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XTI 1000 and XTI 4000 no power


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#1 luckie_boie

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Posted 10 July 2012 - 08:08 AM

I was working as an ICT support in one university and we are using crown amplifier in all the auditorium and halls for almost 5 years. Recently I have some problem with 3 of the crown device. 1 XTI 1000 and 2 XTI 4000, all are black out or no power. Fuses are intact and I can’t find the component having the issue. Are there any know or particular issues regarding power for this models, because it’s happen all at the same time? Can someone give suggestion or advice regarding the same? Appreciate your help. Thank you.

#2 joust

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Posted 11 July 2012 - 03:37 PM

I would suggest you get in touch with Crown and request the XTI schematics for your units. Usually, the problem is with the SMPS bootstrap circuit. Verify for faulty caps (.1UF SMT)! I'd also make sure that the K-Start cap is within tolerance.

Regards,

joust

#3 luckie_boie

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Posted 12 July 2012 - 01:01 AM

Thank you for the respond. I will check and verify.

#4 jesusm247

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Posted Yesterday, 04:33 PM

hi.
right now i got on my bench this XTi4000 amplifier on which the SMPS wont start. i bypassed the kickstar circuit by applying an external voltage of 15V to turn on the oscillator circuit U14 and U16 and notice some oscillation through the scope.still no outputvoltage and noticed that voltages that feeds Q28 and Q31 drops drastically and RT6 is getting hot. so I am assuming theres a shorted component on the primary section. Joust, could be one of those .1uf caps are shorted? i got the schematic
thanks

#5 joust

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Posted Today, 08:39 AM

One of the best equipment purchase that I've done in recent times is the purchase of a capacitor meter. There's a whole slew of inexpensive meters on the market. For troubleshooting purposes, I highly recommend.
The way I test those .1UF, is to use initially the ohmmeter. I usually read at least a Megohm resistance. If lower, use the cap meter to validate measurement. If the 15V stays stable, then I believe no .1UF are at fault.
Is the amp plugged in? Do you have high voltage? If not, how do you get high voltage to the chopper circuit?
Sometimes, a fault in the output circuitry will be detected (high current in the power transformer circuit) and the modulator won't start normally.
Do you have the 3.3V to the controller section?

A.