Resistor identification for 37-620 - Printable Version
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Resistor identification for 37-620 - georgetownjohn - 04-15-2026
When tested this resistor shows 10 ohms. I do not see it as such on the parts list. As you can see from the attached photo, it is brown,black,brown and black. This resistor connects to the positive terminal of the 16 mfd electrolytic cap part number 16 which I have just finished restuffing. Can someone tell me what the value of this resistor should really be? Many thanks
RE: Resistor identification for 37-620 - DaleHCook - 04-15-2026
What is the part number on the schematic?
RE: Resistor identification for 37-620 - morzh - 04-15-2026
10 Ohms.
RE: Resistor identification for 37-620 - morzh - 04-15-2026
A suggestion: why don't you make it one thread about that same radio instead of making each question a separate one?
RE: Resistor identification for 37-620 - glyphmon - 04-15-2026
A couple notes - are you sure that's a Cap 16 and not a Cap 18? Part 16 is a 51K ohm resistor on the other side of the chassis - this is in the tuning sub-chassis.
Second, I just looked at my 37-620 (also a work in progress) and I don't have a resistor anywhere there that you have pictured, nor do I have that standoff. The closest resistors are 19 (10K ohm), also in the tuning sub-chassis but on the other side of the same section, and then 64 which is a very prominent dogbone resistor in the main chassis next to the other electrolytics, erroneously marked on the chassis diagram as part 68.
Best wishes,
Roy
RE: Resistor identification for 37-620 - morzh - 04-15-2026
In case your sch is different from ours. I only have the ability to look at one in Riders at Nostalgiaair.
There is no cap 16.
So, why don't you share your sch link/scan (if no link exists), or re-visit the Riders and see if you gave a wrong number.
RE: Resistor identification for 37-620 - RodB - 04-15-2026
I don't see any low value resistor on that filter cap on the schematic and I've looked at the code 125 schematic too. It might be an add-on of some kind or some rf coil.
RE: Resistor identification for 37-620 - morzh - 04-15-2026
Well, this place was worked on. Quite possible the part is not original.
RE: Resistor identification for 37-620 - RodB - 04-15-2026
I compared your photo with my chassis. In yours, the ten ohm "resistor" attaches to the filter cap and the other end to a terminal, then there's a wire from that terminal to the, what I assume, 70k/20k resistor junction across to the other side of the chassis. In my chassis that wire goes directly to the 16mfd cap, no terminal, no mysterious resistor.
BTW I discovered my 70k resistor is open! What next?
RE: Resistor identification for 37-620 - DaleHCook - 04-15-2026
morzh Wrote: I only have the ability to look at one in Riders at Nostalgiaair.
Why? We have lots of information right here. The OP asked abour "37-620," but did not say if it is code 121, 124, or 125.
For codes 121 and 124, we have the original service manual at:
https://philcoradio.com/library/download/service%20info/wiring%20diagrams/vol2/split/Part18-Philco%20Wiring%20Diagrams%20Vol.%202.pdf
See also Service Bulletin 250 for the electronics at:
https://philcoradio.com/library/download/service%20info/service%20bulletins/Philco%20Service%20Bulletin%20250.pdf
See also page 4 of this issue of the Serviceman:
https://philcoradio.com/library/wp-content/uploads/2018/08/Philco-Serviceman-1937-05.pdf
For code 125, the service manual is in Service Bulletin 251-A for the electronics at:
https://philcoradio.com/library/download/service%20info/service%20bulletins/Philco%20Service%20Bulletin%20251A.pdf
See also the same Serviceman page linked to above.
For all three codes, the dial drive is in Service Bulletin 231-A at:
https://philcoradio.com/library/download/service%20info/service%20bulletins/Philco%20Service%20Bulletin%20231A.pdf
One major resource which many are not aware of is my Philco Service Index, which is very hard to find, but is at:
https://docs.google.com/spreadsheets/d/1iQQcoF_46EVM6IHhn1EvUFdXpEFnU56lvBZJOWmd5nw/edit?gid=1539072455#gid=1539072455
Note that although I created the Index, I do not maintain it. I wanted to put it online as a downloadable spreadsheet file, but Phorum management chose to put it online as a Google Sheets spreadsheet. I maintain my local copy of my original spreadsheet to keep it current and correct, but I don't have the time or inclination to maintain the online version as well, so it is missing some additions and corrections.
RE: Resistor identification for 37-620 - georgetownjohn - 04-15-2026
First of all, sorry, yes it is part 18 not 16. I do not know the chassis number but it is from the chairside version. There are the numbers 38-1655 stamped on the left inside of the chassis. The schematic I have is what was downloadable from online and does not say what version it is. The chassis had a sheet metal cover on the bottom.
RE: Resistor identification for 37-620 - georgetownjohn - 04-15-2026
The schematic I have is off the Radio Museum website and my chassis should be 37-620CS model 125.
When I look at that schematic on that website it looks like that resistor from the 16 mfd cap is a 10K.
Can anyone verify if I am correct.
RE: Resistor identification for 37-620 - morzh - 04-16-2026
https://philcoradio.com/library/download/service%20info/wiring%20diagrams/vol2/split/Part18-Philco%20Wiring%20Diagrams%20Vol.%202.pdf
https://philcoradio.com/library/download/service%20info/service%20bulletins/Philco%20Service%20Bulletin%20251A.pdf
And...you see the same PDFs we do.
It is 10K.
RE: Resistor identification for 37-620 - georgetownjohn - 04-18-2026
First, I want to thank all those who have tried to help a beginner like me asking such elementary questions related to the 37-620 I was working on. Special thanks to morzh for identifying that 10 Ohm resistor. After doing more research, I discovered it was a 37-620CS code 124 not 125.. I found a service bulletin 250 for that model which lists the differences between it and code 121 receivers and that stated putting in the 10 ohm resistor in series with the positive of the electrolytic 18 . That bulletin also gave updated part numbers for the electrolytics which my unit has.
Now I have gone back working on the 37-640 that I originally started with before the 620 Perhaps someone gave me help with this problem. After recapping and putting the chassis back together, a wire had broken off and I can not determine where it goes . I am following the great drawing that Ron Ramirez had prepared. The wire in question is number 5 which shows to be green on his drawing that connects to the terminal where part #45 connects. I have attached a photo of that drawing. Can someone help me determine where the other end of that wire should go? I am also attaching a copy of the schematic I have for the 37-640. Thanks again to all who have helped me.
RE: Resistor identification for 37-620 - RodB - 04-18-2026
The green wire runs past the control shaft and attaches to a resistor on the terminal strip right past the shaft. The resistor is a 51k 1watt resistor which attaches to the nearest coil and consecutive coils in that section.