Low SLC Voltage MS9200UDLS

Fire Alarm Help
1

Hi all,

I’ve got an MS9200UDLS rev B board with a steady SLC voltage of around 6.5 volts on both the A and B circuits, although there is no SLC short or ground fault troubles on the panel. I was wondering in the slim chance that anyone has repaired these boards before or seen this issue before, if there’s a specific component (like a voltage regulator) that could be faulty. The only two components that were visibly broken was the top-right relay and varistor – I replaced both but am still only getting like 6.5v. Or, on the off chance that someone has a schematic for the board let me know as well. Thanks

2

Is the voltage without any devices on the slc port?

3

That is remarkably low, even for SLC. I agree that the first thing to figure out is if it remains low with no devices. If not, then there’s obviously something on the line (possibly a resistor if the system was converted from conventional… I’ve certainly seen it before) that’s causing the voltage drop. Unfortunately it may be going device by device to figure out where the problem is.

4

Yep, voltage with no load is still in that 6.5-6.6v range. Looks like I’ll be doing more digging on the board to see where it drops, if anywhere