briantf27
100+ Head-Fier
- Joined
- Jul 29, 2001
- Posts
- 247
- Likes
- 11
Hey all,
Been a while since I've on the forums here, and I wish I were back under better circumstances...
In any event, my 1.5 year old MG Head DT (not the OTL) has started acting up just today. It is basically distorting all over the place... It sounds like clipping to me.
Some info: I removed the NF loop about a year ago, but never made other mods (I meant to replace the coupling caps but never got around to it). I've reverted back to the original tubes (the Sovteks and JJ) since they have never been used. The problem is real (not a tube problem)
So I thought maybe there was a high voltage problem. I probed the board in a few spots, and the voltages seemed OK. I probed around R13, R14, R15, and R16. Also probed the plates of the 6BQ5s at pins 7, and on the 12AX7 pins 1 and 6. Everything seems to check out there.
What next? I doubt the mylar caps are bad (in fact I don't know what the failure mode of mylar caps would be). Perhaps the C7 and C8,C9,C10 10uF and 100uF caps?
Ideas?
Thanks!!!
Brian.
Been a while since I've on the forums here, and I wish I were back under better circumstances...
In any event, my 1.5 year old MG Head DT (not the OTL) has started acting up just today. It is basically distorting all over the place... It sounds like clipping to me.
Some info: I removed the NF loop about a year ago, but never made other mods (I meant to replace the coupling caps but never got around to it). I've reverted back to the original tubes (the Sovteks and JJ) since they have never been used. The problem is real (not a tube problem)
So I thought maybe there was a high voltage problem. I probed the board in a few spots, and the voltages seemed OK. I probed around R13, R14, R15, and R16. Also probed the plates of the 6BQ5s at pins 7, and on the 12AX7 pins 1 and 6. Everything seems to check out there.
What next? I doubt the mylar caps are bad (in fact I don't know what the failure mode of mylar caps would be). Perhaps the C7 and C8,C9,C10 10uF and 100uF caps?
Ideas?
Thanks!!!
Brian.