Looking for help . I have a philco 37-84 code 121. the only info I can find is for a code 122. I have 4 tubes 80, 42, 77, 77. is the wiring and components under the chassis the same only the tubes are different? The Radio Museum has some info but no prints.
The caps have been changed(kinda messey the way they did it), The radio powers up and hums with 2 spots on the dial having a squeal. Any help much appreciated.
Eric
Use the schematic for Model 84. Although, the only difference between a model 84 (also 37-84 Code 121) and model 37-84 Code 122 are the tubes used. The 37-84 Code 122 uses octals, while the older 84 used the equivalent standard base tubes.
77 = 6J7G
42 = 6F6G
80 = 5Y4G
And please note when I use the equal sign, I mean electrically identical. Of course the bases are different.
Only recently did I become aware of a 37-84 "Code 121," and I see I need to make some changes in my site's Gallery as a result.
Thanks Ron
Just started this got it at a garage sale, now I'm a novice but the under side of the chassis is a real butcher job, I started replacing the dog bone resisters and found 2 that were double in value and 2 more by 50%. The caps have been replaced by somebody and I will start checking to see that there correct. The 77 det-osc seems to be very sensitive.
Eric
Search this phourm for model 84. More than likely the antenna and osc coil are bad. The phourm has the info how to repair them. You will find that just about all of the resistors are out of spec so replace them. On these sets it is important to use a signal generator to align the IF. Some try to do it by ear but that is a bad move!!
Terry
Latest update got the radio up and running turns out one of the Black Bakelite Condensers (#28 2-.015) was leaking pretty bad (the others had been bypassed) and I guess was passing thru a large AC component (loud humming) as one leg of 115 was tied in. That's were I got my handy chart from this site matched up the #'s and read how to remove the old wax and re stuffed with new caps.
I still have a lot of cosmetic work on the underside can't stand the haphazard way they did it. and the resistance on the Vol is twice the 20k ( reads 40k) it shows on the print but it seems to play fine. Thanks again to this site
Eric
Tnx for the update! Glad you got up and running.
Terry
There's a little brown hexagonal adjustment on the back of the chassis; this is the feedback adjustment and it sounds like that's what you need to tweak.
The 37-84 was my first old radio and cost me $1.25 at a junk store in 1956. I recall adjusting that feedback every day depending on station signal strength. At some point in my inexperience days I washed the dial clean with soap and water and then ruined the photofinish when cleaning it probably with wood alcohol. A couple of years ago I bought a replacement 37-84, one in absolutely showroom condition- and I still adjust the little hex feedback "knob".
Pete AI2V
Yes you are right about that adj on the back but the radio looks good
Eric
(05-30-2012, 03:40 PM)Ron Ramirez Wrote: [ -> ]Use the schematic for Model 84. Although, the only difference between a model 84 (also 37-84 Code 121) and model 37-84 Code 122 are the tubes used. The 37-84 Code 122 uses octals, while the older 84 used the equivalent standard base tubes.
77 = 6J7G
42 = 6F6G
80 = 5Y4G
And please note when I use the equal sign, I mean electrically identical. Of course the bases are different.
Only recently did I become aware of a 37-84 "Code 121," and I see I need to make some changes in my site's Gallery as a result.
Ron
A 84B type cabinet uses the old tubes 77,42,80 (code 121) but I recently had two 84B type cabinets for epair using
chassis code 122 octal tubes. I checked your gallery and radiomusuem. It appears that 84B type cabinets used only
code 121 old tubes. Is that correct?
ABV
Correct, model 84 sets only used standard based tubes. If you have a set with an 84 cabinet (1934-1936) and that uses octal tubes, then someone mixed 37-84 chassis and 84 cabinets at some time.
(08-24-2016, 07:12 PM)Ron Ramirez Wrote: [ -> ]Correct, model 84 sets only used standard based tubes. If you have a set with an 84 cabinet (1934-1936) and that uses octal tubes, then someone mixed 37-84 chassis and 84 cabinets at some time.
Ron
Thank you for your quick reply. I need to inform the customers of this issue.
ABV