tube rectifier

[Amberden]

so my idea is to replace the diode driven rectifier in my marshall JCM 800 2204 to a tube driver one. best i can tell is do it like the JTM45. any help would be awesome.

guess what I'm asking is can i simply swap the jtm45 rec to the jcm

[jjman]

The Ceriatone JCM 800 shows the (unused) 5v connections on the power tranny, needed for a tube rectifier. Is yours a Marshall? Does it have a 5v winding?

[martin manning]

You'll also have to reduce the size of the reservoir capacitor following the rectifier from 100uF to 50uF (GZ34 maximum value is 60uF).

[Amberden]

the power trans former has the extra 5v an 0v leads.

its exactly like the circuit shown in the JCM 800 schematic.

which cap is that you're talking about?



is it the one show on the jcm 800 that is a 50/50 cap that has the orange lead going to the old rec diodes?

[ToneMerc]

the power trans former has the extra 5v an 0v leads.

its exactly like the circuit shown in the JCM 800 schematic.

which cap is that you're talking about?



is it the one show on the jcm 800 that is a 50/50 cap that has the orange lead going to the old rec diodes?

yes

[martin manning]

The 50/50 is paralleled to make 100uF, you can disconnect the sections and just use one 50uF.

[M Fowler]

Are you going to remove the can cap near the power tubes to add the rectifier tube, split the 50/50 can cap near the PT so each half can be used and add another 47uf cap mounted on a turret strip infront of the PT?

Or remove the diodes and put the cap there. You could add the diodes back on the tube socket for backup.

Mark

[Amberden]

which of the 2 caps is it. red arrow or blue arrow

[marcoloco961]

which of the 2 caps is it. red arrow or blue arrow

Red one. Remove the connection between the 2 50uf caps in that can and take the orange lead to the cap connected to E. See attached pic.

[Noval_novice]

Why not just use a sag resistor to emulate the effect of a tube rectifier. That way you don't have to change your first filter cap. You can put it on a switch.

[M Fowler]

+1 for the sag resistor

[Zippy]

+2

Mo' simple, mo' reliable.

[Amberden]

okay i think i got it.

I would use a sag resistor but wanted a more traditional tube rec. people say your ear can't tell the difference but what i'm trying to do is change the JCM800 around a lil bit to combine the great sound of analog like my jtm45 and have the punch of the jcm 800.

please check all my wiring from the cap and rec tube to see if you spot any issues with the wiring schematic

[martin manning]

The orange wire from the 50F cap goes to rectifier pin 8, and delete the black wire from rectifier pin 8 to the standby switch.

[M Fowler]

Why not use the can cap hole next to the power tubes for the rectifier?

Clip the can cap right under the PT to use as separate caps then add another 47 cap to the left of that can cap.

Mark