pittsburgh
Well-known member
I'm modifying a tape deck to make a tube pre amp. I've run into a heat issue at R57. When turned on the resistor heated up beyond normal operating levels and began smoking. I checked the resistance level and noted a level around 330 Ohms. The recommendation for that resistor is 270 Ohms. I put in place another resistor rated at 270 Ohms/1%/1W and had the same result. Lots of heat, and the exterior paint of the resistor started to turn black.
Could other resistors around the tube be a factor? The resistor level at R58 is 37K/ v. the 33K schematic, the level at R59 is 440 Ohms v. the 390 per the schematic.
I have had not had the same issue with R23 which is the right channel of the pre amp. I changed out the stock resistor on that side at the same time that I replaced R57 on the left channel.
I have modified the output of T3 and T2 I've taken the yellow lead and put 10 Ohm 3W resistors in series and send them to new 1/4" female Jacks that have an earth ground. Could this modification possibly be causing the failure at R57?
I've put a PDF of the schematic on my idisk. If you have ideas and would like to help this link should automatically download the file to your computer. http://files.me.com/natesbasement/5w2n0v
Thanks for the help.
Could other resistors around the tube be a factor? The resistor level at R58 is 37K/ v. the 33K schematic, the level at R59 is 440 Ohms v. the 390 per the schematic.
I have had not had the same issue with R23 which is the right channel of the pre amp. I changed out the stock resistor on that side at the same time that I replaced R57 on the left channel.
I have modified the output of T3 and T2 I've taken the yellow lead and put 10 Ohm 3W resistors in series and send them to new 1/4" female Jacks that have an earth ground. Could this modification possibly be causing the failure at R57?
I've put a PDF of the schematic on my idisk. If you have ideas and would like to help this link should automatically download the file to your computer. http://files.me.com/natesbasement/5w2n0v
Thanks for the help.