Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
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
Need Help to ID this radio 11 tube Philco
Welcome, the radio looks intimating 11 tubes, wish you well.Jimradio — 07:49 AM
462ron
Hi Dan, it’s been 10 years since I restored the electronics on my 37-116 so I’m going on some foggy memories. I remember...462ron — 07:37 AM
Need Help to ID this radio 11 tube Philco
Yes the 16B as morzh pointed out. Specifically its the January 1935 model version of the 16B. There are a couple earli...klondike98 — 11:51 PM
48-482 rear panel help
Welcome to the Phorum, keithchip! How far you take a radio on cabinet restoration is a matter of personal preference. ...GarySP — 11:28 PM
48-482 rear panel help
I've recently finished the internal restoration of a locally purchased Philco 48-482. The cabinet is in ok shape except ...keithchip — 10:28 PM
Need Help to ID this radio 11 tube Philco
Welcome to the Phorum, Ken! Lots of help here for all of your restoration questions. Take care and BE HEALTHY! - Gar...GarySP — 07:59 PM
Need Help to ID this radio 11 tube Philco
Thank you. I went to your online library and found 2 schematics. I will download and compare to components!Ken D. — 06:31 PM
Need Help to ID this radio 11 tube Philco
It is a 16B tombstone.morzh — 06:13 PM
Zenith H725
David - sorry, I reread your post and finally saw THD - now the % figures make sense. Thanks for explaining. The PSU...EdHolland — 06:06 PM
Need Help to ID this radio 11 tube Philco
Hi Everyone, New member but have been reading this for awhile for tips! Vaccum tubes were before my time so bear with ...Ken D. — 06:03 PM

[-]
Who's Online
There are currently 300 online users. [Complete List]
» 2 Member(s) | 298 Guest(s)
AvatarAvatar

>