I found this site because I blew my 225 HCCA a few years back, and I just found it in the closet and want to fix it. This amp is a classic and I'd love to hear it again!
I took it apart, I found 2 transistors were blown, both NDP7060, I know they're blown because there is burn marks shooting out of them, lol. I would like to know if there is any other components that could have blown too with these? There is no other burn marks anywhere else on the board. FYI the board is the XTR275 REV. C if that helps out at all. When holding the board component side facing, with the words in the lower left corner. The blown transistors are in the lower right corner.
I took it apart, I found 2 transistors were blown, both NDP7060, I know they're blown because there is burn marks shooting out of them, lol. I would like to know if there is any other components that could have blown too with these? There is no other burn marks anywhere else on the board. FYI the board is the XTR275 REV. C if that helps out at all. When holding the board component side facing, with the words in the lower left corner. The blown transistors are in the lower right corner.
All of the NDP7060s need to be replaced.
The driver transistors MPSA06/A56 may be damaged. These will be connected to the gates of the NDP7060s via 10 ohm resistors. There is a 10 ohm resistor between the collector of the MPSA56 driver transistors and chassis ground. Sometimes they open or change value. Also check all of the gate resistors for the NDP7060s after you've removed the FETs (NDP7060s).
It's possible that the audio output transistors failed and that's what caused the power supply to fail. Check them. They generally show a direct short between legs 2 and 3 when they fail.
The driver transistors MPSA06/A56 may be damaged. These will be connected to the gates of the NDP7060s via 10 ohm resistors. There is a 10 ohm resistor between the collector of the MPSA56 driver transistors and chassis ground. Sometimes they open or change value. Also check all of the gate resistors for the NDP7060s after you've removed the FETs (NDP7060s).
It's possible that the audio output transistors failed and that's what caused the power supply to fail. Check them. They generally show a direct short between legs 2 and 3 when they fail.
So as it seems, here in canada no one has or even knows of the NDP7060. Is there a different kind I can use?
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