Ampeg Gemini 1 power transformer wire mystery

[tonefiend]

Hello,

Im wondering if anyone has any Idea what the white wire from the secodary of the power transformer is for? I cant for the life of me figure it out. I cant find in on the schematic. The wire comes from the PT secondary, attachest to a .1 mfd cap which then attaches to ground wire, grounded to the Lug of the cap can. I have attached a picture for reference as well as the schematic.

I measured the voltage where the white wire is attached to the eyelet board and it only measures .26 Volts, Im really not sure the wire is doing anything at all.

Im wondering if the Cap is necessary or could be prone to noise? if not can I remove the cap, and replace it with a jumper wire? ampeggeminiI.pdf Ampeg-G12-Amp-Schematic.pdf

thanks very much for your help.

[Helmholtz]

Probably an internal PT shield. No reason to change the wiring.

[Tom Phillips]

Probably an internal PT shield. No reason to change the wiring.

I agree. The voltage you measure is due to capacitive coupling of the shield to the other windings in the transformer and the fact that you are measuring with a high impedance meter. Ampeg choose to ground the shield through a capacitor. (AC ground setup). If they had connected the shield directly to ground then you would not have read any voltage. The connection is not shown on the schematic. Such schematic anomalies are really common in amps of that time. I have also run across quite a few old power transformers that were constructed with an electrostatic shield that was not connected inside the amp. The connection wire was cut short just outside the end bell. In many cases the shield wire had orange insulation.