Troubleshooting 4
S-Series Oscilloscopes Service Guide 59
 
Using the Power Fault LEDs
A series of 16 LEDs is separated into four sections of four LEDs each, with the 
over-temperature LED by itself at the bottom as shown in the following figure.
By looking at the pattern of LEDs that illuminate briefly after a power failure, you 
can determine the cause of the fault.
The LEDs are interpreted in groups of four. The upper two LEDs in each group 
indicate the type of failure and the lower two LEDs indicate the source of the 
failure. 
In most cases, LEDs from only one of the four sequencers will be lit and the others 
should all be off. If a shutdown occurs, use the following tables to decode the 
LEDs. If a supply is causing a fault, check its inputs (incoming voltage, enable line, 
clock) and the load (in case it is drawing too much).
Fault Type LED1 LED2
Sequence ON ON
Reset ON OFF
Command OFF ON
External OFF OFF