Could you help me with this strange transformer?

[chikov]

I am on the quest to build Deluxe amp from scratch and I am using some parts from the two old Seeburg amps. I started stripping the smaller one and ran into several mysterious transformers. Here is its schematic:
http://arcarc.xmission.com/PDF_Jukebox/ ... ma1-l6.pdf
Right now I am analyzing the power transformer. I figured out all leads but one... If you look at my photo it is a short one with a red clip on it (in the middle). I can not find a pair to it... It went to the pin 1 and 2 on the tube socket next to it... it shows no resistance to the ground...
[IMG:480:640]http://i409.photobucket.com/albums/pp171/alexjohnne/tranny_zpsrramyvuu.jpg[/img]
I decided to open up the housing and discovered another wire that went straight to the laminates. At first I thought it was the second lead of the 6.3V filament supply, but when I read the resistance - it was only 0.2 Ohms. I followed the lead and it seems that it lead to the same terminal. As if the wire was just grounded to the laminates... Does anyone know what it is?
[IMG:480:640]http://i409.photobucket.com/albums/pp171/alexjohnne/tranny2_zps5sq8qhix.jpg[/img]

[Stevem]

It's the core sheild wire and goes to ground with the center tap of the heater winding.

[chikov]

THANK YOU. That makes sense... Question is, where this schematic has 6.3V filament supply?
I looked at all the schematics I could find and the power tranny should have it but mine does not. I remember trying to trace pin 2 and 7 filament wires but they lead to the terminals non relater to this transformer. Boy, and I thought it was going to be an easy week end project
But I determined to master all this stuff, so help me God

[chikov]

One small update in my investigation of the lost 6.3V source. As I was stripping parts off this Seeburg chassis I took a picture of the filament wires leading to this weird plug:
[IMG:640:853]http://i409.photobucket.com/albums/pp171/alexjohnne/IMG_3500_zpslb4cmaoe.jpg[/img]

On outside it looks like this:

[IMG:640:853]http://i409.photobucket.com/albums/pp171/alexjohnne/IMG_3501_zpsn0gm1r12.jpg[/img]
Do you think this plug served as a connection to the external source of 6.3V AC?

[Stevem]

It's hard to tell when I inlarge that schematic , but it looks that the bottom winding is the 6.3.
If you have another amp then jump in its 6.3 volts to that PTs primary side and then measure the secondary voltages !

[sluckey]

Your actual transformer has fewer leads than the one in your schematic. It's very possible that the 6.3VAC source comes from another transformer that's not located on that chassis. In that case, the 6.3VAC would be coming into that chassis via that rectangle plug.

I have a '50s Rock-Ola amp. The PT only has a high voltage secondary and a 5V filament winding for the rectifier. The 6.3 comes from a separate low voltage transformer that's located on a relay control voltage power supply chassis. Yours may be similar.

[chikov]

Your actual transformer has fewer leads than the one in your schematic. It's very possible that the 6.3VAC source comes from another transformer that's not located on that chassis. In that case, the 6.3VAC would be coming into that chassis via that rectangle plug.

I have a '50s Rock-Ola amp. The PT only has a high voltage secondary and a 5V filament winding for the rectifier. The 6.3 comes from a separate low voltage transformer that's located on a relay control voltage power supply chassis. Yours may be similar.

Thank you for your help... Yes, you are right, that is exactly what it was. My small Seeburg amp has its big brother that was supplying the 6.3V. SEE PHOTO:

[IMG:480:640]http://i409.photobucket.com/albums/pp171/alexjohnne/IMG_3508_zpsmqsri1ru.jpg[/img]

http://www.4tubes.com/SCHEMATICS/Music- ... sr1-l6.jpg

the funny thing is that I have no Idea what those two square things are on the right (40's technology, y'know). All I need off this amp is its power transformer, so if anyone wants the rest for the museum - talk to me