Mitchell Pro 100 Schematics?

[balcorn80]

Just picked up a Mitchell Pro 100 that looks, sounds, and operates almost exactly liek a Mesa Boogie Mark I. ANyone know anything about these or where a schematic may be found?

[balcorn80]

Main reason I'm looking for a schematic is I would like to add variable bias to this amp as, like a boogie, it is fixed...

[FYL]

Just picked up a Mitchell Pro 100 that looks, sounds, and operates almost exactly liek a Mesa Boogie Mark I. ANyone know anything about these or where a schematic may be found?

If I understand correctly the Pro 100 was a MK I clone, so all you need are Mesa schematics...

http://www.schematicheaven.com/boogieamps/boogie_marki.pdf

The bias section is done Fender-style (no surprise here : early Boogie amps were modified/rebuilt Fender's), so any "really fixed bias" to "variable fixed bias" mod can be used.

Check for instance http://www.el34world.com/charts/Biascircuits.htm in Doug's library.

[sluckey]

If the MK I schematic is right for you, then look closely at the bias circuit. It also feeds the ss equalizer circuit. So, if you do make the bias adjustable, do it in a way that will not affect the voltage feed to the equalizer.

[FYL]

If the MK I schematic is right for you, then look closely at the bias circuit. It also feeds the ss equalizer circuit.

Bean counters at work. Or very silly engineering. Or both.

So, if you do make the bias adjustable, do it in a way that will not affect the voltage feed to the equalizer.

The easiest way is to add a complete bias circuit, either derived from the xformer tap, or preferably using a dedicated xformer - current demand are very low, so a small surplus xformer would be fine.

[balcorn80]

Well, mine is more like an early mk 1 with no reverb or graphic eq. And I found a schematic for that one. So thanks for your help guys. I really appreciate it. I would be so lsot without this forum... Or all the info and parts Doug has made available to us.

[balcorn80]

Just picked up a Mitchell Pro 100 that looks, sounds, and operates almost exactly liek a Mesa Boogie Mark I. ANyone know anything about these or where a schematic may be found?

If I understand correctly the Pro 100 was a MK I clone, so all you need are Mesa schematics...

I new it was a clone, but I didn't know how much of a clone it was.  I'll have to go over each with a fine-toothed comb tonight after work so I can tell. but having played an early mk1 and this guy side by side, it probably is a clone of, rather than something based on the design of, a Mk 1. And I am really quite impressed with the overall workmanship of the amp. there are NO stray wires in there. Everything is run nice and tight with very little slack. All the wires are ziptied together in groups too. Very sanitary-looking. Someone has replaced a couple of the pots in here, but nothing too serious.

[jerrydyer]

I just bought one too. any luck getting the correct schem. I read the boogie and followed in my amp. they are not dead on, close but not dead on. Im thinking of making mine a mark 2c+.. gotta add a tube. think there is any collector value here? ??? before I mod.
thanks

[HotBluePlates]

Dunno about collector value. It probably has value to folks who want early Mesa without paying vintage prices.

Looking on Ebay, there's one for sale now for $750-800, but two sold recently for $350-399, and another didn't sell at the $399 price. That puts it only ~1/3 below the average price for a comparable non-Mk4 Boogie.