How to Fix Marshall Valvestate No Sound Problem 

It’s awesome that people like you Sir are still around, helping people enjoy their old amps. They are certainly worth it. Have a great day

Good video tutorial. I have fixed loads of Valvestate amps myself. Most of the issues are caused by broken solder joints on the jack sockets, oxidised contacts on the send/return loop, oxidation/dirt on the first gain control and of course that first TL072 chip which is the fault you found here. The chip is knocked-out by static from guitar leads and stray voltages from guitar pedals. It gets noisier as time goes by and eventually dies. Later Valvestate amps have better protection circuitry on the input jack. It doesn't help the way the first gain stage is wired-up on some of these amps. Instead of using a fixed resistor in the feedback loop on that opamp, Marshall have worked the variable resistor in there instead. Dirty contacts on that control sound terrible!

You should make instructional videos for everything. Clear, concise and doesn't get you confused with needless conversation. Excellent video!

Wow! You’re certainly thorough! My 65r valvestate had the same issue so I gave it away. Loved that amp as well!

29:01 The ubiquitous cup of tea. Fuel for every mechanic, techie and engineer in the UK. Bravo sir!

i love the way you did this. Doing it live. It's a ""who dun it" for people like me who love this sort of thing. Fascinating. Thank you.

I really appreciate your videos. They are both informative for specific problems, but also show an effective approach to problem-solving. I have learned a lot of practical techniques from you in a short time indicating to me at least, the effectiveness of your videos. Thanks very much!

Excellent work Stew. Many thanks for posting. Took me back forty-odd years and my training in fault-finding when an apprentice electrician. We actually trained on valve amps etc. Sadly I never stuck at it. If only I knew then what I know now.

Nice to have the thinking behind the troubleshooting process explained clearly. I have a small Marshall amp where the sound suddenly cuts out when in use and it's given me ideas of where to look for problems that are within my ability.

Fine job and I appreciate your diagnostic methods. As an auto technician now retired I was taught the same way. Positive test everything you can to make a determination.

Stuart, I enjoy it when you do the live thing when troubleshooting. The talking through the process is valuable to someone with my level of knowledge. Learning how to think is a wonderful activity and is exacty why i began this journey. I truly appreciate your ability to make it understandable. Mike

Nice fix Stuart, like the walk thru and your clever tricks and methods to find the problems..Great learning experience for us newbies..Thanks again for sharing..Ed..uk..😀

Lovely repair. I bought a vs100 for 100€ which the seller said it had a strange noise. The thing was oscilating because of cracked solder joints. Got that fixed. It still has a bit of a hum, mostly when its heating up the valve. Thanks for the video.

Nice troubleshooting, Stu. Very nice.

Very nice. I've bought many amps for cheap that were heading for the bin. In 95% of cases all the amps needed was a good jack cleaning (sometimes the finger switches are bent) and one or more cold solder joints. On the one hand I hate that people have such a disposable mindset that they would throw away an amp instead of fixing it, but on the other hand, if they fixed them then I wouldn't get perfectly good amps for pennies on the dollar. I just bought today this same amp, the VS580 for $35. Nothing wrong with it except a broken fuse holder.

Thanks for the heads-up on the Duratool de-soldering station Stuart, just bought one for my hobby workshop.

Most techs won't even take in a solid state amp. The repair cost exceeds it's value so good on you for doing it for a nominal fee. I'd pay your price for the simple fact that if I like the amp I'll pay to keep it alive.

Great job Stuart. I enjoyed it very much 👍👍

Don't know how I missed this one. I have worked on this same breed several times, and every time so far, the same culprit. I think we may need to stock up on ic sockets, or design a conversion to a ecc/12ax7 :) Keep them coming always Stu. And always enjoy going on the ride with you. If you are interested in old rotten cars being resurrected, hope you will pop into my new series of videos. I could use as many subscribers as I can get to get off the ground.

I have the Marshall stereo valvestate vs265 and it has the chorus 3-channel stereo, clean, overdrive one, overdrive 2 & overdrive EQ as far as any name goes with this it just says valve state Vs265. Anyway I have saved this video and I'm not really an electric technician but I love electronics, I can troubleshoot a little bit but I'm going to fix my amp, its been my favorite amp, & thanks to you I'm going to have it back up and running again thank you so very much, a very instructional video, I loved it & watching you do it as well.

Excellent video. Those amps are fantastic. I've a loan of a AVT 150. it is a monster.

Wow! That was quite interesting! Many thanks for sharing!

Super troubleshooting job. Great video my friend.

Years ago, I had a 100w valvestate head and a 4x12 cab which served me for a 1000 gigs and never let me down. The sound was superb. Then I became a pro guitarist and thought I needed expensive gear so I bought many various amps including Mesa, soldano etc but they never could produce that sound I got from a £300 rig! I really miss that amp!

This was awesome 👍🏼 great job!

Thanks Stuart. You've inspired me to fix my old Valvestate 8040 which has scratchy pots. The bass control doesn't work either - Yet!

Thoroughly enjoyed that, thank you 😊.

Excellent! Thank you for filming. That particular op amp seems to be famous for giving up the ghost on these Valvestates.

Hi Stuart, I enjoyed this fix. It might be worth keeping a small journal with model names and what the issue was. Easy to flick through when you receive more work. I'm aware yes it is already on film, just thought it might be easier to get the data you need.

A good informative video, well done and thankyou 😁👍

Hi Michael Two possibles. If the amp has FX send/return jacks or a headphone jack (I can't remember if it does) then squirt some switch cleaner in and work a jack plug in and out a few times to clean the contacts. If it doesn't have those it could be a power resistor on the main board, these come unsoldered with the heat. Maybe one for an amp tech in that case? If you're comfortable taing the chassis out then power it up and try tapping, wiggling some of the larger components to see if the sound comes and goes. Good luck. Stuart

That was fun Stuart. Thank you.

Hi Stuart, I'll be receiving next week a Marshall Valvestate 8080 with a similar symptom, the clean channel is not supposed to work but the overdrive channel allegedly works. I hope it is something similar to the issue you addressed here. I will be using the same "signal injecting" technique (thanks for that), also I found very helpful the explanation about the operational amplifiers, thanks again and greetings from Colombia.

Very nice video, nicely explained, all in place, cool :) Thank you

excellent dig mate!

Lovely channel! 👍👍

Great job Stu! It's always interesting watching the detective work of electronics fault finding. I just acquired a free but broken 10W 8010 amp which is clockwork in comparison to its big brother Valvestate. When I looked at the circuit diagram I laughed, wondering where all the components had gone. 😂 Edit: I'm a betting man too and my guess without even plugging it in is the MC1458 chip on the input stage. The giveaway is the 3.5mm audio adapter left in the back of the cab, suggesting that it has been thrashed to within an inch of its life. Hopefully it's not the power amp chip... which is RIVETTED in place. Seriously. Why??

Great video. Gives me hope of saving a bricked Hiwatt amp.....

Hi Mark. One way to rest for loose connection or dry joint is to play some music through it (e.g. from your phone) then give the amp a couple of sharp bangs on the top with your fist. If you hear loud crack when you do this, or sound comes/goes it's defo a dry joint etc. Other than that, an amp tech should be able to sort it for you.

Hello Stuart, do you know where to get a transformer for the Valvestate amps? I have an 8040 from the USA which has the 120v volt PT. It seems there are no other taps on the transformer to use for 230v. Any ideas? Thank you for an interesting video.

Hi MrPink. Have a look at the answer blow I gave to Michael. Is it possible your FX send/return jacks (if tyhe amp has them) need a clean?

Great job stuart. Like your channel just found it and subbed. Quick question? I have a marshall valvestate 40v and was giving a super super loud hum and after diagnosing i found the problem with the ic1 chip tl072 replaces and was fine. Now after about a week of playing it it developed a different problem. After playing gor oh sometime 20 minutes to 45 minutes it starts cutting out and gets worse till i have to shut it off and wait for it to cool down to be ok again. Any ideas for me?? Thanks so much and again like the channel and I hope to see more amp repairs as i have so many vintage classic amps and newer ones as well but some vintage need some restoring and some just maintain clean and freshen up. I believe your never done learning and will click on notifications.Thanks and wish you well. Sincerely, michael

DUDE! WTF! YOU'RE AMAZING!

Good job! I like that signal bypass thingy you used to help you diagnose the problem. Would using a surge protector help the operational amplifiers to last longer?

Nice video, Stuart. I’m forced to try this for myself, but have no knowledge of this kind of thing. Mostly I’m abit worried about getting electricuted. Any tips on what to stay away from? Greetings from Denmark

Great job!

Wouldn’t it have been possible to place a chip socket in there so that if there’s a next time you/us won’t have to do so much disassembly and soldering work replacing the chip should it go faulty again ? If so I’m wondering why the OM didn’t do that at the outset. Any ideas why it failed ? I had someone point out that here are different shapes of Jacks plugs and the jack sockets. Jack plugs that’s come on some leads are slightly different in shape where they mate up with the socket spring and that at the mutual point of contact between the two aren’t making a completely effective contact and as they can not make contact properly after a little use, they stop working after a little wear, it’s hard to spot unless you know to look out for it and unlucky to come across it and don’t look hard at them. Nice viewing, an educational, practical and worthwhile and clearly presented video, thanks very much. It’s great of you to open it up for us and guide us around. Nice tips about the lead labelling for the reverb unit and the signal through a capacitor used as a probe too. I’n guessing a transistor radio or tuner with an output could be used as a sound source for the probe . Any recommendations for an alternative valve, TL072 chip swap, or any other mods ? Maybe a cheap attenuater device for it ? I’ve got an 8080 one that had a nasty bit of noise on turning on mine, but it went away after I’d jiggled about a bit with my lead and knobs. It is Very loud amp for my flat, and I don’t know why the old lady downstairs has to watch so much day time tv, especially there’s so may other things to do. I thought they had signing and sub-titles so why’s she banging on her ceiling with a broom handle, just because she can’ t hear it because of my guitar.

Hello. I have the same model at home. I have some problems with it. The two speakers work separately if put the jackstick in from the back. I cant make the other ports work(i have only tried with jacstick from my phone, not a guitar) and if i turn the volume up and down it makes a lot of loud noices. To me it sounds like a loose connection, but i would like to get an other opinion and ofcourse know if it's worth the time and money it will take to fix it. I really hope you will answer. Regards Mark

Looks like there would be be a way too modify the chassis for future service,, too access the circuit board.. Great video content.

Great Video. Thanks! I´m trying to fix an 80s Fender MIJ Stage Lead II amp. I changed a pot to sort out the reverb, Now there´s a loud POP through speaker when i turn amp on or off - even with master volume turned down. Maybe i disturbed a ground/earth connection when i removed the mother board?? I usually consult Uncle Doug. but he is more a fan of Valves & Horsepower. Hard to find repair videos of Tranny amps! 😁THANKS

Hi Stuart- fantastic video! Thanks! So do you know where to find a COMPLETE manual online for this series? I have an 8280 and it has 4 speaker outputs. The manuals I find online don't have the rear panel illustration so the text references are hard to figure out for that section. The writing on the amp below the output jacks says 100W/4 ohms per channel 80W/ 8 ohms per channel So does that mean its serving up 80 watts with all 4 jacks in use?? and 100 watts with only 2 in use? Does it matter if you use the inside and outside jacks in various combinations or do you have to use inside R and inside L or outside R outside L only for instance? Thanks again!

I bought a vox vt30 for £30 all it needed was a new valve and a volume pot amazing sounding amp for not much money :)

That was fun to watch and informative. I have a VS100 I got in 1994 that's giving me issues. A few years ago the valve was blown but now it's intermittently working. I did notice that if I whack the top of the amp it'll come alive for a moment and then go out. I don't think it's a bad op-amp like yours was. From what you said, it sounds like dry joints might be the culprit? I'm a hobbyist with electronics so I am familiar with soldering but I really wanted to avoid removing the board. I might have a go at it. These amps are cheap now but it's got a lot of sentimental value for me plus I think it sounds nice. :)

I'd be tempted to socket that TL072, as long as I was in there.

I gave my dad a Boss Katana amp that he's been very happy with, and he gave me his very poorly Valvestate S80, because I've always quite loved the Valvestate clean tones. It sounds very different than any of the famous classic tube amps, yet I don't think it sounds sterile at all. I hope some of this will help me getting it in shape. The main problem though, is that the beautiful spring reverb jumps in and out whether it's turned on or off. Any suspicion what it might be?

Great video thanks

Brilliant! Great to watch on live what is going through your mind and how you make different hypotheses. I have one question: that "tone generator" you use to test the power stage first and every component (with the capacitor) afterwards, is a normal signal generator, am I right? So what voltage level do you set up on the generator? Wouldn't it be risky to plug in a signal with a considerably higher voltage level than what a guitar does? Thank you! And sorry for my english level

thanks for this video. I had a question for you. I have a Rocktek RK20R. The amp is very loud but the sound is muddy and too saturated. The tones are not clear and can't hear the characteristic sounds of my strat and tele. I plugged it into a stereo and the speaker is perfectly clear in playing radio music. All the cords are good. I think the issue is the sound processing in the pre amp part. Can circuit problems make the sound muddy and overstaturated? or is it just a poor amp. I wanted to see if it's worth going through all the circuit board looking for problems. I've played with all the setting for several hours to no avail. Thanks sir

Nice one Young Stuart! 5 *****

Thanks from spainn

Hi Stuart. I've raelly enjoyed your videos on fixing up old Marshall Valvestate amps. I just bought an old Marshall Valvestate 8100 head that is in dire need of some maintenance (I only payed the equivalent of 50£!). I'm fairly sure it's just the pots that need a good cleaning. I am however in doubt if there are any high voltage filter caps in the amp that I have to look out for? Or are these only used in "true" valve amps with valves in the power section? I'm still very much a novice when it comes to electric circuits and the likes, but I'd love to learn how to maintain, repair, and perhaps even mod guitar amps when my knowledge and skills allow.

That signal injection trick is genious. What capacitor should be used there?

All the valvestate line of amps have issues with bad soldering and poor design schematics. I had to have a circuit board repaired and he said it was not built well...getting hot, and something to do with the tubes I can't remember but my tech said that was also an issue that was common, might be the one you mentioned? It's all good now. New tubes and some soldering fixed. I had power and sound, but on the acoustic simulator channel(that's channel 1 on these) if I wanted to turn the volume up it would hum and it was a wavy kind of hum that would go up and down and loud and quiet and it was really annoying. I really wanted to use that channel. I have the Big one 2x75 valvestate 2000. It's a heavy beast, but not bad for a 2x12 considering. Problem is it doesn't sound very good turned up to the second slash mark on the master volume. I don't think they put very good speakers in them maybe? Just kinda farts out. I added a big rack mount EQ to the efx loop and that tamed it a bit and helped with the fizz, which was weird because I added more highs. Man it screams. I don't normally turn it up to that second dash mark on the master because that's ear bleedingly loud. Halfway to the first dash mark is plenty loud for practice and up to that mark is great for jamming with a band. I've been told it's too loud a couple times...eh what can you do? lol

Cool video

Beautiful work sir , I still have my Marshall Valvestate VS100 laying around , abandoned it years ago after it wasn't giving any guitar output , all it does when you turn it on is crackle & pop , loud as hell , the Power Module board is 100% fine , I'm pretty sure its the preAmp , but I had "amp technicians" reject it , and I bet you would be able to easily fix it

Hi Stuart, I have Marshall AS80R which gives crackling noises when powered on. I have looked a the circuit boards and I found no bad solders or burnt components. What is common problem with this amps? Mine is about 15 years old and it was working until it was stored away a couple of years. Appreciate your advice at what I should to fix the problem.

Thank you Sir, I've learned a few things and subscribed to your channel

Very nice logic reduction ... reducing or cancelling everything... to the opamp. In real time no less. I like your makes shift signal probe. What was the value of the orange cap. ? Regardless. Very nice job... A magic trick right in front of the audience... for everyone to see. HAH !

That was cool injecting the signal through a capacitor like that.....was it a .022u cap or can it be basically any size as long as it can pass the whole signal?

Hi Stuart, I hope you're doing great, Do you have an advice about an amp I have, this is a Marshall Valvestate AVT20, the thing is that it doesnt bring any sound, I thought that the bulb was the problem but I just got a new one but is still mute, I noticed that the clean\od button light doesn't respond when I turn on the amp, maybe there is the problem, do you know what might be the problem with this amp? Thank You in avance :)

Hi Stuart, I have a fender 15g frontman and the volume level is at a level 2/3 no matter how high or low you turn the knob. Whether you raise the volume knob to 10 or to 0 it stays at the same volume which I would say is about a 2/3.. the drive volume works but not the normal volume. What do you suggest?

Big surprise. I watched this video last night. I just got an 8280 that I tested today. EXACTLY the same issue. No sound what so ever plugging it in normally. Send/return worked fine. So next step for me, is to swap that chip.

Hi Stuart, an update on my 40 watt Hiwatt amp. Used your technique of poking board with a stick, looked for signal using tone generator app on my phone

Hi Stuart. I was just wondering if you offer any valve testing services? I have a box of old Soviet EL84s and I simply want to know which ones are ok and which ones to bin. Thanks!

My MG50DFX clean channel has very low volume, the channel switch is temperamental, do you know where to look at please? thanks in advance.

Hi Stuart, I have a Marshall DSL20CR ( a year old), and I flipped the stand-by switch from 20 to 10 amp. while it was in play mode.Now I only get very faint sound when I try to play it. I've ordered new tubes.Do you think the tubes are the problem? Thank You.

Any Opamp circuit, I check the DC on power pins AND inputs/outputs straight away. Almost everyone I've seen fail has the rail voltage at the ins/outs

Please, how much watts each speaker have? I got that they are phisically same as g12t-75, but this is stock version...without numbers :)..only "g12t"....so are they 2x75 watt or?? THX

I have a VS100 that makes a loud popping noise when I switch it on or switch channels, but doesn't play anything it should. Speaker works. Somebody said it is likely the tube. Any other ideas?

did the amp sound better after too? any tonal changes you've noticed?

Would you have an idea why the effects might have stopped working on my amp ? It is a Marshall AVT150X. It has multi effects - delay, chorus, flanger etc that were all going fine until yesterday. The amp itself seems ok , problem seems to be from the presence right through the effects mix, selector etc.

Hi Stuart, awesome work, glad you got it sorted. I have a similar problem with my VS100, turn it on, almost no sound, you hear the guitar pretty low almost inaudible. Do you have any ideas what could it be? Thank you

I wonder why I don't have that "reverb spring" in the back. I have a reverb knobs on the front. Same model but as he said different variations.

great!!

I have a question if you could please help me out on this. I have a 1972 U-400G Univox 35 watt guitar amplifier that I believe has the same problem but I cannot find a replacement chip. The op amp chip number is 8022A and it seems to be not in production anymore. Do you know of a replacement number I could try? Thank you, Charlie

I find that fitting an op-amp socket helps for the future repairs etc. And they are cheap.

hi Stuart please could you give me some direction on checking my marshall mg 30 fx,everything lights up but no sound not even a hum -thank you

I often wonder, when an amp has two channels, and is rated at 100 RMS (I have a 2 channel 100 RMS Hartke GT 100), is it two discrete channels all the way through to the power stage, which would mean it’s really only 50 RMS when you plug into one or the other channel, or is it two preamps fed into one 100 RMS power amp? Thinking back to a Sears Sivertone two channel tube amp I once had (unfortunately lost track of), that used four 6L6 power tubes. Rated at 100 watts (not sure if that’s RMS), driving six 10 inch Jensen speakers. Too late to look now, but of course I could have answered the question by looking to see if there were two audio output transformers. I see two channels on the amp you just gave a second lease on life. Is that two preamps, fed into one power amp? Curious what is the RMS if you happen to know it as well. Thanks!

I have a Valvestate 8040 that I bought new in 1992. It’s had a few minor repairs including bypassing the Pre-amp jack around 10 years ago which fixed a faulty jack socket (I didn’t use this facility anyway so was easier to delete it). I also replaced some of the scratchy pots (although cleaning them would have been easier!) My amp was unused for 4 weeks whilst I was holiday and on return, there is almost no sound. The spring reverb works (you can hear when tapping on the tank) and when I plug into Power-amp IN, I get sound. I replaced the 12AX7 with a new one (I assume the new one works) and no change. I’ve checked for dry solder joints and have refreshed a few joints. There is some sound on full volume on the clean and boost channels but not close to normal. There is also a noticeable hum at high volumes. Any advice? I suspect an Op amp chip but I don’t have equipment to check them.

Watching this because I have an 8080 valvestate and the normal channel volume is low and reverb does not work. Boost channel is fine. Tested reverb leads and tank, both test out ok.

Stuart, I just picked up a Valvestate 8040 40 watt with 1 x 12” Celestion. The symptoms were the same as the Valvestate in your video, power up but no sound. The previous owner said he took it to Guitar Center here in Texas, and they told him there was a problem with the board, so he bought a new amp from them. I just got the amp home, plugged it in and moved the amp, and what did I hear - loud reverb spring noise. There is no sound when I plug in the guitar into input. But when I plug the signal out from my Tascam portable guitar trainer into the preamp in, I get a strong signal, when I plug it into the guitar input I get a lower volume signal, and the sound gets louder when I increase the gain, so it’s not the jack. Do you think it could be the valve? Or would it be an op amp, What are your thoughts ?

Master laney hcm120 hardcore max no sound haw to repay

Hey Stuart, I came across your awesome video because I'm trying to fix the amp (Marshall Valvestate 40V Model 8040) my brother gave me. I made a reddit Post with a video showing what I think is wrong with this amp. Sadly my comment gets deleted when I write out the link. Is there a way I can send you the link? Here is the text I wrote: Hey, my brother gave me his old amp, since I recently started playing guitar. He said I can try to fix it and that the gain and volume knobs are the problem. But I guess there are more problems, since the crackling sound and this periodically appearing knocking sound are always present. In the video you can hear what happens when I'm turning the volume knob of the boost channel. The volume knob doesn't work smooth at all and sometimes there is this low cut happening. The other knobs do something but this is my first amp so I don't really know what sounds to expect. Moreover, sometimes there is this reverb coming through without it being turned on. I am an electrical engineering student and I want to learn a thing or two, since my studies are mostly theoretical. Best Regards Finn

Hi Stuart. I am very interested in the signal generator testing method. I could also give in an audio signal out of my phone (played song, signal generator app) right? Also: what are the specs for the capacitor you´re using if you don´t mind me asking?

I have the 8280 bi chorus and only can use the left output speaker but the right output is death and i dont know how to fix it 😓 both speakers are ok but i feel bad for not find a way to fix without help from a tech.

I have a single speaker AVT 50 w valvestate. Same issue as the one in this video, I have a small dc voltage on the amp chassis when switched on. Any thoughts? Also wher do you buy the replacement op amps please?

It's always a difficult choice to repair these amps. I have an 80 watt Valvestate which cuts in an out and the cost to repair it would outweigh its value but then you have an emotional connection with these old things.

I'm not familiar with those Integrated power amplifier SIPs. Does anyone know enough about them ? Who makes this type of IC: They certainly take some massive heat sinks, don't they !

😊👍

Hi William. Well this one isn't easy to fix if you have NO knowledge of electronics, plus those darn 8 pin chips are a little tricky to get out. This is probably one for an experienced amp tech. I you do have a go yourself unplug the amp leave it for an hour or so before working on it.