dgulli Posted November 17, 2013 Share Posted November 17, 2013 Hi All, Love my DT50 Head and Cab combo. i use it in conjunction with the HD500 for gigs and so far i've been really happy with it. Except today! basically i set it all up as normal, and i found no sound was coming out of the amp. Having a look at it, i took the HD500 out of the equation and plugged in directly to the amp.. then changed the guitar, the lead, and the speaker cable, and still no sound :/ mind you, the DT50 lights up to show it has power, but it also appears that the valves at the back arent warming up. - I've also checked the fuse next to the power input and that appears to be fine. I'm not sure if its just a valve replacement that needs to happen here or whether there is a bigger problem.. any tips/troubleshooting i can take? if one valve goes out of the 2 power amp ones and 2 preamp ones, does this lead to problems like this? or can it run off 3/4 rather than the full 4/4? Quote Link to comment Share on other sites More sharing options...
AParedes Posted November 17, 2013 Share Posted November 17, 2013 A couple things you can check: reflash the DT firmware: always a good call to ensure there isn't something corrupted in the software. http://line6.com/support/page/kb/_/amplifiers/dt50dt25/dt25dt50-firmware-installation-instructions-r120 Speaker cabling - be sure things are plugged in, even try a different speaker cable out to a different cab would be a good call to ensure there isn't something wrong with the speaker connection. preamp tubes: these can be changed without biasing. the two preamp tubes in the DT50 act as a booster and phase inverter, so if either of these are "bad" that could be the root of the problem. Any quality 12AX7 will work for this application. Power amp tubes: these need to be replaced/biased by someone with experience, as there are a number of potential problem areas for the "inexperienced". When in doubt, take it to a Line 6 service center. Quote Link to comment Share on other sites More sharing options...
dgulli Posted November 19, 2013 Author Share Posted November 19, 2013 Hey, I've never actually flashed the firmware of the DT50 Head - what is strange is i did flash the HD500 the day before this all went pear shaped. but the problem exists even with the HD500 not even in the equation. I Changed speaker cabling with the other guitarist who has a Spyder IV and it had no affect, i wish this was the issue. Preamp Tubes - Ok cool, i can see these are pretty easy to remove and put back in. neither of these were lighting up, and i have noticed there seems to be a black smokey looking ring on the inside between the metal and the glass.. normal? Power amp tubes - Yeah, these looked like serious bad boys. Thanks for the help, i'll post an update asap. Quote Link to comment Share on other sites More sharing options...
dgulli Posted November 20, 2013 Author Share Posted November 20, 2013 Ok update 1 - Firmware: Updated the firmware to 2.00 successfully! 2- changed the speaker cable, just to be sure. no joy. 3 - Changed the preamp tubes - No joy, the tubes arent actually warming up or glowing... So after trying these things.. no joy :/ whats annoying is it seems the only australian service centre is in sydney. And i'm in melbourne, which is in a completly different state. is there some kind of melbourne service center?! Quote Link to comment Share on other sites More sharing options...
Brazzy Posted November 20, 2013 Share Posted November 20, 2013 Hey thanks for sharing what you have so far. Are you looking into dealing with the power tubes yourself? Quote Link to comment Share on other sites More sharing options...
stumblinman Posted November 22, 2013 Share Posted November 22, 2013 There are two fuses. One below the power plug and a smaller round fixture labeled tube protection fuse. Have you checked both? I'm guessing the smaller round fuse blew. This is generally a sign of a bad power tube. Quote Link to comment Share on other sites More sharing options...
swing_girl Posted December 31, 2015 Share Posted December 31, 2015 I have the same problem, one day the amp worked, the next there is no sound. The amp has not moved or anything, just switched off properly (standby off then a minute later, main power off). There was no issue before the problem, everything lights up as it should, fuses are fine, tubes are securely attached, not loose. The amp has only been used a few times at home since purchase so the tubes are still quite new. Quote Link to comment Share on other sites More sharing options...
Brazzy Posted December 31, 2015 Share Posted December 31, 2015 (edited) I have the same problem, one day the amp worked, the next there is no sound. The amp has not moved or anything, just switched off properly (standby off then a minute later, main power off). There was no issue before the problem, everything lights up as it should, fuses are fine, tubes are securely attached, not loose. The amp has only been used a few times at home since purchase so the tubes are still quite new. This is what happened to my DT50HD. It's been a while now but I had to send it in to Line 6. I had to send it in 3 times if my memory serves me, lol. It's working ok but I just noticed that the L6 Link isn't working with my HD500 since I mainly use it with MIDI and the other inputs. I really should've checked everything when I got it back. Forgot to mention that this amp sounds excellent. It's the best sounding amp I've got. Edited December 31, 2015 by Brazzy Quote Link to comment Share on other sites More sharing options...
swing_girl Posted January 1, 2016 Share Posted January 1, 2016 Thanks for sharing Brazzy. It is such a heavy amp, it is hard my me to lug it to the service center via public transport on my own. I am going to replace the 12AX7s and see if that helps. I like the amp because of the Class A chime ... I use a HD500X too (with a JTV) and I like the versatility, I hope the tube replacement can fix the problem. Quote Link to comment Share on other sites More sharing options...
Brazzy Posted January 1, 2016 Share Posted January 1, 2016 Thanks for sharing Brazzy. It is such a heavy amp, it is hard my me to lug it to the service center via public transport on my own. I am going to replace the 12AX7s and see if that helps. I like the amp because of the Class A chime ... I use a HD500X too (with a JTV) and I like the versatility, I hope the tube replacement can fix the problem. I hope the tube change works for you, wasn't the case for me. I had to send mine back to Line 6, it made an approx. 3000 mile trek, lol. I ended up shipping it back in the original box it came in since I saved it but I probably could've just removed the chassis and sent that back leaving the cabinet at home. They sent a call tag so they paid the shipping the last two times, the first time it was a few days out of warranty so I shipped it (paid). It's a long story, lol. Quote Link to comment Share on other sites More sharing options...
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