[MarkinK-zoo]

Oh well, it was a long shot, but thanks for looking.    Mark

[harley92]

Hi all,
I have several 37-620 chassis and am restoring my second one. I have done one already. Even between code 121's there are differences. There are differences between the code 125's. There are differences (maybe errors) in the schematics. the biggest problems are in the number of coils in the RF chassis done during various production runs. Some changes include the original number of coils and compensating capacitors. Later production runs have fewer coils and fewer compensating capacitors on the underneath side of the chassis. The run with fewer coils and caps changed the tuner with compensating caps as part of the tuner. I have also found the coil resistances as indicated on the schematic may often be different than what the coil actually is. this was usually a minor change during a production run to improve performance and or reduce costs.
Removing any of the coils for a rewind is not for the faint of heart. The wires are very small and fragile. Some of the coils are wound/terminated with llintz wire. The key is using the correct wire and rewinding exactly like the original.
Best results are obtained by removing the RF chassis and then removing each of the three sections and working on each section in something like a Pana-Vise.

The easiest way to remove the RF chassis is to unsolder and tag each of the wires going to the RF chassis. Next remove the dial components. Then remove the power switch/tone control and lay to the side (don't unhook the wires to it.) Next remove the hex screws holding the front chassis plate keeping the volume control shaft attached to the plate (don't lose the clip on the VC). Finally remove the rear screw/rubber holding the RF Chassis to the rear chassis plate. Finally tilt up the rear of the RF chassis and slide forward for removal. It may not slide out easily as the rubber grommets may have decomposed and corroded on. Once the RF chassis is removed, you can remove the side covers and remove section, tagging any wires necessary to take out each section.
Be careful around the coils. They are fragile! You can then carefully remove and replace or rewind the defective coil.
Take lots of photos prior and during disassembly. Also make a line by line step log of all wires/steps as you go. Reverse all steps to put it back together. I hope this info helps.
Gerald D.

[MarkinK-zoo]

    Here is a photo.  There was a paper band around the primary, which I removed so that I could get a better look at it.  I re-soldered the connections just in case I would get lucky and fix the problem, but no.

[MarkinK-zoo]

Well, I ordered the RF coil replacement from AES.  since I only needed the primary side, I nestled it in between the BC and SW coils.  reception is greatly improved.  Not the most elegant solution, but good enough for now.

[harley92]

Hi,
I have both a code 121 and a code 125.  Philco may have done some changes along the way as the way as the code 121 has an RF sub-chassis with the coil line up of a code 125 and the code 125 has the line up of the code 121. Some of the coil resistances listed in either service bulletin 250 or 251A do not match the values listed on the schematic. Some of the coils are wound with lintz wire and some used that wire to go from the coil terminals to the band switch. Removal of a bad coil is best done by removing the RF sub-chassis then removing each section one at a time starting with the Antenna section (rear of chassis), then the RF section (mid chassis) and finally Osc. section (front of chassis). Mark all wires and de-solder carefully. The coil terminals and the eleven lug terminal strip lugs on the side are easily broken.

Make a step list as you go so reinstall is just the reverse. Hint - Remove the power/tone switch and lay to the side. Then remove the hex screws that hold the front chassis panel and remove it with the volume control shaft still attached to it. (keep track pf the brass clip on the end of the shaft that inserts into the volume control.)

Then it is a matter of removing the center RF chassis screw and rubber bushing, and tilting the RF sub-chassis up and forward with the band switch still in place. Note the band switch shaft has a small tit on the rear end with corresponding notches on each wafer. With the RF sub-chassis on the bench, removal of the shaft and sections is straight forward.

If you go to all of this trouble, replace all the paper caps with new 630 volt units. mine were all leaky. Some of the resistors were OK and some were not. Some of the resistors are of odd values not made any more. The color code follows the standard body-end-dot code. Using the value on the resistor or schematic, if any are over 20% off, you can use any replacement that a standard value part falls in the 20% range. I used 5% resistors as replacements and found they work fine.

FYI, I have a Morris replica that I have rewound some of the coils with. The ones with Lintz wire, I didn't have much luck with.

Good luck with your restoration. Please feel free to ask any questions. If possible zap a photo of the RF sub-chassis section and I will see if I can rewind to coil for you or provide a replacement from my parts chassis.

Gerald D,
grumpysailor2016@gmail.com

[harley92]

Hi again,
By the time I finished with the long post, I discovered the photo of your defective coil. Which section is bad - the helix wound section or the longer flat section?
I will look for a replacement in my parts chassis.
Gerald

[harley92]

Hi,
I looked at my parts radio and the coil you show in the photo is not like any in the radios I have.
Sorry,
Gerald