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 Post subject: Philco Hippo 49-900
PostPosted: May Wed 16, 2018 5:13 pm 
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Joined: Feb Sat 28, 2015 10:50 pm
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Location: Decatur Alabama
I am currently without a means to post photos so bear with me- I''l try to make it as clear as is possible. I have been working on a Hippo 49-900 which is pretty close to the 46-420 model but instead of a 35Z5 rectifier the 49-900 has a 35Y4. The schematic is in Rider's volume 18, pages 209 and 210. There are 2 existing wires that come from pins 1 and 2 of the 35Y4 that are supposed to be for a dial lamp. But when I connect a lamp the radio loses signal until it is gone. What am I missing here? I don't even have to plug in a lamp-I just wire a socket in place and it does the same thing.


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 Post subject: Re: Philco Hippo 49-900
PostPosted: May Wed 16, 2018 5:40 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: San Jose, CA USA
Since merely connecting the socket is causing a problem, there is most definitely something wrong with the socket. Most likely there is a short between the two wires. Check with an ohmmeter. Another possibility is a short between one of the wires and the chassis mount, although it is less clear how that could cause the radio to stop functioning.

Take a close look at the 35Y4 filament when the socket is wired in. Does the filament glow stop?

Even if the socket is shorted, it would not normally cause the complete filament to stop glowing. Is there any possibility that you've got the numbering of the pins wrong on the bottom of the socket? If you've wired the socket (with short) to pin 8, you could cause this problem.

In any case, if the socket has no shorts, wiring it into the circuit anywhere would have no effect on anything. So that's the place to start. Find out what is wrong with your socket. Then see if it is wired to the right pins.

One more possibility: Has the 35Y4 been replaced with the octal type 35Z5? 35Z5 is a much more common tube, and Philco often switched back and forth between Loctal, Octal, and Miniature tube types within the same model. If yours has a 35Z5, the pinout will be totally different (see here: https://www.radiomuseum.org/tubes/tube_35z5gt.html ). If it has a 35Z5, the dial lamp should be wired between pins 2 and 3.

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 Post subject: Re: Philco Hippo 49-900
PostPosted: May Wed 16, 2018 5:58 pm 
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Joined: Feb Sat 28, 2015 10:50 pm
Posts: 470
Location: Decatur Alabama
Its definitely a 35Y4 loctal socket tube, and it is wired correctly (I didn't rewire it). I think the only possibility is a shorted lamp socket so I'm going to try another one. Thanks!


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 Post subject: Re: Philco Hippo 49-900
PostPosted: May Wed 16, 2018 6:21 pm 
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Joined: Feb Sat 28, 2015 10:50 pm
Posts: 470
Location: Decatur Alabama
Okay, the socket was rusty inside and probably shorting..so I tried another one. This time it doesn't affect the output but when I install a lamp the volume slowly disappears. But the 35Y4 filament still burns. I rechecked the wiring of the pins and everything seems to be correct.


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 Post subject: Re: Philco Hippo 49-900
PostPosted: May Wed 16, 2018 9:01 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Fernandina Beach, FL
Is the output tube gassy?

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 Post subject: Re: Philco Hippo 49-900
PostPosted: May Wed 16, 2018 9:07 pm 
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Low emission 35Y4. Adding the lamp reduces filament heat causing emission to fall below a point your radio operates properly.

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 Post subject: Re: Philco Hippo 49-900
PostPosted: May Wed 16, 2018 10:01 pm 
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Joined: Feb Sat 28, 2015 10:50 pm
Posts: 470
Location: Decatur Alabama
Thanks! I'll try another 35Y4 AND change the 50L6.


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 Post subject: Re: Philco Hippo 49-900
PostPosted: May Wed 16, 2018 11:06 pm 
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Location: Fernandina Beach, FL
doc612 wrote:
Thanks! I'll try another 35Y4 AND change the 50L6.

Certainly have nothing to loose...

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