62 S-Series Oscilloscopes Service Guide
4 Troubleshooting
 
Sequencer Group Faults 
Sequencer 1 Group Faults  If the fault occurs in the first group of LEDs 
(Sequencer 1) then the problem is with the 12 V bulk power supply, the power 
cables, or the acquisition board. You should check the power cables first, then the 
bulk power supply, and finally the acquisition board. Reinstall any power supplies, 
cables, or acquisition boards that turned out not to be the problem.
Sequencer 2, 3, or 4 Groups Faults  If the fault occurs in any of the other 
groupings, the problem is most likely the acquisition board. If replacing the 
acquisition board does not fix the fault, the power cables may be causing the 
problem.
Over Temp LED Fault  If the Over Temp LED is lit, first make sure the air flow is 
not blocked. The oscilloscope must be placed directly on a hard, flat surface with 
nothing under it (such as a piece of paper) that could block the vents. There also 
must be proper clearance behind the oscilloscope. 
If the clearance is adequate, then investigate the fans. If one or more are not 
turning, the problem is with one or more of the fans or fan cables. 
If the oscilloscope still will not power on after you have followed the required 
steps, refer to the “Motherboard Troubleshooting” section in this chapter for more 
diagnosis suggestions.