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Dating a JCM 800

Discussion in 'Marshall Amps' started by HogDad59, Jun 11, 2021 at 12:47 PM.

  1. HogDad59

    HogDad59 New Member

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    I’ve been trying to date my JCM 800 and the more I research it the more I get confused. The back panel serial number begins with S/A, which my research tells me it’s a 50 watter. Yet, also on the same panel it says Master Model 100w Lead and also says, model 2203. So, is it 50 or 100 watts and an 81 or 82? I defer to the experts here and thanks in advance.
     

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  2. Gunner64

    Gunner64 Emotional Support Animal Gold Supporting Member

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    What letter does the sn end in?
     
  3. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    there should be an inspection tag on the inside, w/ signatures & a date...
     
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  4. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    ser.jpg
     
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  5. HogDad59

    HogDad59 New Member

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    It ends with a “P” which means 1982, I believe.
     
  6. Gunner64

    Gunner64 Emotional Support Animal Gold Supporting Member

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    I couldn't see the P. The arrow thingy is in the way viewing it on my phone, and the image is upside down for some reason. P would be 1982.

    And if it has 4 big tubes it is a 2203, 100w and 2 big tubes it is a 2204 50w.
     
    Last edited: Jun 11, 2021 at 2:09 PM
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  7. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    yeah, I flipped, cropped & darkened it in Photoshop...
     
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  8. HogDad59

    HogDad59 New Member

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    It can’t be read.
    Thanks, that’s what I was thinking but everywhere I’ve looked tells me “S/A” means 50 watts. Some mods made maybe?
     

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  9. fitz288

    fitz288 Well, Known Member Silver Supporting Member

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    why the close ups?
    How many big tubes?
    [​IMG]
     
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  10. Gunner64

    Gunner64 Emotional Support Animal Gold Supporting Member

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    Seems the s. S/a thing was intermittent after the M year production. Theres a thread on that very thing you are asking about here somewhere. If it has no sign of being messed with, has 4 big tubes, says 2203 on the tag it's a 2203....And I have to agree with Fitz..your pics suck!. Lol...:D...them original G.E. 6550 power tubes are nice though..

    And it has too many can caps for a 2204..it's a 2203.
     
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  11. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    you need to pull that chassis out of the box & give it a good cleaning. I'd at minimum, blow it all off w/ compressed air & dust it real good...

    Be careful w/ the underside, don't touch anything inside there, just blow it out real good...

    I might pull the tubes out, 1-at-a-time & clean them up w/ alcohol & spray the pins w/ de-oxit before putting them back in...

    while it's out & clean, take some better images!
     
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  12. HogDad59

    HogDad59 New Member

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  13. HogDad59

    HogDad59 New Member

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    Thanks to all for your insight and advice. Yes the pics suck, all I had on me. I’m learning about what I have here. This amp was given to me with a 4x12 cab with G12H black backs. The rig sounds great!
     
  14. Gunner64

    Gunner64 Emotional Support Animal Gold Supporting Member

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    That's awesome. Lucky you!

    Do you see what Black backs are going for? Holy crap. You have $1000+ just in speakers there according to the going rate.
     
    Last edited: Jun 11, 2021 at 3:14 PM
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  15. Gutch220

    Gutch220 Well-Known Member

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    yea, it's a 1982

    4 large tubes = 100w
    2 large tubes = 50w

    since the label says 100w I'd say it's 100w.... unless somebody in the factory has some 'splainin' to do. Don't worry about the SL or SL/A....it can be either one.
     
    Last edited: Jun 12, 2021 at 8:18 AM
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  16. houseofrock

    houseofrock Well-Known Member

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  17. wntbtw

    wntbtw Well-Known Member

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    Funny thread title!
     
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  18. OriginOfTheSpecies

    OriginOfTheSpecies Active Member

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  19. pedecamp

    pedecamp Well-Known Member

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    This is what I'm thinking every time I see this title, and I see it alot! LOL
     
  20. pedecamp

    pedecamp Well-Known Member

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    Dude dont worry about the serial number, you havent told us how many power tubes you have, 2 or 4! The pictures you posted tell us NOTHING. Post a picture of the back so we can see the whole thing, pull the chassis from the headshell and photograph the internals.
     
    Last edited: Jun 12, 2021 at 7:15 AM
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