How to repair a Marshall JCM 800 Amplifier model 2210 100 watt
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- เผยแพร่เมื่อ 28 ส.ค. 2024
- Welcome to Eric's Guitar Amplifier Repair. Today we will repair a Marshall JCM 800 Amplifier model 2210 100 watt. Customer complaint is no output sound.
I will perform a general service including a replacement of several output EL34 electron tubes. A rep-bias procedure etc.
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Category
Science & Technology
I would have liked you to have seen you test one of the new EL34's, so as to see the strength of a new vacuum tube.
Excellent advise. That’s exactly what I will do in the nearest future👍
I really enjoyed the vid, except the repetitive music. It would be nice to have some more fluff discussion around common points of failure, modding, building and also general work methodology around the amp on the bench.
Excellent advice. That’s exactly what I will do for now on. Thanks.😀
@@FeeserAmplification Cheers! I'm trying to learn as much as possible so that I maybe can work on my own amps someday.
I had a friend show me how to test tubes today how ironic but still very interesting
Nice video. I got that same tube tester. It was a kit. Never has let me down
Love your channel ! New sub here from Quebec !
Great video! Thank you!
Could you turn the music down low please. It's too loud. Or you could just leave it off altogether as I'd rather just hear you speak.
I'm amazed you didn't even check to see if it had the proper fuses in the amp??? Should have be one of the first things to check!
Procedure is always to check the electron tubes first. Fuses and component check is done during visual inspection of the circuit board.
@@FeeserAmplification Procedure. I guess as long as you check them before applying any power.
That amp at the beginning is not the 2210. At the end you show the 2210, what's up?
2203 to the 2210 Splitch?
Not sure. Maybe video mix up.
Nice, I subbed to your channel. Is this amp 'easy' to repair? I know there is no comparison but I recently sold a Marshall MG100FX, it had a scratchy master potentiometer, I opened it up to take a look and didn't like the fact that (of course it was a solid state) it was all digital, everything was SMD components and it even had a fan right below the main amp's heatsink, so it was a mechanical part that in case of failure would burn the amp, and I read online that it was a common issue, it didn't sound horrible (I've heard worst ones) but I didn't want to bother with having to replaced burned amps or getting a digital PCB replacement for it in the future so I sold it. Now I am looking forward to get a 'real' tube amp and there's a JCM 800 2210 for sale near the place I live, would you consider this amp to be a good purchase, I want something durable that can sounds good and is made to be fixed in case it fails, what are your opinions on this one? Thanks by the way and greetings from Colombia.
I believe that you will be happy with the tube amplifier of your choice.
Were you not supposed to move the switch to "D" when you tested the power tube
Not for this particular go no go tester as per manufacture instruction manual.
I try not to judge people but how do whack stains end up on an amp?
Yes. It’s ok to love our amplifiers but we shouldn’t love love all over our amplifiers🤪 Gross!
I’ve never seen anybody just hook a voltmeter up to a resistor and get those readings can you do that with a super lead also
Yes. So every amplifiers will have its own schematic allowing the technician to detect the bias point location.
Why do people buy Bias probes or run a resistors from pin to ground maybe I am Not seeing this right
@@bobbarcus8310 Yes. All engineer technician are well versed in this method of biasing an amplifier.
@@bobbarcus8310 This guy answered in a very ambiguous way as he is hiding that he does not know ! You get dazzled with the visuals of the equipment as a smoke and mirrors show. On the schematics, you find where the bias voltage circuitry is and they give you a voltage number which represents a reference point BUT its a reference point on that particular amplifier they used when they drew the schematic which means conditions as to what tubes were in the amplifier at the time and the wall voltage that was present when the amplifier was powered up.......all of which are variables and do not carry over.......the whole point is that it is a generality. The proper way to bias the amplifier is by measuring the current draw of the pair of power tubes. Pair is the relationship to the function of the output circuitry as this is a PUSH/PULL type amplifier......one will be the PUSH tube and the other will be the PULL tube. Being this is a so called 100 watt amplifier, the Push side will have 2 power tubes in parallel as will the Pull side. You have to measure current draw to determine the PLATE DISSIPATION factor because bias setting is based on the PLATE DISSIPATION. The TUBE DATA BOOK that the manufacturer's publish for their tube line will list the engineering data for each tube they make and give maximum values and parameters for that tubes optimal operation. BUT this is based on the tube MANUFACTUERER and it doesn't always match exactly to another Tube Manufacturer's equivalent tube ....but can be very close, if an accurate statement were to be made. The purpose of determining the Plate Dissipation is to find a narrow range of operation with the tubes as the bias current range is between 50% and 70% of the maximum Plate Dissipation number. Translated, the range gives a variation in performance and tone as a result. A 50% bias is relative to a cold bias that's within specification in the low limit. You do not want a cold bias amplifier as the operation of the power tubes is in an area where they will make a distortion character that is not musical as they are not getting enough electrical energy to operate properly. A medium bias in the 60% range would seem to be the logical point to bias BUT its not if you are optimizing the amplifier for tone. A hot bias of the 70% range is where you need to be for optimal operation and tone. So the real window of range is between 60% and 70% which is not much of a swing. In fact, as the tubes burn in after a number of hours playing and being ON.....you need to check the bias again to see if it has drifted due to the burn in as the tubes settle in and stabilize. Hence the TUBES are what determine the bias, not some voltage reference point on a schematic, and each tube set can be unique so the numbers and values generally are never the same when changing out power tubes. GROOVE TUBES used to have a grading method when they sold their products as they were graded and matched sets. Thier grading and matching let them use a scale number on the tubes sets where you could buy the same set number and put them in an amplifier without the need to bias the amp when doing the tube swap out. BUT that was a sales and marketing situation with that company, I would always determine the bias with each power tube set change out...to determine the optimal performance. The voltage reference point this guy is using is NOT the way you bias a tube set, but you could get a reading for the test point he is using after you bias by the Plate Dissipation method....just to get a reference number for that point with the particular tube set you put in....in that moment of time, BUT AS MENTIONED the tubes will drift after burn in and the proper way is to recheck and reset the bias point back to a 70% bias factor to the Plate Dissipation if it has drifted up or down from the initial setting. To me, I can't say if this guy has credentials as in being schooled in electronics, but by what he presents....he doesn't know vacuum tube technology. Vacuum tube technology is obsolete beyond obsolete and is not really taught in modern electronics schools.......they teach the technology of the day...DIGITAL LOGIC. The big give away that he doesn't know vacuum tube technology is where he presents his tube testing machine and puts in the 12ax7 tube to test...his statement was about there not being any script label left on the glass of that tube and thus he did not know. THE FACT OF THE MATTER is NOT THE LABEL ON THE TUBE......but the guts of the tube which you can clearly see through the glass. IF YOU KNOW VACUUM TUBE TECHNOLOGY THEN YOU WOULD SPECIFICALLY KNOW THAT EACH TUBE MANUFACTURER USES GUTS THAT DIFFER FROM ANY OTHER MANUFACTURER>>>ITS A PROPRIETARY THING.......they are stamped metal parts in that glass and each manufacturer has their own stamp. AND NOT ONLY THAT, There are other factors as being LONG PLATES OR SHORT PLATES...AND EVEN MEDIUM PLATES. SO YOU CAN IDENTIFY BY THE PHYSICAL VISUAL APPEARANCE OF THE METAL STRUCTURES BEHIND THE GLASS. The tube he was handling by a glance of it.....its a chinese manufactured tube which was a common used tube OEM as well as another common tube you'd find which would be a Sovtek 12ax7 WA....they were both very cheap 12ax7 tubes which is why they were commonly used. BUT they are not the best musically sounding 12ax7 tubes one could use in an amplifier if you want optimal performance for musicality and tone.....as that is subjective to one's ears. Amplifier manufacturer's like any other manufacturer follow the philosophy they teach in business schools......minimize/maximize theory......minimize costs and maximize profits......translated.... they use the cheapest parts and components to send their product out to the market place for sale. There are a limited number of vacuum tube factories producing vacuum tubes in the world, and there are many companies that buy from these source manufacturer's and thus rebrand the tubes they buy to their label. They may also put those tubes they relabel through a screening process and a grading process, so you have to know what you are buying when buying tubes. You want to buy matched sets for power tubes, but not whole re-tubing sets for an amplifier....as the pre-amp tubes are what determine the tonality of the amplifier circuitry. SO using a typically marketed re-tubing set as by JJ as sold by some music stores.....is not a 100% good thing to do for full on musicality and tone. You have to find the right pre-amp tubes for your ears which will often be a mix of different manufacturers pre-amp tubes and not consistently one manufacturer's product.
@@mikecamps7226 thanks I guess my best bet is some sort of bias probe for my power tubes and my ears for the preamp tubes I thought that guy was BS hooking up to some resistor and getting max bias I didn’t see it coming off pin8 to ground
Hmmmm,
I don't watch amp repair videos to listen to royalty-free loops. With the loop SO BLEEDING LOUD compared to the spoken narration, turning it down to non-abusive levels means that the voice can't be heard.
Had to stop trying to watch this one. With SO many amp repair channels by skilled and interesting techs, the obvious choice is to move on to one of those. Sorry.
Yes. Excellent advice. All videos moving forward will be without the annoying background music and, I will raise the speaking volume 200%. Thank you for reaching out to me in this matter.
@@FeeserAmplification
I will look (listen) forward to your future videos.
Skilled people who want to share their insights and knowledge are a commodity not to be taken for granted.