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

38-690 -- silent tweeters
#1

I got my 38-690 up and running but there's no sound at all coming out of the tweeters. (The woofer sounds awesome.) It has the 4.7 uF cap in place of the stock 1 uF, and I played with the phasing. I troubleshooted all the connections and they seem OK. The 4.7 uF cap tests OK on my Fluke meter. The field coils and voice coils of both tweeters seem to measure fine with an ohmmeter. The resistance of the secondary of the output transformer to the tweeters measures 2.8 ohms. Does that sound like it's in the ballpark?

If the tweeter secondary is shorted, I'm assuming I'll never find a replacement transformer since it's an unusual design that also feeds the woofer. I could try to wire a separate output transformer to the tweeters in parallel with the original, but I wonder how that would work without messing up the feed to the woofer. Anyway, I hope the transformer is OK.

Does the 2.8 ohm measurement seem correct for the tweeter secondary? I'm kind of at a loss as to why there's no sound from the tweeters.

Thanks,

Bob


Messages In This Thread
38-690 -- silent tweeters - by Guest - 08-06-2008, 01:18 AM
[No subject] - by Texasrocker - 08-06-2008, 03:31 AM
[No subject] - by Ron Ramirez - 08-06-2008, 06:46 AM
[No subject] - by Guest - 08-06-2008, 09:52 AM
[No subject] - by Guest - 08-06-2008, 11:17 PM
[No subject] - by Ron Ramirez - 08-06-2008, 11:27 PM
[No subject] - by Guest - 08-07-2008, 01:02 AM
[No subject] - by Guest - 08-07-2008, 01:56 AM



Users browsing this thread: 3 Guest(s)
[-]
Recent Posts
trying to identify this wire type
Thanks to all for the feedback. As Arran said, it is probably an older replacement and yes it has a grid cap so I will ...georgetownjohn — 09:32 PM
trying to identify this wire type
It's possible that the red wire, actually a grid cap lead, is a very old replacement, I can't remember seeing a pre 1939...Arran — 09:18 PM
Gilfillan Brothers Car Radio?
Hi everyone,  Special thanks to Joe Rossi for tracking down this obscure radio and thanks to others who took up the hun...Antipodal — 08:15 PM
trying to identify this wire type
Here's one source for your wire of many. Take care and BE HEALTHY! Gary P.S. Can't get the right color you need? I ...GarySP — 06:40 PM
trying to identify this wire type
...and modern wire of the appropriate gauges and insulation V-rating (300V minimum, usually shown right on the wire) is ...morzh — 05:47 PM
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

[-]
Who's Online
There are currently 6304 online users. [Complete List]
» 1 Member(s) | 6303 Guest(s)
Avatar

>