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  1. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    Forum Members I am doing some testing on this amp before calling my friend to come over and have a listen. So far, the fabricated Mix Input jack is working well. The modified footswitch is also working well. Talking with my friend today, he mentioned to me that compared to his other Marshall...
  2. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    Ok.... as promised, here are some photos of the "guts." Please visit the sister thread titled Marshall JCM 800 Series 2000 235w amp, Mix A&B Input Jack. This amp has been modified and I would say it has some Revision 2 changes and then changes to the output tubes. On the preamp, the 68K...
  3. TomCarlos

    Marshall JCM 800 Series 2000 235w amp, Mix A&B Input Jack

    One last thing... I posted the schematic above as to how I wired up a two button switch. Here is a photo of the inside of the footswitch. Notice that one switch is a SPDT and the other a SPST. I also had to fabricate some extension arms for the Mix Input jack. Modern jacks (even those branded...
  4. TomCarlos

    Dim bulb tester or limiter

    I did not see anyone post a circuit for the bulb limiter. So here it is. I built a simple bulb limiter and then a combination Isolation Transformer, Bulb Limiter with a lamp bypass switch. I will typically connect this to my Variac. Once I know the amp is not pulling excessive current, I...
  5. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    No, I won't !! The next round of photos, schematics, footswitch wiring, etc will be on me. Once I get the Mix Input jack installed and footswitch rewired, I will be posting several photos. And thank you!!
  6. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    DOD DoD ... Once I finish my repairs and have the amp "working the way it is supposed to work", I will take photos of the guts, front, and back. I believe the amp I have in front of me is a Revision 1. It had multiple 68K grid resistors on the PC board. Revision 2 and Revision three calls...
  7. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    After resolving the problem of the Mix Input Jack, which must be Tip=NO, Ring and Sleeve=NC, I did some testing for the Footswitch. I took a Stereo cable but stripped the ends off one end. So you insert the plug into the Footswitch Jack (and of course your guitar plugged into the Mix Input...
  8. TomCarlos

    What type of jack is this?

    After much research, I have learned there was a limited run of the 2000 (the guitar head) and the 2001 (the bass head). Both amps have the "Mix Input" and use a VERY RARE jack for the time. The Tip is Normally Open, the Ring and Sleeve are Normally Closed. I confirmed this with testing. I...
  9. TomCarlos

    16 ohm out works but NO sound from 8 ohm outs on TSL100?

    Did you look inside the amp to see if there are wires between the Output Transformer to the Impedance switch for both the 16 and 8 ohm outputs?
  10. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    Deftone... Was that in the Auburn to Sacramento area? Just curious.
  11. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    Ok.... It turns out, you CANNOT use a simple two button SPST switch. When you do channel adding, you need something like what I am showing in the attached photo. I have tested this theory with jumper wires - it works.
  12. TomCarlos

    Marshall JCM 800 Series 2000 235w amp, Mix A&B Input Jack

    Ok... Problems solved. Confirmed... the schematic shows a stereo Tip=NO, Ring=NC, Sleeve=NC. This jack was used for the Marshall Series 2000 guitar head and 2001 bass head. The jack must have been a special order. To the best of my knowledge, Marshall never used them again. I believe they...
  13. TomCarlos

    What type of jack is this?

    Confirmed... the schematic shows a stereo Tip=NO, Ring=NC, Sleeve=NC. This jack was used for the Marshall Series 2000 guitar head and 2001 bass head. The jack must have been a special order. To the best of my knowledge, Marshall never used them again. I believe they abandoned the Mix A&B...
  14. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    I am using a two button, simple On/Off (SPST) switch. The channel interaction is one thing - and it might be resolved. The problem with my amp is with the Mix Input Cliff Jack. If you look at the schematic, it is NOT clear if the TIP part of the jack is Normally Closed (as are 99.9% of the...
  15. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    I a
  16. TomCarlos

    1980s Marshall 2000 Lead 250 Watt Head

    Yes, I am working on a Series 2000 right now. It belongs to a friend of mine. But I am having difficulty getting the MIX inputs and Channel Switching to work. I posted a couple threads on here but so far, no replies that might help me. I would love to get my hands on an April 1981 schematic...
  17. TomCarlos

    What type of jack is this?

    Thanks Dtier ... that is what the schematic indicated for the JCM 800 Series 2000. I noticed the 2001 also has the same design for the inputs. It is just that I have never seen a jack configured with NC, NC, NO (NO on the tip).
  18. TomCarlos

    What type of jack is this?

    Forum members... I wanted to call attention to just ONE thing, so I will open a separate thread. Please take a look at a small piece of a Marshall schematic. You will see input jacks for Channels A and B. These are mono cliff jacks. Now take a very close look at the MIX input jack. That is...
  19. TomCarlos

    Marshall JCM 800 Series 2000 235w amp, Mix A&B Input Jack

    Would anyone, ANYONE, happen to have the Revision 1 schematic for the Power Amp section? If yes, please send. I realize there are not many of these amps in circulation. But it appears (not just to me, but others), that there are notable errors in the schematic as Marshall moved from Revision...
  20. TomCarlos

    Marshall JCM 800 Series 2000 235w amp, Mix A&B Input Jack

    Thanks Neil... maybe when I am done with repairs my friend will sell it - and I will KEEL him!! I will fully document the revisions made previously and what I am doing to put this back to (or as near as stock to Revision 3). What has become obvious is that the amp has been modified, in the...

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