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Philco 48-482 low vol on AM
Micro9
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#1

07-15-2017, 02:33 PM
Had low vol on AM/SW but FM was ok before recapp..Did recap and replaced a handfull of resistors.
It still has low vol on AM/SW!!FM works fine.This set has the 7B6  tube  not the 6SQ7.
All IF Xformers treak up EXCEPT the 4th.It doesn't treak on AM or FM!!
Checked the windings and they show correct ohms on both Pri and sec.
Anyone have any ideas of where to look next..
TKS!!
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morzh
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#2

07-15-2017, 02:47 PM
Was does "treak up" mean?
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
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klondike98
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#3

07-15-2017, 02:52 PM
Good clear schematic HERE or Nostalgiaair schematic HERE.

Lots of push button switches in that set, be sure all those contacts are cleaned.
Cheers,
Bob
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Micro9
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#4

07-15-2017, 03:46 PM
trying to adjust the screws on the top of the can.
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Micro9
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#5

07-15-2017, 03:49 PM
I have cleaned the switches twice with Deoxit...
No change..
TKS!!
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Radioroslyn
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#6

07-16-2017, 02:48 AM
(07-15-2017, 03:46 PM)Micro9 Wrote:  trying to adjust the screws on the top of the can.

So are you using a signal generator to properly set rf and IF stages or just twiddling them willy nilly? The latter is not a great idea you make things worst pretty easily.
I would go though and test the tubes to be sure you don't have a weak one creating your low volume issue. If all is well on this front then pull out the the volt meter and measure the voltages around the tubes and compare them to the service info. When using a digital meter voltage are going to read a bit higher maybe 10% which isn't a big deal.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
(This post was last modified: 07-16-2017, 02:49 AM by Radioroslyn.)
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Micro9
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#7

07-17-2017, 03:44 PM
Yes...The IF cans were tweaked using a signal gen...
Using Sams 4720-24 the voltages on pins 3 and 6 of the 7F8 are off.Pin3= 115 should be 138
Pin 6= 111 should be 130
ON pins 5& 6 of the 7B6 are both -.45
pin 5 should be -.50 and pin 6 should be -.23
The rest of the tube pin voltages are ok..
(This post was last modified: 07-18-2017, 05:02 PM by Micro9.)
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klondike98
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#8

07-17-2017, 06:27 PM
You've probably seen it but in case you haven't the service bulletin that Philco put out for the 48-482 has a pretty comprehensive troublshooting guide, going from section to section. The bulletin can be downloaded from the audiophool site: http://www.audiophool.com/Philco.html You need the DjVu reader plugin to read it. If you can't get it to read let me know and I'll convert it to a PDF for you.
Cheers,
Bob
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