02-10-2019, 02:12 PM
Rich,
im gonna rattle off a few thoughts, & share a few things that were odd ball for my past repairs and hair pulling events.. might help and it might not.
not that i can help but i can say a few things that hit me as i think of them.. your latest FM swagging from left to right and not being consisntent mirrors exactly what happened to me on a recent Zenith am/fm set yet my root cause cant apply to you because mine is slug tuned..... with a metal elevator plate over top the am tuning cap. my root cause was a previous repair man tried to compensate for something,, and do a repair but the pulley that drives the FM cam and shaft was installed many many degrees out of wack... plus it was missing a tension spring.
ive been reading this thread each time to keep up to date since day one.
-just because you see what looks to be a "domino" cap doesnt mean its a capacitor. In my Zenith am/fm set it appeared to look like a domino cap but it is a 25ohm resistor.
-are you absolutely positive you are work from the correct code & run number for your philco?
I started off working on my 46-1226 and discovered that only by close examination of the removable tuning chassis,, some of the resistors were totally not matching the schematic i had ,, so i ordered the correct prints. this may be a stupid question but i digress.
-are you sure any of your loctal sockets are not failing due to carbon trace issues?
-based on your most recent couple pages of posts,, how do you know for a fact somebody did not fiddle with the tuning of the FM stuff. you described most recently that your able to manipulate things to get faint FM to happen with the aid of the signal gen but the stations dont follow the knob properly... and your fm is mostly if not properly addressed as inop.
-once on a radio i got it to *finally work* but when i mounted in the chassis, it would fail within a few minutes. i found that if i did not tighten down the mounting screws really tight, the set works,, so that means that mounting the radio into its cabinet was "twisting" the radio chassis. there must be a random cold solder joint somewhere but i decided to just document it and let it go till some day down the road.
-on a radio one day i finally solved crackle and poping that would occur after about 5min. it ended up that from the vol control there was a shielded wire. this shield was soldered to the chassis in a few places along its path. bypassing the shielded wire with a replacement solved this issue. root cause is that over a period of time, the insulation on the wire inside the shield was eventually arch flashing due to a insulation crack or something. over time i would experience automatic lowering of volume until a point where cracks and pops were all that could be heard. this symptom was appearing to be silver mica issues but that ended up not being the case.
-i have seen a few newer pics and i would not allow any original resistor to remain in the set. you can not be sure there isnt a microscope crack or some fault with a particular resistor contributing to the FM osc section 3 if i am following you on this band sw location your on now.
-some radios manuals have a table that basically gives you the expected voltages on each pin,,, my 46-1226 code 125 run 3 doesnt have this like many other radios do.
-if you can get some faint FM to come in,, can you make an FM adjustment on one of your IF cans and make the station go away ,, then bring it back with your non conductive adjuster tool???????? can you do this same step for all the other FM adjustments??????
(you'd have to mark your original locations first so you can put the adjustments back close to where they were.)
-have you tried to to make an FM antenna and get it outside? i made a few lately they are real easy.,, but must be a specific length.
-i see you have new tubes... spares are good.
-are the smaller copper looking blades on your tuning cap dedicated to the FM tuning? if yes, i noticed on my radios there are two or three adjustments there,, on my zenith these small mica caps really made the big difference on getting FM back into good harmony. i ended up abandoning the FM alignment instructions because i discovered that adjusting just these caps fixed made FM come around loud and clear. This was good because it told me that my IF can adjustments were somewhat ok ,,, the little caps near the tuning cap,, there are two that made things better, one adjusted the station to the left or right of where my needle was,, the other adjustment seemed to increase the reception. I discovered that if i just adjusted my needle to a particular station like fm99,, where i do have a station,, i adjusted by ear either of these small caps till the station agreed with my needle location. I went up to 106.9 and repeated,, went down to FM 88 and it was dead on.
sorry for the long babble,, looking forward to what you find.
scott
304 772 3411
im gonna rattle off a few thoughts, & share a few things that were odd ball for my past repairs and hair pulling events.. might help and it might not.
not that i can help but i can say a few things that hit me as i think of them.. your latest FM swagging from left to right and not being consisntent mirrors exactly what happened to me on a recent Zenith am/fm set yet my root cause cant apply to you because mine is slug tuned..... with a metal elevator plate over top the am tuning cap. my root cause was a previous repair man tried to compensate for something,, and do a repair but the pulley that drives the FM cam and shaft was installed many many degrees out of wack... plus it was missing a tension spring.
ive been reading this thread each time to keep up to date since day one.
-just because you see what looks to be a "domino" cap doesnt mean its a capacitor. In my Zenith am/fm set it appeared to look like a domino cap but it is a 25ohm resistor.
-are you absolutely positive you are work from the correct code & run number for your philco?
I started off working on my 46-1226 and discovered that only by close examination of the removable tuning chassis,, some of the resistors were totally not matching the schematic i had ,, so i ordered the correct prints. this may be a stupid question but i digress.
-are you sure any of your loctal sockets are not failing due to carbon trace issues?
-based on your most recent couple pages of posts,, how do you know for a fact somebody did not fiddle with the tuning of the FM stuff. you described most recently that your able to manipulate things to get faint FM to happen with the aid of the signal gen but the stations dont follow the knob properly... and your fm is mostly if not properly addressed as inop.
-once on a radio i got it to *finally work* but when i mounted in the chassis, it would fail within a few minutes. i found that if i did not tighten down the mounting screws really tight, the set works,, so that means that mounting the radio into its cabinet was "twisting" the radio chassis. there must be a random cold solder joint somewhere but i decided to just document it and let it go till some day down the road.
-on a radio one day i finally solved crackle and poping that would occur after about 5min. it ended up that from the vol control there was a shielded wire. this shield was soldered to the chassis in a few places along its path. bypassing the shielded wire with a replacement solved this issue. root cause is that over a period of time, the insulation on the wire inside the shield was eventually arch flashing due to a insulation crack or something. over time i would experience automatic lowering of volume until a point where cracks and pops were all that could be heard. this symptom was appearing to be silver mica issues but that ended up not being the case.
-i have seen a few newer pics and i would not allow any original resistor to remain in the set. you can not be sure there isnt a microscope crack or some fault with a particular resistor contributing to the FM osc section 3 if i am following you on this band sw location your on now.
-some radios manuals have a table that basically gives you the expected voltages on each pin,,, my 46-1226 code 125 run 3 doesnt have this like many other radios do.
-if you can get some faint FM to come in,, can you make an FM adjustment on one of your IF cans and make the station go away ,, then bring it back with your non conductive adjuster tool???????? can you do this same step for all the other FM adjustments??????
(you'd have to mark your original locations first so you can put the adjustments back close to where they were.)
-have you tried to to make an FM antenna and get it outside? i made a few lately they are real easy.,, but must be a specific length.
-i see you have new tubes... spares are good.
-are the smaller copper looking blades on your tuning cap dedicated to the FM tuning? if yes, i noticed on my radios there are two or three adjustments there,, on my zenith these small mica caps really made the big difference on getting FM back into good harmony. i ended up abandoning the FM alignment instructions because i discovered that adjusting just these caps fixed made FM come around loud and clear. This was good because it told me that my IF can adjustments were somewhat ok ,,, the little caps near the tuning cap,, there are two that made things better, one adjusted the station to the left or right of where my needle was,, the other adjustment seemed to increase the reception. I discovered that if i just adjusted my needle to a particular station like fm99,, where i do have a station,, i adjusted by ear either of these small caps till the station agreed with my needle location. I went up to 106.9 and repeated,, went down to FM 88 and it was dead on.
sorry for the long babble,, looking forward to what you find.
scott
304 772 3411
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