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 Post subject: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 1:57 pm 
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For my second restoration (first was an Emerson 543 http://antiqueradios.com/forums/viewtopic.php?f=3&t=271064&p=2264307#p2264307), I've chosen a more complex AM/FM model, a Philco 49-905. Philco seems to be more complex than other brands, so this will be a fun challenge. Some pix:

Attachment:
File comment: This is my next project.
As Received - Front.jpg
As Received - Front.jpg [ 53.19 KiB | Viewed 5287 times ]


Attachment:
File comment: Decent condition, but dirty. Spiders have lived here.
As Received - Chassis.jpg
As Received - Chassis.jpg [ 65.94 KiB | Viewed 5287 times ]


Attachment:
File comment: Way more old caps, and way more crowded, than the Emerson 543.
As Received - Chassis Underside.jpg
As Received - Chassis Underside.jpg [ 67.39 KiB | Viewed 5287 times ]


A question on the electolytic capacitors in the cardboard tube (see photos below): there are six connections under the chassis, in an inner and outer ring. Based on the schematic (http://www.nostalgiaair.org/Resources/674/M0013674.htm), it seems that the outer connections are the ground/negative connections, and the inner ones the positive? If someone could confirm this, it would be a great help.

Attachment:
File comment: Electrolytic tube.
Capacitor Canister.jpg
Capacitor Canister.jpg [ 56.42 KiB | Viewed 5287 times ]


Attachment:
File comment: Inner connections positive, outer connections negative? All negatives equal, or individual for each capacitor? If separate, which goes to which?
Capacitor Canister Socket Connections.jpg
Capacitor Canister Socket Connections.jpg [ 52.86 KiB | Viewed 5287 times ]


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 3:46 pm 
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The outer contacts are common negs,the inner 3 are separate positives.
Phil

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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 5:22 pm 
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Did it come with a back?

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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 7:08 pm 
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"Spiders lived here" in Latin is something along the lines of "araneus vivere hic".

Nice set by the way, funky looking.


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 7:21 pm 
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Philco Fan - thanks. My plan is, then, to solder the negative leads to the new electrolytic capacitors to the existing negatives - i.e. leave what's currently soldered to the negatives still soldered there - but take the positives from the new capacitors and solder them to what's currently connected to the positives, but *no longer* soldered to the positive leads. This will leave the old electrolytics in the can with their negative leads still connected, but their positives not.

Is this safe to do? Or, should I unsolder everything from the current negatives, and resolder them to only the negs on the new electrolytics, leaving the old can completely disconnected, nothing soldered to any of its leads any more?


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 7:23 pm 
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1st plan is OK-I usually just cut the + terminal right off the old can with everything still attached and use that for the new caps' +.
Phil

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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 7:29 pm 
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Thanks Philco Fan. That's what I'll do.

When you said "common negative", does that mean that all three negative leads are physically, electrically connected inside the socket/can? Or, are they electrically separate within the socket/can, and just externally all connected to negative, separately?


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 7:48 pm 
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Also, if they're "common negatives", can I connect any of the new electrolytics to any of the existing negative terminals, or must they be connected to the proper negative, that goes with a particular positive? From the schematic it would seem so, as the negs of all three capacitors all go to a common negative/ground line.


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Wed 25, 2015 8:28 pm 
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sdyer wrote:
Also, if they're "common negatives", can I connect any of the new electrolytics to any of the existing negative terminals, or must they be connected to the proper negative, that goes with a particular positive? From the schematic it would seem so, as the negs of all three capacitors all go to a common negative/ground line.

You can connect them all to common as long as the schematic shows it that way.

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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Thu 26, 2015 4:08 am 
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glasdave - no, it did not have a back. I plan to fabricate one out of something. Why do you ask?


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Thu 26, 2015 4:56 am 
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I was wondering because, sometimes the antennas are mounted to them, and they are part of the tuned circuit.

I have a slightly newer philco am-fm,nice and clean , got it for a good price, but no back, and the guy I got it from doesn't have it.

So I'm stuck till I find a parts set :cry:

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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Thu 26, 2015 7:00 am 
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This is what I did with the replacement electrolytics on my 49-905. That's hot glue that keeps them all together.

Attachment:
wiring.jpg
wiring.jpg [ 80.36 KiB | Viewed 5170 times ]

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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Thu 26, 2015 1:27 pm 
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Hello Eric,
Wow that chassis was crowded ! anyway you did nice clean job .

sincerely Rich


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Tue 31, 2015 3:53 am 
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Hi Eric - what is the chassis number on yours? Mine is 121. I ask because the wiring in my chassis doesn't match the manual I got from NostalgiaAir (http://www.nostalgiaair.org/PagesByModel/674/M0013674.pdf). There are more capacitors in my chassis than in the manual, and than appear in your unit. Could someone have rewired it? Everything looks pretty original and undisturbed, but it's possible. Is this not the manual for chassis 121? The manual doesn't explicitly say "121" on it so it's possible.

I'm tempted to replace the capacitors as I find them, regardless of what the manual says.


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Tue 31, 2015 4:20 am 
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Rich,

I don't have it anymore but I'm pretty sure that it was a 121. Being a member of radiomuseum.org, I was able to download the schematic from there. I didn't have a problem.

Unless you are having a problem with the radio and need to follow the schematic to effect a repair, don't woryy about it. You'll be fine just replacing the capacitors one for one. Works for me :wink:

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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Tue 31, 2015 5:07 am 
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OK, here's what I found. The C315 capacitor is supposed to be .05mf, going to ground. Instead, it looks like a .03 was installed, with an extra not-in-the-manual .01mf from one end going to ground, and a strange cylinder/wrapped component going from the other end to ground. The photos below show this. Would this have been some factory or repair-man fix because they didn't have a .05? Is it some later factory mod or fix to improve the radio? I replaced it with a .05mf as called for in the manual.

--> Did I do the right thing?

Attachment:
File comment: Bottom wax cap is C315, but it is a .03 not a .05, and it is wired to pin 8, not 9. The white jumpers indicate where the .01mf was (not in manual), and you can see the tube thing to the right, joining the cap to pin 9. Note - no other components use pin 8, so the .03 cap and tube thing are wired in series.
pt-01mf (white jumpers), pt-03mf, tube thing.jpg
pt-01mf (white jumpers), pt-03mf, tube thing.jpg [ 77.02 KiB | Viewed 5080 times ]


Attachment:
File comment: The manual shows C315 as a .05mf cap. My notes show how one end has a .01 on it to ground, C315 as installed is actually a .03mf, and there's this tube thing on the right end of it.
Notes show actual components.jpg
Notes show actual components.jpg [ 67.9 KiB | Viewed 5080 times ]


Attachment:
File comment: Here are the .01mf, .03mf and cylinder thing after I removed them. The cylinder thing looks like it has wires wrapped around the outside under some wax, and there's a red mark at one end.
pt-01mf, pt-03mf, tube thing.jpg
pt-01mf, pt-03mf, tube thing.jpg [ 78.16 KiB | Viewed 5080 times ]


Attachment:
File comment: I replaced these three with a single .05mf, as specified in the manual, connected to the pins specified in the manual.
pt-05mf installed.jpg
pt-05mf installed.jpg [ 78.96 KiB | Viewed 5080 times ]


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Mar Tue 31, 2015 11:47 pm 
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Does anyone know what the tube thing is on the right?


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Apr Wed 01, 2015 12:05 am 
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Looks like an RF choke.

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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Apr Wed 01, 2015 12:12 am 
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Hmm. Maybe this unit/model had a problem with noise on this circuit. Should I put it back, do you think?
Also, I googled an RF choke and get that it cuts down noise on a circuit. What else can you tell me about them? (edit: further reading indicates that's not right. So, what *do* they do?)
And what about the .01mf cap that was attached to its other end, going to ground - should that go back as well?


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 Post subject: Re: Philco 49-905 - My second restoration
PostPosted: Apr Wed 01, 2015 2:52 am 
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Don't really know that much about the choke, only that I'd put it back. Don't worry about the .01 cap. Just continue on replacing one at a time. Then check all of the resistors.

Good luck!

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