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

Model 650 Tone Control Question
#43

BINGO!! NOW IT ALL MAKES SENSE!! SUCCESS! A Pic is worth 1K words!!

Hi Hamilton,

Thanks for the great pix! They are the telling of the story!!

OK, the reading between Pins 3 and 4 is not 0 Ohms, it is "OL" KOhms, a resistance higher than the meter is capable of reading. It is infinite ohms. In other words, one leg of the transformer is open. The transformer is bad. With the speaker unplugged, and radio powered off and unplugged, if you got the same reading between pin 2 of one output tube and pin 2 of the other, this is normal. So, a dead short in the transformer and a dead short (0 Ohm) between the 2 output tube plates with the speaker plug unplugged would be rare, But "OL" between the 2 pi 2s and between 3 and 4 on the speaker is explainable as a single event. The transformer primarytcoil "opened".

In the current condition, the radio will play, but not as well as it would with the transformer fully functional. It may be bad for the tube reading only 38V also.

Looking at the side view of the transformer, showing connection 3 and 4 and the secondary, the burn mark may indicate where the transformer burned out and the wiring may be repairable. However, this is a gamble. You have to peel away the paper wrapping. this may totally ruin the transformer, however.

Next step is to figure out the correct replacement transformer. I will defer to the experts, Ron Ramirez, terry (Radio Roslyn), etc. Primary impedance of the transformer (This is very different from resistance, although still measured in Ohms) is 8K Ohms Plate to Plate per RCA receiving tube Manual or 10K Ohms per a Tung Sol Spec Sheet. The issue is the speaker voice coil impedance. the resistance is 1.1 Ohm. If the impedance is 4 or 8 Ohm, then a transformer will be easy to find. If the impedance is much less than 3 Ohms, it may get interesting. Experts on this Phorum can suggest a replacement.

Again, great work for an electronics newbie, tour persistence, good work and good pix paid off! And a wonderful job on the cabinet! Any Museum would love to have your radio (But museums being non-profit, they wouldn't pay for it. Don't part with this, this is your trophy!!

Get a new transformer, add a radio phono switch and this radio will be a really great performer. It would be a nice sounding amp for guitar, but you would not be able to overdrive it without a preamp. The rating for this configuration of 42 tubes in class AB Push Pull is 15Watts!! (Per RCA and Tung Sol specs for triode 42 driver and triode P-P 42 outputs being fed by 350V B+ on the output tubes).

"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis

Best Regards, 

MrFixr55


Messages In This Thread
Model 650 Tone Control Question - by Hamilton - 06-27-2023, 10:45 AM
RE: Model 650 Tone Control Question - by morzh - 06-27-2023, 12:11 PM
RE: Model 650 Tone Control Question - by Hamilton - 06-27-2023, 05:49 PM
RE: Model 650 Tone Control Question - by morzh - 06-27-2023, 07:26 PM
RE: Model 650 Tone Control Question - by Hamilton - 06-29-2023, 08:03 AM
RE: Model 650 Tone Control Question - by RodB - 06-29-2023, 09:09 AM
RE: Model 650 Tone Control Question - by Chas - 06-29-2023, 10:26 AM
RE: Model 650 Tone Control Question - by morzh - 06-29-2023, 10:57 AM
RE: Model 650 Tone Control Question - by Hamilton - 06-29-2023, 11:46 AM
RE: Model 650 Tone Control Question - by RodB - 06-30-2023, 08:31 AM
RE: Model 650 Tone Control Question - by Hamilton - 06-30-2023, 11:45 AM
RE: Model 650 Tone Control Question - by Hamilton - 06-30-2023, 02:07 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 06-30-2023, 05:22 PM
RE: Model 650 Tone Control Question - by Hamilton - 06-30-2023, 07:57 PM
RE: Model 650 Tone Control Question - by Hamilton - 06-30-2023, 08:13 PM
Hamilton - by Hamilton - 07-03-2023, 10:13 AM
RE: Model 650 Tone Control Question - by Hamilton - 07-03-2023, 12:10 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-03-2023, 11:25 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-04-2023, 12:40 AM
462ron - by 462ron - 07-04-2023, 08:56 AM
Hamilton - by Hamilton - 07-04-2023, 09:54 AM
462ron - by 462ron - 07-04-2023, 10:06 AM
RE: Model 650 Tone Control Question - by Hamilton - 07-04-2023, 03:13 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-04-2023, 04:26 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-04-2023, 04:38 PM
RE: Model 650 Tone Control Question - by Hamilton - 07-06-2023, 08:11 AM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-06-2023, 11:40 AM
RE: Model 650 Tone Control Question - by Hamilton - 07-07-2023, 07:48 AM
RE: Model 650 Tone Control Question - by Hamilton - 07-07-2023, 02:59 PM
RE: Model 650 Tone Control Question - by RodB - 07-07-2023, 03:11 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-07-2023, 09:23 PM
RE: Model 650 Tone Control Question - by Hamilton - 07-08-2023, 09:30 AM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-08-2023, 12:07 PM
RE: Model 650 Tone Control Question - by morzh - 07-08-2023, 05:32 PM
RE: Model 650 Tone Control Question - by Hamilton - 07-09-2023, 06:15 AM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-09-2023, 07:55 AM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-10-2023, 04:39 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-11-2023, 09:10 PM
RE: Model 650 Tone Control Question - by Hamilton - 07-12-2023, 07:50 AM
RE: Model 650 Tone Control Question - by Hamilton - 07-12-2023, 12:20 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-12-2023, 05:58 PM
RE: Model 650 Tone Control Question - by Hamilton - 07-12-2023, 06:46 PM
RE: Model 650 Tone Control Question - by Hamilton - 07-12-2023, 06:49 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-13-2023, 04:13 PM
RE: Model 650 Tone Control Question - by Arran - 07-13-2023, 04:39 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-13-2023, 05:13 PM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-14-2023, 06:05 AM
RE: Model 650 Tone Control Question - by MrFixr55 - 07-14-2023, 06:25 AM



Users browsing this thread: 7 Guest(s)
[-]
Recent Posts
Heathkit Sweep Generator TS-4
Ron Instead of Quick reply, go to New Reply, then go to the title of the very first post, and change the title text the...morzh — 02:00 PM
6TPZ and 5TPO Radio Help
I am not a specialist in car radios. I suspect they might use vibrators to convert 12V to acceptable tube voltages, so ...morzh — 01:58 PM
6TPZ and 5TPO Radio Help
Welcome to the Phorum, R3Sons! I have very limited experience with car radios other than installing custom radios back ...GarySP — 01:08 PM
462ron
OK, I need to rename this thread to say..Eico 368 TV/FM Sweep Generator instead of the current title..Heathkit Sweep Gen...462ron — 12:49 PM
6TPZ and 5TPO Radio Help
Hello, I have a Philco (Ford) 6TPZ and a 5TPO radio.  I replaced the electrolytic capacitors in both.  I have the SAMS m...R3Sons — 12:29 PM
The list of my radio & TV collection!
Hello Peter, Thank you for posting that !! Sincerely Richardradiorich — 09:40 AM
Eico 232 VTVM Schematic
It's a microwave antenna. ?;-p?. I substituted 1N4002s off the 6.3 vac winding for the 1.5 volt battery. Uniprobe is the...RodB — 05:50 PM
Eico 232 VTVM Schematic
Try BAMA for a schematic. Looks like a replacement power source for the D battery has been installed. The tube may be...Chas — 04:51 PM
Eico 232 VTVM Schematic
Is that a battery holder?morzh — 04:43 PM
Eico 232 VTVM Schematic
A friend gave me this Eico 232 VTVM and I'm having trouble locating the schematic for it. This one seems to be a later v...RodB — 04:17 PM

[-]
Who's Online
There are currently no members online.

>