I have a preamp that I'm planning on cloning because I want to make mods to it and don't want to devalue it since I'm sure I'll eventually sell it. It also happens that everything is soldered to the underside of the board and it's a major PIA to get to the leads due to the way it's constructed.
I've already made a schematic as a place to start, but what I'm wondering is how to identify the transformer when there's not makers mark on it?
My wall voltage is 121VAC, I measured 140V to ground on each leg of the secondaries (no CT) that provide B+ to the board and 9.5VAC on each leg of the other secondary that supplies the heaters. The heater supply goes through rectification a heavy duty (ish) voltage regulator and so supplies 12.2VDC to the heaters.
I've only built a couple of amps (and ODS and SSS), both of which were less of a rats nest than this but this preamp has two white wires (one solid, one striped) hooked to the neutral leg of the IEC plug and three black wires (one of which is striped) going through the power switch and to the hot leg of the IEC. IIRC, the two PT's I've used before had one black, one white for the power in. There are also two more windings that are taped off.
Is it a reasonable guess that it's not a custom PT, or why would someone go to the trouble of adding two unused windings? Any other hints I can use to identify this?
I've already made a schematic as a place to start, but what I'm wondering is how to identify the transformer when there's not makers mark on it?
My wall voltage is 121VAC, I measured 140V to ground on each leg of the secondaries (no CT) that provide B+ to the board and 9.5VAC on each leg of the other secondary that supplies the heaters. The heater supply goes through rectification a heavy duty (ish) voltage regulator and so supplies 12.2VDC to the heaters.
I've only built a couple of amps (and ODS and SSS), both of which were less of a rats nest than this but this preamp has two white wires (one solid, one striped) hooked to the neutral leg of the IEC plug and three black wires (one of which is striped) going through the power switch and to the hot leg of the IEC. IIRC, the two PT's I've used before had one black, one white for the power in. There are also two more windings that are taped off.
Is it a reasonable guess that it's not a custom PT, or why would someone go to the trouble of adding two unused windings? Any other hints I can use to identify this?
