Tullfan Posted May 22, 2016 Share Posted May 22, 2016 Hi, My Fender TB600 Combo has started to sound jangly and fuzzy and i think it must be the death of the valves in the preamp, so have searched for replacement valves online and am about to jump in and have a go at replacing myself. Searched youtube for videos and nothing specific for the tb600/1200 there, though much about how to replace valves in other amps. the manual says 12ax7wc (sovtek) valves but i have 12ax7 electro harmonix-cryo coming from watford valves. So...... it does look easy, but should i call in - your advice/an expert to do it/an undertaker?? Please advise. thanks for reading. Quote Link to comment Share on other sites More sharing options...
Twincam Posted May 22, 2016 Share Posted May 22, 2016 (edited) No special requirements at all. It's Pre tubes so just gently wiggle the old tube out and put in the new tube making sure it's well seated. Obviously have the power off and unplugged or switched off at the socket. The amp will still contain enough power to electrocute you badly so touch nothing else but the glass tube. Edited May 22, 2016 by Twincam Quote Link to comment Share on other sites More sharing options...
Tullfan Posted May 22, 2016 Author Share Posted May 22, 2016 Thanks Twincam, it does look easy, in principle, but as its new to me and to open up the amp for the first time, I wondered if there was anything model specific. Perhaps a worrier thats all!! Quote Link to comment Share on other sites More sharing options...
Tullfan Posted May 29, 2016 Author Share Posted May 29, 2016 (edited) [url="https://www.talkbass.com/threads/fender-tube-bass-tb600-head.539138/page-3#post-13478877"]https://www.talkbass...3#post-13478877[/url] found this post for anyone else occupied with this task, its not the inside of a TB600 it must be the TB1, hope it helps. Guess who opened up his amp to get that surprise! Edited June 4, 2016 by Tullfan Quote Link to comment Share on other sites More sharing options...
claustra Posted June 19, 2020 Share Posted June 19, 2020 Hello, This is a bit of an old topic, I know. How did the story finish ? I have just received a Fender TB1200 and the tube overdrive channel does not work, it produces no sound at all when fully balanced to the overdrive channel. (the other channel is a killer, apart from that) This must be the tube that is either dead or has moved during the shipment. I have already changed 12AX7 tubes in other amps without any problem, but I have to say that there are some metal protections screwed above the tubes and in view of the masssive transformer I do not dare touch the metal pieces in there : I am not even sure what screwdriver I shoud use And there is one side without a screw, but some resistor underneath : Any advice would be welcome ! Quote Link to comment Share on other sites More sharing options...
Thunderbird Posted June 19, 2020 Share Posted June 19, 2020 If it was me I'd leave it powered off overnight and just use an insulated screwdriver to remove the cover but I'm no amp expert 1 Quote Link to comment Share on other sites More sharing options...
Matt P Posted June 20, 2020 Share Posted June 20, 2020 (edited) You don't need to use a screwdriver to remove these covers, they are a 2 part design, if you push down on the top and then rotate a bit they will slide off, very much like a bayonet fitting light bulb. Matt Edit to add that the covers will most likely be earthed so should be safe to touch, the advice of leaving the amp unpowered overnight before starting is good advice for working on any mains powered equipment. Edited June 20, 2020 by Matt P Extra info 1 Quote Link to comment Share on other sites More sharing options...
claustra Posted June 20, 2020 Share Posted June 20, 2020 (edited) Thanks a lot for this Matt ! Really usefull, I'll have a go asap. Cheers Edited June 20, 2020 by claustra Quote Link to comment Share on other sites More sharing options...
Salt on your Bass? Posted June 20, 2020 Share Posted June 20, 2020 Sub'd Quote Link to comment Share on other sites More sharing options...
claustra Posted June 20, 2020 Share Posted June 20, 2020 Thanks again for the tip @Matt P, I have just replaced the overdrive tube with the preamp tube and it now works perfectly fine ! The covers simply needed a small push down and rotation indeed I have swapped the preamp tube with a new old stock RCA grey plate 12AX7, and the sound is much clearer when the gain is pushed up, you have to push it really high to get a little overdrive. Some would say it is more hifi. @Salt on your Bass?, everything is sorted now and I'm happy with the amp ! I did not have the time to test the former overdrive channel tube, I might do some day. 1 1 Quote Link to comment Share on other sites More sharing options...
Salt on your Bass? Posted June 20, 2020 Share Posted June 20, 2020 @claustra perfect!!! Enjoy dude. I'm missing that transformer a little already 1 Quote Link to comment Share on other sites More sharing options...
claustra Posted June 20, 2020 Share Posted June 20, 2020 29 minutes ago, Salt on your Bass? said: @claustra perfect!!! Enjoy dude. I'm missing that transformer a little already Your back will be grateful. 1 Quote Link to comment Share on other sites More sharing options...
Matt P Posted June 20, 2020 Share Posted June 20, 2020 1 hour ago, claustra said: Thanks again for the tip @Matt P, I have just replaced the overdrive tube with the preamp tube and it now works perfectly fine ! The covers simply needed a small push down and rotation indeed I have swapped the preamp tube with a new old stock RCA grey plate 12AX7, and the sound is much clearer when the gain is pushed up, you have to push it really high to get a little overdrive. Some would say it is more hifi. @Salt on your Bass?, everything is sorted now and I'm happy with the amp ! I did not have the time to test the former overdrive channel tube, I might do some day. excellent, it's amazing what differences there are between different valves, glad to be of help. Matt 1 Quote Link to comment Share on other sites More sharing options...
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