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 Post subject: Philco 40-180 - cap question
PostPosted: Sep Sat 04, 2010 11:53 pm 
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Location: Lehighton, PA.
If you look at the photo you'll notice a large maroon cap in the upper right corner. It is a .1mfd, 600v cap connected between pin 8 of the 7J7 tube and ground. It's not listed on the parts list. Is it supposed to be the .2uf shown as #33 on the schematic or did I miss something?

Image

Schematic here:
http://i863.photobucket.com/albums/ab191/rocketeer_2010/Radios/philco40180.jpg

Thanks,
Larry

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PostPosted: Sep Sun 05, 2010 12:27 am 
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Pin 8 is the heater; pin 7 is the cathode.


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PostPosted: Sep Sun 05, 2010 2:53 am 
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Larry

Doesn't look right from here. Are you sure that's a 7J7? Photo looks like an octal tube rather than loctal tube.

Schematic doesn't show any octal tubes, maybe a different revision?

http://www.nostalgiaair.org/PagesByMode ... 013336.pdf

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PostPosted: Sep Sun 05, 2010 3:38 am 
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Holy crap! It's a 6J8G! That tube had a paper sticker on it and I could not see the number but since all the other tubes matched I assumed ( :oops: ) that it was what the schematic said, a 7J7. Now I'm really confused. The tube socket is factory riveted so it hasn't been replaced, or at least doesn't appear to have been. Now what?

The rear of the chassis is clearly stamped 40-180 Code 121. It does have the factory remote TV sound capability but wouldn't the code be different if it was a deviation?

OK, I looked it up in my RCA Tube Manual. If I read it right while pin 8 is the filament in a 7J7 it is the cathode in a 6J8G. That right? So why a .1mfd 600v cap on the cathode?

Larry

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PostPosted: Sep Sun 05, 2010 1:03 pm 
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that may not be an original capacitor. the exact value of a cathode bypass capacitor is not critical. you just want it to have a reasonably low reactance at the if frequency.

most likely the original was a 200 volt capacitor, the lowest common paper cap rating. as a cathode bypass, it would only see maybe 4 volts, but that's the thinnest they could make paper back then. it wasn't until the mid 50's that they started making capacitors with 50 and 100 volt ratings.

so to make a long tory short, you could replace it with whatever you want.


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PostPosted: Sep Sun 05, 2010 2:08 pm 
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it always surprizes me everything you have to read on this Philco 40-180 and all the changes Philco made on them , maybe even had more counting UK models , I have maybe 4 of them ,Table and Floor models


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PostPosted: Sep Sun 05, 2010 4:37 pm 
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I have one of these with the same tube change but since I had printed out the schematic and went over it before I tore into the radio I knew about the prouction changes (see page 4 of the schematic listed above). By the way, the wiring in your chassis looks alot better than mine did.

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PostPosted: Sep Sun 05, 2010 5:22 pm 
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There are two wires where the rubber is disintegrating but so far so good. One is the lead to the dial lamp. I need to replace that, and the other is a short lead under the chassis. There are a few that are as hard as a rock but not breaking up. I'm considering leaving them alone. Thoughts?

Larry

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PostPosted: Sep Mon 06, 2010 7:20 pm 
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Ask yourself this; if the insulation were to crumble off, would the wires be in danger of touching anything? If they are isolated, I'd leave them alone...if not, I'd replace the wire(s).


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PostPosted: Sep Thu 30, 2010 1:19 am 
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I just started surgery on my 40-180 as well. I looked at mine and it is a 0.2 mf in that corner and looks the same brown wax version as the others. I too have a 6J8G there. Mine is a Run 5 version and I discovered a 150 ohm 1/2 watt resistor just off the back side of the push button switch unit that is not on any drawing but is mentioned under Production Changes that goes to the 6J8G.

I just removed the 8 coil assembly and the switch assembly to work on the stuck switches. This was not a fun part of the project and it is Miller time now. Fortunately all coils were fine and all the switches now function fine mechanically and electrically.

I have lots of rotten rubber wire that will need replacing so with the switches and coils out of the way and safely aside on the bench I can go thru and replace wires, caps and resistors. Amazing how much room is there now to work on the guts.

Let me know how your update is going. I'll try to get some pics posted as I progress.

Gary


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PostPosted: Sep Thu 30, 2010 5:00 am 
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on all philco radio I take panel light socket apart because lot of them have a rubber like gromet holding center bulb contact that shorts out , I make a fiber washer to fit socket and use heat shrink on the wire coming out of socket , if you need help on these please PM me ,, I have a 40 180 chassis i could send picture of it also

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PostPosted: Sep Thu 30, 2010 6:30 am 
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Daniel Hilderbrand wrote:
on all philco radio I take panel light socket apart because lot of them have a rubber like gromet holding center bulb contact that shorts out , I make a fiber washer to fit socket and use heat shrink on the wire coming out of socket


On those lamp sockets. Someplace unfortunately I forget where I bought a few years ago a box of 1000 nylon shoulder washers that fit perfectly inside those lamp sockets. You keep the Contact point to the bottom of the bulb... solder it to a new wire.. and the spring. with this nylon washer in there.. pull it into place and your done. Same as what Daniel is talking about with the fiber washer. Need to remember where I bought them. A few thousand of those split up at radio meets to all the ARF guys and none of us would have beans in any of them to speak of price wise. Think they were something like 10 bucks a thousand.

On the 40-180 chassis don't forget to look at the rubber wire that goes up into the IF cans as well. A bad wire up inside one of those can really mess you up if a bare spot of B+ Plate side rubs the can cover.

John k9uwa


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PostPosted: Sep Thu 30, 2010 3:50 pm 
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I saw the wires in the cans as well. I am trying to figure out how I want to tackle those with sleeving versus new wire. Lots to do on this one but it is a labor of love.

The tube sockets will need special care as there is lots of green in the pin sockets. There won't be much left by the time I get done I suspect but I am anxious to see it play again.

Someone was in this radio many years ago and removed the electrolytics from top side and installed caps underneath which are also bad. I am going to post another post to see if anyone has a couple of original caps they would like to part with so I can reinstall for aesthetic reasons only. Looks strange with two big holes in the chassis.

Gary
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 Post subject:
PostPosted: Sep Thu 30, 2010 4:10 pm 
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Location: Leo, IN or Zellwood, FL
glwells wrote:
I saw the wires in the cans as well. I am trying to figure out how I want to tackle those with sleeving versus new wire. Lots to do on this one but it is a labor of love.

The tube sockets will need special care as there is lots of green in the pin sockets.

Gary
WB9AYD


The IF cans are a bit of a PITA to take apart with that goofy metal strap that holds the coil in place. but they do come apart. I have done the wire in the cans both ways. Sleeved slid in and ripped the cans apart.

Tube Socket Cleaning. I first brass brush the TOOBE pins. Then I Deoxit spray the TOOBE PINS. NOT the Socket but the Tube Pins them selves. Then I stuff the tube in and out of the socket a few times. It seems to work most of the time.

Some guys have said they spray a pipe cleaner with the cleaner but it would have to be a cleaner that totally flashes off and NOT one that leaves behind any lube and then run it through the tube socket holes.. never tried that but might next time I do one.

The worry with using that method is you dare NOT get anything in between the layers of the sandwich on the bakelite tube socket for fear of later arcing between the tube pins. And there is no way of seeing that you left something in there while doing the cleaning.

John k9uwa


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 Post subject:
PostPosted: Sep Thu 30, 2010 5:42 pm 
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glwells wrote:
Someone was in this radio many years ago and removed the electrolytics from top side and installed caps underneath which are also bad. I am going to post another post to see if anyone has a couple of original caps they would like to part with so I can reinstall for aesthetic reasons only. Looks strange with two big holes in the chassis.

Gary
WB9AYD


Gary, I snap Knockout Plugs into the chassis holes. You can get them in lots of sizes where electrical supplies are sold, they are used to fill the open holes in electrical wiring boxes and panels. This is what they look like http://www1.mscdirect.com/CGI/NNSRIT?PM ... 7&PMT4NO=0
Don


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