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Marshall 1987X help!!!!

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  • Marshall 1987X help!!!!

    Hi all, I used to post here a while ago but it looks like things have changed and I had to re register.  So I was out for a wlk with my dog a week ago and came across some bulk trash set out for pickup, inside one of the boxes there was a really nice looking transformer, very clean, nice leads, so I brought it home.  Later that night I was looking at it and it had the same color leads as one of the transformers in my 50W Marshall head.  I was feeling a little bold and remembered reading how guys swap out transformers to make their amps sound better, well you can see where this is going......

    I pulled out the transformer that looked like the one I brought home and marked which wire went where and put the one I found in the amp (there was an extra purple wire on the transformer so I taped it off), powered the amp up and nothing happened.  Tried some old tubes I had lying around and still nothing.  I put the original transformer back in (following the wiring that I wrote down when I removed it) and still nothing!  It worked fine before I took it out.  I tried everything, tubes, cables, cleaned the jacks and it still doesn't work.  I think I may have really hosed something up, anyone have any ideas?


  • #2

    That is very sad! But it's hard to know where to even begin giving you anything that might be a shred of useful advice. Do you even know the difference between a power supply transformer and output transformer?

    Your amp requires troubleshooting by qualified technician with the right equipment, and knowledge of that kind of device.

    There are some things you can try, like: Does the indicator lamp on the front panel come on? Are the tubes glowing? Can you try a different cabinet with the amp? Or a different amp with the same cabinet?

    Both the transformers in your amp are special to that amp, and cannot simply be replaced by other transformers that have a few wires of the same color. The transformers are fairly complicated, with multiple taps on boths sides, and all those sections of coil have to have the right number of turns.


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    • Crqc
      Crqc commented
      Editing a comment

      I don't really know the difference between the power supply and output, the one I replaced was the bigger one (the one I found looks just like it, same size and everything, I took both transformers out of the amp so I could get a closer look before deciding which one to replace with the one I found). Maybe the purple wire needs to be attached to sometihing?  

      I'm not an electrician by any means but I read a lot and can figure stuff out pretty quickly.  I read a lot about swapping out transformers and improving the tone of an amp, I'm guessing I must've missed something but can't figure out why the original transformer doesn't work now.

      Anybody familiar with this amp?

  • #3


    A few days after my last post I wired the new found transformer in and it blew a fuse.  I then put a jumper across the fuse holder and went to bring it up slowly on a variac that I made a few months ago.  Unfortunately I didn't realize that I had left the variac set full up so when I flipped the switch there was a blinding flash and that was the last I remember.

    Apparantly I was holding onto the edge of the chassis when I flipped the switch and took a pretty big shock that threw me to the floor and knocked me out cold, as well as setting the amp and the workbench on fire.  Luckily it knocked the power out upstairs and my roommate came down to see what had happened.  She grabbed a fire extinguisher and was able to get the fire out (the amp is ruined as is the bench and a lot of my tools), and called 911 to get me to the ER.  Suffered a pretty bad concussion, burns on my hand and arm plus singed hair on my face.

    The Dr. there told me I should consider taking a beginner electronics course or maybe even think about doing something safer.  LOL


    • Steve2112
      Steve2112 commented
      Editing a comment

      That above post didn't help the troll accusations. You've violated just about every single basic rule of electronics. How is it possible?

      You killed the amp AND nearly killed yourself? Saved by your rommate with a fire extinguisher? The best trolls of the old HCAF couldn't have done any better.