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#16
08-13-2010, 10:45 AM
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OK. Here we go. FIRST PICS of the DuMont!
The 2 open back pics are the ones that do it for me. The set is for the most part clean inside. The last pic is inside the HV cage. No signs of damage that I can find. Stuck my nose in there and smelled no burn smells. Note that the tuner is set at channel 3, or so. I wonder if this set was ever connected to cable, or did it last run WBTV channel 3 in Charlotte NC? On the chassis, there is no place to connect 300 ohm twin lead. Just a connector that looks like an RCA phono plug. It also has a phono input. I like that. I have a couple of old turntables I can use here. The kine appears to be OEM. Someone at some point cut the wires at the speaker. This was done within site of a nice 2 pin plug that connects it to the chassis. Stupidity? EDIT: Not stupid. Someone replaced the output transformer, but did a sloppy job of it. Did DuMont buy tubes from RCA? This set is full of silver lettering RCA tubes. Last edited by holmesuser01; 08-13-2010 at 09:16 PM. Reason: UPDATED speaker comments. 
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#17
08-13-2010, 11:07 AM
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And a few more...
Check out that speaker repair work. Ugh. I like that chassis nameplate. See the RCA plug looking antenna connector on the left? Is there an adaptor that I should look for here? The R5 in orange paint... Maybe this is to identify the chassis to the set? Last edited by holmesuser01; 08-13-2010 at 08:36 PM.
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#18
08-13-2010, 12:41 PM
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WOW! thanks for posting the Pix of this rare DuMont!
 Quote:
 jr
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#19
08-13-2010, 08:39 PM
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Somewhere in this disaster that I call home, I have an F connector to RCA plug. I appreciate your booklet scan.
Bruce
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#20
08-13-2010, 09:03 PM
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Awesome! I love Dumonts. Looks like it's in pretty good condition.
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#21
08-14-2010, 12:12 AM
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Quote:
Phil
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#22
08-15-2010, 05:39 PM
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Quote:
OK, there's more to tell. I have the set at my house now. Pulled the chassis and cleaned everything. Started by testing all of the tubes. 1 weak 6SN7, and a fried 5U4GB. The fried rectifier made me feel funny in the pit of my stomach. All other tubes are good, testing around 90-100% on my Sencore. No leakage either. The CRT checks about 98% and the needle slowly drops to 0 when I cut the filament power. YAY!! Here's the bad part. Started looking at the underside of the chassis and found a fried electrolytic first thing. This is probably what fried the 5U4. I pulled the spare 5U4 that I had installed, and using my variac, applied about 5 volts to the transformer. Instantly, my amp meter on the variac jumped to 2A. Not good. I looked around the chassis for obvious shorts, found nothing. In the 2 minutes that the variac was turned on with the chassis, the power tranny got very warm to the touch. I can smell it, too. I stopped testing. Im afraid I need a transformer. See the following pics... 1st pic: The bottom of the tranny that you cant see when the chassis is installed. 2nd pic: General chassis condition 3rd pic: The Offending Cap 4th pic: The source of the stinking burning smell. The smoke is rising from the hole the wires come through. Last edited by holmesuser01; 08-15-2010 at 10:10 PM.
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#23
08-15-2010, 08:01 PM
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Quote:
Have you tried disconnecting all of the secondary leads from the power transformer? Long shot... the 6.3 V heater voltage could be shorted to ground somewhere, or the 5U4 socket could be charred from arcing. I sadly agree, however that the transformer is likely fried. jr
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#25
08-15-2010, 09:22 PM
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Quote:
760Vct @ 260ma 5V @ 3A 6.3V @ 7.4A DuMont #20005011, Stancor #P-6134, Merit #P-3074 jr Update...I posted the wrong PNs... the above are for the isolated damper filament transformer... the correct numbers for the power transformer are: DuMont # 20004711 Stancor # P-6315 
Last edited by jr_tech; 08-15-2010 at 10:53 PM. Reason: correct PNs
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#26
08-15-2010, 09:23 PM
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From the Ryders, its:
115v primary secondaries: 5v for rectifier 380v w/center tap 6.3v for about 22 or so tubes, and kine (The sweep tubes have their own transformer for filaments) For now, I hope to find an original type. I know Hammond sells some fine trannies. Thanks, JR TECH.
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#27
08-15-2010, 09:26 PM
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My transformer is fried. I disconnected the secondaries, and turned it on with the variac. Smoke...
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#28
08-15-2010, 09:30 PM
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My Ryders lists the transformer from DuMont as a 20004771
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#29
08-15-2010, 09:40 PM
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Quote:
Sams Sez (if I look in the correct place): DuMont # 20004711 Stancor # P-6315 Sorry, jr
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#30
08-15-2010, 10:12 PM
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Jr. Dont be sorry. Now I have the Stancor numbers! Thank YOU!
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