Another Crown 602

[Ancient Engineer]

Hello everyone, I'm new to this particular forum, but have many years experience on repair & installation of audio & video electronics, in the broadcast industry.

I took on a Crown XLS 602 for a friend, thinking that it would be like Amcron amplifiers I used to work on, however having read most of the relevant existing info I now know different...
The one in my posession is exhibiting all the signs of s/c output devices, except that they are not! Powering up just leaves the PTC on the soft start getting hot, as obviously there is a problem, so the relay does not close. Disconnecting the mains TX HV secondary from the bridge, results in all the earlier stages coming to life.
There are no measurable shorts on the HT rails at all.
Presumably something is turning hard on once HT is applied.

The correct circuit diagram would help, the ones I have seen do not exactly match the unit I have, which was manufactured in 2007.

Before I get the variac out, has anyone experienced anything similar?
Thanks,
David.

[pinkmouse]

Hi David, the one I had I recycled as it was just too much effort to fix!

That aside, if the outputs seem fine, the first thing I'd check would be the protection circuitry, starting at the output relays and working back. If that all works, then it's down to pulling and testing transistors I'm afraid.

The schematic I have has drawing number C1071-6 if that's any use.

[ohio buck]

Check here, might be of help to you.
Discontinued Amplifier Products
Best of luck to you. John

[Ancient Engineer]

Thanks both, for such a speedy reply, much appreciated. I am most impressed!

The 602 appears to be a current product, so unfortunately, the relevant cct diagram was not there, in the discontinued product page.

It sounds as though I will as you suggest, have to work my way through the "protect" circuit, which was what I had initially thought when I first started on this beast.

Al, I would appreciate the diagram you mention, it may be relevant.

Thanks again,
David.

[djk]

Crown will send you the schematic for current product if you request it, Kevin sent me one this morning.

Kevin B Gring

Field Support Technician

Crown Audio



1718 W Mishawaka Rd

Elkhart, In 46517

Phone: 574-294-8006

Toll Free: 800-342-6939

Fax: 866-762-2862

Email: kevin.gring@harman.com

Web: HARMAN - Premium audio and entertainment for automotive, home, and professional. Speakers, amplifiers, headphones, microphones, home theater and personal audio.

www.crownaudio.com

[Ancient Engineer]

Thanks very much indeed, I will try contacting Kevin, again - I had previously sent an email but as yet had no reply.

Have now taken out the main PCB, & definitely no s/c on any of the output devices, so am pursuing the protection circuit , which will no doubt be easier with the correct schematic.

Thanks again to all who have replied, much appreciated.
David.