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
Last edited:
Hifonics Zeus
1N4004 is a slow diode with 3usec Trr.
HER106 is a 100nsec Trr diode.
Did you honestly expect a 1N4004 to switch at 50KHz?
Zed Audio
Steve Mantz
1N4004 is a slow diode with 3usec Trr.
HER106 is a 100nsec Trr diode.
Did you honestly expect a 1N4004 to switch at 50KHz?
Zed Audio
Steve Mantz
I didn't understand how D10/D11 were actually connected plus the original HER106 blew open prior anyway. Do you have a schematic?
Black soot. The pad cleaned up ok. The leg of the old c2238 did get hot though. This amp passed stress tests pulling about 120A well into clipping at 2ohms per.