Jmp Schematics 100w Mv

Discussion in 'Building the Classics' started by valvehead, Jan 23, 2019.

  1. valvehead

    valvehead New Member

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    I have a 1980 100w JMP here. Looking for a close schematic..Ive got a few but nothing dead on. Its a 2203--JMP Mk2 Master Volume --unclear on inputs--looks like 4 factory holes. Unclear on speaker jacks--looks like 4 factory holes .
    It absolutely has can cap holes for SIX caps.

    Im asking because this thing has been cut / modded/ butchered.

    Im going to return it to stock 1980 wiring..but , im going with 3 , 50/50 filters , and id like to stay with hi/lo ins and 2 speaker outs. EL34's

    What can you share as far as a 1978-1980 100watt 2203 schematic , EL34 , NON jcm800 ? . Theres a lot of variations on these !!!
     
  2. mickeydg5

    mickeydg5 Well-Known Member

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  3. valvehead

    valvehead New Member

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    yea...but this is stamped JMP...not jcm800...lots of weirdness from Marshall. Some of those scems..very hard to read values...I know they used leftover parts / chassis at some points during the transition from early 70s 2203 to jcm800 80's 2203
     
  4. ampmadscientist

    ampmadscientist Well-Known Member

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    can you post pictures
    can you post pictures of the insides?
    It doesn't match the description of a normal Marshall head.
     
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  5. valvehead

    valvehead New Member

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    i will tomorrow---this things a mess....but the speaker jack holes look factory ( 4)...and the in jack holes look factory (4) . I cant find a 1980 JMP 2203 MV image like that online.... also , its got the rocker switches and grommet / thru-style ac cord--not a factory IEC style socket.
     
  6. ampmadscientist

    ampmadscientist Well-Known Member

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    If it has 4 holes, it would be a 1959 head.
    If it has 2 holes it would be a 2203 /2204 head.

    But what you are saying is: 4 hole 2203 head with master volume? From the factory?
    That's what is sort of odd about it.

    However there have been "transition amps," which are like a new and old amp blended together.
    We have seen a few odd ball amps like that from the factory. So it is still possible.
     
  7. Micky

    Micky Well-Known Member VIP Member

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    What version does the board say?
     
  8. mickeydg5

    mickeydg5 Well-Known Member

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    I pointed him to what he is looking to accomplish but yes it seems he has a modded/butchered JMP MKII 1959, yes?, maybe?
     
  9. valvehead

    valvehead New Member

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    hold on--ill try to post pics in a few--
     
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  10. ampmadscientist

    ampmadscientist Well-Known Member

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    Did it start out as 1959?
     
  11. valvehead

    valvehead New Member

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    no--its dated 1980....and a Master Volume model
     
  12. valvehead

    valvehead New Member

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  13. Marshallhead

    Marshallhead Well-Known Member

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    Whoever modded it drilled out the front panel and added the two extra input jacks.
     
  14. Micky

    Micky Well-Known Member VIP Member

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    Still don't know what the main board says...
     
  15. valvehead

    valvehead New Member

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  16. valvehead

    valvehead New Member

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    Marshall ST1
    Issue 202
     

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