I had one of these, I took it to Marshall for an intermittent fault, they did a repair service on a Friday, so I booked a factory tour as well! They couldn't trace the fault ( it cut out randomly) and they had it on the bench for a week, so what they did was order a complete board with my name on it! And run it through the factory (they work the lean system) so I got a brand new preamp apart from the case ! And as they couldn't locate the fault on the day they only charged...... wait for it.....£40 labour!!! What incredible service, had a brilliant time , got my amp fixed and a factory tour!! I finally got peed off lugging a rack system about and got one of the little jcm 2000 tsl 601 combos, good little amp nice with a 4x12 up graded to a tsl 100h now that was a good amp But it eventually succumbed to the dreaded PCB malady after its 14th birthday, have fitted a new board myself with the help of Mr McKenzie's excellent video it's now as good as new, I upgraded the terrible footswitch design with Bigger coloured LEDs to match the channels and a seven pin din socket, six years of gigging very reliable, up graded to a JVM 100H But never spent the time with it A change of life came and I now use a Boss katana 100, it's perfectly adequate for the band I'm in now, and cost less than a good set of valves,
You are indeed a master of the art. In 35 years of working on electronic and mechanical devices I have never once picked the correct size tool by eye the first time ;)
Maybe I just got lucky! Have you seen Back To The Future? There's a great scene where Doc goes back and talks to his past self who is up a ladder adjusting something. 'Past' Doc asks 'Future' Doc to hand him a 3/8th wrench and future Doc says something like "3/8ths?? Don't you mean 3/4?" Hilarious and SO true of engineers!
I have a JMP-1 and one of the main reasons you lose the locknut on the 1/4 inch jacks is precisely because the thread pitch is so coarse. The shallow pitch facilitates the nut working loose. Use locktite blue to stop it from occurring.
The bad valve had very mismatched triodes I noticed when you retested it a 2 and a 9 I think . The Orange tester fails valves with more than a 5 digit mismatch I believe because it is a severely unbalanced tube . I use socket savers in my Orange tester , and when they began to wear out it caused a few erroneous readings . So I simply replaced the worn out socket saver . Good for another few thousand insertions then . Cheers for the great videos .
Hi Yes I noticed that when editing the video! Missed it at the time. I don;t test a HUGE number of valves so didn't bother with the socket saver. I might get one though thanks.
I have 2 JMP-1 preamps, the first one, if I put my Midiverb IV in the FX loop, every so often the delay effects will just cut out. I have to restart the JMP-1 to get the delays back. both of mine are in dire need of a service, as I use them on a daily basis. Great to connect with a JMP-1 repair video,
I had the same problem. I bought one on Reverb, and it was missing the nut and bezels for the input and headphone in. I got black replacements from Plasma music in England. Took a couple weeks to arrive here in the US, but fit perfectly.
I'm afraid I have to totally disagree with you on this one Stuart... I repair lots of these and they're fairly easy to get apart and work on. Once it's out of the box you can run them to fault find with no issues. Totally serviceable and 'chucking it in the bin' because people are too lazy to work on them is a terrible suggestion ! Standard faults include... Input socket (which is a mirror image of a 'normal' socket), the pot gets noisy and will require replacement and the mains transformer tends to go O/C on the HT winding. Marshall still supply the correct socket nuts and surrounds too, in fact they supply just about anything for any amp, very unusual these days to be able to get parts for a 50+ year old amp from the company that produced it! As for the Orange Divo, I wholly agree, you may as well just toss a dice!
Hi I agree with you, maybe I wasn;t clear on the video but I thought I said something like "Unless it's a simple fault like a jack, a regulator, and so on." If that microprocessor side oes down you're all out of luck, I reckon!
@@stuartukguitarampguy5830 All parts are available for the JMP-1 from Marshall. Actually they are very reliable and the only common problems I've noted above. The only tricky fault I had that took some head scratching was the bass control not working. That was a S/C cap accross the IC that controls it. They're still massively popular and still fetch good money. As I've said, I do loads of these still.
@@DrWatts-bi1jv I have to agree with you here. I did actually have a Microprocessor fault. Before I disappeared off to try and find one, a call to Marshall and they could provide one no problem. The sad part is I wasn't an authorised tech at the time and although I knew the fault, I had to take it to them. But yep, done and dusted in 30 minutes. I just told the technician what I found, came out and agreed the processor had indeed failed. I didn't do the factory tour, but was happy that they only charged me £20 or so and I was on my way home within the hour.
You don't need to remove the gold front panel to remove the lid. Just remove three screws at the back, one on top, then the six holding the rack ear reinforcers on and the lid will come off.
I have a pedal with a tube preamp, and I wouldn't be surprised if the tube were completely dead and the user didn't notice. Switching channels, you never really know if you are on tube preamp or solid state. You might get one used and have some channels that just scream or show show some other issue and simply never use it. And the heart of the problem might be a microphonic or bad tube and you just never address it. Tubes can show their ugly faces in alot of ways, be fine in one position, but move it to pushing your reverb or phase invertor and be a complete failure. This guy might get back his rig and find it has alot more to offer that he was ever aware of.
True. whilst editing the video I noticed that the FAIL problem was a massive imbalance in the two halves. If you look again you can see one half comes up '2' or whatever, and the other half '9' or whatever. So it was the imbalance which was causing the FAIL light.
Once again, a very intresting video! You have a self made tester voor power amps? Maybe a good item for another intresting video? Continue the good work!
Use a dremel tool to make a slit into the screw and use a flat screwdriver to get it out... So easy instead of drilling and you are not gonna damage something as fast as with a drill. Kind regards
The reason it rejected the valve was the very poor balance between the sides.. Man of no faith ...One side 2 the other side 9 ... The tester is quite good . I ave checked it against my At1000 and it was actually better !!
Hi. Yes I noticed this whilst editing the video. Missed it at the time! However, I have defo had problems with my orange tester. The problem is this: If I test a batch (say 20) of brand new preamp valves, sometimes after a few (6? 10?) it will start to fail them. It doesn;t matter how many more I try and test, they all fail,. If I then try the ones it passed earlier, it fails those too. Switch it off for a while and it starts passing them again, So not really sure what's hapening there.
@@stuartukguitarampguy5830 I had considered purchasing that same Orange tester a couple years ago but the user reviews on it dissuaded me. So, you're not alone in your problems with it.
Why on earth are you endlessly messing about with £12 preamp valve..Surely just replace and forget and at the same time exchange the memory battery ..? Spray the contacts and 90% should be good to go ?
I had one of these, I took it to Marshall for an intermittent fault, they did a repair service on a Friday, so I booked a factory tour as well! They couldn't trace the fault ( it cut out randomly) and they had it on the bench for a week, so what they did was order a complete board with my name on it! And run it through the factory (they work the lean system) so I got a brand new preamp apart from the case ! And as they couldn't locate the fault on the day they only charged...... wait for it.....£40 labour!!! What incredible service, had a brilliant time , got my amp fixed and a factory tour!! I finally got peed off lugging a rack system about and got one of the little jcm 2000 tsl 601 combos, good little amp nice with a 4x12 up graded to a tsl 100h now that was a good amp
But it eventually succumbed to the dreaded PCB malady after its 14th birthday, have fitted a new board myself with the help of Mr McKenzie's excellent video it's now as good as new, I upgraded the terrible footswitch design with
Bigger coloured LEDs to match the channels and a seven pin din socket, six years of gigging very reliable, up graded to a JVM 100H
But never spent the time with it
A change of life came and I now use a Boss katana 100, it's perfectly adequate for the band I'm in now, and cost less than a good set of valves,
Wow sounds like you got a really good deal there!
You are indeed a master of the art. In 35 years of working on electronic and mechanical devices I have never once picked the correct size tool by eye the first time ;)
Maybe I just got lucky! Have you seen Back To The Future? There's a great scene where Doc goes back and talks to his past self who is up a ladder adjusting something. 'Past' Doc asks 'Future' Doc to hand him a 3/8th wrench and future Doc says something like "3/8ths?? Don't you mean 3/4?" Hilarious and SO true of engineers!
Glad to see you're keeping it real. Thanks for the video on the jmp1
I have a JMP-1 and one of the main reasons you lose the locknut on the 1/4 inch jacks is precisely because the thread pitch is so coarse. The shallow pitch facilitates the nut working loose. Use locktite blue to stop it from occurring.
Ah that makes sense. Thanks so much.
The bad valve had very mismatched triodes I noticed when you retested it a 2 and a 9 I think . The Orange tester fails valves with more than a 5 digit mismatch I believe because it is a severely unbalanced tube .
I use socket savers in my Orange tester , and when they began to wear out it caused a few erroneous readings . So I simply replaced the worn out socket saver . Good for another few thousand insertions then .
Cheers for the great videos .
Hi Yes I noticed that when editing the video! Missed it at the time. I don;t test a HUGE number of valves so didn't bother with the socket saver. I might get one though thanks.
Another trick with those stripped screws is to use a dremel and cut a small slot across the top, then use a flat head screw driver to remove it.
Great idea thanks Jim.
Great videos. Just found you, i can see there is allot i need to see, ✊🏻👍🏻
Thanks Thomas I hope you enjoy some others.
I have 2 JMP-1 preamps, the first one, if I put my Midiverb IV in the FX loop, every so often the delay effects will just cut out. I have to restart the JMP-1 to get the delays back. both of mine are in dire need of a service, as I use them on a daily basis. Great to connect with a JMP-1 repair video,
Hi Steve that sounds like a nasty one. These are hard/impossible to repair due to the microprocessors etc in them. Good luck.
@@stuartukguitarampguy5830 my guess is it's the effects loop jack socket... thanks for the reply
Good job! I love your videos.
Thanks Zack!
Splendid . On kung fu .. Bruce Lee was the catalyst for the craze .. I queued an hr to see Enter the dragon 🐉 .Happy days 😃
I had the same problem. I bought one on Reverb, and it was missing the nut and bezels for the input and headphone in. I got black replacements from Plasma music in England. Took a couple weeks to arrive here in the US, but fit perfectly.
Great, yes those inserts are not easy to get!
Why isnt that unit reparable ? The ADA MP-1 (JMP-1 "brother") had several guys reparing it.
I'm afraid I have to totally disagree with you on this one Stuart...
I repair lots of these and they're fairly easy to get apart and work on. Once it's out of the box you can run them to fault find with no issues.
Totally serviceable and 'chucking it in the bin' because people are too lazy to work on them is a terrible suggestion !
Standard faults include... Input socket (which is a mirror image of a 'normal' socket), the pot gets noisy and will require replacement and the mains transformer tends to go O/C on the HT winding.
Marshall still supply the correct socket nuts and surrounds too, in fact they supply just about anything for any amp, very unusual these days to be able to get parts for a 50+ year old amp from the company that produced it!
As for the Orange Divo, I wholly agree, you may as well just toss a dice!
Hi I agree with you, maybe I wasn;t clear on the video but I thought I said something like "Unless it's a simple fault like a jack, a regulator, and so on." If that microprocessor side oes down you're all out of luck, I reckon!
@@stuartukguitarampguy5830 All parts are available for the JMP-1 from Marshall.
Actually they are very reliable and the only common problems I've noted above.
The only tricky fault I had that took some head scratching was the bass control not working.
That was a S/C cap accross the IC that controls it.
They're still massively popular and still fetch good money.
As I've said, I do loads of these still.
@@DrWatts-bi1jv I have to agree with you here. I did actually have a Microprocessor fault. Before I disappeared off to try and find one, a call to Marshall and they could provide one no problem. The sad part is I wasn't an authorised tech at the time and although I knew the fault, I had to take it to them. But yep, done and dusted in 30 minutes. I just told the technician what I found, came out and agreed the processor had indeed failed. I didn't do the factory tour, but was happy that they only charged me £20 or so and I was on my way home within the hour.
You don't need to remove the gold front panel to remove the lid. Just remove three screws at the back, one on top, then the six holding the rack ear reinforcers on and the lid will come off.
Thanks I think I eventually worked that out!
I have a pedal with a tube preamp, and I wouldn't be surprised if the tube were completely dead and the user didn't notice. Switching channels, you never really know if you are on tube preamp or solid state. You might get one used and have some channels that just scream or show show some other issue and simply never use it. And the heart of the problem might be a microphonic or bad tube and you just never address it. Tubes can show their ugly faces in alot of ways, be fine in one position, but move it to pushing your reverb or phase invertor and be a complete failure. This guy might get back his rig and find it has alot more to offer that he was ever aware of.
True. whilst editing the video I noticed that the FAIL problem was a massive imbalance in the two halves. If you look again you can see one half comes up '2' or whatever, and the other half '9' or whatever. So it was the imbalance which was causing the FAIL light.
Once again, a very intresting video! You have a self made tester voor power amps? Maybe a good item for another intresting video? Continue the good work!
Hi William. Funny you should say that, I had the same idea myself just yesterday!
Yes let's see a video about that valve tester 👍🏻
Use a dremel tool to make a slit into the screw and use a flat screwdriver to get it out... So easy instead of drilling and you are not gonna damage something as fast as with a drill.
Kind regards
Good idea. Thanks.
The reason it rejected the valve was the very poor balance between the sides.. Man of no faith ...One side 2 the other side 9 ... The tester is quite good . I ave checked it against my At1000 and it was actually better !!
Hi. Yes I noticed this whilst editing the video. Missed it at the time! However, I have defo had problems with my orange tester. The problem is this: If I test a batch (say 20) of brand new preamp valves, sometimes after a few (6? 10?) it will start to fail them. It doesn;t matter how many more I try and test, they all fail,. If I then try the ones it passed earlier, it fails those too. Switch it off for a while and it starts passing them again, So not really sure what's hapening there.
@@stuartukguitarampguy5830 I had considered purchasing that same Orange tester a couple years ago but the user reviews on it dissuaded me. So, you're not alone in your problems with it.
@@divebomb99 TBH it's better than nothing - and that's what else is on the market - nothing!
I had the single valve version. I cheated on me and went home with someone else after a gig. Sadness.
That's the JMP1 for you. Feckless and unfaithful. Didn't your mother warn you?
We call mole grips vice grips in america...lol
Why on earth are you endlessly messing about with £12 preamp valve..Surely just replace and forget and at the same time exchange the memory battery ..? Spray the contacts and 90% should be good to go ?