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Getting started on tube amp repair.

Discussion in 'Amp Tech Center' started by Jesse1973, Apr 18, 2020.

  1. Jesse1973

    Jesse1973 TDPRI Member

    Jul 8, 2018
    Besides reading a slew of books on the subject .How did everyone get started working on their own tube amps?Build a kit?Buy a non functioning amp? Buy an less expensive vintage amp and restoring it?

    Sent from my iPhone using Tapatalk
  2. elpico

    elpico Tele-Afflicted

    Sep 14, 2011
    Vancouver BC
    Most people arrive here with a broken amp and either not enough money for a tech or simply a desire to fix it for themselves. In the DIY forum you see more first time kit builders. I wouldn't buy any books right away. There's tons of info online these days. I would strongly encourage you to try some projects that aren't tube amps as well. It's easy to get tunnel vision if doing what leo did is the only thing you've ever explored. Build some pedals or check out diyaudio and build a headphone amp, or maybe play with an arduino board an automate something at your house. If you want to really learn a lot about what not to do in your audio projects build a simple radio.
  3. Texicaster

    Texicaster Tele-Afflicted

    May 9, 2018
  4. Whatizitman

    Whatizitman Friend of Leo's

    Feb 18, 2018
    Friend gave me an SF Champ that needed work. I also came across a few vintage amps for cheap that needed work. That, and a LOT of reading was where I started. I dabbled in some electronics and soldering before that, so wasn’t completely blind going in. I haven’t built a kit or anything from scratch. A little cost prohibitive for me to go all in that way. Not right now, anyway.
  5. trber

    trber Tele-Meister

    Jun 4, 2016
    I am still very much a beginner, but I can share my path and a few things I discovered along the way, some of which may help you focus your efforts more effectively than mine were!

    I started working on amps when I wanted to mod a Blues Jr I owned and bias a Marshall amp. Youtube videos and directions from the suppliers of the mod kit were how I learned to do these projects. I also learned on YouTube how work in an amp safely namely how to discharge capacitors. Even though I successfully completed these jobs, I was still not very solid on how amps work. Hold that thought.

    Next, I decided to buy an inexpensive (relatively) amp to recap and learn some point to point work since my other amps were PCB boards. I also thought it would be fun to have a vintageish amp and learn to work on it, so I found a Silverface Champ on Craigslist and recapped it. For this, I followed a bunch of videos on Youtube, mostly D-Labs who has a lot of Champ information, and also the Guitologist. Both great sources of info for me. Doing this I learned even more about working on amps, but still didn't understand how they work, though my knowledge grew.

    After that, I found I enjoyed working on amps and learning about them and that I was interested in another project, so I found a Musicmaster Bass amp to recap which didn't break the bank as I found it was not working properly when I purchased it, so I got it for a good price. It actually had a bad pot which made it more affordable since the seller just knew it was not working correctly. My point is that you can find, if you look a bit, reasonably priced projects to learn on, as you noted in your post. Here, too, YouTube videos and threads in this forum were my main sources of information.

    My curiosity and interest in amps continued to grow so I wanted to build a kit. It was a more affordable way to get into an amp I'd wanted but could not afford, a 65 Princeton Reverb. I built the kit, because I knew I could wire it up, follow directions, and solder, so what could possible go wrong? Here, I learned building an amp was not hard, but troubleshooting problems that arose is another thing altogether!

    Fortunately, I found some great people on this forum willing to guide me through the troubleshooting process, and now the amp works beautifully. And, of course, I learned a bunch more about amps. I did not, however, know how they work. Part of knowing how they work is learning the amp specific vocabulary to work on them at a level deeper than just soldering a resistor, etc. This was when I learned what I should have started with, but did not know about.

    Go to Rob Robinette's website, and read his explanation of how they work. This is a great starting place! If I had known about this website, and also known about the videos Uncle Doug has on the topic on YouTube, I would have had a very different learning curve and early experience. So, I'd recommend starting here. You could also follow along on forums, such as this one, which will be interesting reading for someone who likes that kind of thing, and even more meaningful when you understand amp basics.

    There was a thread like this one recently on this forum, but I don't recall exactly when or the name of it. Maybe 3 months ago? Anyhow, a lot of members chimed in there, so if you track it down, it might answer some of your questions.

    Enjoy, and I can say for me learning about how amps work, how to work on them, and enjoying the results has been a very rewarding process, though certainly not without a few headaches along the way. Hah.

    Spooky88 likes this.
  6. Paul G.

    Paul G. Friend of Leo's

    Mar 17, 2003
    Rhode Island
    Basically disappointment with techs. I had a Dual Showman I spent a crapload of money on in the 70s, ended up tossing it. I had a Vibrolux Reverb that 4 different guys couldn't find the source of a loud buzz. I ended up selling it. I had a Princeton Reverb that would just go crazy, no tech could fix it. One day I opened it up and saw right away that a connection to the (added) bias pot was bad and I was losing bias intermittently.

    After that, I bought books, taught myself electronics, ended up maintaining and repairing my own amps. In 2007, I built my first amp. I started helping out my friends, doing maintenance, eventually doing repairs and mods. Now I'm retired from my day job and take any amp work I can because I like it. Not getting rich, but a earning a couple of bucks doing something I enjoy is welcome. Most of the money goes right back into equipment and supplies anyway.
    Lowerleftcoast likes this.
  7. AlbertaGriff

    AlbertaGriff Tele-Afflicted

    Mar 2, 2016
    I started with an interest. Over the years I have read a lot, talked to my tech a lot, and looked inside my own amps and their schematics. Then I built a kit, which gave me the confidence to poke around inside the chassis safely, as well as some experience. After that, doing a standard cap job was fairly straightforward. It's if you run in to problems you can't diagnose that you will have a tougher time... but expertise comes with experience.
    Last edited: Apr 18, 2020
  8. kbold

    kbold Tele-Afflicted Silver Supporter

    Jul 21, 2015
    I restored an old amp head, then did some minor mod's and upgrades to my amp.

    Whatever approach you take, always remember there can be nasty voltages (lethal) inside, even when power is disconnected.
    Most amps have around 300 to 500 volts DC inside. Some have over 700 volts (the one I restored had 770 V).
    Keep one hand in your back pocket.

    I mean none of us want to read a post "Oh, whatever happened to jesse1973 - haven't heard from him for a while."
    Lowerleftcoast and boredguy6060 like this.
  9. Milspec

    Milspec Poster Extraordinaire Silver Supporter

    Feb 15, 2016
    Join the military in avionics repair.

    I have read a few books and worked on some amps, but I think it really takes a few years working alongside someone who knows what the heck they are doing before you really learn. Just like teaching yourself to play guitar can often mean that you end up learning the wrong ways, so is true with teaching yourself amp repair. Sadly, there aren't that many good techs around so finding one that will take you under their wing is going to be very rare.
    Lowerleftcoast likes this.
  10. Dacious

    Dacious Poster Extraordinaire

    Mar 16, 2003
  11. Kerberos

    Kerberos Tele-Holic Silver Supporter

    Nov 27, 2016
    Long Island
    I have a 65 DRRI, it's 22 years old. I figured it was about time I changed the Filter Caps, so I decided today was a good day to do that. The operation was a success, but man I'm tired. Several lifetimes ago I was a Marine Electronics Technician, I've had several technical careers during my working years, and I've been retired for sometime now. This was like real work...but I did enjoy it.

    Tear Down-50.jpg New Caps-50.jpg
    Spooky88 and Paul G. like this.
  12. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

    Dec 30, 2019
    I was exposed to electronics at an early age. I was kinda born into it.

    Repairing someone else's busted amp was my first entry into the guitar amp world.

    If you are *truly* interested in a project, you will finish it. You have been given good advice in starting with pedals. They are cheap and a good way to hone skills. You may have more interest in an amp though. You will be more likely to learn if you follow your interests.

    I will assume you are interested in a tube amp.
    The cheapest way to start is with repairing/modding a used amp. There is a lot of info concerning the Blues Jr so it is a good candidate. I will also mention the Carvin Vintage 16.

    For learning, I really like the Pignose G40V and it's big brother G60VR. These are derived from the Fender 5f6a Bassman and Marshall JTM 45 circuit. Mods are available online for the G40V but any Bassman mods work.

    If money is not an issue a kit will provide the parts and instructions. These can be advantageous in that they use turret or eyelet boards which are not damaged as easily as PCB. You can end up with a very nice amp this way.

    Good luck.
  13. Spooky88

    Spooky88 TDPRI Member

    Oct 26, 2019
    Bend Oregon
    After starting out with the transistor amps and junk that was pouring out of the guitar stores in the late 80’s, I tossed it all looking for better tone and my own “sound”. I bought a new Marshall JCM 900 4502 in 1990? and beat the crap out of it, gigging regionally and learning to replace and bias the tubes myself and eventually working on resoldering pots and building guitars along the way. I’ve only really gotten into more difficult repair work in the last 3 years but it beats the hell out of paying someone else to do the work that I feel I do better anyway. All the posts leading up to mine have excellent insight as to how to approach learning. YouTube and online videos are your greatest asset as well as forums like this. I would also look to buy a very good soldering station that has temperature control on an LED readout. That’s huge. When I’m working on a mixer that has “tight” areas in which to replace TRS inserts or w/e heat control makes a big difference. Good luck.
  14. dkevin

    dkevin Tele-Meister

    Mar 13, 2011
    Seattle, WA
    I had a guitar amp that couldn't be repaired locally and had the time and desire to learn how to do simple repairs. I found non-functioning simple guitar tube amps for $50-100 and read all the free books I could get my hands on. I also bugged the heck out of the people on this and other forums and they patiently corrected me and guided me to other resources. I started with simple designs and bought Silvertone and Gibson amps. I usually bought the cosmetically damaged examples because no one else wanted them. At the time, they seemed to be readily available while the Fender and Marshall amps were in high demand and therefore more costly. I have always found the older, more experienced people to be very kind and helpful to a newbie. I tried very hard to listen to their advice and remember it since nothing bugs them more than an askhole. Also, the local Ham radio club is full of older tech-savvy people with tools and test equipment that they are looking to sell. The prices sure beat the auction sites!
  15. muchxs

    muchxs Doctor of Teleocity

    Aug 14, 2004
    New England
    There is a big gap between reading all about it and doing it.

    My instructor for "electronics 101" was an "attack boat commander". Bill was the retired commander of a nuclear submarine. He had been charged with curatorship of nuclear missiles as well as Cold War surveillance missions.

    While I generally resent authority I would have gladly served under Bill. Helluva a guy! He knew every system on his attack boat on a nuts 'n' bolts level, everything from care and feeding of the batteries to care and feeding of the reactor.

    Hassle with The Magic Internet is we don't have old timers like that to separate the information from the fertilizer.
    Last edited: Apr 24, 2020
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