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joust

Member Since 02 Dec 2004
Offline Last Active Apr 16 2015 09:24 AM
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Posts I've Made

In Topic: PSA-2

16 April 2015 - 09:27 AM

Verify low voltage psu : Make sure that the filters are filtering and that you have all the pertinent voltges : +/-15V, +/-20V
Verify high voltage psu : Make sure +/-75V is available to both channels; Make sure ripple is minimum.
Verify that C4 (8uf 250V) is within tolerance; It may be resistive!
Also, the fact that the 387 ohms is shorted out, you may have shorted driver or output devices.
You should have 5,6 ohms (+6 ohms in NPN) at BE junction on the output devices.

A.

In Topic: PSA-2

15 April 2015 - 08:13 AM

Since you've been able to determine that you have DC at the output before the relay disengages, it appears you may have a drive issue, a faulty driver or predriver, or more probable, an open low value resistor. I believe your output devices are probably OK, since you don't mention blown fuses or breaker.

I would also suggest, while you are at it, to remove and clean (if necessary) all devices in contact with the heatsinks. If you have mica type isolators below the output transistors, to replace the isolators with silicon fabric isolators.

Hope this helps!

Alain

In Topic: XLS 2000 Fault 21/99,26/99.....please help!

14 April 2015 - 07:41 AM

Is it possible that the XLS unit is still under warranty?
Check the date code on the serial number sticker. Also, if you still have your sales receipt, AND it is within three years it may be possible to send unit in for warranty checkup and repair.
What is the date code on the sticker? Do you have the original sales slip and is the purchase date within three years?

A.

In Topic: Xti 4002 dead beyond repair?

10 April 2015 - 11:17 AM

Hourah for Crown! As I mentionned before, Crown has one of the best warranty service that you can have. I am proud to be affiliated with these guys! :)

A.

In Topic: Crown xti 4000 RBV5006 failure after breaker pop from the mains

10 April 2015 - 11:12 AM

Hello Raimo, That must have been a bad scene! I hope the rest of the equipment faired better than the XTI! :) As I have mentionned often in the past, if you need to go to 4 ohms Bridge (2 ohms per side in Dual mode) be extremely carefull with overdriven signal. Potentially, 3200 watts! Just for the amp, you'll need a 10 to 15A breaker! Furthermore, that's a lot of heat to evacuate!

First thing first : Locate the fault :
Verify the 2 Tracker modules at the rear; Components are fets and diodes; Easy to evaluate (for your 'mecanic'; Can he read schematics?)
If evaluation has found faulty devices, remove module and continue : Verify output devices; If faulty devices found, remove heat sink and components;
Verify driver devices; Verify for shorts; Measure B-C: Should read around 430 ohms; Replace defective components;
Verify diode string between heatsinks and replace faulty components;

Verify the SMPS :
Beware of reference measurements! BULK_REF is NOT the LV ground reference but the AC reference;
Note : DO NOT CONNECT SCOPE TO THE BULK_REF TP21 IF SCOPE IS AC GROUNDED!!!

Verify the chopper devices : If faulty, verify and replace (if necessary) gate buffer (FAN7380) and carrier modulator (TL494);
Verify for carrier traces at gate buffer outputs : If successful, replace choppers; If not, continue troubleshooting;
Verify and measure capacitance of C196 (kickstart cap) : Replace if lower than 220uF;

Check the Crowbar circuit! When the breaker enabled, it is possible that the amp may have tried to protect itself by triggering the Crowbar circuit.

Hope this helps!

Alain