Philco 66B restoration - Printable Version
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RE: Philco 66B restoration - klondike98 - 09-27-2018
thanks mike!
RE: Philco 66B restoration - klondike98 - 09-28-2018
Here's something I haven't seen before. This set does not show evidence of having been serviced before. I found this unused terminal strip with an unusual looking coil on it. It is not connected to anything in the set except the screw mounting it to the chassis on a small standoff.
[Image: https://www.dropbox.com/s/qk1g4hihb7lmnbk/Philco66B_08.jpg?raw=1]
RE: Philco 66B restoration - morzh - 09-28-2018
Could be used as a wire support. I do not remember anything like it in mine.
If the spiral were grounded, it could be a small gimmick cap to the GND for the wire that goes through, except there is no wire plus the capacitance would be extremely small.
RE: Philco 66B restoration - Radioroslyn - 09-28-2018
The K type spkrs have a very similar part. It's used to support the two wires coming from the voice coil. They are pinched in between the turns of the spring.
RE: Philco 66B restoration - klondike98 - 09-29-2018
Just a little time today to check a few things out. Power transformer, field coil, voice coil and all the other coils show good continuity...amen. I stuffed the line filter bakelite block with the x1/y2 .01uF cap. The tar was much less amenable to sliding out than other sets but it did soften up and a little digging got it out. I did take that odd part out to get a better look see...
[Image: https://www.dropbox.com/s/wnlxf8lvmew6wbk/Philco66B_09.jpg?raw=1]
RE: Philco 66B restoration - OldRestorer - 10-02-2018
YAY!
I have held that one for 3 years. Im glad it is getting restored finally!
RE: Philco 66B restoration - klondike98 - 10-06-2018
Its raining again so no lacquer spraying today...
The 66 has a board with a variety of caps and resistors mounted to 14 connector/lugs. I had read a previous restoration write-up that said you might as well just resign yourself to taking the board off since there are caps under it that you can't reach without doing so. I chose to stuff all the bakelite caps first which went just fine. A 1 meg dogbone was reproduced and replaced along the way (there will be others later) and then I started on the board. I drew out what I could see and then started desoldering leads starting at one end and working my way around. Once I thought I had it completely disconnected....I was wrong...several more unnoticed connection needed to come off and finally the board could come out...
[Image: https://www.dropbox.com/s/2m1wz2vtkcbdq4x/Philco66B_10.jpg?raw=1]
(sorry...looks like I was a little shaky taking the photo
) the big 2 watt 37k (orange-violet-orange) resistor is reading 46k so I will probably replace that. The 100k (white-white-orange) resistors are reading 80k and the 70k (violet-black-orange) resistors are measuring 60k so I will probably just leave them alone. The 500k (yellow-white-yellow) is reading 880k so it will be replaced also. All the paper caps will get stuffed.
RE: Philco 66B restoration - klondike98 - 10-10-2018
All the caps are stuffed and some dogbones replaced. I elected to leave the large 37K resistor alone, we'll see if that was a mistake or not...
[Image: https://www.dropbox.com/s/awxj3a75svmrfvu/Philco66B_11.jpg?raw=1]
Everything put back in place...
[Image: https://www.dropbox.com/s/y24zjhfns5hdprl/Philco66B_12.jpg?raw=1]
RE: Philco 66B restoration - Nathan Slingerland - 10-10-2018
Looks great Bob! Keep it up!
RE: Philco 66B restoration - klondike98 - 10-14-2018
Dear RadioAbby
Call me confused.
I have been working on stuffing the electrolytic caps #49 & #50. 49 went smoothly using the same process as I used in the Philco 60MB.
The #50 shows in the schematic as two separate 8uF caps and the actual Philco capacitor part #30-2028 does indeed have two lugs on it as you would expect.
[Image: https://www.dropbox.com/s/2m60cf1nzl7vxt0/Philco66B_13.jpg?raw=1]
The common negative connection is made with the usual small metal lug physically held next to the outside of the capacitor can by the cardboard sleeve that insulates the common negative (which connects to the power transformer center tap) from the chassis. When I pulled the cardboard sleeve off of the can I found some stamped markings that list the cap as a 16uF cap. What the heck…?
[Image: https://www.dropbox.com/s/ga3448755352ksm/Philco66B_14.jpg?raw=1]
Then after a little internet searching I found a restoration done on retrovoltage.com that says the schematic had an error and that there was a connecting dot missing that makes the two 8uF electrolytics into a parallel configuration and in effect a 16uF cap. I've included the link to the retrovoltage.com article and here is the relevant image showing the correction [image from retrovoltage.com site]
[Image: https://www.dropbox.com/s/vprkxatomf0vwnp/philco66B_15schematic%20errro_retrovoltage.jpg?raw=1]
When I measured the capacitance, each lug displayed 17 or 18uF. If I wired the two lugs together and measured the capacitance, it still only showed 18uF which says to me that it is indeed a single 16uF cap it just has two lug (but for some reason there is no continuity between those two lugs when checked with an ohm meter).
The wires in the radio connected to the “red” lug go to the 1st IF compensator cap #17 and to one end of resistor #28.
The wires in the radio connected to the other "plain" lug go to the filament of the 80 rectifier and to the green/white wire leading to the field coil.
While tracing these all out it became apparent that there was another connecting dot missing from the schematic because there is continuity between the end of the #28 resistor, the #17 compensator AND the White wire connecting to the field coil. Here is a portion of the original schematic and my addition of the correction from retrovoltage.com (RED dot) and my correction (BLUE dot).
[Image: https://www.dropbox.com/s/k9cn1sdj0e3dv5n/philco66B_17%20base%20schematic.jpg?raw=1]
[Image: https://www.dropbox.com/s/b17utigao0dyk7u/philco66B_16schematic%20error.jpg?raw=1]
This lead me to thinking you would not connect the positive of a single 16uF cap to both sides of the field coil (assuming the retrovoltage.com correction is actually correct)…
I was all set to stuff in two 8uF solen caps each wired separately to one of the two lugs like its shown in the schematic but now I’m totally confused…
RE: Philco 66B restoration - Steve Davis - 10-14-2018
There should be a connection at your "blue" dot but not your "red" dot. The capacitor in the photo looks to be a single 16uf and could never be used to replace the two 8uf caps. A connection at the red dot would short out the field coil and kill the bias.
Steve
RE: Philco 66B restoration - klondike98 - 10-14-2018
Thanks Steve! Yes there is definitely a connection at the blue dot in my radio, confirmed with the continuity check. I just could not reconcile what I was measuring with what the fellow in the retrovoltage article said. The strange thing is that the printed label on the side (not shown in the picture) has the correct part number ( 30-2028) for the radio. I did find another restoration discussion where the person mentions the missing blue dot error in the schematic.
I will stuff the cap with two 8uF solen caps and wire it up as the schematic shows with the blue dot connection.
RE: Philco 66B restoration - klondike98 - 10-20-2018
Cap #50 has been stuffed. It was one of those foil wrapped in wax types that took a good bit of heating to pull it out. I screwed a long screw into it first so I would have something to grip with the pliers. Photos follow. All the caps are now stuffed and I'm waiting for a tube order to arrive with the missing 6A7. I haven't really started working on the "white" 116B I picked up I did pull the tubes to check them so I could put together the order. Boy was that chassis dirty!! Surprisingly, all the tubes in the set tested good. I was trying to pull the top cap lead off of one of the 77s and pulled the whole cap off. Even then the tube tested good so if I can get the cap back on it I'll be all set. There were several more of those top cap leads on other tubes so I gave them all a small dose of WD-40 and let it sit over night. The next day they all came off easily.
Pulling out the original caps...
[Image: https://www.dropbox.com/s/ufiw536ti1vw7uy/Philco66B_18.jpg?raw=1]
Adding in two 8uF solen film caps....
[Image: https://www.dropbox.com/s/d5nidrc6tqycpmk/Philco66B_19.jpg?raw=1]
All set to put it back into the chassis...
[Image: https://www.dropbox.com/s/ghlypx0cosy2d9z/Philco66B_20.jpg?raw=1]
RE: Philco 66B restoration - klondike98 - 10-26-2018
My 6A7 and a few other tubes arrived today from Bob D's FindATube so I was all set to fire the 66B up and get it aligned...ho ho ho
Getting past the dim bulb test OK I powered it up at about 115v. The 80 filament lit as did the dial lamp but the set was ominously quiet! I flipped the tone switch and did hear a small click through the speaker and a screwdriver on the cap of 75 produced a buzzing through the speaker so at least the audio seems to work. Voltages on the tubes were as follows:
[Image: https://www.dropbox.com/s/qeoad4s7k6uzv4h/Philco66B_21.jpg?raw=1]
Voltages on the electrolytics were:
Electrolytic Cap#50 (red lug)= 293v
Electrolytic Cap#50 (plain lug)= 350v
Electrolytic Cap#49 = 0v
Gotta be the choke #48... and indeed when I checked it (I swear I checked it earlier
) it is open. Its a bit of a tight fit where its located so I'll have to see what I can find to replace it. I don't have a spec on it but following Terry's previous advice on an open filter choke is go with the highest Henrys that fit the physical dimensions for the choke. More later...
RE: Philco 66B restoration - Ron Ramirez - 10-26-2018
If my health permits, I hope to restore my 66B chassis this winter. Watching your progress with interest, especially regarding the choke to see what solution you come up with as mine may also be bad.