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Crown XTI 4000 burning smell; flickers on and off


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#1 yogithecamel

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Posted 04 July 2014 - 07:00 PM

I've had this amp for 3 years and it has less than 25 hours of use (I know!). I've been super busy with work and I've been using smaller speakers to practice with the band. The XTI was in a clean environment so I don't understand how this happened. Anyways I go to power it up and everything is working as it should until it makes a crackling sound and I immediately turned it off. I try it again and the display just flickers on for a moment and then turns off. After this second attempt I can smell smoke and I knew something wasn't right. My XTI has a build date of 11/29/2009 and the Crown website has confirmed it could be an affected unit. I know I'm out of my 3 year warranty window. Am I SOL?

I popped off the top cover and I couldn't find anything that looked burned. The only thing I could remotely find was this transformer; if you look closely it looks burnt on the right side at the bottom. Any help/guidance would be awesome. I've built my own tube amps for guitar but I know this a lot more complicated than a Marshall Plexi.

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#2 joust

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Posted 07 July 2014 - 09:08 AM

Hello!

You may have had an output fault. This fault has to be cleared (replace defective components) before the amplifier can power up normally.

- Verify the tracker modules : make sure there is no shorted components; If tracker is short, remove module, recheck o/p devices, make sure the green Silpad is not compromised;
- Verify the o/p devices; If found short, remove the heatsink;
- Verify the driver transistors; If found short, verify the string diodes, located between the o/p heatsinks;
- Verify the smps IGBTs; If found short, replace modulator and buffer;
- Verify C196 : If out of tolerance (220uF), replace cap.

Hope this helps!

Alain