#16
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Quote:
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Martin Logan Motion LX16's & B&M 704's ML Dynamo 300 sub Outlaw RR2160 Empire 298 TT W/Denon 103 cart Marantz CD6006, Pioneer DV-588 SACD |
#17
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I have found the schematic for a Philco model 48-460 which uses a PM speaker and the same case as yours.
The filter network in this radio is a 30ufd on pin 7 of the 35Y4, a 220 ohm resistor, a 25 ufd cap, then a 1200 ohm resistor, and finally another 30 ufd cap. The speaker output transformer is tapped into the center 25 ufd cap. The rest of the radio is powered from following the 1200 ohm. See below. ***************** --------------- to audio out transfromer. *****************| ***********220***|****1200 35Y4 -------\/\/\/\/------\/\/\/\/-----to rest of radio ******|***********|*******| ******----*30*****----- 25 *----*30 ******----********----- ***---- ******|************|*******| ******--------------------------- ******************| ****************------ *****************---- ******************-- The tube lineup is 14AF7, 7B7, 7B7, 7C6, 50L6, 35Y4. Please excuse the *s, for some reason when I posted, my spaces in the picture were wiped out so I replaced them with *.. Probably related to crappy Microsoft software. Last edited by peverett; 10-31-2009 at 01:23 PM. |
#18
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Thanks!
That's exactly how my filter network is wired except I have 7C7, 7A8, 7B7, 7C6, 50B5, 35Z5 . So it is original after all Last edited by bandersen; 11-05-2009 at 10:11 PM. |
#19
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Good luck with your restoration. I like the sound and the excelent reception of this type of late 1940s Philco radio.
I am near Austin, Texas and the nearest AM station that plays music that I like is in San Antonio, 60 miles away. These receive the station fine. Other radios that I have without a RF stage or two IF stages, have a hard time. |
#20
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Sister set arrives from Boulder
My buddy in Boulder, CO just sent me this set with a big chip missing.
Exactly the same 46-420 variation - PM speaker, 50B5 audio output, etc. How crazy is that! Best of all - it has the original back It's a little warped, but maybe I can steam and flatten it out? I've started recapping the other set and hope to power it up tonight or tomorrow. |
Audiokarma |
#21
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As mentioned before, I have a couple of empty cases for these. Do you want to have two restored radios?
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#22
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Quote:
PM sent. |
#23
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Looks like all the tubes are the originals Philcos and they test real strong
Maybe this set did see much use. I'm gonna try powering it up later tonight for the first time. Last edited by bandersen; 07-03-2015 at 09:28 PM. |
#24
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I finished recapping and replacing out of spec resistors. I powered it up but only get a loud hum - the tuning and volume controls have no effect
I'll double-check all my work - I hope it's nothing serious like an open coil. |
#25
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As to that back, spritz it good with water on the side towards the inside of the radio, flatten between weighted boards, leave for a few days to a week.
Reece
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Reece Perfection is hard to reach with a screwdriver. |
Audiokarma |
#26
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Just use a signal generator to inject signal along the line, you'll find the fault. You can also just apply a soldering gun to the center terminal of the volume control, which should give you a hum if the audio amp is working okay.
Maybe you'll get lucky like I did with mine and find that the grid cap on the audio output is shorted to a pin on the rectifier socket. That is a pretty cramped chassis under there! |
#27
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It sure is cramped.
I pulled out my second chassis (the one that just arrived from Boulder) and quickly tacked some new electrolytics in. Bam! Works just fine Great sensitivity and a lot louder than I expected. That skinny 50B5 output tube runs pretty darn hot though. I wonder if that's normal or it's biasing is off a bit? Some of the resistors have drifted a bit and I haven't swapped them out yet. I'll do some more checking tomorrow. Last edited by bandersen; 07-03-2015 at 09:28 PM. |
#28
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Thanks for the tip. I'll give it a try.
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#29
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Re-stuffing electrolytics
I'm just about done restoring one of these 'hippos'. It's playing great with excellent reception. I decided to re-stuff the one electrolytic for a final touch. I've restuffed a few metal can types, but never a paper/wax one.
Here's how it went. First I pulled the old caps. out of both radios. 3 new caps need to go into each one. I tried heating up the caps to free up the innards. After a few minutes I gave up The tubes were starting to fall apart which is the only part I cared about salvaging. Why not roll my own? I painted them yellow with some kids paint. Then I made some water-slide decals using paper left over from another project. I also 'dirtied' them up a little using a light spray of flat black paint. I don't want them to look brand new. The original is in the middle. Next, I soldered the 3 caps together and reused the original wires. Finally, I inserted the caps and filled up the tube with wax. First, I stuffed up one end and filled it 3/4 with wax. Then removed the plug and filled the other end. One down, one to go Last edited by bandersen; 11-27-2009 at 05:28 PM. |
#30
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Thanks- that shot of those caps puking their guts out is just what I wanted to see before sitting down to Thanksgiving dinner. Have a great holiday!
ps- where did you get your waterslide decal paper from? Is it inkjet printer friendly? |
Audiokarma |
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