Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

This radio doesn't know the words!
#1

Because at low volume it hums Icon_crazy
The latest subject is a DeWald C-800 . With the volume turned all the way down, I have a steady hum. It doesn't get any louder when the volume is turned up. It just hangs back in the background when tuned into a station.
All caps replaced (except micas). Resistors checked and replaced as necessary. All tubes tested ok. Alignment done. On both AM and FM stations come in loud and clear.

Any ideas? This has really got me . I may take a ride over to freezing lake Michigan and jump in-like someone else we know Icon_lol Icon_lol  

Thanks,

Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org

#2

Eric

There have been several threads lately addressing the similar problem.

All I can tell you:
1. Check all tubes for shorted Filament and Cathode (uually output ad Det/1st Audio)
2. Bad grounding - rivets etc
3. Shorted Gnd to chassis if separate, or shorted Filament wire to chassis.
4. Mechanical noise from the power transformer


You have to poke around.

Like, pull tubes one by one, see if it stops and with what tube. Then go from there.
#3

Agree with Mike but when you start pulling tubes leave the rectifier in. If you pull it you will loose all HV Also replace the tube back into it's socket before going to the next one. You don't want to have with just the rectifier tube in it at the end of testing.
Terry
#4

Yep, that's the point - one at a time while having the HV, we need to know which one it stops at.
#5

Thanks for the ideas, guys. I don't think that I should pull tubes because it has no power transformer. I have swapped out each tube one by one with no change. I'll check grounds. Anything else you can think of for this AC/DC beauty?

Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org

#6

Rotate power pug?
#7

Nope. has polarized plug - common to ground.

Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org

#8

Don't bet your life or your reception on wall socket being wired correctly. Try in another room where a similar set works OK.
#9

Although I try to wire chassis following Wide-Neutral convention. I would never rely on it for safety. For exactly the same reason - it cannot be guaranteed.
#10

 I would loose the polarized plug, at least temporarily, I see that this is an AM/FM set so I would go back to how the factory had it wired until you can rule that out. Some AC/DC sets do not like having the neutral and hot side swapped on the power switch since it's often on the back of the volume control, I also noticed that the FM and AM detector tubes have their heaters connected closest to common negative/AC Neutral at the end of the filament string. If it is not being caused by this, or a heater to cathode short, then there must be an open ground connection, or something incorrectly wired.
Regards
Arran




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
I have a question about this radio, is there anyone that has access to this radio that has an intact unmolested speaker ...captainclock1988 — 04:28 PM
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
Well what makes me confuse all of those companies is that all three of those companies (Setchell-Carlson, Stromberg-Carl...captainclock1988 — 04:21 PM
trying to identify this wire type
The red wire is rubber covered wire. The others are cotton braid over rubber often in colors or a tracer, also strand...Chas — 02:43 PM
trying to identify this wire type
Greetings Phorum members, Hope you can help me identify this type of wire in the photo I have attached.  I am not sure ...georgetownjohn — 01:53 PM
Philco 60 Squealing
All correct shields must be in place, all tubes correct no subs of any kind. Check any soldered, riveted ground conne...Chas — 01:24 PM
Philco 60 Squealing
I have recapped and replaced out of tolerance resistors and so on. Radio plays nicely on fairly strong stations. The pro...dconant — 10:55 AM
Philco 46-420 Code 121 Reception issues
Welcome Eric, I agree with Bob and far as the two main electrolytic filter capacitors did you change them yourself or w...radiorich — 11:43 PM
Philco 46-420 Code 121 Reception issues
You mentioned the Philco manual and going through the check points...just to be sure we're on the same page here's the m...klondike98 — 08:13 PM
Philco 42-1008 conversion kit
Interesting. I haven't seen that before.klondike98 — 07:02 PM
12' Philco
Yes I had looked for it on the web as well some time back and could not find it. I was glad to see it turned up in Ron'...klondike98 — 06:59 PM

[-]
Who's Online
There are currently 3783 online users. [Complete List]
» 1 Member(s) | 3782 Guest(s)
Avatar

>