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Philco 38-12 radio
Well just picked this radio up and seems to be common one and chanced turning it on using an inverter and it's got the typical buzzing that am radios have but it didn't pickup any stations but I'm going to recap it. I'll have to chance this after recapping because I have no clue if the tubes are good or not since these tubes are so early I gave away my tube tester that would have tested these now I have none to test them with. If anyone knows these radios , is there any known problems with these radios that need special attention.
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#2
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Like most of the starter Philco sets, I think this one is relatively simplistic. Just don't forget about the bakelite capacitor block, If I recall correctly, this set uses one
__________________
"If it isn't broke, you aren't trying hard enough" |
#3
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What is that capacitor block which is listed as a compensator, whatever that is. how is anyone able to make out the colors for the values of the resistors in this radio, the colors are weird and don't make sense.
Last edited by timmy; 06-10-2018 at 01:29 PM. |
#4
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I don't remember the resistors used in the radio. Just use the schematic from Nostalgia Air. |
#5
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Standard transformer powered five tube radio. Initial check procedure: Remove 84 rectifier tube and see if the rest of the tubes light up, of course with power applied. Replace the electrolytic caps and the coupling cap from the 75 plate to the 41 output tube. Make sure the two resistors are good in the bias line. Then try it! Tubes are the last things I worry about in a radio that basic. |
Audiokarma |
#6
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Schematic here:
https://www.google.com/search?q=phil...O2nPfkz-m59jM: I don't see any capacitor blocks... looks pretty simple. jr |
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#8
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Yeah, that's the one I was referring to, however, I've had experience with Philco substituting items sometimes. I've found capacitor blocks where they shouldn't have been, and tubular caps the same. Could have been factory, or someone replacing with OEM parts, either way they were genuine philco stuff. Either way, they matched the schematic, though not the under chassis diagram provided.
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"If it isn't broke, you aren't trying hard enough" |
#9
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#10
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Most of the riders manuals were poorly scanned back in the 90's and no one ever bothered to fix that. The original books are much better, but the print is rather fine...One day I gotta get me the full paper riders.
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
Audiokarma |
#11
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Let me know what ones you need. BTW, the N/A scans are pretty good. |
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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. |
#13
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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. |
#14
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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. |
#15
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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 . |
Audiokarma |
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