Hello - I'm new to this group. I'm renovating/repairing a 46-480. Someone before me went in and "repaired" it. They have created their own RC network (don't know why)and they managed to take both ends of a 0.5uF cap to ground for their RC network. Other resistors were moved from where they should actually terminate. I know there are many ways to rewire things, but these termination points are going to the wrong places. I have spent the better part of a day reconstructing the circuitry to see if I missed something. Everything that I can tell, this is an "add-on", maybe an attempt to filter noise(?). There is no way this unit could have operated because I found chassis connections that were severed. I also saw where they changed resistor values from the original schematics ( by orders of magnitude). So my question is: is it a wise idea to restore the circuitry connections and components back to match the schematics? ( I'm also asking if I can trust the schematics). I have to do all of this before I even consider a dim bulb tester - along with full re-cap.
For the most part I've found the Philco schematics are accurate. Not always, but usually. You can search the electronic restoration threads to see what others have found as they restore a 46-480. For example there is this thread https://philcoradio.com/phorum/showthrea...ght=46-480 where there is discussion on the first page about a discrepency in the schematic value for R300 and the parts listing for R300. You may find other gems of wisdom in the on-going discussion.
If I were working on the chassis I would try to put it back together the way the schematic has it. Go slow, take photos of the underside as you go for reference, check your wiring (i've spent more time than I care to think about chasing down a wire that I misplaced when recapping), and post your progress and questions in this thread as you go along. Lots of very knowledgable people here happy to help.
Here are some components that I need to replace: R205 should be 220k, it is 560k. They paralleled two 100k resistors to get about 50k for R300 - should be 4.7k according to other posts. They also set up a voltage divider and connected R201 to it instead taking R201 to chassis ground. They attempted to connect a capacitor into the circuit but ended up running both sides of the cap to chassis ground - plus , one end of the voltage divider circuit had a cold solder joint. On that same tube (6SQ7), there was a broken connection to chassis ground. Maybe their mod was an attempt to fix that loss of ground ( or build an RC filter)? I also found a couple of broken wires going to the selector switch and a broken wire to one of the variable chokes. I make personal notes, drawings and take pictures as I go.
I checked the resistance of the main transformer, it was 190 ohms from top to bottom feeding the 7Z4. The prints said "1300 ohms" to the center tap (2600 ohms total). I recently restored/repaired a 46-1226 and I thought that many companies standardize parts. On the 46-1226, the transformer part number is Philco 32-8248. That is the exact same transformer that I have on this 46-480. So, here is another small thing that is not correct on the prints. The DC winding resistance of T100 should be 100 ohms to the center-tap giving 200 ohms total. I gave terminal strip designations so I can completely reconstruct the rebuild. Next I need to finish the re-cap, along with installing the correct resistors. I have to do all of this before I can even consider the dim bulb tester. It's now been two days of completely tracing every component and termination in the circuit.
Good afternoon, Harry! Wow, how cool that I'm finally seeing others encountering the same discrepancies. When I restored my 46-480 a couple of years ago I, too, discovered that R300 should be a 4.7 kΩ resistor (the original Philco schematic and parts list were at odds with each other, but my chassis had a 4.7 kΩ resistor which matched the original schematic). R205 should also be 220 kΩ.
For your convenience, I've attached a Rev. 0 copy of my digitized schematic that I created when restoring my 46-480. It depicts the exact original wiring. I will also attach my Rev. 1 schematic, which shows how I modified the power supply for safety and captures any other modifications (i.e., changing C101 from a 20 µF to a 22 µF capacitor, due to commonly available values in today's electronics market).
I can't speak for this particular model but one area where they had some leeway was in the plate load resistor on the 1st audio tube, it could be 470K, or 500K, or 250K or 270K Ohms, and all will work with little to no difference in performance as plate voltage is less critical then either cathode or grid voltage. The usual production variants that Philco engaged in, unless it was a needed design modification (lots of those in early TVs) was in swapping tubes, particularly from Octal to Loctal, or back again. For some reason a lot of their early 40s models went "retro" on the tube types, they started using things like #84s, and #41s, #42s, even though they had used "G" style octals in 1937-38, it's really funny seeing a set with loctal types, with a pair of #41s as power outputs, and also a 6A8G. This is why you need to confirm the Code number, and production run of your chassis, or it can be very confusing working with the wrong diagram. When Canadian RCA, or CGE made changes they changed the model number by adding a suffix like "A" after the model number, Canadian Philcos were even worse in that liked to do their own thing, and used their own model numbers, usually two digit ones like "Model 76" which has no relation to the early 30s model at all. One thing that I will say about the Toronto Philco sets is that they usually stuck to the same schematic through the life of the model year.
Regards
Arran
jrblasde: Your schematics are great! What did you use to generate the schematics? For my transformer, the winding DC resistance was about 100 ohms to the center tap (200 ohms total). That is because they installed the same transformer model number that was installed in the 46-1226 Code 125. (They were the same transformer) The 480 didn't need the blue set of secondary windings, so they were cut and taped-up.
Arran: I think the code for this 46-480 is 121 but from the picture, the corner of the tag is missing. Is there anyway to determine the 'run' number or to get any information from the pictures I've attached? That may help clarify the plate load resistor that I need.
Thank you - I will have to try that software. I did see on the back few pages of the service manual they list the differences in each "run". I know with the 46-1226 they list "code" improvements like 121, 122 and 125, each having some modification and circuit design changes. They actually tell you what 'code' the system has on the model sticker in the left rear of the cabinet. What I was asking is: is there any number printed or stamped to identify which 'run' has been modified in the 46-480 - if they do happen as runs being made for subsequent improvements as time passes. I may be wrong but I imagine each 'run' to be some change order for improvement. Or, do I need to check for each improvement/modification to determine which 'run' I have?
Aside from that decal inside of your cabinet (which has the code portion torn off, conveniently ), just about the only way to tell is to start looking at the circuitry to see if yours has any of those production changes. Some Philco chassis will have a code 121, 122, etc.) stamped on them, but I don’t see it often. My 46-480 did not.
Most often, I believe the code will be on the model label or ink stamped on the rear of the chassis. Which means you could find contradicting codes if both are used.
Then again if the "Mods" make zero sense, like having both ends of some component tied to chassis ground, or having one end go to nothing, or is obviously not original like added switches, jacks, or terminals, then it's probably the result of someone's meddling. It was not uncommon for new capacitors to be installed bridging old ones, this was either bad service practice, or someone was attempting to find a fault like an open cap.
Regards
Arran
Thank you for the feedback! I checked C206 and it was 1000V - don't want to make any rookie mistakes. I also saw a thread about the cabinet dipole for the FM. It had a link ( https://www.rfcafe.com/references/radio-...l-1947.htm) for a folded dipole. The thread was closed and I have a couple questions for anyone with 46-480 experience. Can I run a single loop ( 300 ohm cable) around the perimeter of the console frame shooting for a wavelength of about 116"? If I use the flat 300 ohm pair cable, will it mess up the reception if the shape is not exactly a "T" (by following the inner shape of the cabinet)? I'm asking this because the cabinet dipole has been stripped out.
I can't see any reason why C-206 would need to be 1000 VDC rated, it's an audio coupling cap with only 118 volts on the other side. That paper label with the part number 10631, is the part number for the cabinet, believe it or not they used to supply replacement cabinets for many model, though I haven't seen the console ones in a parts catalog yet.
Regards
Arran
Per the service manual, C206 was changed in a later production run (run 7) to a 1000V rating to protect against a sudden spike in voltage if the speaker is abruptly disconnected. This was a common revision in the late 40’s models.
), just about the only way to tell is to start looking at the circuitry to see if yours has any of those production changes. 
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