Stuart, excellent video. I think those handles are good for about 15kg. Anything more than that could result in failure. A good leather strap is likely the best repair. 👌
An outstanding demonstration of how to employ the process of elimination to diagnose fuse failure. Wholesome instruction, Stuart! I hope the owner of this De Ville returns to have a recap upgrade, and the power resistors modified; lifted mounting off the surface enough to allow adequate circulation of air to prevent the traces, and board from being seared to a crisp. This session was presented in a classroom setting. I am grateful for your candor in the matter. Enjoy the weekend. Cheers!
I had a Traynor YCV40 tube amp before that was also keeps blowing fuses. Also have not used for months and one day decided to give it a try but surprised when I heard a buzz and went off. My guess was the power tubes, and your video proved me right. I've already sold the amp for a cheap price coz cost of repair is high. And after that I told myself not to buy tube amps ever 😅
Hi Mark. The problem is they sound so great compared with solid state. I just repaired an old Fender Twin Reverb Solid State - they didn't sell many. It sounded like totally crap!
For those who are comfortable with high voltages and doing some checking, before putting in the new valves, I would check the Bias voltage on pin 5, then the Plate voltage on pin 3, followed by the Screen voltage on pin 4. If the voltages look correct, you can plug in the valve. Do this on both tubes.
Great stuff Stuart.. I noticed that the large ceramic dropping resistors looked very clean with no signs of scorching on the PCB. It suggests that the amp was not in heavy use but gigged at most, once a week for a few years. Great amp if you have a tame osteopath to call on !
Brilliant video Stuart..! Step by step fault finding, great info and method...you play fine by the way..😀 Thanks for sharing once again...I'm learning all the time..Ed..UK..😁
when i power an amp for the first time i always use the bulb limiter in series,and a power meter,this way you don't blow fuses and immediately know if it's drawing a reasonable amount of current
Stuart your videos are so great for everyone who wants to learn how to troubleshoot a Valve amp, I have the euro tubes bias probes I like the old ones better than the new ones.Stuart what’s your take on the JJ el34l tubes I have 2 sets left 2 out of the 8 were bad I had gotten 8 EXH el34s matched also, it’s seems to me that Marshall’s don’t do well with the newer JJs i think I’m gonna go with the EXH el34s or the Millard reissues in the future if I can get them?
I have the 4 x 10 version..... Recapped and did all the upgrades to make it gig reliable..... It is a fantastic amp but I never really gigged it because it is too heavy to lift on and off of the van without putting my back out 🤣🤣
Yes I guess I COULD have done that. I always like to have both in though as otherwise the amp is very unbalanced. Probably would have been ok though. Interestingly I've just tested BOTH output tubes and they are both faulty! Odd.
@@stuartukguitarampguy5830 I was wondering about that. I saw a flash in one of the bad tubes when you powered the amp on. Interesting to know both were bad. You always want to replace tubes in matched pairs or matched quartets anyway. Never a good idea to replace just one power tube. They will not be balanced. Only 1 bias adjustment for the pair.
@@TheCyberMantis I saw that too and upon slowing the video replay down it clearly was the right tube. Video cameras can come in very handy when trying to trouble shoot something that happens faster than the human eye can catch.
I too thought that was baffling - maybe Stuart forgot to do the other or he did it and left it out of the video to save time. It should heve been mentioned though...
@@brettwalmsley3434 That is why you replace both tubes with a matched pair. The bias adjustment is for both tubes. So if you set one, the other will also be set the same. No need to check each one separately. Sometimes if you have 4 power tubes, you can have 2 bias adjusters. 1 for each pair. In that case, you have to check both pairs.
To me, I've seen way too much "crap quality" coming from Fender in the last 2-3 decades. It's like you have to go thru the Custom shop to get what I consider "quality". This just shows me the " Profit at all cost of quality sacrifice" way of thinking.
Hi Rich, To be fair I don't think it's really insane profit grabbing. It's more customer driven, They don't want to pay £3,000 for an amp, they want to pay £700. So.... Having said that I do see an annoying number of really poor design decisions in amps (every make). It's like they have younger designers who didn't learn how to avoid the obvious silly mistakes from an older crew.
@@stuartukguitarampguy5830 Yes, I agree. I assume you know about Fender's IPO and NASDAQ, Investors! Investors that have to be "pleased". That's a story that is as individual as a company it's self. Be it what it may, we see the same results. Good chatting with you, sir.
Can't get enough of your videos Stuart. Who needs Netflix !
Thanks Robert!
Stuart, excellent video. I think those handles are good for about 15kg. Anything more than that could result in failure. A good leather strap is likely the best repair. 👌
An outstanding demonstration of how to employ the process of elimination to diagnose fuse failure. Wholesome instruction, Stuart! I hope the owner of this De Ville returns to have a recap upgrade, and the power resistors modified; lifted mounting off the surface enough to allow adequate circulation of air to prevent the traces, and board from being seared to a crisp. This session was presented in a classroom setting. I am grateful for your candor in the matter. Enjoy the weekend. Cheers!
Thanks Alex.
Stuart, this was an easy one but generally speaking I love your videos because you are great to make complex issues simple.
Many thanks.
I had a Traynor YCV40 tube amp before that was also keeps blowing fuses. Also have not used for months and one day decided to give it a try but surprised when I heard a buzz and went off. My guess was the power tubes, and your video proved me right. I've already sold the amp for a cheap price coz cost of repair is high. And after that I told myself not to buy tube amps ever 😅
Hi Mark. The problem is they sound so great compared with solid state. I just repaired an old Fender Twin Reverb Solid State - they didn't sell many. It sounded like totally crap!
@@stuartukguitarampguy5830 totally agree ☺
Another great video, I learn more about amps every time I watch
Great that's exactly why I make them! (That and the money, girls and drugs of course...)
For those who are comfortable with high voltages and doing some checking, before putting in the new valves, I would check the Bias voltage on pin 5, then the Plate voltage on pin 3, followed by the Screen voltage on pin 4. If the voltages look correct, you can plug in the valve. Do this on both tubes.
Thanks Thomas yes that's solid advice.
Great stuff Stuart.. I noticed that the large ceramic dropping resistors looked very clean with no signs of scorching on the PCB. It suggests that the amp was not in heavy use but gigged at most, once a week for a few years. Great amp if you have a tame osteopath to call on !
It's not as dire an issue in the DeVille series in my experience. The worst affected are the Hot Rod Deluxe and Blues Deluxe series.
Brilliant video Stuart..! Step by step fault finding, great info and method...you play fine by the way..😀 Thanks for sharing once again...I'm learning all the time..Ed..UK..😁
Thanks Ed!
Simple yes, but I like the way you teach thinking 101.
Thanks Michael. I think the main focus of my channel is 'aspiring guitar amp techs'!
when i power an amp for the first time i always use the bulb limiter in series,and a power meter,this way you don't blow fuses and immediately know if it's drawing a reasonable amount of current
Excellent introduction to fault finding.
Thanks David.
Stuart your videos are so great for everyone who wants to learn how to troubleshoot a Valve amp, I have the euro tubes bias probes I like the old ones better than the new ones.Stuart what’s your take on the JJ el34l tubes I have 2 sets left 2 out of the 8 were bad I had gotten 8 EXH el34s matched also, it’s seems to me that Marshall’s don’t do well with the newer JJs i think I’m gonna go with the EXH el34s or the Millard reissues in the future if I can get them?
Hi Ricky Yes I defintely prefer the old ones. I never use JJ in Marshall 100W amps as the plate voltage is just too high. I've had a few arc over.
Stewart, thanks for the video, your a good guitar player!
Thanks Brandon, I have a very limited repertoire!
I have the 4 x 10 version..... Recapped and did all the upgrades to make it gig reliable..... It is a fantastic amp but I never really gigged it because it is too heavy to lift on and off of the van without putting my back out 🤣🤣
I was just a bit curious. Is it not possible to put in the power tubes 1 at a time? Just like you did the pre amp tubes?
Yes I guess I COULD have done that. I always like to have both in though as otherwise the amp is very unbalanced. Probably would have been ok though. Interestingly I've just tested BOTH output tubes and they are both faulty! Odd.
@@stuartukguitarampguy5830 I was wondering about that. I saw a flash in one of the bad tubes when you powered the amp on. Interesting to know both were bad. You always want to replace tubes in matched pairs or matched quartets anyway. Never a good idea to replace just one power tube. They will not be balanced. Only 1 bias adjustment for the pair.
@@TheCyberMantis I saw that too and upon slowing the video replay down it clearly was the right tube. Video cameras can come in very handy when trying to trouble shoot something that happens faster than the human eye can catch.
Here is not a single EL34 tube left anywhere, let alone matched. If you find them somewhere they have a price of gold. Cheers, Stuart. Take care.
I switched to solid-state digital modelers years ago. No problem for me. You tube guys are in trouble now.
Watford Valves.
@@biggestgerbil Thanks
Exactly how I would have approached the task. The customer should upgrade to a leather handle
Hello!
I see that biasing only one tube is necessary ?
I too thought that was baffling - maybe Stuart forgot to do the other or he did it and left it out of the video to save time. It should heve been mentioned though...
Hi Gilbert. Yes assuming you have a matched pair, only one tube needs biasing. You can always check the other one if you are concerned.
@@brettwalmsley3434 That is why you replace both tubes with a matched pair. The bias adjustment is for both tubes. So if you set one, the other will also be set the same. No need to check each one separately. Sometimes if you have 4 power tubes, you can have 2 bias adjusters. 1 for each pair. In that case, you have to check both pairs.
@@TheCyberMantis Thanks! I missed the 'matched' reference in the video and was not thinking further...
Good point!
Good man!
Since the tubes are most delicate, why not just test the tubes and be done with it?
Hi. They are not that delicate, Quite robust actually!
To me, I've seen way too much "crap quality" coming from Fender in the last 2-3 decades. It's like you have to go thru the Custom shop to get what I consider "quality". This just shows me the " Profit at all cost of quality sacrifice" way of thinking.
Hi Rich, To be fair I don't think it's really insane profit grabbing. It's more customer driven, They don't want to pay £3,000 for an amp, they want to pay £700. So.... Having said that I do see an annoying number of really poor design decisions in amps (every make). It's like they have younger designers who didn't learn how to avoid the obvious silly mistakes from an older crew.
@@stuartukguitarampguy5830 Yes, I agree. I assume you know about Fender's IPO and NASDAQ, Investors! Investors that have to be "pleased". That's a story that is as individual as a company it's self. Be it what it may, we see the same results. Good chatting with you, sir.
Love your videos but a lot jerky camera movement, makes me car sick to watch
YEs I'll try and cut that down. Thanks for the heads up.