Recapped model 80 and have problems - Printable Version
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+--- Thread: Recapped model 80 and have problems (/showthread.php?tid=2164)
Recapped model 80 and have problems - wmcpherson99 - 01-16-2010
I just finished recapping a model 80 and I'm just getting a light static from the radio when I attach a 20 foot antenea to it. I've checked the tubes, the speaker, all the resistors and volume control and everythings good. So is there common problems with this model I should look for? I have a schematic but my radio doesn't follow it exactly. I an electrical novice so I could use some direction. I'd like to start checking the coils in the IF cans. Do I need to unsodder the leads to the cans to check them?
Re: Recapped model 80 and have problems - Steve Chambers - 01-16-2010
There are many possibilities, but these radios are prone to have open coils. Start with the tickler winding on the oscillator coil. It leads from the cathode of the detector-oscillator tube to a cap and resistor (5 and 6 on the schematic). You should measure some resistance. Let us know what you find.
Steve Chambers
Re: Recapped model 80 and have problems - Radioroslyn - 01-16-2010
As Steve said You should measure a very low resistance across those two points on the order of 10 ohms. If it is much higher you with need to rewind that part of that coil. It's pretty easy. http://www.philcorepairbench.com/tips/svctip36.htm
On the model 80 I'd go with 25 turns turn of #32 to 36 wire. As you might know these 4 toober are not the hottest sets. It may require a good outdoor antenna to get good reception. I just finished up a model 600 which is about the same as your 80 it had a few resistors that where out of tolerance and an open osc coil. On these superhet/regens It's important that all of the caps, tubes, and resistors are in good shape to get the maximum performance and smooth regeneration.
Terry
Re: Recapped model 80 and have problems - wmcpherson99 - 01-17-2010
Thanks Guys, The coil is open and I'll give re-winding it a try.
Re: Recapped model 80 and have problems - Radioroslyn - 01-17-2010
Just for grins unplug the set turn the volume control all the way up and measure the resistance from the antenna post to chaiss ground. Should read very low like 100 ohms or lower. If it is like a couple of K your primary on your antenna coil is open too. Set may work but not well. I don't remember how many turns the winding is but it isn't very critical just rewind to fill the space with the same wire you are using for the osc coil. It's only 25 or 30 turns not hundreds. That will work fine. On the osc coil when you get it fixed up and back in the set the set should spring to life! If not just flip the two connection for that winding you just wound backwards. It too will work great ! Also see: http://www.philcorepairbench.com/tips/svctip44.htm Tnx Ron!
Enjoy your model 80!
Terry
Re: Recapped model 80 and have problems - wmcpherson99 - 01-21-2010
Well I just installed the rewound coil and I could tune in a couple of stations at the top on the dial. The rest of the dial was just howls. I used 25 turns of 30 guage wire. The stations I tuned in sounded great. Should I try less turns, more turns or a larger guage of wire?
Re: Recapped model 80 and have problems - Chuck Schwark - 01-21-2010
I would not touch the coil just yet.
The Model 80 has a regenerative detector circuit and it sounds like trimmer cap #18 (on schematic) is/was mis-adjusted during alignment.
This trimmer is the feedback path for the regeneration. It's covered in the alignment instructions.
Chuck
Re: Recapped model 80 and have problems - wmcpherson99 - 01-21-2010
So the old timers nicked name this set the âsquealerâ . Now I understand why. Good news, I've got it tuning in stations all accress the band. Next a good alignment and then I'll refinish the cabinet. Thanks for all the help guys.
Re: Recapped model 80 and have problems - wmcpherson99 - 01-22-2010
While I just followed the service hints and tips 43 and 44. The difference is amazing. The sets really plays great now!