Marshall DSL-100 Dual Super Lead Repair - New Power Tranny & Tubes

PART 2 follow-up video: • Solving Bias Problems ...
In this video we take a look at the innards of a JCM2000 Dual Super Lead 100 Watt Head. This one needed a new power transformer and a new set of output tubes. We also look at a couple of the very vulnerable spots on the circuit boards prone to breakage. The power transformer was replaced with a Classic Tone, Magnetic Components Inc. Part #40-18084. Finally, we will install a new matched set of JJ EL-34 output tubes and bias them.
triodeelectroni....

[@JohnIainMcFarlanewaspfactor]

It's the details Brad,and in my opinion it's what makes you an excellent tech.You didn't have to hot glue that impedence switch,but you spotted the problem could re-occur and made a fix.Top notch!

[@suzukiyesteryear]

Lucky break and not a complete restoration!. Always a pleasure to follow your commentary. God bless ya!!!

[@thromboid]

You're a braver man than I, making such big bias adjustments (even though the service bulletin specifies the target voltage drop). :) I'd be wanting to check the voltage at the grids for sanity...

[@TheGuitologist]

There is a Part 2. I went back and did some more research and did something else.

[@hrsey71]

watching these older videos..... you have come a LONG way haha

[@jhs5150]

This is why surface-mounting jacks and switches to a PCB instead on them being mounted to the chassis as per pre-900 series amps was a bad idea. They may cost the factory less in production costs but the consumer ends up paying more in repairs which ultimately gives these amps a bad reputation and reflects badly on Marshall as well.

[@aryankabir4167]

pro trick : you can watch movies on Flixzone. I've been using them for watching lots of of movies during the lockdown.

[@kevinkylo9297]

@Aryan Kabir yea, have been watching on flixzone for years myself :)

[@blakecase3885]

@Aryan Kabir Yea, I have been using Flixzone for since november myself :D

[@Mindstrikedojo]

Thanks so much for this just bought a jcm2000 100 watt noticed the vent on top was really hot and felt i needed to check the bias as i bought it used from guitar center

[@TheGuitologist]

+Brandon Archer Be sure to check my follow up video on this amp too! I go deeper into biasing it after getting it back again from the customer.

[@patricksoler]

This video is great. Thanks for going into such detail. Now I'll know what I'm talking about when I take mine in for service.

[@arose460]

I took all the blade connectors out of my Marshall and just soldered the wires. I don't know why but I'm not a fan of blade connectors.

[@jimbradley727]

Does anyone ever show the actual tube replacement? I have attempted to pull with much resistance...Love to see the simple yet much needed video..

[@JimSlimjimCassi]

Here is the problem i had while biasinmg my JCM 2000 DSL 50, I bought it with JJ's EL34's installed, I had a tube go bad, so i bought a pair of Groove Tubes GT-EL34-MD-H 113558, on the box they have a rating of 10. So the JJ's checking the bias when I 1st got the amp, had them set to 38mv, after replacing them with the GT's, while biasing, I could not get the tube lower than 55mv, turned all the way down, so i was having the opposite problem you had. Calling GT / Fender i guess.... They told me the tube was too hot, and they no longer make a 10 rated tube, 4 is the highest now. I'm waiting for my new tubes to arrive today to continue my testing. I found that JJ's at least the ones i have seen, are very low power rating.. I don't know shit about tubes, but it looks like all EL34's should be in the same ballpark for power rating.

[@rickmedina7107]

I want to hear the tone...Your Playing is great Brad...

[@CarlosCentenoOB]

hi! i dont know if i am wrong, but, i just bias this same amp and what happens was that, when you turn the left little white screw on the pins panels, this apparetly affects the other pairs of tubes as well, so you need to balance the voltage using both white screws. this works for me :) great channel by the way!! :)

[@TheGuitologist]

No matter where you sat the bias on both pots, there was no way to get the bias correct without modification. If this amp comes back across my bench with more bias issues again, I'll probably perform the drill out procedure to remove an possibility of a conductive board.

[@troyredford149]

I have a JCM 2000 just like the one in the video and still has the same tubes in it when I got it a few years ago and I checked bias to make sure it's at 90mv because it hasn't sounded good to me no matter what I did. The bias was around 35mv on both sides so I adjusted them to 90mv. One side stayed at 90-91mv and the other side kept climbing even when I turned it as low as it would go and it climbed all the way up to 189mv and I heard a crackle from somewhere around the tubes and then the speaker crackled for a split sec then the voltage started dropping rapidly and the two tubes where glowing brighter as the voltage dropped but I shut it off to prevent any further damage. What do you think happened? Was it just old tubes that finally went bad or did something wors happen?

[@johnnybravo4704]

Your bias is on lower side because higher negative voltage on new trasformer..Its no big deal, but guitarist want them biased hot for great sound.

[@chrisf6216]

Good Day! I have a troublesome JCM2000 DSL 100W (head) which exhibits the growing bias issue then, eventually, blows the HT fuse. Like you, I initially noticed the HT fuse blown, replaced it, installed new matched quad EL34s, biased the amp, then let the amp sit to bake 'em in for any bias drift. Returning an hour later, found bias was insanely high. Research exposed the "conductive PCB" flaw. I replaced the main PCB (that houses the pre and post tubes) as I thought that would be the fix. Unfortunately, the trouble remains. I did not change out the EL34s, again, as I did not want to ruin another matched quad. I don't suppose a previously new EL34 could be destroyed by, then exhibit the same symptoms of, the "conductive PCB"? How does one determine the transformer is bad... such as you did in this case (fwiw, I compared readings with a TSL secondary and they seemed to match up)? Pardon the shotgun questions. I am frustrated though mostly bummed my fix wasn't. Any suggestions and guidance greatly appreciated.

[@lennyluzitano8920]

i read that some years they had defective printed circuit boards that "Leak " ....thus causing .serious damage to components...can you tell me what years....also Marshall does not ..take any responsibility to compensate ..the people that bought these ...crappy DSL.....i need to get to the exact info on this ......

[@nevillegoddard4966]

Hi Brad! Yeah please!, please do a demo with this upgunned beast!!! Ya got a speaker stack to cop the 100 watts? Or is it the neighbours? That ClassicTone output trans. is a BIG BEAUTIFUL BEAST! Gonna be awesome mate! Might have to hire a masonic hall or a pub lol! Make your heart palpitate & your ears bleed & your knees weak...A bit like the WWIII spikey flu! - but in a good way!? Gotta disagree with the holt-melt glue job sorry. Waste of time. Araldite or some kind of epoxy or bondo maybe around the terminals pins of the switch & the top of the pcb. Drill holes of suitable diameter in the pcb close to the switch pcb pads for the much preferred araldite to 'key' into. The extra holes in the pcb probly don't even have to be drilled through all the way if you're able & careful enough. I promise! - These pcb holes are like 6 foot deep foundations in your house compared to surface ones. The plastic 'give' in the holt-melt will only slow down the same eventual fault. But yeah. Immobilise the switch tag/pcb switch tag solder pad junction, problem solved.

[@jacobbockover1628]

Ive noticed all these dsl amps your working on are 100 watt. Im considering a 20 watt dsl. Im wondering if they are lemons

[@TheRustedShackleford]

You should be fine. It was really just the 100w DSL and TSL that had all of the issues.

[@green323turbo]

Is the standing bias current suppose to be 90ma ? Wow thats a lot of wasted power coming from the poor high voltage powersupply. It may be a good idea to leave it turned on for a few hours and check the temp of the transformers with a digital temperature meter.

[@jonathanberrier5018]

So it looks like you connected the heater center tap to ground with the green/yellow wire. Did you remove the 100 ohm resistors from the board, or was this an oversight?

[@Jupiter2ignite]

I have a 90s Peavey ultra plus 120 watt head. What's your opinion on those? Doesn't seem like you work on peavey's very much. Is that a testament to their quality or is it just a fluke?

[@RasCuban33]

Did the revision 20 motherboard swap and it’s starting at 90mV per side with the VPR button engaged? Check the 220v caps or 0.047uF?

[@Ramo_Baramia]

Hi, I have dsl100HR power switch light kept coming on/off sent it to Marshal they repaired it. after six months or so the problem is back on. do you know what can cause this issue? Amp works fine, just light flickering on/off.. Thanks in advance.

[@hadleymanmusic]

Would you reccomend a dsl 100?

[@briankoch4025]

I have a 99 dsl100h, what output transformer did you use? I'd like to beef mine up a little bit. Thanks

[@juliocarrilho7834]

I have a dsl401 keeps blowing the main fuse the moment i turn it on.

[@landonjackson3064]

Have you worked on any of the Rivera era Fender Concert's ? I am very curious about a mod that can be done to make it pristine fender cleans on the first channel , and on the other channel super high gain boogie style . Let me know . I am in Orange County and if you know anyone I would appreciate it. Thanks

[@Ammo150]

What amp tubes does the jcm 2000 dual super lead use?

[@bengordon7635]

when turn on the effects loop on the overdive its real static like bad tube sound then effects slowly cut out I replaced 12ax7 tubes still have the same issue I was wondering is the power tubes liked with the effects .. because the clean channel works fine effets loop and everything .. the overdrive side when effects off its fine super quiet effects on like bad tube sound just started this .. Marshall TSL 112 combo amp

[@mikeanonymous669]

So you believe a 1 ohm drifted and you still set the bias using the reading off the 1 ohm resistor that you believe drifted? Then you adjusted the other side (which could have drifted too) and now both readings "matched"? With bias resistors that you believe drifted? SAY WHAT?

[@paulkielt9301]

Those Marshall biasing specs are little bit weird! The bias of an amp should be checked and adjusted for each power tube separately and not for a pair, because in that case you'll never know if they are well matched. If you set an EL34 for about 90 mA, it will be ready for cooking not to play guitar!

[@guitargeek2891]

The bias is set in pairs on this amp. If you buy a matched set you should have no problems biasing. 90mA is the factory spec on the DSL100 (JCM2000).

[@TimmyP1955]

The factory bias level on these is mighty hot. Then there's the highly interactive bias pots. And the issues with some having slightly conductive PCBs - I had to resort to the "grind the board away around the power tube grids" mod to finally get one to hold its bias instead of baking itself.

[@eddiedisaster1]

I got this same head and the output transformer needs to be replaced, I bought the classic tone replacement output transformer, do you have any videos on how to install the output transformer?

[@TheGuitologist]

+edward granillo No, sorry.

[@JosipNovak]

I have question? Im from europe and my voltage is 220v and 50Hz, what is proper mV for bias on my voltage? is it the same like you? i have the same amp.Thanks

[@TheGuitologist]

I assume it should be the same.

[@silasfatchett5693]

If your mains voltage selector is set to 220V then all the voltages in the amp after the mains transformer will be the same as in the US version, including the voltage at the test points.

[@JohnIainMcFarlanewaspfactor]

Yup,it's the same.

[@CyclopsGuitars8642]

I have a jcm 900 -2100 series.Will you fix my amp for me? Yes I’m being serious,I need help

[@johnnybravo4704]

Rule for new tubes is ; first bias them low ,then let them run for 5minutes, then go to medium settings and let them run for 30minutes, then gradualy turn them up to allmoust max and wait and monitor each side of push pull. Leave them playing2hours and then put amp off. Come back tomorrow and plug it in and let it run for 3hours and then bias to the max..After month playing rebias again, and you are done,,

[@TheGamerx584]

whats the difference between the low bias ? is can I do it at home ? Also, do you have to always bias after you swap out the tubes the same that you had before ?

[@TheGuitologist]

If you're swapping tubes, rebiasing is a good idea.

[@currituck]

If Marshall cabs at least the good ones use 16 ohms mono as the basis. Why don't these models have a 16 ohm selection on the back just 4 and 8. I know you can the 4 ohm selection in mono on the back of the good cabs but some like to run their amps at 16 ohms. Little odd.

[@randallissimo]

Love your videos, but do yourself a favor and don't poke around high voltage with a pencil. Carbon is conductive.

[@guitarzarfun]

these amps do sound good, but my god those components! Ceriatone point to point amps are starting to make a ton of sense to me.

[@p_1210]

Great vid! I have a 1998 50 watt version and it has an audible hum when you switch the Power on even with standby still off. What could that be or is this an inherent thing with these amps? Thanks

[@TheGuitologist]

+Peter Cross could be a grounding issue, but some slight noise wouldn't be out of the ordinary. Could also be caps, I suppose.

[@p_1210]

The Guitologist thanks I just picked it up. It had been sitting idle for 6 months or so! I didn’t turn it off standby, left in on for few minutes then turned it off. I don’t want to do damage? Could it be a faulty 16ohm jack and the head might not think it’s got a load? In any case I think I’ll take it to a tech.

[@djeyesacs]

Just bought one of these amps and after playing for awhile the other night, I had left the room to smoke and came back and there was no power. So I did the common knowledge troubleshooting and found a blown mains fuse. After closer inspection, I noticed the blown fuse was a 25 amp 250v fuse. I'm no electronics engineer but I've deduced that its not a good sign. I haven't gotten a replacement fuse yet, and when I do, the first thing I'm going to do is try the things you showed here. But my question is, what does it mean if my amp blew a 25amp fuse and what potential damage could this inappropriate fuse cause. Thanks.

[@TheGuitologist]

The fuse youre talking about is a .25 amp fuse. Note the decimal.

[@djeyesacs]

Well there's not a decimal. Am I missing something?

[@TheGuitologist]

25 amps is HUGE. No guitar amp is going to use a 25 amp fuse. Check the chassis or service manual for proper fuse.

[@djeyesacs]

Well if one would fit in the amp, I would say anything is possible, wouldn't you? Previous owner had it for 14 years so I wouldn't understand why he put a 25amp fuse in it but I'm just speculating.

[@dimebagtribute]

Same trouble on my first version of jcm2000 for the bias adjustment! Marshall say 90mV but I can't have more than 75/80mV with the bias pot cranked... And I tried a lot of differents tubes, modern and NOS, all tested and a lot above the datasheet specifications!! So my tubes are always bias a little bit cold but it sound pretty good!

[@TheGuitologist]

+alex Aragorn alex, I eventually got the amp back and found a solution. Watch this video, it should help: kzbin.info/www/bejne/m5XbY3WXft-Jmac

[@dimebagtribute]

+The Guitologist In fact I found a solution on Dr Tube, he propose a pcb to rebuild correctly the bias circuit with the correct components values!! And it's pretty cheap. You should go on his website, it's really interesting, but thanks for the link, your video are very pleasant!!

[@dimebagtribute]

+The Guitologist In fact I found a solution on Dr Tube, he propose a pcb to rebuild correctly the bias circuit with the correct components values!! And it's pretty cheap. You should go on his website, it's really interesting, but thanks for the link, your videos are very pleasant!!

[@jhs5150]

The Dr. Tube kit still requires you to drill holes in the existing PCB in addition to relocating components to their board so if part of the problem was the construction of the PCB (inferior plastic) you are better off replacing it with a new PCB.

[@AdamRainStopper]

You said it's a "JCM2000 DSL," so that means it is one of the actual old JCM2000 models, not the new "DSL" series, right?

[@TheGuitologist]

+Adam Rainstopper That is correct. This one is a year 2000 model.

[@AdamRainStopper]

Brad Linzy Is it true they used diode-clipping in these? I hear the new ones have clipping diodes in the gain channel signal path.

[@TheGuitologist]

Not sure. I didn't really look at that.

[@AdamRainStopper]

Brad Linzy Huh. I know some (or maybe all?) of the 900's were just done with so many shortcuts, clipping diodes, and I think the 60 and 120 watt head versions actually had an op-amp right up front, to "push the tubes" for more gain. They had a good idea, make something like an 800 but with one extra preamp tube. That would've been plenty of gain for anyone's style by itself. The diodes weren't necessary, never mind a solid state first gain stage. Then the 2000's came out, and I liked them, but not as much as an 800 with a really good, non-compressing clean boost in front. On an unrelated note, my dad's (jesus, I have to stop referring to stuff as his, stop using present-tense verbs like "my dad *has* a Les Paul") Reverberocket is humming and popping. I know it needs to be retubed, but it might need more. It's not the reissue, it's an original, one of the 7591 models. I want to be able to play through it for almost clean reggae rhythm guitar, and bass sounds amazing through it. It's a big heavy combo amp, so it would probably cost a fortune to ship, otherwise I'd send it to you in a heartbeat. What are some things to look for? Some likely culprits?

[@TheGuitologist]

humming is probably caps. Popping could be a number of things, but I'd first try the simple stuff - clean tube sockets and pins, pots, etc. Then if it's still popping, turn it on while it's open and get a wooden chopstick or something and wiggle components until you find one that is making noise.

[@ScottRay77]

The only decent Marshalls I've ever heard were modded by Mike Fortin, but I'm a metalhead though.

[@cgavin1]

These 90's and 2000's Marshalls were just total junk. Sound wise some were great obviously, but they were made so cheaply and so shoddily its a wonder they are still in business. Its no coincidence that the Vox amps they were making then in the same factory were also total crap.

[@1273seant]

hi can you show how to drain the caps -thanks

[@TheGuitologist]

In a future video I'll do that. I also promised someone else Id show exactly how to change to a 3-prong cord also.

[@jeremiahwilson1781]

Wow..production amp brands and manufacturers really use bottom of the barrel in quality components these days. Horrible.

[@davidfuller581]

The only big company I've seen that's worse than Marshall is Fender. Those are horrendously awful

[@brianpeter7139]

I don't understand what the speaker impedance selector could have to do with the mains fuse and the power transformer - if it was disconnecting and putting no load on the amp, would it not blow the output transformer and the HT fuse instead?

[@TheGuitologist]

+Brian Peter I never figured out what exactly caused the PT issue, I just happened to notice the selector switch was also not soldered properly, so I fixed that too.

[@pjf7943]

It isn't a good idea to be poking around inside the amp with a leaded pencil whether it's hot or not. The old fashioned wooden chop-stick method of prodding and pointing is much safer.... Just sayin'...

[@TheRustedShackleford]

It was in fact NOT ready to rock. I love these amps, but they can be such a pain in thr ass.

[@w1third]

What if you play one and it gets hot fast?

[@TheGuitologist]

If the bias is drifting, that could cause excessive heat, and it could cause some major problems. I suggest turning the amp amp with the rear steel guard off so you can get a good look at the tubes. If the plates (those are the big metal parts in the power tubes) are glowing red hot, shut it off immediately and don't play it again until you get it looked at. You might also feel the power transformer with your hand while it's on and make sure that isn't getting hot. Either way, if it's been a while since you had your Marshall DSL or TSL serviced, it's probably a good idea to go ahead and have that done. Many of them are just now starting to show problems. Some of those problems have been discussed here in the comments already, The boards are notorious for becoming conductive, and the solution might involve dremeling some holes in the actual board.

[@jhs5150]

It might be cheaper just to get a later revision board from Marshall. It's got all the fixes the boards from '97-03 didn't have. You won't have to drill any holes or relocate components.

[@eddiegeorge4047]

wouldnt it be 45 mV for each pair of EL34 ?

[@basstard13]

One thing is what you're adjusting, one thing is what you're reading. In many amps you're adjusting all 4 tubes together with one single pot and you're reading the value for one tube. But you can have any combination, depending on how the amp is built and how you're measuring [if from the amp test point or a bias probe, for example]. In this case you're adjusting and reading for each couple so you get the current for two tubes together.

[@lennyluzitano8920]

ok 1997 to 2003......bad circuit boards....gotta see what year m DSL is....thanks ....saw it on one of the comments.......

[@AdamRainStopper]

Huhuhu, huhuhu, heh, huhuhu.....he said "tranny" Heh Heh Heh....Yeah, then he said "head" heh heh heh. And "blowing" .... hehe heh

[@AdamRainStopper]

Brad Linzy I believe you.