Do not forget the pots - they can crack or the solder under them can fail. 9th September 2005, 10:16 PM # 3 In accordance with Marshall JCM Handbook model 4200 does not exist. Please take a look once more. 10th September 2005, 04:11 AM # 4 I didn't think to actually look... The JCM900 series included the 4100 and the 4500 series of amps. This includes the variants like the 4101 and 4102 or 4501 and 4502. The JCM800 series does include a number of 4200 series number models. 14th September 2005, 07:33 PM # 5 Join Date: Apr 2004 Location: Philly The 4000 series marshalls were jcm800 combo amps post 1989. There are lots of schematics for these out: 18th September 2005, 04:35 PM # 6 I'll ask my friend again about the model number thank you Just remember: in theory there's no difference between theory and practice. Bob Pease
Combinations of these two controls can take you from classic Marshall crunch in lower positions, to pure overdriven outrage on maximum. Page 5 NOTE: Combinations of the two gain controls (items 2 and 3) provide a wide range of clean, crunch and overdrive possibilities. Experimentation will reveal the optimum settings for each. 4 & 5. Master Volume "A" Master Volume "B" Twin footswitchable Master Volume Controls. Master "B" controls the overall volume exclusively when a footswitch is not connected. Page 6: Rear Panel Functions REAR PANEL FUNCTIONS 10. Valve Failure Fuse Operates in the event of an output valve failure and The Hi Gain Master Volume SL-X and Dual prevents any internal damage to the amplifier. Reverb models feature comprehensive connection NOTE: and control facilities on the rear panel which are common to both ranges. Page 7: Front/Rear Panel View JCM 900 SL-X HI GAIN MASTER VOLUME FRONT PANEL 11 10 9 JCM 900 SL-X HI GAIN MASTER VOLUME & DUAL REVERB REAR PANEL NOTE: On Combo models the rear panel is reversed 9 10 11 12 13 HI GAIN DUAL REVERB FRONT PANEL NOTE: On Combo models the front panel is reversed 13 12 11...
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I also have a Model 800 2203, and yes - it is VERY similar sounding to that 800 when the gain is set at approximately the same... IMO, the MKIII's got that much desired "Model 800" sound in spades... #10 I liked the sound of my dual reverb - both channels - it did have to be pretty loud to sound its best. bass and mids up, treble and presence way down helped. recently I ended up replacing the preamp board with a homebuilt job, not primarily because the tone was bad - but it started having these occasional dropouts, and the volume wasn't what it should be. It's basically a marshall 1987 preamp: It's now a 4-input marshall, and sounds great too: Last edited: Aug 22, 2012 #11 That's the same model I have and I freakin' love it! I scored it off ebay about ten years ago from a guy who kept it in his studio. Looks brand new and sounds amazing. I hope I will never have to sell that one. Here's a little info on it... #12 There's one of these Mkiii 1x12 combos for sale locally. Now y'all have me interested... #13 People pay top dollar for an original JCM800 and you can still get the model 2100 (100w) and 2500 (50w) for around $'s a no-brainer for me.
4th September 2005, 08:33 PM # 1 diyAudio Member Marshall JCM 900 schematic or service manual? Hi, I'm looking for a service manual for this guitar amp. The full reference is JCM 900 4200. A friend has one, and it doesn't work properly. When cold, there's no problem. But after a few minutes, the sound stops, comes back, re stops... Sounds like a faulting solder join. What do you guys think? __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease 7th September 2005, 04:06 AM # 2 Join Date: Sep 2004 Location: Lansing, Michigan You want a schematic for a Marshall 4200 then, JCM900 doesn't specify an amp model. Look at the tubes, in particular the first preamp tube. Does the heater go dark when the sound goes away? If so, there is a square black bridge rectifier in the midle of the board, and it probably needs to be resoldered. Otherwise use an insulated probe - fancy words for a chopstick or something non conductive - and push on things to try to isolate what has an intermittent connection.
I love how I can plug those guitars into the amp with no effects and it roars! If you are a fan of Angus Young's he just plugs his SG straight into his Marshall Wall Of Terror with no effects. But each 2 their own. Reviewed in the United States on August 3, 2013 Meh. I owned this amp and is not very good in comparison to the 1959 SLP and the JCM 800. It's emphasis is more on gain, than tone.
Top reviews from the United States There was a problem filtering reviews right now. Please try again later. Reviewed in the United States on January 30, 2015 The Amp that hit the 80's and shaped a decade - no modifications needed. This was the Dual Channel High Gain amplifier after the JCM 800. Although the JCM 800 had great tone like the plexi, it lacked the needed breakup for Metal, Neo Classical Rock, Fusion and other Heavy styles. That is why many people still used distortion and overdrive pedals with that amp. Enter the JCM 900. Although not QUITE the same tone, the amp was just as good for stage use without mods. That was the problem with the plexi - it needed to be at high volumes (unusable unless in a large venue) to get the needed breakup and tone. That is why many plexis were modded with the post phase inverter (master volume) and the cascading gains for channel 2. I love the JCM900 for the versatility of the dual channels which includes both Master and Preamp volumes for both channels.
Looking at the schematics, the preamp is different between the two, more specifically, from the input to V1 to the start of the tone stack. From there onwards, the two share the same tone stack, effects loop and power amp. The SL-X was produced between 1993-1999. Many of the SL-X amps came with 5881 power tubes instead of EL34′s when Marshall switched over in late-1993 to early-1994. This change is another reason why to me, the SL-X lost some of that Marshall mojo. My advice for the SL-X is the same as for the 4100/4500 Dual Reverbs; if you want one, get one with EL34′s. #17 I had a 4100 head and 4x12 cab when I was 16. This was before anyone really had an internet connection. I thought it was the coolest thing ever. I eventually moved on to other amps.... But we actually have a 4100 head at our church. I keep it on Channel A and use plexi voiced pedals for higher gain. It can be a little shrill, thin, and overly crispy on the B channel. I remember Jeff Healey liked those MK's back in the day.
I think it is basically a JCM800 with a little bit more gain on #14 MkIII is the only good one... #15 I agree. When using Channel A and cranking it up, my 4502 (JCM 900 Dual Reverb 2x12 combo =C= EL34's) sounds a lot like my JMP 2204 and my 1987x the way I run them all. #16 this topic gets resurrected now and then I have the exact opposite opinion and for me the only one is the early MKIV, the EL-34 SL-X (2100 = 100 watts 2500=50 watts) that at some point were offered with 5881's, around '95. All tube path except for the OP-Amp based FX Loop and A/B Master Volume Switching setup which are transparent tonally. It is the most 800 sounding imo and its basically a hot rodded 800 with the addition of a "Sensitivity" control which is post V1 and Pre-Amp pot and is VR2 on the shematic. The Pre-Amp and Sensitivity are where you can find classic 800 to modded 800 tones. The 2100 & 2500 amps were superceded by the SL-X amps in 1993 I couldn't disagree with this more and he omits the major difference, the non SL-X JCM900's are laden with Op-Amps and clipping diodes.
7K - 4 / 8 /16 Ohm Laydown OT) *Disclaimer: Magnetic Components, Inc. is not affiliated with Fender Musical Instruments Corp., Marshall Amplification, Vox Amplification, Ltd., Leslie & Valco **All of the above listed amplifier models are trademarks of Fender Musical Instrument Corp., Marshall Amplification, Vox Amplification Ltd., Hammond Suzuki USA, Ltd. (Leslie) & Eastwood Guitars (Valco) Copyright 2009-2020 Magnetic Components, Inc. All Rights Reserved. WARNING: Transformers should always be installed by a professional electronics technician since there are high voltages involved and may result in serious physical harm to yourself, the transformer and/or your equipment if installed incorrectly. Paper layer wound like the vintage era originals! Made in USA by us at Magnetic Components, Inc. Made with premium materials Features custom, solventless, varnish for vintage look and high performance Proper raised mountings / No chassis modification required on most Made with pre-tinned "Topcoat" PVC appliance wire for ease of soldering RoHS Compliant ClassicTone Series: Vintage, Plus & Custom