I made a mistake in this video. I said they used 10uf caps in the DC heater supply based on an older handwritten/xeroxed schematic that said that. Looking closely at the actual caps and finding a more legible schematic, they are be actually 10KuF caps. Much better. But they still have ground references on each side of the bridge.
I’ve recently found your repair videos and I absolutely love them. Even though I have no experience as a tech I love hearing your explanations. Very cool. That’s the good news….the bad news is the Mesa videos in particular make me very nervous since I own 4. Thank you for the awesome video content. Cheers
Watching these videos has taught me a valuable lesson: don't buy a Mesa amp. Compare the layout of this admittedly more complex amp to the Excalibre 15 that Lyle built and, even from just a visual standpoint, ask yourself which one would you buy? Inside the Excalibre chassis there's enough room for a sleeping bag and a camp stove with elbow room to spare. You couldn't get Whoville's dust speck in the Mesa without bumping into something. Lordy, what a mess.
Alright, here's my Messy Booger story: I've owned one of them over the years. It was serial# dc2-00060 Studio Caliber. It was adorned in that custom grayish tolex. Not bad sounding, though the dillhole who sold it to GC had of course lost the footswitch. It ended up getting stolen. And while I was good and pissed off at the time, in hindsight all I can say is: have at it, bro! Now the funniest part: I had called Mesa with the serial# to try and get a date if manufacture. They finally got around to calling me back after it got lifted. lol
Thank you for this detailed video . I dread it when customers call with a MB . I'm sure the information you've given will be used soon . How I wish they had put a removeable panel underneath like in older HiFi amps .
My studio preamp really need a service-door under the board. But a readable and correct schematic would be also a good thing. I like the sound of there amps. But i will try a blackface clone next time. That a complex pc- board thing is really not designt for repair.
Love the straw..Inventive..😀 God, I don't know how you figure this stuff out Lyle, but great to follow through your tech journey with the Messa..Ed..uk..😀
Nawww....they should be called the Mesa Dual Rectum-Fire. Because it's exactly what it feels like to work on and deal with these diabolical bastards; a big hemorrhoid. Should come with a tube of Preparation H and a theme song, _Ring of Fire._
I feel for you Lyle.. Boogies SUCK to repair!😫 Had one with a torched board that almost burnt through.. I closed it up and apologized to the customer and told him to send it back to boogie . 😕
I hate working on Mesa amps. Last was a Tremoverb with optocoupler issues everywhere. I have relegated myself to Mark I and II. The rest you can work on!😝😝
Well I hope my trem-o-verb isn't going to be as bad as this one. Im really thinking Mesa could do alot better. I wish you the best. Gus's fried chicken was great 👍. Take care.
@@rickluke1747 I know there are alot of layout issues with Mesas but i really enjoy the versatility of the trem-o-verb. I hope Lyle can make my amp more reliable and sound better. The amp is too fizzy and noisy. It will be interesting to see Lyle work his magic at managing the magic smoke.
Not sure if you know but the popping noise when using the foot switch is completely normal. Every single one does it. It usually goes away after switching through all channels once though.
That was a mistake on my part due to a handwritten earlier schematic. They are 10KuF caps not 10uF. I found a more legible schematic. But damn, try to make sense of the the grounding.
Mesa what a rats nest! InterFET now sells many of these old TO-92 JFETS, sadly with prices between $3-5.50 each...At least they don't use optos anymore...
Hi my friend! My dual has a problem with fx loop. When fx loop is active SOLO and OUTPUT doesn't work properly, sounds very low.  in bypass all channel master works and the volume is perfect. I thought was V4 but isn't.
Curious builder of my own electronics here. One, why would you want such large power supply filtering caps? (4700uF I think you said?) seems vastly more than is needed to filter 60Hz out. Two. Are tantalum capacitors considered inferior?
Look up the DC heater supply filtering thing. The answer is chapter length. Tantalums are usually fine if their voltage is never exceed. Mesa likes to use 16V caps on 15V supplies, so their tants like to go bad. Even on a cathode that is normally 2V can have spikes. An electrolytic that has its voltage rating exceeded by a little bit for a short while is usually fine. A tantalum will be toast.
I bought a single rec head on the merits of my friend's 1st gen dual that he loaned me for a gig. Hated it. It functioned perfectly, sounded great dead clean or full out striped ass baboon distortion, but my natural habitat is crunch/clean riding the guitar volume, something the Dual did very well but the single couldn't - it sounded horrible. Dumped it on eBay asap. I should have had you mod it.
The JFET switches used all through Mesa products are the cause of way too many failures. They are really dropping the ball in the design department, where improvements net gains all the way through production to the user experience. They use rather complex circuitry to achieve the crazy flexibility for which they’re famous. Complexity hurts reliability, all else equal. There is a big divide between the audio circuit designers and the total product designers and that should not be so. The switches wreaking so much havoc in their end products are part of the whole product design, replacements for many relays in the past. Any part which serves dozens of different purposes should be very highly developed and it obviously is not. I am simply amazed how long this issue has existed.
WOW... Talk about penny pinching... V1's heater is DC and the rest are AC? They probably saved 10¢ on the parts to rectify and filter the supply to handle the current of the full compliment of heaters. The more I watch Mesa repair videos the more I despise Mesa, good tone or not. It's just kind of pathetic.
