ORANGE MKII schematic

[Bruce / Mission Amps]

Does anyone notice anything odd about the power supply in this Graphic MKII schematic?

[Don Moose]

Well, do you mean the hum balance pot on the V1/V2 heaters and separate heater winding for the big bottles?

Or is it the HV CT tucked between the series filter caps, effectively raising the whole winding by (B+/2)?

Or the superfunky way the bias recto is drawn?

[teemuk]

The rectifier bridge is drawn incorrectly.

[Don Moose]

The rectifier bridge is drawn incorrectly.

Hey!

So ... I guess I need to change my answer to No. Not until it's pointed out.

[Le Basseur]

The rectifier bridge is drawn incorrectly.
...and the C25,C26 HT electrolytics don't have bleeders across?

[dai h.]

Well, do you mean the hum balance pot on the V1/V2 heaters and separate heater winding for the big bottles?


that's interesting. Wonder what the rationale is behind that. The push-pull cancellation can be counted on for big hum reduction but heater balance for the preamps has more benefit?

re: the B+ center tap--that's the same on a 100W marshall isn't it?

(so I guess teemuk is right about the bridge orientation?)

[Bruce / Mission Amps]

It wasn't a trick question.
I just happen to be looking at one and saw this Shcem.
The FWB's diodes are screwed up alright.
That 180-0-180 written in the PT is a little misleading since that actual voltage across the FWB is 360vac.
The '0' point center tap of the PT acts like a voltage divider so each series Power Supply caps have similar impedance and half the supplied voltage.
The hum balance is more critical in the preamp tubes and with separate windings, it makes sense to only have hum balance on them.


The FWB should look like the attached schematic.