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Posted on Feb 11, 2018

I have a Marshall JCM 2000 DSL 100 - with weak output - Plate voltages are fine and I am getting signal when I plug into the effects loop, but it is low. Preamp out is fine. I have checked most of the components in the output section and have found no problems - also bias is stable as well.

5 Related Answers

Anonymous

  • 1 Answer
  • Posted on May 02, 2007

SOURCE: marshall tube amp problems

There is a bridge rectifier and red and black wires jumping from preamp tube to preamp tube. These need to be resoldered, take it to your favorite pro audio service center. I'm doing this to the same amp right this minute! Send it to me, I'll fix it. Tom Peary Norman's Electronics Atlanta, Ga 770 451 5057 www.neiusa.com

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Anonymous

  • 4234 Answers
  • Posted on Mar 06, 2009

SOURCE: Marshall jcm 2000 dsl 100 head not powering cabs 4/8ohm outs

Since you are getting some output, the amp section is probably OK. There are circuits designed to handle thge difference impedence outputs. This should be a relatively simple repair for any shop that handles these units. If you don't have one local to you, let me know and I'll locate the service info and get you more specifics.

Dan

Anonymous

  • 1 Answer
  • Posted on Apr 17, 2009

SOURCE: I have a marshall 100w

Most 1960 cabs have an option for 8 or 16 ohm... i dont think there is a 4 ohm option. The Jcm 2000 heads have the ability to do all three ohm setting. Thats all you really have to worry about. Make sure the ohms match up. The 1960 cabs typically have 4 t-75 speakers in them which are 75 watts each so wattage is not a problem. There is some argument about what ohms sound best. It doesn't really change that much in the sound in my personal opinion. I run mine at 16 ohms though cause i think it sounds brighter...

Anonymous

  • 208 Answers
  • Posted on Aug 10, 2010

SOURCE: hi i m sanjay i

there is a possibility of a shorted turn of the flyback transformer. To test. short B-E together on the horizontal output transistor and connect 60W globe across C-E. measure voltage across lamp - if it comes up to 135v then you have a short either in the horizontal circuit or secondary circuit off the flyback transformer or even the transformer itself.

EBC ELECTRONICS

  • 163 Answers
  • Posted on Sep 15, 2011

SOURCE: Denon AVR2106 One output channel shorted and

I would also replace 2sa992 (2pcs) and 2sc1845 on preamp board- sometimes they look ok when you test them by regular meter. Check 1.2 kOm and 4.7ohm resistors at preamp pcb. Check diodes on output pcb (could be smd type, connected from base of output transistors to emitter i think)

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I have a marshall jcm 900 slx 100 watt head and 1960a cab, when i went to use my amp i got no signal from my guitar. none of the fuses had blown and there was still a hum coming through the speakers. I...

It sounds like you have a dead guitar cable or the preamp section of the amp is blown. It needs to go to the shop. It's way cheaper in the long run to just take an amp in. If you try poking around without knowing what you're doing you can fry something more expensive or worse yet yourself! There are leathal voltages in a guitar amp!
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Hiwhat is the best way to connect my DigiTech RP10 to my Marshall MA100H Guitar Amplifier

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The loop and the manual tone store functionality !

Usually the loop in is used with an EXTERNAL effects module where the audio signal is "looped" out through the external effect module and then back to the power amp to drive the speaker in the cabinet. The LOOP IN jack would receive signal from the EFFECTS module OUT jack.

The source to go TO the effects module INPUT may come from a jack such as preamp out, or sometimes the same loop jack if it usess the TRS (Tip-Ring-Sleeve) connection method.

If you do not have an external effects module, all this is a moot point in your case.
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Yesterday, I accidentally switched off the powerstrip which my 100 Watt JCM2000 DSL is plugged into. I immediately turned it back on, without shutting off the power, and heard a "POP" I then tested the...

It is unlikely that your actions with the plug strip caused any permanent damage to your unit.

If you unit has a digital effects unit, probably the setting for that got disturbed and you need to reset it to your desired setting.
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Since you are getting some output, the amp section is probably OK. There are circuits designed to handle thge difference impedence outputs. This should be a relatively simple repair for any shop that handles these units. If you don't have one local to you, let me know and I'll locate the service info and get you more specifics.

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