapped now and it works but the volume has to be maxed to here anything the audio is super very low, but I am unable to test the tubes so I'm assuming the 84 is good as well as the 6a7 being its pulling in a station which is local here to me. So is it possible one of the other tubes may be bad like the IF, 78 or the 75 2nd Det 1st audio tube, or even the 41 output tube ? Maybe rule out anything else.

Last edited by timmy; 06-12-2018 at 11:37 AM.
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  #17  
Old 06-12-2018, 11:36 AM
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I don't know what the proper ohms should be on the Transformer on the speaker but I measured the primary input .730k ohms and the secondary to the speaker,2.0 ohms and the speaker coil itself, 4.5 ohms. I originally plugged it in and got the typical loud buzz and hum out of the speaker so if anything the speaker and coil should be good. The field coil that's on the speaker itself measures 1.758k

Last edited by timmy; 06-12-2018 at 12:11 PM.
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  #18  
Old 06-12-2018, 12:37 PM
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Quote:
Originally Posted by timmy View Post
I don't know what the proper ohms should be on the Transformer on the speaker but I measured the primary input .730k ohms and the secondary to the speaker,2.0 ohms and the speaker coil itself, 4.5 ohms. I originally plugged it in and got the typical loud buzz and hum out of the speaker so if anything the speaker and coil should be good. The field coil that's on the speaker itself measures 1.758k
Did you check the voltages?
Those are all DC resistances on the output transformer, speaker and field coil and they look alright. Also the negative on the input electrolytic should go to the bias line instead the chassis. Also check the bias resistors, 400 and 75 ohm.
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  #19  
Old 06-12-2018, 12:50 PM
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Originally Posted by dieseljeep View Post
Did you check the voltages?
Those are all DC resistances on the output transformer, speaker and field coil and they look alright. Also the negative on the input electrolytic should go to the bias line instead the chassis. Also check the bias resistors, 400 and 75 ohm.
The 2 electrolytics, one is chassis ground the other is not . I just checked the schematic and the speaker output
primary does show its 450ohms I'm getting .730k. There is a 70 ohm resistor and it's ok but I don't see a 400 ohm resistor. the 190k I replaced with an array at 186k and the 490k I replaced with 470k .
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  #20  
Old 06-12-2018, 01:40 PM
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the 190k I replaced with an array at 186k and the 490k I replaced with 470k .
Seems ok,

How long of an antenna wire are you using?

jr
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  #21  
Old 06-12-2018, 03:21 PM
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Seems ok,

How long of an antenna wire are you using?

jr
Well the schematic shows 190,000 so that should be 190k . Wire for the ant is like 3feet long.

Last edited by timmy; 06-12-2018 at 04:19 PM.
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  #22  
Old 06-12-2018, 04:41 PM
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10'+ is better. 100'+ is ideal.
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  #23  
Old 06-12-2018, 04:52 PM
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I'm pulling my hair out , this simple radio should work, well unless a tube is bad then I would have to get 4 of them since the voltages look good so then rectifier tube is good.
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  #24  
Old 06-12-2018, 05:17 PM
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It doesn't look like you have many strong AM choices.

https://radio-locator.com/cgi-bin/lo...req=&sort=freq

Have you tried peaking the if transformers? Longer antenna wire?
Is the dial calibration fairly close, or does the set need alignment?

jr
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  #25  
Old 06-12-2018, 05:32 PM
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Originally Posted by jr_tech View Post
It doesn't look like you have many strong AM choices.

https://radio-locator.com/cgi-bin/lo...req=&sort=freq

Have you tried peaking the if transformers? Longer antenna wire?
Is the dial calibration fairly close, or does the set need alignment?

jr
I have one strong local am station and it comes in but no volume only max can I here it. I even tried the radio outside still no volume very low. The ant wire is really long. While listening to the station I tried tweaking the screws but it's all right on the money , I marked them befor touching them and it's right there. I went over my work and can't find anything. But if a tube is bad I have no way to tell which one it is since I don't have an older tester to test them nor do I have an idea which one it might be instead of buying them all. If I had an idea of what to try as far as testing to maybe see what tube it is that would be good.
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  #26  
Old 06-13-2018, 12:42 AM
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You may be able to rule out audio by injecting audio past the detector and seeing if volume is adequate.
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  #27  
Old 06-13-2018, 07:12 AM
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Quote:
Originally Posted by Electronic M View Post
You may be able to rule out audio by injecting audio past the detector and seeing if volume is adequate.
I was just about to ask what happened to standard troubleshooting? An inexpensive signal generator/tracer would make simple work of this, and one should be in every TV/radio hobbyist's possession.

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  #28  
Old 06-13-2018, 11:32 AM
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Quote:
Originally Posted by timmy View Post
I have one strong local am station and it comes in but no volume only max can I here it. I even tried the radio outside still no volume very low. The ant wire is really long. While listening to the station I tried tweaking the screws but it's all right on the money , I marked them befor touching them and it's right there. I went over my work and can't find anything. But if a tube is bad I have no way to tell which one it is since I don't have an older tester to test them nor do I have an idea which one it might be instead of buying them all. If I had an idea of what to try as far as testing to maybe see what tube it is that would be good.
What kind of reception do you get on another AM radio in the same location, especially the station you are receiving?
That Philco radio is just as hot as any other AA5 with similar circuitry. It's a standard AVC equipped radio, not one of those non-AVC circuits, where the volume control is located in the antenna and bias circuit.
Make sure the bias voltages are on the money as they affect the first and second audio stages.
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  #29  
Old 06-13-2018, 01:05 PM
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Originally Posted by Electronic M View Post
You may be able to rule out audio by injecting audio past the detector and seeing if volume is adequate.
If you don't have a signal generator, just touch the grid cap of the 75 tube... if a fairly loud hum/buzz is heard through the speaker, the audio section is likely working ok. Try the "one finger signal injection" both with the grid cap connector on and off the tube.

jr
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  #30  
Old 06-13-2018, 02:05 PM
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Ok I have a cheap am radio and it works fine and loud strong signal, since the station is near me. The 75 tube cap off there is a buzz touching the cap and not all that loud and cap on less buzz touching it. The 6a7 wet my finger and touch the cap and the station comes in Alittle stronger. I will check the voltages on the 78 and 75 tubes again.
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