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The PT used in this schem is a 540v. I have a 740v that I would like to use if I can. Is it too much? 5R4 rectifier?
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You mean 540 V AC from the entire HT secondary, right? 270 V AC from the center tap? Yes, the 370 V AC one will increase the voltage significantly, but not exceed the 5U4 PIV.
Edit: The 20 uF caps MUST also support the increased DC voltage. 270 VAC would peak at 381 V DC, which 500 V caps support. 370 V AC would peak at 523 V DC and will quickly damage any 500 V DC caps you have in there. -
You will need to use JJ6V6 with a 740VAC (370-0-370VAC) PT too, not NOS types. You could use anything up to a SS rectifier as long as you have decent current load.
Just rewire the main & screen supply filter caps as 50uf 700v (or better) totem poles, using 2x100uf 350v caps in series, each cap bypassed with a 220K 2W resistor (see Fender 59 bassman RI schem for an example). Connect the main filter cap to the hot side of the standby switch, not the cold side.Comment
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