banditnga Posted December 2, 2009 Share Posted December 2, 2009 Ive got a V2 Valve jr combo amp. Its got a hammond 125ese OT. I just bought the supro style board from watts tube audio. Problem is the sound is maybe a tenth of what it was before. the tubes also look like they maybe glowing brighter than usual. i got rid of the pc 3 prong and wirred a cord to the switch. I have alot of left over power transformer wires 3 blue, 1 brown, 1 white, 1 black. Ive kept the volume pot off the chassis cause im mounting everything in a special cab. the center of the pot is going to the 12ax7 and one wire to ground one to the board. here is a link to the wirring diag i followed http://turretboards.com/layouts_schematics/vjr/vjr_layout_main_suprolicious_el84.pdf any help suggestions? Link to comment Share on other sites More sharing options...
cGil Posted December 2, 2009 Share Posted December 2, 2009 Look for a connection problem around the volume pot or the coupling caps and resistor network leading to it. If there's a break in the circuit, the signal will just ride the rail from the 1st gain stage's plate resistor, and sneak in through the second. Hence the volume drop. Also, look for a bad connection on pins 2 and 3 of the el84, as that can make them kinda angry and hot under the collar. Gil... Link to comment Share on other sites More sharing options...
peeper Posted December 3, 2009 Share Posted December 3, 2009 Have you tried re-flowing your solder? It sounds like you aren't making a connection somewhere. Link to comment Share on other sites More sharing options...
banditnga Posted December 3, 2009 Author Share Posted December 3, 2009 ive tried reflowing the solder no luck. looks like the output tube is glowwing good but im getting very little from the 12ax7 Link to comment Share on other sites More sharing options...
jefrs Posted December 7, 2009 Share Posted December 7, 2009 Then you are going to have to trace the signal back from the output valve to find the fault, just don't do it with your finger. Do you get output if you put some sort of signal directly on the EL84 input grid (R15), between the ECC83 on the vol control (VR1), at R6 or R2. Without a signal injector, I'd use an insulated probe and wire (antenna) to get some sort of a buzzing from the output. Double check your HT voltages, the bottles should not be glowing ever-so very bright, just the heaters. Re-seat your bottles, swap the bottles. First find the fault. Link to comment Share on other sites More sharing options...
cGil Posted December 7, 2009 Share Posted December 7, 2009 Tube filaments are like basically little light bulb filaments at low voltage, so they need to glow a bright yellow. It's when the plates start glowing red that you gotta worry. No glow is bad, but red plating is worse than no glow at all! Here's some examples of what tubes look like when they glow. Your typical 12ax7 http://en.wikipedia.org/wiki/File:Tubes.jpg And down at the bottom of this page is a pretty good pic of a tube that's red plating. http://thetubestore.com/blueglow.html And a whole bunch of cool looking gassy tubes! http://www.jacmusic.com/html/articles/blueglow/blueglow.htm Jefrs' right. Just take it slow, follow the schematic as you confirm every component, wire, and all their connections on the board. The bright side is that you'll come out the other side with a working amp, and a better understanding of the circuit. Gil... Link to comment Share on other sites More sharing options...
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