It is amazing how many issues amps can have. It is interesting too see you work through finding the problem and fixing it. This is what is so captivating with your videos.
As for the reinstalling the "hidden" nut on the underside edge of the fan, I often epoxy glue the nut onto the fan before reinstalling. JB "Qwik" 5-minute epoxy with powdered steel in it works well for this, especially if you replace the original nut(s) and lockwasher(s) with a "Keps" nut that has a built-in star washer. I don't know if you can get JB Weld epoxy in the UK or Europe but the stuff is freaking awesome. The slow cure version is so tough that people have repaired cracks in engine blocks and automotive water pumps with it. Another option for gluing the nuts in place over the mounting holes on the fan, although not as strong, is an ultraviolet-activated instant-curing glue such as Bondic, Zap-It, Zap-fix, or Rapid Fix (I use Rapid Fix frequently).
@@stuartukguitarampguy5830 , grease the threaded shaft of the bolt lightly and put it through the hole in the fan housing, thread the nut on from the other side and tighten it down,, then put the epoxy on the outside of the nut. In 5 to 10 minutes you can unscrew the bolt and then mount the fan back into the amplifier without having to try and reach underneath the flange or edge of the fan to get those bottom 2 nuts in place on the bolts. I have used this technique many many times.
Hey Stuart, I find your videos extremely entertaining, informative, pleasantly videoed, honest and I am learning loads off your channel..I have found there is the odd unintelligent 'Cretin' probably from across the pond, professing their supposed superior knowledge on electronics and technical abilities with sadly no proof, commenting in a rather aggressive and unkind manner..I trust you probably know who they are..I would ban them from you channel if it was me...Keep up the good work ,and spread your expertise as it's refreshing to learn something new from such a great tech as yourself..Peace, and keep em' coming..Ed..uk..😁
Hi Ed thanks for your support, I really appreciate it. I know exactly who you mean.... It's a very odd thing really, someone goes to a lot of trouble to create and post a video for free to help others, and the best a small percent of people can do is leap in with sneering, superior knowledge. Thankfully it's a very small number and I've only ever had to delete one person (who angrily swore that DeOxit eats carbon tracks and simply would not accept the obvious evidence that it does not). He became quite aggressive! As for 'other' people, if the post contains knowledge that I think would be useful for other readers, I bite my tounge and I leave it in and ignore the tone of it. All the best Stuart
@@stuartukguitarampguy5830 You are right mate, and a very nice and intelligent person..Just ignore these people and ban them..Life is too short and we have so much to learn yet..Keep up the fab work, hundreds of us love your channel..Ed
When you run into mysterious bias and overheating/red-plating problems like this that you cannot duplicate, check the soldering of the pins on the bottom of the output tubes. I've seen a couple of cases where pin 5 to the grid of the tubes, which is where the bias as well as the audio signal are applied, appears to have been cold soldered at the factory. If the hollow pins do not appear to be fully filled with solder at their tips, resolder them. They appear to have been factory soldered with lead-free, and we all know how poorly that stuff works.
@@stuartukguitarampguy5830 , You misunderstood me: I meant the soldering on the pins of the tubes themselves, not the saldering of the socket contacts to the circuit board. Everybody with any sense checks the soldering to the sockets but rarely does anyone check the pins of the tubes themselves.
@@goodun2974 Hey, Hey...! I have followed your comments recently and was wondering why you haven't got a channel with uploaded videos of your work and so called self expertise on show..You gave a' kind of afraid of the wife' excuse for not doing so..! But your aggressive tones here against Stuart saying 'Everybody with any sense checks the soldering etc.etc.' eluding to incompetence to a professional UK tech from someone who appears to be 'Pussy whipped' is out of order..Rail your neck in, or be nice..! Peace.!
Interesting amp, and interesting problem. Maybe you couldn't duplicate the issue because all the smoke leaked out of the wiring and it needs a recharge. I had a 71 Triumph that did that quite often so I kept a smoke recharge kit in the boot along with the other spares.😂😁
Not sure what the intent of the dual volumes is on this amp, but a very useful feature would be able to foot-switch/MIDI switch between two different volume settings, e.g. rhythm and lead.
Mesa Boogie made a conceptually similar 100 watt per channel power amp but with *8* 6L6's crammed inside a similar size chassis 😖; Brad's Guitar Garage just repaired one. He's in Oz and pronounces it Mess-uh, which is absolutely appropriate (Mesa Boogie products are unreliable and not designed not designed to be efficiently or economically repaired). This Engl amp here has a much cleaner layout and build.
very interesting video! but im trying to read/adjust the Bias of this TPA with a multimeter but i have no idea where the test points are located on the board ? i can see the trim pots to adjust the Bias but not the test points (as you're using testing tube sockets here!) where i should put the red probe ?? does anyone can help me here ?
It is amazing how many issues amps can have. It is interesting too see you work through finding the problem and fixing it. This is what is so captivating with your videos.
Yes thanks Michael. Hardly a week goes by without my coming across a fault I've never seen before!
Well, no smoke, no fun. But a happy costumer in the end.
Hi Daniel, I'm glad you enjoyed it!
As for the reinstalling the "hidden" nut on the underside edge of the fan, I often epoxy glue the nut onto the fan before reinstalling. JB "Qwik" 5-minute epoxy with powdered steel in it works well for this, especially if you replace the original nut(s) and lockwasher(s) with a "Keps" nut that has a built-in star washer. I don't know if you can get JB Weld epoxy in the UK or Europe but the stuff is freaking awesome. The slow cure version is so tough that people have repaired cracks in engine blocks and automotive water pumps with it.
Another option for gluing the nuts in place over the mounting holes on the fan, although not as strong, is an ultraviolet-activated instant-curing glue such as Bondic, Zap-It, Zap-fix, or Rapid Fix (I use Rapid Fix frequently).
I find when I try that a small amount of epoxy often gets into the nut and that makes it hard.
@@stuartukguitarampguy5830 , grease the threaded shaft of the bolt lightly and put it through the hole in the fan housing, thread the nut on from the other side and tighten it down,, then put the epoxy on the outside of the nut. In 5 to 10 minutes you can unscrew the bolt and then mount the fan back into the amplifier without having to try and reach underneath the flange or edge of the fan to get those bottom 2 nuts in place on the bolts. I have used this technique many many times.
Ah yes, that would work. I find my way a lot quicker though.
Hey Stuart, I find your videos extremely entertaining, informative, pleasantly videoed, honest and I am learning loads off your channel..I have found there is the odd unintelligent 'Cretin' probably from across the pond, professing their supposed superior knowledge on electronics and technical abilities with sadly no proof, commenting in a rather aggressive and unkind manner..I trust you probably know who they are..I would ban them from you channel if it was me...Keep up the good work ,and spread your expertise as it's refreshing to learn something new from such a great tech as yourself..Peace, and keep em' coming..Ed..uk..😁
Hi Ed thanks for your support, I really appreciate it. I know exactly who you mean.... It's a very odd thing really, someone goes to a lot of trouble to create and post a video for free to help others, and the best a small percent of people can do is leap in with sneering, superior knowledge. Thankfully it's a very small number and I've only ever had to delete one person (who angrily swore that DeOxit eats carbon tracks and simply would not accept the obvious evidence that it does not). He became quite aggressive! As for 'other' people, if the post contains knowledge that I think would be useful for other readers, I bite my tounge and I leave it in and ignore the tone of it. All the best Stuart
@@stuartukguitarampguy5830 You are right mate, and a very nice and intelligent person..Just ignore these people and ban them..Life is too short and we have so much to learn yet..Keep up the fab work, hundreds of us love your channel..Ed
Speaking of odd fuse sizes, my 1976 Fender Super Twin Reverb calls for a 6 1/4 watt fuse. Six 6L6's producing 180 Watts RMS.
Hi Michael do you mean 6 and a quarter amps?
@@stuartukguitarampguy5830 Yes, Stuart. Amps not watts. I was thinking ahead to the power output of the amp when I typed that.
When you run into mysterious bias and overheating/red-plating problems like this that you cannot duplicate, check the soldering of the pins on the bottom of the output tubes. I've seen a couple of cases where pin 5 to the grid of the tubes, which is where the bias as well as the audio signal are applied, appears to have been cold soldered at the factory. If the hollow pins do not appear to be fully filled with solder at their tips, resolder them. They appear to have been factory soldered with lead-free, and we all know how poorly that stuff works.
Yes good advice. You'll notice that's exatly what I did in the video.
@@stuartukguitarampguy5830 , You misunderstood me: I meant the soldering on the pins of the tubes themselves, not the saldering of the socket contacts to the circuit board. Everybody with any sense checks the soldering to the sockets but rarely does anyone check the pins of the tubes themselves.
Oh ok. No I've certainly never checked that!
@@goodun2974 Hey, Hey...! I have followed your comments recently and was wondering why you haven't got a channel with uploaded videos of your work and so called self expertise on show..You gave a' kind of afraid of the wife' excuse for not doing so..! But your aggressive tones here against Stuart saying 'Everybody with any sense checks the soldering etc.etc.' eluding to incompetence to a professional UK tech from someone who appears to be 'Pussy whipped' is out of order..Rail your neck in, or be nice..! Peace.!
Interesting amp, and interesting problem. Maybe you couldn't duplicate the issue because all the smoke leaked out of the wiring and it needs a recharge. I had a 71 Triumph that did that quite often so I kept a smoke recharge kit in the boot along with the other spares.😂😁
I must get me one o' them!
Not sure what the intent of the dual volumes is on this amp, but a very useful feature would be able to foot-switch/MIDI switch between two different volume settings, e.g. rhythm and lead.
Yes I guess that must be it. A bit of an oddity all around, this amp!
Would be for stereo
Mesa Boogie made a conceptually similar 100 watt per channel power amp but with *8* 6L6's crammed inside a similar size chassis 😖; Brad's Guitar Garage just repaired one. He's in Oz and pronounces it Mess-uh, which is absolutely appropriate (Mesa Boogie products are unreliable and not designed not designed to be efficiently or economically repaired). This Engl amp here has a much cleaner layout and build.
Hi. OMG I can hardly beat to think about that! I almost never take on Mesa amps. As you say, very hard to work on and repair.
All the best
Yes, I think people just give Brad Mesas just to annoy him! Btw, I'm in Oz and it's Mess-uh all day long down here.
very interesting video! but im trying to read/adjust the Bias of this TPA with a multimeter but i have no idea where the test points are located on the board ? i can see the trim pots to adjust the Bias but not the test points (as you're using testing tube sockets here!) where i should put the red probe ?? does anyone can help me here ?
Hi. I can;t recall on this amp but 90%+ of amps don't have bias test points so this one probably doesn;t.
Same problem on mine ; my tech did a repair twice but now I use only the channel which works .
Ok thanks. Seems like it might be a known issue on these amps.
How long did you have it for? I was thinking of buying one before this video
@@d77sauce 15 years
@@mrjoe9308 damn I didn’t even know they’ve been making the power amp that long. Seems like a decent unit if it lasted that long
Hi Stuart, is something wrong with this video? I just can not start playing it ...
Finally i could start the video! Probably it was held up at the customs in Dover, before crossing to the continent .... ;) Als always very intresting!
Hi William. How strange. I've had a few hundred views already and a handful of comments. Just clicked on the link and it worked ok. Try again?
Let me guess,faulty powertube.The thing about those Engl´s is that they are crappy made with subpar Tubesockets.-Get a Tubetester oldman.