Refurbishing a Model 60 - Printable Version
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Refurbishing a Model 60 - retired2020 - 08-29-2021
I am refurbishing a model 60 B. All tubes replaced as well as capacitors ( excluding mica capacitors ) Attached is the schematic, and results of the voltage readings at the tubes on Table 1. As you can see there are no volts at most of the plates and grids except tube 80 reading 330 volts. All filament volts are okay Table 2 has the power transformer data and while terminal 3-5 is only 3 volts the plates at tube 80 are 750 volts. Tubes 42 and 80 light up but not so for the other tubes. Needless to say there is no sound. Any Thoughts?
RE: First Resto - Philco 60B - Radioroslyn - 08-30-2021
Hi,
Didn't see a schematic so here's a link: https://philcoradio.com/library/download/service%20info/wiring%20diagrams/vol1/split/Part39-Philco%20Wiring%20Diagrams%20Vol.%201.pdf
Now for troubleshooting. Use an ohmmeter and measure the resistance from pin 1 or 4 of the 80 tube to and the + side of 46. Then to the + side of 45. Next connect the ohmmeter from the - side of 45 and to the chassis. note resistances and report back.
Logic would dictate to check the 80 tube, the polarity of the filter caps, open bias resistor, or an open field coil.
RE: First Resto - Philco 60B - retired2020 - 09-01-2021
The resistance from pin 1 to the +side of 46 reads 0 ohms, continuity. From the + side of 45 it's Infinity ie no continuity. From - side of 45 to chassis is 268 ohms. Regarding the wiring when I replaced the caps I followed the existing wiring. I notice now on the schematic that the plus from 45 should connect to tube 42 directly as well as a 70 K resistor. These wires are not there as noted on the attachment. I also noted there were several versions of the model 60. The one I have is the 60 B based on the cabinet face. Attached is the new schemo for 60 B from the Radio Museum (Its A pdf so you need to open it ) which seems to more closely match what is there but again these wires are missing. I would think the newer schemo is more accurate? Regarding tube 80 its base was loose so I purchased some NOS for that tube as well as all the others. I have a tube tester Sencore TC 136 but it does not have the sockets for these types of tubes .
Thanks
RE: First Resto - Philco 60B - retired2020 - 09-01-2021
I forgot to add that model 60 B is version 4 since it has the wave trap.
RE: First Resto - Philco 60B - Radioroslyn - 09-01-2021
Well the good new is seems I like I know what's wrong. Bad news is the field coil is open which is part of the speaker. You might want to double check it, might be a bad connection.
As for models the 60B the B indicates that it's in a baby grand cabinet. This would be a cathedral style. There was a bunch of other cabinets that the 60 chassis was used in with different letter designations. If it still has it's blue sticker it will read model 60 code 121. The code number would indicate differences in speaker setup, chairside, or radio phono combos. 121 is the base model sorta.
RE: First Resto - Philco 60B - Radioroslyn - 09-01-2021
On the back of the spkr there is a small metal cover attach w/2 1/4 hex screws. Remove them slide the cover out of the way and you see 3 solder lugs on the top of the opt. Two of the wires go directly to the field coil. Measure the resistance across these two connections. Should see abt 1140 ohms. If much higher fc is toast.
RE: First Resto - Philco 60B - retired2020 - 09-02-2021
I presume you mean the speaker filed coil Part number 42 It measures 1171 ohms .
RE: First Resto - Philco 60B - Radioroslyn - 09-02-2021
Ok so if you measure an open circuit between the +'s of 46 & 45 then there is bad connection or something is miss wired. You should see the same resistance as the field coil. Without this connection you will have no hv farther than 46. And yes # 42 is the field coil.
The diagram from RM is pretty hard on the eyes. https://philcoradio.com/library/download/service%20info/wiring%20diagrams/vol1/split/Part39-Philco%20Wiring%20Diagrams%20Vol.%201.pdf