I have two Pyrotronics/Siemens SXL-EX boards with no display. The problem started when someone tried to use the 24 volt battery charging circuit. They used this same power on the alarm contacts on the board to energize a solenoid upon alarm. This may have worked in the past but I found the batteries were very old and maybe created a surge when the panel would go into alarm. When it went into alarm the board went out.
Long story short: the panel shows no display, not even the AC led illuminates. The zones have no output voltage. However the charging circuit still works. The 2 fuses are good and did not blow. There are no burn marks or anything one the board. This happened to two panels before I moved the solenoid circuit to a separate 24 Volt power source.
Anyone know what component may be bad and preventing the displays from working ?
There should be 3 fuses on the SXL-XMAIN board: F1 for AC input, F3 for the charging circuit, and F4 for the AUX power. You cannot visually inspect the F3 fuse, but if the charger is operating this is moot.
Does the “CPU FAIL” light above the zone terminals illuminate? Does pressing any of the keyboard keys result in a response from the panel piezo?
As I said before, there is “NO display” anywhere.
I get no response when I press any of the buttons.
Where is F3 located?
I was wondering if it could be one of the many IC chips ? This same thing happened on two different boards. Has to be a component somewhere !
The F3 fuse is located directly below the F1 AC Input fuse.
What revision are your SXL boards? The board in my panel I am referencing is the newest version of the panel board. Several older versions of the XMAIN board exist that are quite different.
Thanks for the reply,
I have all the fuses and their locations and they are good.
Amazing how a $500 circuit board will protect a 30 cent fuse…lol…
The revision numbering the Chip is
SXL.EX U9
REV 2.2
161-595990.
Tried posting a picture but was unsuccessful.
Thanks again.
Thanks, I have a manual. It doesn’t provide to much technical info or list the problem of a “half dead board” The charger circuit works, I have voltage at B+ & B- Have a supervisory voltage on both NAC terminals BL1 & Bl2.
No lamps or digital display light up.
A schematic would be much more useful.
Well thanks to all for their inputs. I’ll keep on digging.
It seems the most likely culprit would be the L296 step-down regulator at the top-right hand corner of the board. This, and associated external circuitry, provide the low voltage power to the CPU chips, display, and IDC circuits (zones), all of which you say are inactive. The circuitry that uses the main 24V power feed from the transformer and LM317K regulator, NACs, battery charger, etc, are still active.
With that in mind, I still think it’s safe to say that the boards have sustained significant damage and most likely cannot be recovered. The solenoid being connected to the batteries terminals would have forced high voltage and high current spikes through the board when it went into alarm. Both the inrush current and the EMF voltage spikes when the solenoid was powered down could have damaged any number of components in addition to the L296 regulator.
Thanks for the reply.
I have been trying to get in touch with Siemens ( the manufacturer) for some input but had no luck as of yet.
I would think they would have engineered a few diodes on the board to prevent this problem.
As I said earlier, a five hundred dollar circuit board sure protected a few thirty cent fuses.
I will post again if I find a solution to this problem.
There are plenty of components to prevent damage to the board. The problem is that the connections that were made to these boards were so far out of line from the correct practices, that it was no longer protected. The designers can’t anticipate everything, unfortunately. Especially when considering the intended operators of these systems are trained professionals.
If the connections are made properly, the boards can handle a few wiring mistakes. Once things start getting wired into where they should never be, all bets are off.
You could contact International Systems of America. They offer repair services on boards from various manufacturers, including Siemens. http://www.isa-net.com/fire/repair/
Repairing a fire alarm system board brings on a great amount of liability. In your case the board was damaged by possible overloads and/or EMF spikes from an incorrectly connected solenoid. It is possible that replacing a power supply regulator might bring the display back up and make the board appear to be working correctly. However there could be hidden damage in other components that might not be evident until the board is called upon to perform all the functions required in an alarm situation. If it failed to work correctly during an alarm the person who repaired the board could be on the hook for an untold amount of $$ in liability damages.
