On my last post, I have a theory that DC protection is kicking in for this Crown XLS 202 amplifier and that is what’s causing the FAULT condition.
So now, it’s time to open up this amplifier and verify that theory.
NOTE: You need star-security bits to open up the cover on this amplifier. Good thing I have some of that special screw driver heads in my shop.
They basically look like this:
Since this is my first time repairing this amplifier, I want to be able to put everything back together properly and taking lots of pictures of everything helps me figure out where things need to go. I can’t rely on my memory to remember stuff.
So open up the top cover and let’s do what I call a VISUAL and SMELL check.
1. VISUAL check: Does something look out of the ordinary? Are there bulging capacitors? Blown out fuses? Are there loose wires, disconnected wires? Is there foreign matter inside the case that’s not supposed to be there? A piece of wire, paper clip, aluminum foil that may be causing a short?
2. SMELL check: Does it smell burnt? Are there black charring or burned out resistors or components? Sniff around and check if it has that burned out smell.
For this amplifier both kinds of tests, pass. So now let’s see if we can do some voltage checking without disconnecting everything.
Some photos:
The power input and XLR input section.
The binding posts and output Speakon connectors. They’re just wired in parallel.
Bird’s eyeview of the main amplifier board. 
Another view of the board, here you can see the output inductors.
These are the comparator chips for the “logic” control of the relays and fans. 
A nice big heavy power transformer. 
That black square component beside the inductor is the output relay that disconnect the speakers from the amplifier if there is a FAULT condition.
There is a glue-like substance around the wires. I guess this offers additional mechanical support for the wires so the individual copper strands don’t weaken and possibly break off. 
There is a gray ribbon connector on the board, but no jack connector is used. Instead, the ribbon wire is soldered directly to the board and a good amount of “goop” is also applied to it making a strong connection. — I really hope I don’t have to remove any of these stuff!
to be continued…
