I just finished putting a G9 together. Then I powered up for the first time, the tubes heat up, the light comes on and everything seems to work. But when I hook up a microphone and turn up the gain and output, the output seems to work reverse turning and when I turn up gain beyond 5 or so I hear a horrible high squealing noise. Other than that there is only a (very faint) signal coming through. I already checked about the output pot wiring, that should be ok.
Now I suspect that maybe I made a mistake hooking up the two 10-pin wiring connectors from the main pcb to the control pcb´s.
On the schematic the main pcb connector says (from right to left) : To Outamp / Trafo - / Trafo + / Out - / Out + and so on ..
On the control pcb is written (from right to left): To Outamp / OUT - /OUT + /Trafo - /Trafo + / and so on ...
So the Trafo -+ and the Out -+ should be twisted? But I just wasn´t sure about this and hooked them up straight. So can it be that I made the big mistake there? I´d like to ask before I take it all apart again, as I said I was really not sure about this when I put it together.
Once I get it working and my knobs arrive I will post pictures soon.
thanks for any help,
Thanks for posting your results. I just had the exact same problem which was resolved exactly the same way. One channel is still dead but it's most likely just a bad connection somewhere.
Sorry for bumping such an ancient thread, but I'm approaching this point in the construction of my G9.
If I understand the discussion correctly, the wiring from the main PCB to the control PCB's, XLR connectors, and power transformers seems fairly idiot proof. Simply make sure the 10-pin connectors between the main and control PCB's match wire-for-wire (no crossovers). The XLR in's and out's seem just as simple. Just follow the legend for those.
As far as the instrument jack, I can see where a good look at the schematic is in order, but everyone else seems to have figured it out with a minimum of bloodshed.
Have I missed anything??
Jakob, it looks to me like you've taken most of the guesswork out of this design, and I salute you for that!
I'm in the home stretch. I just have to get my tubes and my audio transformers, and she's as good as done!
P.S. I certainly don't mean to suggest that those who've had trouble are idiots. I had many of the same doubts. I tend to over-think these things and get myself into trouble. But then again, are you really paranoid if they really are out to get you??