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[Eugen Tkachenko]

Hi all,

A Crown XLS-602 has failed in a local church, so I'm trying to troubleshoot it and get it back up and running.

All power supply voltages are present. No speakers and no inputs connected (happens with connected load/input too). Level potentiometers are set at zero on both channels. So far so good. Let it warm up for about a minute. Then raise the level on one of the channels to any position, and protection kicks in within 1-20 seconds, holds for about 10 seconds, then returns to normal.

What could cause this problem? Thank you.

[Mike Caldwell]

Hi all,

A Crown XLS-602 has failed in a local church, so I'm trying to troubleshoot it and get it back up and running.

All power supply voltages are present. No speakers and no inputs connected (happens with connected load/input too). Level potentiometers are set at zero on both channels. So far so good. Let it warm up for about a minute. Then raise the level on one of the channels to any position, and protection kicks in within 1-20 seconds, holds for about 10 seconds, then returns to normal.

What could cause this problem? Thank you.

Just to be clear, with nothing connected to the amp, no inputs and no speakers it appears to work fine, never goes into protection?

After connecting the speaker and the inputs then turning up either level control or is it just one them that will cause the amp to go into protect?

During your test are you sending any program audio to the amp or is the system just powered up but with no audio level?

If the problem is only when the amp is connected to speakers and input cables see what happens when you disconnect the speaker cables but leave the audio input cables connected and turn up the level controls.

[Ray Aberle]

I think, based on his OP, that it does indeed happen both with or without speakers/input connected.

-Ray

[Eugen Tkachenko]

I think, based on his OP, that it does indeed happen both with or without speakers/input connected.

-Ray

Yes, it happens with and without inputs and loads connected. It happens when I turn level pots.

[Ray Aberle]

I would give Kevin Gring at Crown a call/email. He's their resident amp expert.

first name dot last name at harman dot com

-Ray

[Mike Caldwell]

Yes, it happens with and without inputs and loads connected. It happens when I turn level pots.

After you turn up a level control and it goes into protect and then resets itself does it cycle back into protect after so long starting a in and out of protect cycle loop with out touching any of the level controls.

Does it go into protect any time you change the position of a level
control regardless of the controls position before you move it?

When and if the amp is not in protect with the level controls turned up will the amp pass audio and sound good.

This is a long shot guess but maybe there is a bad cap leaking some DC voltage into the input section prior to the level controls and bringing up the level control allows the DC to pass into the amp section.
Finding a schematic would help to take a look at what is going on in the input section.

On the other hand those were very basic low cost amps that would not really be worth putting a lot of deep trouble shooting time into.

[Dave Pluke]

On the other hand those were very basic low cost amps that would not really be worth putting a lot of deep trouble shooting time into.

True enough.  If the unit in question is no longer under warranty, it's probably time to shop for a replacement.

Dave

[Ron Hebbard]

After you turn up a level control and it goes into protect and then resets itself does it cycle back into protect after so long starting a in and out of protect cycle loop with out touching any of the level controls.

Does it go into protect any time you change the position of a level
control regardless of the controls position before you move it?

When and if the amp is not in protect with the level controls turned up will the amp pass audio and sound good.

This is a long shot guess but maybe there is a bad cap leaking some DC voltage into the input section prior to the level controls and bringing up the level control allows the DC to pass into the amp section.
Finding a schematic would help to take a look at what is going on in the input section.

On the other hand those were very basic low cost amps that would not really be worth putting a lot of deep trouble shooting time into.

While we're taking "long shot" guesses, Why not monitor the output with a scope and / frequency counter to see if it's oscillating at a frequency above your hearing and / or its output devices?  I once found a 70 volt amp cooking itself to death oscillating at something like 22 or 23 KHz.  It was one of JR's Loftech TS-1's that put me onto it.
Toodleoo!
Ron Hebbard.

[Eugen Tkachenko]

After you turn up a level control and it goes into protect and then resets itself does it cycle back into protect after so long starting a in and out of protect cycle loop with out touching any of the level controls.

Does it go into protect any time you change the position of a level
control regardless of the controls position before you move it?

When and if the amp is not in protect with the level controls turned up will the amp pass audio and sound good.

This is a long shot guess but maybe there is a bad cap leaking some DC voltage into the input section prior to the level controls and bringing up the level control allows the DC to pass into the amp section.
Finding a schematic would help to take a look at what is going on in the input section.

On the other hand those were very basic low cost amps that would not really be worth putting a lot of deep trouble shooting time into.

I measured DC on the outputs of each channel. Put my meter onto a trigger, because it spikes and protection shuts off the outputs. When pots are at 0, DC offset is 10mV on each channel. When I start moving the pots, DC starts jumping between 0.5V and 3V, stop moving - goes back down to 10mV. But sometimes it just spikes very high (protection instantly shuts it off, I was able to measure 8.8VDC before meter went OL, but it's obviously much higher).

Crown tech support suggested a leaky component or open resistor causing this.

What I don't understand is that this behaviour is common to both channels.

[Dave Pluke]

What I don't understand is that this behaviour is common to both channels.

It's not a "dual mono" amp, it's "stereo".  So, some components (eg. power supply) are shared.

Dave

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