http://www.voxamps.com/forum/ VOX | Discussion Forums Topic: Problem with ad120vtx en Wed, 19 Jun 2013 01:23:22 +0000 http://www.voxamps.com/forum/topic.php?id=4801&page=2#post-35481 Sun, 28 Oct 2012 04:19:48 +0000 voxman 35481@http://www.voxamps.com/forum/ <p>Delay light always blinks (tap tempo) whether you have delay engaged or not. I use Servisol Super 10 (red &#38; white can) but any electrical contact cleaner that lubricates and is safe on plastics is fine. </p> http://www.voxamps.com/forum/topic.php?id=4801&page=2#post-35476 Sat, 27 Oct 2012 22:17:05 +0000 brion 35476@http://www.voxamps.com/forum/ <p>Voxman my valvetronic ad 120 is having same issues as last year.<br /> Delay light is always blinking. All other ad 120s don't blink.<br /> Also crackle when I turn amp on. What type of contact cleaner should I use. </p> http://www.voxamps.com/forum/topic.php?id=4801&page=2#post-25666 Fri, 09 Sep 2011 13:38:06 +0000 voxman 25666@http://www.voxamps.com/forum/ <p>That's not bad at all! </p> http://www.voxamps.com/forum/topic.php?id=4801&page=2#post-25663 Fri, 09 Sep 2011 10:49:20 +0000 robertray 25663@http://www.voxamps.com/forum/ <p>He charged $40 for the repair. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25662 Fri, 09 Sep 2011 09:56:42 +0000 voxman 25662@http://www.voxamps.com/forum/ <p>A fried cap in these amps is somewhat unusual, but glad you got it sorted and are enjoying your amp again. I wouldn't be too concerned re tube height, but it's probably worth pointing out to your tech to clarify why. </p> <p>Out of general interest, and for the benefit of anyone else that may encounter this problem, how much did he charge for the work? </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25656 Thu, 08 Sep 2011 22:20:33 +0000 robertray 25656@http://www.voxamps.com/forum/ <p>UPDATE: Well, I took it to the shop. Turned out it was a fried cap... one of the green ones. She`s good as new now. The only thing that disturbs me a bit is my left side tube now sticks out farther then the right one. I dont know what he did, but it definitely sticks out more now. Oh well... at least I can grab the left one now without using the tape method. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25431 Mon, 29 Aug 2011 02:21:43 +0000 retrobob 25431@http://www.voxamps.com/forum/ <p>You are welcome, glad I can help.</p> <p>It is always a good idea to keep electronics cool, and high temperatures along with high humidity will definitely accelerate corrosion. While it is possible the heat and humidity could have contributed to the problem, I don’t think it was the only cause. </p> <p>Dirt and corrosion can get into any thing, vibrations and impacts can cause stress fractures and loose parts, as can excessive expansion and contraction (heating and cooling rapidly). </p> <p>I’ve played outdoor gigs where it is so hot it warps the plastic parts, yet every thing works fine. Most of time it boils down to sh-t happens. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25429 Mon, 29 Aug 2011 01:45:43 +0000 robertray 25429@http://www.voxamps.com/forum/ <p>Thank you retrobob for taking the time to walk me through this. I greatly appreciate all your help. The master volume looks like its gonna be a pita to get to. I can barely see it when peeking through the board, so it looks like I<code>m gonna have to pull the top board to get to it - along with all the knobs, ect. ect. I think I</code>ll hang it up for tonight. I will keep you posted, and again - thanks. One more thing, if this has anything to do with it: This amp has performed flawlessly since buying it last year. The night when this happened, I was at band practice and it was insanely hot in the practice room. I live in the south and it is quite hot and humid and that night was brutal. Just wondering if that somehow contributed to this issue I`m having. -Rob </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25421 Sun, 28 Aug 2011 21:49:18 +0000 retrobob 25421@http://www.voxamps.com/forum/ <p>Yes, the master volume is a dual pot on the 120 and is fed from the RETURN left and right jacks (master is after the loop). Try cleaning the master pot, if cleaning doesn't work, look at the pot's film board (internal part of the pot that the wiper arm rotates on) and its board's solder connections for damage. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25420 Sun, 28 Aug 2011 21:31:32 +0000 robertray 25420@http://www.voxamps.com/forum/ <p>so... I pulled the board with the effects loops jacks. I cant find anything that looks suspect. Everything looks intact, solid solders, nothing looks discolored or cracked. Dont know if this helps, if I unhook the right speaker from the back and turn the master volume quickly up and down, I get a low scratchy signal in the left speaker. Like a dirty pot sound... its there, but no volume. Could the master volume have anything to do with it??? </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25419 Sun, 28 Aug 2011 21:13:47 +0000 retrobob 25419@http://www.voxamps.com/forum/ <blockquote><p>I should be looking next at the left return jack for a cracked/broken solder.</p></blockquote> <p>Correct. </p> <p>Look at the board from the bottom side with a cable insert in the jack and wiggle the cable while looking at each connection for movement. When you spot it, it will be obvious and most likely the jack’s pad connection will be separated from the circuit board's trace, you’ll need to make a bridge across the break using a short piece of wire and soldering it in place.</p> <p>Join us at Valvetronix.net and you can view articles on how to do this type of repairs;</p> <p><a href="http://www.valvetronix.net/forums/how-to-repair-the-solder-connections-yourself-t3272.html" rel="nofollow">http://www.valvetronix.net/forums/how-to-repair-the-solder-connections-yourself-t3272.html</a></p> <p><a href="http://www.valvetronix.net/forums/vox-ad-60-120-vt-vtx-series-solder-connections-part-2-t3273.html" rel="nofollow">http://www.valvetronix.net/forums/vox-ad-60-120-vt-vtx-series-solder-connections-part-2-t3273.html</a> </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25417 Sun, 28 Aug 2011 20:36:54 +0000 robertray 25417@http://www.voxamps.com/forum/ <p>OK, so by the left send working in the right return (which it does), I should be looking next at the left return jack for a cracked/broken solder. Thank you retrobob. I`ll keep you posted. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25416 Sun, 28 Aug 2011 20:07:01 +0000 retrobob 25416@http://www.voxamps.com/forum/ <blockquote><p>OK, left send into right return gets me the same results... no sound from left side.</p></blockquote> <p>A slight miscommunication; Left SEND into right RETURN should only yield sound on the right side of the amp and this is what we are looking for. Jumping the left SEND into the right RETURN bypasses the the right pre-amp and left power amp (left side will not work).</p> <p>Keep in mind, I’m not there working on your amp, so I am relying on you doing and confirming troubleshooting steps for me. </p> <p>What we are trying to accomplish, is to establish where the signal stops on the left side of the amp. If the above works, we will know that the signal gets to the left side send of the loop, but does not go any further. We already know the left side of the power amp circuit is not working (you have already jumped the right SEND into the left RETURN). Further, the left side does not work in the headphones or the speaker, with those being two independent circuits we’re are pretty sure the problem is not in the power amp section. You have already swapped the tubes, so we know the tube is OK (right side tube works in the right side, but not in the left side), this most likely places the problem before the tube. </p> <p>So, if the left SEND works in the right RETURN, this confirms the left side pre-amp signal is getting to the loop, but not going past it and this tells us the left side of the circuit is not getting any signal beyond the left RETURN section into the left side of the circuit going to the tube. But, before we go into the driver circuit (circuit between the tube and loop), lets rule out the EASY and check the left side RETURN jack, and its board connections. We know stress is applied by the cables and such every time the amp is moved, thus applying internal movement to the board’s jack connections (weakest link) and possibly breaking a solder connection.</p> <p>If the left SEND does not work in the right RETURN, then the entire left side of the amp is not working and we’re looking for another problem, possibly a power source failure to the left side of the amp’s circuits and it maybe as simple as an internal connection has become loose. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25415 Sun, 28 Aug 2011 18:51:13 +0000 robertray 25415@http://www.voxamps.com/forum/ <p>Thanks for your reply retrobob. OK, left send into right return gets me the same results... no sound from left side. If I reverse and go right send to left return I get virtually nothing. I have to crank the amp up full blast to hear the signal, and what I hear is very light guitar in the left and hum only in the right. I`m stumped... now what? </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25412 Sun, 28 Aug 2011 17:30:36 +0000 retrobob 25412@http://www.voxamps.com/forum/ <p>Try plugging a cable into the left SEND and into the right RETURN. This will let us know if the signal is getting to the loop, it may simply be a bad solder connection at the left return jack not allowing the signal to complete. The effects loop jacks are on their own board along with the eithernet plug. The board uses plugs, mark them and the board for their locations and check the board, while you have it out check the jack with a meter to make sure the jack is OK. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25403 Sat, 27 Aug 2011 19:55:21 +0000 robertray 25403@http://www.voxamps.com/forum/ <p>Thanks voxman. Hopefully retrobob can steer me in the right direction. All the music stores around here send amps out for repairs... which means it will probably cost almost as much as I paid for the amp to get it repaired. I tried one more thing... I sent a cable from the right fx send to left fx return and got virtually no sound at all. Dont know what I might have accoplished from that but... trying to figure this out. Also, my two other blue faces always gave me a sign that a jack cleaning was in the near future... this vtx did not, It just stopped. Thanks again. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25402 Sat, 27 Aug 2011 19:03:03 +0000 voxman 25402@http://www.voxamps.com/forum/ <p>Retrobob's your man here as to what you should look for and how to test the joints - but it still sounds like a jack or a solder issue. You may need to get a tech to check it over. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25399 Sat, 27 Aug 2011 15:35:34 +0000 robertray 25399@http://www.voxamps.com/forum/ <p>Thanks for responding Voxman. I did switch the tubes around and the problem persist... no sound from left side. Even with eqs in both loops and headphones plugged in, you still think it might be a stuck jack??? If its a dry solder (which I already took the chassis out and gave it a look over... all looks brand new and sound) is there any particular place I should be looking??? Thank you. </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25397 Sat, 27 Aug 2011 14:54:34 +0000 voxman 25397@http://www.voxamps.com/forum/ <p>It still sounds like a coroded/stuck jack problem or it could be a dry solder joint as per the FAQ at Valvetronix.net. </p> <p><a href="http://www.valvetronix.net/forums/maintenance-tips-on-valvetronix-amps-t141.html" rel="nofollow">http://www.valvetronix.net/forums/maintenance-tips-on-valvetronix-amps-t141.html</a></p> <p>I certainly don't think it's anything more serious than that. Badly oxidised/sticking sockets can need 10 or more cleanings - &#38; it's also important to check the line-out sockets too. It also might depend on what you're using to clean the sockets with. You need an electrical switch cleaner like Super Servisol 10. </p> <p><a href="http://www.amazon.co.uk/gp/product/B000L9CVSE/sr=8-1/qid=1314453017/ref=olp_product_details?ie=UTF8&#38;me=&#38;qid=1314453017&#38;sr=8-1&#38;seller=" rel="nofollow">http://www.amazon.co.uk/gp/product/B000L9CVSE/sr=8-1/qid=1314453017/ref=olp_product_details?ie=UTF8&#38;me=&#38;qid=1314453017&#38;sr=8-1&#38;seller=</a></p> <p>Re valves, it's unusual for these to 'go' but have you tried swapping the valves round to see if the problem swaps over to the other channel? </p> <p>Rich </p> http://www.voxamps.com/forum/topic.php?id=4801#post-25396 Sat, 27 Aug 2011 14:21:46 +0000 robertray 25396@http://www.voxamps.com/forum/ <p>Well, its not the tubes. With the headphones on and turning the volume knob from low to high repeatedly and quickly, I get scratching sounds from the left speaker/side. Also, when switching speaker wires the problem does go from the left to the right side... so I can def. rule out speakers. Which wearing the headphones told me anyhow. What do you guys think? I really hate to crack her open... but I guess I`m gonna have to. </p>