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

Issue with rebuilt 38-690 audio transformer
#31

It appears that way, I guess. Thank you for being patient. Now, another stupid question on my part:

I'm confused about part 172, marked "tweeter field" on my schematic. Obviously this part is open, and I'm assuming it's the main speaker field coil. However, why is it marked "tweeter field" on the schematic? Obviously I wouldn't be thrilled about having the coil on that massive speaker rewound, but would do it if I needed to. The main speaker's field coil reads about 4.2K ohms. Don't know how far off that is, as there are no resistances given on the schematic for it.
Again, thank you for your patience.
#32

If it says tweeter coil, it is tweeter coil. 4.2K is not open and it says right there in the sch 4300 ohms. (yes it is given in the sch, just take a good look).
So, disconnect your tweeter, measure its field one more time, it will likely show full open.
Again, open means just that, open, no finite resistance present.
Check the wires just in case they are broken, but likely you will have to have your tweeter field redone.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#33

Thanks, Walrus. I can stomach that a heck of a lot more easily than having the big speaker field coil done. I will check in the morning. For now, going to bed and will likely dream of speakers, multimeters and OLs. Thanks for the help, I'll let you know and will try to make it as clear as possible Icon_wtf
#34

Suerte!


PS. For testing purpose, you could use a big 470 ohm resistor with proper power dissip rating (possibly 10W) to put instead of tweeter coil, this way you can have sound and do other stuff while your tweeter is being redone.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#35

Well, I fixed the problem.
YOu were on track with the tweeter field being open. Only it wasn't open; both tweeters tested fine. So I started tracing the wire from the speaker wiring harness all the way through the chassis, into each tie in point. Everything checked out OK on the first field coil. When I got to the second, one of the two field coil wires showed no continuity. The only thing thta that could be was a chafed or corroded wire. So I cut it out, removed the clamp holding the wiring bundle to the chassis and Bingo. Under the clamp, the wire was abraded in that spot and though it wasn't separated, it read open. Solder a new one to the pin, rewired, restored continuity to the tweeter field and cautiously started up the radio.
HOLY COW this radio cranks! Sounds fabulous!
Morzh, I can't thank you enough for helping me through this. It would have been a hard thing to spot if not for your guidance. I'm in your debt, and will post updates as I continue to go through the set.
Imagine that ... an abraded wire!

Ted


Attached Files Image(s)
   
#36

(07-01-2015, 12:57 AM)Diverted Wrote:  Imagine that ... an abraded wire!

Ted

Ted


My post #32

>>> ...disconnect your tweeter, measure its field one more time, it will likely show full open...... Check the wires just in case they are broken.....     


Icon_smile



Yes you always have to allow for the less likely (albeit favourable) scenario Icon_smile




Glad it worked, I am sure it is fun to listen to. Hope to find me one one day.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#37

I hope you do too. It's a beast. Very intimidating, but it's an impressive thing.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
1930s Stromberg-Carlson Tombstone Radio need help identifying model number
Hi Cap'n Clock, Unfortunately, I do not have this radio.  This is a shame because this should be a good performer.  2A5...MrFixr55 — 06:48 AM
American Bosch Model 802 auto radio
I think it would come under either American Bosch or United American Bosch. American Bosch made sets for the American We...Arran — 05:53 AM
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

[-]
Who's Online
There are currently 6903 online users. [Complete List]
» 1 Member(s) | 6902 Guest(s)
Avatar

>