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Old 19th June 2004, 09:21 AM   #1
nikos is offline nikos  Greece
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Default help converting conrad johnson MV-55 into triode!

Does anyone have any idea of how to convert conrad johnson's MV 55 into triode operation mode?The amplifier was offered in both ultralinear and triode configurations.
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Old 19th June 2004, 01:05 PM   #2
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In UL, the screen grids are connected to taps on the O/P trafos. Disconnect the leads connecting the screen grids to the trafos at the tube sockets. THOROUGHLY insulate the ends of the disconnected leads and tuck them away neatly. Connect the screen grids to the plates at the sockets via 5 W. 100 Ohm resistors.
Eli D.
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Old 19th June 2004, 01:42 PM   #3
dhaen is offline dhaen  Europe
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I have one on the bench for repair, so I've taken a picture.
In the picture you can see the output transformer wires connect to the PCB.
The blue wire is the anode (plate)
The green wire is the screen (G2)
There is a link that should be easy to pull out and re-plug, but on this one it's been soldered in. If yours is soldered, I'd recommend just cutting it, else the PCB might get damaged.
What you have got to aim at, is to make the link horizontal, thus isolating the green wire that goes to the primary tap, and connecting together the anode and screen grid.
There are 4 to do, each near the PCB corners.
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