I have been working on my Philco 37-650 PX and My Friend Dick Morgan has been trouble shooting and helping me a great deal and we stopped because of his time and is not feeling well , all the voltages are good and plenty of audio also the coil for the am band is not open, when I put my finger on the grid cap of one of the tubes, I can faintly here some talking coming over the air. The radio /phono switch is set to radio , all the tubes check very good . The oscillator is dead to the bone . Any ideas on what could be the culprit. I know its not easy and could be a number of things but Dick cant get to it for a while, was the 650 prone to this problem and what the action taken to correct it?
(This post was last modified: 03-13-2016, 07:47 AM by Fred Taylor.)
Would check the grid 2 voltage on the 6A8. In SW the hv has to go though the osc coil on the BCB it doesn't. I would think that you should have about 100dcv there in SW and BCB. If not you've got open winding on the coils.
(03-14-2016, 08:42 PM)Radioroslyn Wrote: Would check the grid 2 voltage on the 6A8. In SW the hv has to go though the osc coil on the BCB it doesn't. I would think that you should have about 100dcv there in SW and BCB. If not you've got open winding on the coils.
Terry
OK, I will tell Dick and he can check out what you described , Thanks a bunch.
The osc circuit is a little odd on this set as it looks to me that it is using two different types of feedback. On the BCB it's using a single winding with a tap and on the SW bands the coils have a primary and secondary. If it is an open coil issue I'm not sure how difficult it would be to repair them. On the other hand you may have something else that's ailing it.
GL
Terry
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