Received this amp for repair. Being a Zed Audio Revision A board, this amp has a few dozen post-manufacturing modifications but was also apart before me.
At first I found a few straight forward things wrong with it; D10 blown open and a resistor under the board detached from Q122. D10 is a HER106 and is connected to Q120. I figured since the resistor was detached that caused D10 to blow open. Also R15 & R16 have been replaced with two parallel 10w 150ohm resistors.
I replaced D10 and D11 with 1N4004 as that is what I had close to HER106.
Out of the sync I got the amp to work and so I put it back in the sync.
The amp will play both channels, but when it starts to draw about 10A of current; the R15/R16 resistors start to smoke up and all of a sudden I measure ~50+vDC across these resistors. The new D10 also cracked and will need to be replaced again. It doesn't matter if I put the load on Right or Left channel - the amp still "locks up".
Q120 is a 2SC2238
Photos next post
At first I found a few straight forward things wrong with it; D10 blown open and a resistor under the board detached from Q122. D10 is a HER106 and is connected to Q120. I figured since the resistor was detached that caused D10 to blow open. Also R15 & R16 have been replaced with two parallel 10w 150ohm resistors.
I replaced D10 and D11 with 1N4004 as that is what I had close to HER106.
Out of the sync I got the amp to work and so I put it back in the sync.
The amp will play both channels, but when it starts to draw about 10A of current; the R15/R16 resistors start to smoke up and all of a sudden I measure ~50+vDC across these resistors. The new D10 also cracked and will need to be replaced again. It doesn't matter if I put the load on Right or Left channel - the amp still "locks up".
Q120 is a 2SC2238
Photos next post
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