Garbled sound on Philco 46-131 - Printable Version
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Garbled sound on Philco 46-131 - markskala - 03-28-2012
Hello,
I've been working on a Philco 46-131. All the caps (except mica) have been replaced as was a bad resistor. The tubes were checked and replaced as necessary. Radio plays and receives stations without problem. The trouble is garbled audio. I can't get it to clear up even after alignment.
The one thing I did notice was 90 volts where I'm supposed to have 79. Could that be my problem? I am using my Silvertone Powr Shftr. My Silvertone battery radio works well on this. Now that I think about it I have another Philco battery radio that also has the same audio issue I never resolved. Perhaps this is the problem?
Thank you for any comments/suggestions.
Mark
RE: Garbled sound on Philco 46-131 - Arran - 03-28-2012
This is really in the wrong forum, it should be in the electronic restoration section. In any event I would check the other resistors in the set and see if any have drifted in value. I would also check the tubes, although I wouldn't expect any problems there. I would also check the polarity of the battery leads if they don't have plugs, I would also check the condition of the battery leads near where they go into the plugs.
Regards
Arran
RE: Garbled sound on Philco 46-131 - Radioroslyn - 03-28-2012
Check grounds and your C battery connections. Set should work well on batteries, like some D cells and 9v jobs in series. Is your loop ant connected?
Terry
RE: Garbled sound on Philco 46-131 - markskala - 03-28-2012
Sorry about wrong forum location. There is no loop antenna and schematic does not show one either. Also, the radio back had no loop.
RE: Garbled sound on Philco 46-131 - Arran - 03-28-2012
Post war battery sets like this one don't normally use "C" batteries, in fact very few 1.5 volts sets do, they use resistors for bias instead, this model included. So if there is a bias problem it's likely a bad resistor, or one with an open connection. It does however use loctal type battery tubes that use short pins, sometimes the pints or the sockets can develop oxidation that leads to poor contact so it's worth checking that as well.
Regards
Arran
RE: Garbled sound on Philco 46-131 - markskala - 03-29-2012
Thank you, I will double check these items in the next day or two and provide an update.
RE: Garbled sound on Philco 46-131 - markskala - 03-30-2012
First, thank you to everyone for their assistance with this radio. Here's the latest:
Went through every component again and did find a resistor that was about 45% higher than it should be. Replaced that item and moved on. I tried a different speaker again - no change in sound. Even though I had already checked the tubes I decided to replace the audio tube again anyway. BINGO! The sound is acceptable. Goes to show that even a tube that tests well may not actually be a good tube.
The simplest things...
RE: Garbled sound on Philco 46-131 - baarf - 07-18-2012
I also have a 46-131, what antenna do you use? I am struggling to get my wife to agree to mount a huge longwire in the family room for it to be correct, so I am thinking about building a loop that would look correct for the late 40's.
Any help would be appreciated.
RE: Garbled sound on Philco 46-131 - codefox1 - 07-18-2012
I would substitute a known good speaker/output transformer to rule them out or not.
Agree that miswired loops, open antenna coils can do same, but can be eliminated by working backwards from loudspeaker to antenna to isolate problem. Well, that's how I was taught all those decades ago.
Always try to post schematic or link if you can. Some of us old f**ts can nail it in 10 seconds. Not me, I take much longer.
RE: Garbled sound on Philco 46-131 - TA Forbes - 07-19-2012
You will need a sun dial in order to measure the time it takes me to "nail" it.
RE: Garbled sound on Philco 46-131 - jerryhawthorne - 07-20-2012
Mark, in my limited time on radios and tube testers, the following is what I have found.
1. A tube that tests "good" is PROBABLY good.
2. A tube that test weak, is PROBABLY good.
3. A tube that tests shorted or dead, has a high certainty of being bad.
Please note the "PROBABLY". The best test is to replace with a known tube, but then again, make certain that tube works in another radio. Oscillator tubes can be particularly problematic on a tube tester.
Jerry
RE: Garbled sound on Philco 46-131 - codefox1 - 07-20-2012
Restae, somewheers between speaker and and the antenna is the frammus. Kill the frammus.