I just finished a 4 6L6 Non-HRM that has a problem with the phase inverter plate voltages. I can't figure it out. Here are the Plate voltages:
194, 196
196, 202
261, 431
6L6's have 450V and 44ma
I tried to take some pics that may uncover a problem but I have searched. If I could get some input to try and look at this from a different light that would be great. Thanks for you time. In terms of sound I get signal through but it is weak. Thanks for you time!
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That doesn't make any sense. What's your B+3 voltage? Did you wire you B+3 right to one of the PI plates instead of the trimmer wiper?
Thats what I thought too but there is no continuity between the B+3 which is a couple of volts higher than that and the PI plate point. I will check this again just to be sure.
I will also reheat my solder connections again and see if there is a problem there. Thanks for the suggestions guys keep em' comming.
Last edited by tonejunkie on Mon Jan 28, 2008 10:51 pm, edited 1 time in total.
Forgive me if this schematic does not match yours (it's #124) but do you have a voltage drop across the 120K resistor. If there were little or no current flow through this resistor (as in no cathode current flowing through the tube) there would be very little voltage drop. I'm reading between the lines on your post and it seems there is just a little drop in voltage. So, as pointed out make shure the path from cathode to ground is OK on each side. Just based on the #124 schematic, the path from cathode to ground would be 820 + 24K + 390 and should be the same for each PI tube cathode.
It would be interesting to see on your schematic how the voltages compare from side to side across each component from B+3 to each PI plate.
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Last edited by ic-racer on Tue Jan 29, 2008 12:37 am, edited 1 time in total.
Do you have a supply wire laying against the underside of the board that got soldered (solder bridge thru the insulation)) along with the RP connection by mistake?
I ended up taking out the plate wire thinking that Histhl was correct. I did not see any bare wire so I don't think that was it. Then I said and replaced the tube socket. Viola
New Voltages:
188, 193
193, 200
301, 302
and the same bias.
Now I have some pretty horrible distortion on the clean channel which I will trouble shoot next weekend. I have no more time. Thanks to you guys one problem down the next one to go. Thanks again.
Next weekend turned into next month. My next problem is the clean channel is very weak especially for a 100 watter (less than champ loud at at volume and master at full) then when I switch in the OD it can only be on OD at 9 o clock and OD Master at 9 o clock and it is louder than the clean channel. I will be checking the circuit several times in the next couple of hours but if anyone has some troubleshooting ideas for me that would be great. Thanks
I think I found it. I had been lookin at this for a while today and I knew that if I posted somthing either someone would lead me to the aha or I would find it. I put 200k resistors in the loop on v1b. I will be tweaking now and when that begins maybe a new post is in order. Another working dumble what a great feeling.
and see if there is a problem there. Thanks for the suggestions guys keep em' comming.
