Members bluesboy Posted September 16, 2008 Members Share Posted September 16, 2008 my friesnd was playing along whne his power tubes popped. he said he smelled something burning. i think it might be a screen resistor. any body deal with this issue before? can you just replace the resisiotr that is burned? Link to comment Share on other sites More sharing options...
Members bluesboy Posted September 16, 2008 Author Members Share Posted September 16, 2008 BTW the amp is a TSL, and he's had problems with power tubes in this amp previously (blown fuse only, no burning smell) Link to comment Share on other sites More sharing options...
Members newholland Posted September 16, 2008 Members Share Posted September 16, 2008 had it happen. it wasn't too horrible a fix, but when yer broke and in your 20's, it sure seems expensive.. a retube, the bench fee, and the week without an amp was traumatic.. but it wasn't a tragedy, all told! but tell him to replace his power tubes more often and he won't have to worry about it! Link to comment Share on other sites More sharing options...
Members bluesboy Posted September 16, 2008 Author Members Share Posted September 16, 2008 i was hoping to help him do it. he already has new tubes and fuses... if i can easily see the burnt resistor, it shouldnt be too hard to replace (unsolder the old one, put in a new one)? Link to comment Share on other sites More sharing options...
Members newholland Posted September 16, 2008 Members Share Posted September 16, 2008 y'know-- i dunno how difficult it'd be-- one resistor wouldn't be too bad-- it's just what it did further down the line that you couldn't test for that i'd be worried about! i had NO idea at the time-- so i had a tech do it-- but ask! somebody might know what the possible outcomes of a fried resistor'd be and give you things to look out for.. drain your caps! Link to comment Share on other sites More sharing options...
Members skaaks Posted September 16, 2008 Members Share Posted September 16, 2008 I had the same thing happen to my amp. I could definitely tell it was blown because it had split into two pieces. I replaced it myself which wasn't too much of a difficulty. Just make sure to drain the big power supply capacitors before you do anything. I used a high wattage (10-25 I think) resistor with alligator clips attached to the leads to do it. Unsoldered the old one and soldered in the new one with no problem. Replaced the tubes and fired it up and it worked like a champ. Good luck w/ yours! Link to comment Share on other sites More sharing options...
Members phyrexia Posted September 16, 2008 Members Share Posted September 16, 2008 I traded a box for four resistors and did it myself, then put a spare set of tubes in the amp. Checked bias and plate voltage before running the amp hot again. Total cost: $0 Skaaks, mine was in two pieces as well. It was very obvious what the problem was. Link to comment Share on other sites More sharing options...
Members bluesboy Posted September 16, 2008 Author Members Share Posted September 16, 2008 thanks guys Link to comment Share on other sites More sharing options...
Members 496dart Posted September 16, 2008 Members Share Posted September 16, 2008 they are real cheap , might as well do all 4 . I get those for about $1 each , 5watt 1k Link to comment Share on other sites More sharing options...
Members tommythelurker Posted September 16, 2008 Members Share Posted September 16, 2008 It's not uncommon for a power tube to take out it's screen resistor when it goes bad, which is why you're supposed to replace power tubes regularly instead of waiting till they fail completely. You can't just replace the resistor though, you have to grind up the bones of a bats wing and spread the dust over a sacrificial lamb during a full moon the night before you replace it. Link to comment Share on other sites More sharing options...
Members bluesboy Posted September 16, 2008 Author Members Share Posted September 16, 2008 It's not uncommon for a power tube to take out it's screen resistor when it goes bad, which is why you're supposed to replace power tubes regularly instead of waiting till they fail completely. You can't just replace the resistor though, you have to grind up the bones of a bats wing and spread the dust over a sacrificial lamb during a full moon the night before you replace it. wow really? THANKS Link to comment Share on other sites More sharing options...
Members n0fx Posted September 16, 2008 Members Share Posted September 16, 2008 If that's true, hope you have a schematic. Obviously you'd need to knowthe value of said blown componets. Some PCB's have the value ofthe component silkscreened right there. Link to comment Share on other sites More sharing options...
Members tommythelurker Posted September 16, 2008 Members Share Posted September 16, 2008 Resistors usually have the value right on them. They can also be easily measured. There's probably at least one good screen resister he can check to get the value. And TSL schematic is easy to find on the web. And even if he couldn't find a schematic or determine the value, 1k 5W is a pretty safe guess. Link to comment Share on other sites More sharing options...
Members Johnny Z Posted September 16, 2008 Members Share Posted September 16, 2008 Usually it's caused by a short in the tube, which takes out the grid resistor. I haven't done any TSL amps I'm thinking it has EL34's, usually they run a 1K (1000 ohm) resistor 1 to 5 watt, not sure. If it has 6L6's or 6V6's it should take a 480 ohm and usually 1-2 watt is all you need. This is a good time to learn something about how tube amps work. I advise you get the tubes tested before doing anything else. Link to comment Share on other sites More sharing options...
Members 9ball Posted September 16, 2008 Members Share Posted September 16, 2008 This is a good time to learn something about how tube amps work. Link to comment Share on other sites More sharing options...
Members bhsbhswarp Posted September 16, 2008 Members Share Posted September 16, 2008 if you don't know your way around the inside of a tube amp DON'T {censored} WITH IT!there is voltage in there that can kill you. Link to comment Share on other sites More sharing options...
Members Johnny Z Posted September 16, 2008 Members Share Posted September 16, 2008 if you don't know your way around the inside of a tube amp DON'T {censored} WITH IT!there is voltage in there that can kill you. So you discharge the amp. Nothing to fear. Link to comment Share on other sites More sharing options...
Members 9ball Posted September 16, 2008 Members Share Posted September 16, 2008 what do they have capacitors inside tube amps for anyways? it's not like you need them to help turn it on... you leave it in standby for a minute or two Link to comment Share on other sites More sharing options...
Members tommythelurker Posted September 17, 2008 Members Share Posted September 17, 2008 what do they have capacitors inside tube amps for anyways? it's not like you need them to help turn it on... you leave it in standby for a minute or two http://www.tpub.com/neets/book7/27e.htm http://en.wikipedia.org/wiki/Rectifier#Rectifier_output_smoothing Link to comment Share on other sites More sharing options...
Members Rich Posted September 17, 2008 Members Share Posted September 17, 2008 what do they have capacitors inside tube amps for anyways? it's not like you need them to help turn it on... you leave it in standby for a minute or two They are in their to keep HC kids out of them. Link to comment Share on other sites More sharing options...
Members ZCat Posted September 17, 2008 Members Share Posted September 17, 2008 they help with capacity and stuff Link to comment Share on other sites More sharing options...
Members Johnny Z Posted September 17, 2008 Members Share Posted September 17, 2008 what do they have capacitors inside tube amps for anyways? it's not like you need them to help turn it on... you leave it in standby for a minute or two Different kinds of caps do different things in an amp. Changing the values of certian caps can change the way the amp works. Not something I can explain to you on this forum. Trust me once you know them you'll love them. Link to comment Share on other sites More sharing options...
Members 9ball Posted September 17, 2008 Members Share Posted September 17, 2008 i'd also like to know why a rectifier is called a rectifier- do they change the A/C current to D/C inside of themselves and run on D/C? Link to comment Share on other sites More sharing options...
Members 9ball Posted September 17, 2008 Members Share Posted September 17, 2008 They are in their to keep HC kids out of them. so what you're saying then is that they're TARPS? :oh Link to comment Share on other sites More sharing options...
Members Cyber_Chyld Posted September 17, 2008 Members Share Posted September 17, 2008 I had to change a screen resistor in my 79 twin when a POS chineese output valve blew. And I do mean blew! Flashed white like a lightbulb, the amp went bang and smoke started rising out of it! Very Rock and Rol! It was VERY obvious that the resistor had gone when I took the chassis out. It was all blackened around the valve base of the valve that had blown. I simply read the value off one of the other screen resistors and changed it over. Dead easy, and probably a 20 minute job tops, including taking the chassis out and putting it back in again Link to comment Share on other sites More sharing options...
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