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Member Since 01 Mar 2007
Offline Last Active Jun 07 2013 02:37 PM

Posts I've Made

In Topic: Crown XTI 2000/4000

03 June 2013 - 10:14 PM

I guess I will try to follow the "Kick start" routine and try to replace a couple of things...

Kick start
Once voltage is present on U14, switching begins. The clock frequency is determined by C69 and R367 and oscillates at approximately 250-260kHz. 180-degree phased clock signals are provided to U18 for generation of the low and high side gate drive waveforms on pin 7 and 5, respectively. The transistors Q26-Q30 serve to increase the current drive to the IGBTs Q28 and Q31.
Switching commences for the time allotted by the discharge of C196, or approximately 100mS. During this time period the IGBTs transfer energy from the primary bulk storage (C57-C60) and the AC line through the resonant tank (C68 & L3) to the transformer, T1. The energy is magnetically coupled to the secondary of the transformer and hence C43-C48.

Energy is also transferred back to C196 through D26. If the voltage at C196 is
maintained at a point greater then the lower bound for the Vkstart sense comparator, U16B, then the controller circuitry becomes sustained by the converter itself and the kick start cycle is terminated. If for any reason the converter does not sustain the voltage on C196, the kick start cycle will repeat indefinitely approximately every 500-800mS.

             I will try the easy to find first (C196, D26). It looks like C196 is the one 'deciding' if the amp finishes the startup sequence... I will measure voltage at C196, if its ok I will replace it.

In Topic: Crown XTI 2000/4000

03 June 2013 - 07:17 PM

Same issue no matter how many amps are powered.

In Topic: Crown XTI 2000/4000

03 June 2013 - 09:46 AM

Well, this issue continues to be a problem. 3 XTI 4000 and 1 XTI 2000 on the same rack and all connected to same AC. When power is 100% all amps work fine. If power is not great, lets assume an 9 out of 10 (voltage about at 112 instead of 120+), one of the 4000´s fails to start. It turns on but never completes start up , shutting off right before it should open the channels(turn green). The reason I am posting again is that I had two amps fixed and are no longer having power up issues. The problem was that the service center replaced main boards on both amps, which is very expensive compared to the current price of these amps, specially used ones. Does anyone out there know where in the amp I should look to get this fixed? I would imagine that the power supply is detecting voltage that is lower than the actual one... I really dont care If I do something that completely breaks the amp, as I will apparently have to replace the mother board again....