11-26-2017, 07:36 PM
Back to the Philco again! I had to deal with a few other projects and the holiday tasks. Today I managed to install a new AC cord for the set. The old one was hopelessly falling apart. Even the molded rubber grommet on the cord was cracking and coming apart. I had a suitable two-piece strain relief of the more modern type. I had to use a 3/8" drill bit to begin enlarging the opening in the chassis to hold the new strain-relief. I finished shaping the opening with my Dremel tool equipped with a small cylindrical diamond grinding bit. The hole for the two-piece strain-relief has to be somewhat elongated. After about 10 minutes of work I had the opening shaped well enough that the strain-relief would fit when the AC cord was placed inside it and compressed.
I did some preliminary ohmmeter checks in the B+ circuitry and found no shorts and the electrolytics slowly charged up. Tomorrow I plan to do an AC power on test and make a few more measurements, while watching for any possible smoke!
All of the essential paper-wax-foil capacitors have been changed. I had planned to change the two AC input .01 filter capacitors, but discovered I had used up all the ones I thought I had, so I stopped to order some more from a supplier. I may get lucky and receive those by the end of this week. For now I will operate the set with the OEM capacitors. They check OK for now.
One thing more that I need to do before applying power tomorrow is to check all the tubes. No point in applying power if one has a short in it! I suspect however that they are OK except some may have low emission after so many years. You never know though. The Philco 40-201 I restored had all of its original tubes except for one and it worked quite well for signal pulling power etc. after I got the paper caps, some resistors and rubber wiring replaced. It will be interesting to see how this one compares to the 1940 model. The RF loop antenna on this set is a much lower impedance than the one that was in the 40-201.
I am not sure where the schematic that I am using came from. I think it may actually be a Beitman's generated schematic. In any case most of the parts I have checked match the values shown in its schematic. There are however a few differences in the power supply and those were taken care of in the supplemental schematics that jcassity had contributed in his thread on this model and production code.
One neat feature I discovered about this chassis is that there is a spring loaded slide switch on a bracket that mounts where movement of the record changer forward when opening the changer compartment allows the switch to move and engage power to a dial lamp so that the changer compartment has light while loading or unloading records. The switch was almost impossible to move so lubrication and cleaning had to be done. Now it moves easily once again.
I also repaired the two speaker leads where the arms of the changer mounting had cut them. When the chassis goes back into the cabinet the lead dress of these wires will have to be watched and secured in such a way that the brackets and levers associated with the changer compartment do not cut them again.
Joe
I did some preliminary ohmmeter checks in the B+ circuitry and found no shorts and the electrolytics slowly charged up. Tomorrow I plan to do an AC power on test and make a few more measurements, while watching for any possible smoke!
All of the essential paper-wax-foil capacitors have been changed. I had planned to change the two AC input .01 filter capacitors, but discovered I had used up all the ones I thought I had, so I stopped to order some more from a supplier. I may get lucky and receive those by the end of this week. For now I will operate the set with the OEM capacitors. They check OK for now.
One thing more that I need to do before applying power tomorrow is to check all the tubes. No point in applying power if one has a short in it! I suspect however that they are OK except some may have low emission after so many years. You never know though. The Philco 40-201 I restored had all of its original tubes except for one and it worked quite well for signal pulling power etc. after I got the paper caps, some resistors and rubber wiring replaced. It will be interesting to see how this one compares to the 1940 model. The RF loop antenna on this set is a much lower impedance than the one that was in the 40-201.
I am not sure where the schematic that I am using came from. I think it may actually be a Beitman's generated schematic. In any case most of the parts I have checked match the values shown in its schematic. There are however a few differences in the power supply and those were taken care of in the supplemental schematics that jcassity had contributed in his thread on this model and production code.
One neat feature I discovered about this chassis is that there is a spring loaded slide switch on a bracket that mounts where movement of the record changer forward when opening the changer compartment allows the switch to move and engage power to a dial lamp so that the changer compartment has light while loading or unloading records. The switch was almost impossible to move so lubrication and cleaning had to be done. Now it moves easily once again.
I also repaired the two speaker leads where the arms of the changer mounting had cut them. When the chassis goes back into the cabinet the lead dress of these wires will have to be watched and secured in such a way that the brackets and levers associated with the changer compartment do not cut them again.
Joe
