I am the owner of this amp and I just had to share with all the other nerds out there…not only was Lyle’s replacement OT a 1965 (125A6A), the same year as the original but both have date codes for the same week!! 606-5-13!!!! Maybe I should buy a lottery ticket! I mean, what are those odds?!
I work on and build tube amps myself and that also rings a bell with my OTHER hobby: restoring old cars. Swapping in a working part and finding it date matches is a bonus !!
Just typed a comment on the first part and out the second one! One of my guesses is right 😁. Your work is truly a sight to behold. Thank you so much for the things you share!
Might be worth doing some forensics on that OT. I'd imagine the most likely scenario is: at some point in time a large signal was applied with no load. The huge ac level punched through insulation in the primary winding. And as time went on, the copper of the winding failed due to arcing , causing the intermittent connection. And this in turn, caused the choke failure. If that's the case, no hope for this soldier. Very small chance the intermittent connection isn't buried in the winding but in the area beneath the cover. Worth a look, though.
@@Jonathan_Doe_ DC issues in the PI wouldn't make their way to the output tubes unless one of the coupling caps failed. That doesn't seem to be the case here.
@@retread1083 I guess your scenario would give a reason for the amp having been sold to the guy as a project, but it did seem to be throwing screen voltages off all over the place.
Nice trouble shooting, worth every penny. The video lesson, priceless. The real question is this: once you get the old girl up and running, how hard can you flog the mule before it gives up the ghost. A well set up Fender from that era will take serious abuse. That is their claim to fame.
@@rickya3877 Lyle is trying to establish a base line. He wants to find the right guitar tone and response, then move on to each job. Show a cause/effect. I have great respect for his efforts.
What is your opinion on having on having an old output transformer rewound? Is that something you'd sometimes recommend, or never at all? I suppose in terms of repair bills it's not recommended.
I'm interested in hearing Lyle's opinion on this, too. In my estimation, it would probably cost more to have the original transformer rewound than it would to use a good quality replacement. Plus you have the delay of shipping them the transformer, waiting in queue to have yours rewound, then shipped back. Sounds like an option best reserved for a very rare amp?
This is what happened.....without being witness. The amp looks very clean and not beat up. ALL the stuff that would need serviced is replaced.......which is part of the give away. This amp probably was used over it life time but sparingly used.......and probably somebody who played over time at a younger age and who eventually got away from playing the electric guitar or guitar all together......so it sat, being ALL original parts. Birth year 1965, service life average of 15 years would put the amp to 1980 when it should have been serviced. So if it was used sparingly and not ridden hard, the power tubes could have sailed 15 years.....BUT on the cusp of where they were subject to their wear & tear point and starting to taper off. THE AMP got mothballed as is......in or around 1980, only to be rediscovered and to be of value AND the amp got sold off ! The next owner not knowing anything.....buys the amp as a pristine original thinking its a plug and play item and the SHIZZZZZZNIT....proceeds to plug and play and run with the ball thinking this old amp is just out of the factory shipping carton and brand new and ready to launch. So thinking its 100 %.....and playing the amp and thinking its THE SOUND....and cranking it up......>>>>>>>>the amp blew a power tube or a power rail cap....or definitely both in the end result......whether it be the chicken OR THE egg.....and along for the ride went the output transformer.......on a catastrophic sleigh ride. WET CHEMICAL CAPACITOR DRY OUT.......they have a service life. The birthdate is when the clock start ticking for service life.......its not necessarily usage....., as for wet chemical components......they start drying out from day one
you have to consider how tubes work......tube amps, as the tubes reach wear and tear age the bottom end starts to taper off. Same thing happens off the power rail caps too as they age......and its unique when both situations run in tandem.....which is most likely what went on.....if the amp was used sparingly and not ridden hard. For if you had rode the amp hard within the service life parameters of the power rail caps......and noticed a drop off in power, when it was still the vacuum tube era of electronics going into the early 1970's crossing over from the 1960's peak and transition to solid state with general consumer electronics......you would have known to get a new set of power tubes.......as most likely you were playing in a band and probably playing out and making money as a young man. But if you were an average player playing in the garage or basement.....maybe once or twice a week......because you graduated high school and got a job and had a girl and got married......or worst case in 1965 era years......you went for a tour of duty in viet nam for Uncle Sam. So what ever the case may be.....the amp got parked and in the latter situation playing in the garage for a fun hobby.....you wouldn't catch the gradual taper off in power tube performance because of the quality of the then state of the art vacuum tube technology......but that doesn't mean tubes last forever and specially power tubes. The energy aspect of the power in a tube amp and power tubes is concentrated in the lower end notes that have to be reproduced by the amp.....by the power amp section. So as the tubes would taper off in their natural decline......you'd slowly over time be turning up your volume a slight notch or 2 to compensate which could go on awhile before it got too flubby and obvious. BUT when an amp was parked as I speculate.....under the conditions I speculate.....the later owner thought there was nothing wrong with an all original amp and it was plug and play......cranked it.....trying to dial in tonally since the bottom end is at question.....and one thing leads to another and BOOM. NOT UNDERSTANDING THE EQUIPMENT.....so unfortunate.
too many publications and media people promote originality as to promote a snobbery where its just insane.....because they as authors don't understand the equipment but write away as if they do which steers mis-information......>>>>>>snobs go bananas if its not original or how it came from the factory.....even if there was a defect in design that should be corrected electronically for proper electronic operation.......and if a set was corrected.....somebody goes by a schematic or layout diagram that was never revised.....or was not officially revised on the schematic but through a service bulletin that the writers of books never discuss because they don't know but want to project themselves as experts as writer/authors......
Love your channel Lyle! Help! My 100watt '74 Superlead is not reading any milliamps on 1/2 of its tubes at pin three! Plate voltage on all 4 tubes is good, and negative bias good at pin five on all four tubes! I am setting the bias for 60 to 80 milliamps per side, but again, one side is reading zero milliamps! (the good side is reading negative milliamps in the correct range for my El34's) My output transformer measures 16.9 and 15.4 on its primary's to centertap which is good. What could cause half of my tubes on one side to measure zero current? I have used two meters and two sets of tubes. My Dan Torres book "Inside tube amps" has been read by me dozens of times, but I can find no answer to my problem.
I found out the hard way that from here on out I should only work on amps in proper light, wearing glasses, and using alligator clips! I am 56 years old and my eyes are terrible now compared to when I was in my 30's!!! I repaired and modified half a dozen amps (I still own them) back in the 90's up until 2005. But times are a changing, I am getting old and blind! I will have to work on this amp when I am properly set up... I put the red lead on the OT transformers centertap, and the black lead to what I thought was pin 3 (while on DC milliamp setting on VOM ), but was in fact pin 2...pow! My beloved amp doesn't make any sound now! I will get this amp up and running again, and I will use a lot of your excellent advice from your library of golden videos to boot upon it! Man, it was sounding the best it ever did just a few days ago! But I heard a funky distortion the other night coming from it, so I looked and saw one tube out of the four starting to red plate. I messed up by trying to diagnose and fix it by poking around pin three with my now bad eyesight, improper lighting, and having no alligator clips to work with on hand! Forgive me guru Lyle...I learned a valuable lesson!!!
It honestly wasn’t a hard guess from the last video. OT issues are the most common in the Bandmaster. A Mercury replacement for regular use is wise imo.
@@Jonathan_Doe_ Being a head might have something to do with it. Being inadvertently ran without a speaker/load will kill anything eventually. The Black Vibrolux 2X10 combo has the same OT and rarely has issues. The Black Tremolux shares the same OT and it’s a head with rare issues(itself being more rare an amplifier). Both of those run at slightly lower B+ too. So, yes. Slightly under specced in combination with user error is my best guess.
