5 Blinks SOS (1)
The 5V SOS may be caused by a defective shift register located on a ribbon cable that connects the C
boards to the panel. A shorted shift register typically shorts out both the Vda and 5V inputs. To determine
whether a shift register is shorted or not, disconnect the connector SS23 and measure the resistance
between pin 12 of the connector C23 and ground. The normal resistance is approximately 110000 ohms. If
the panel is shorted, the resistance to ground is very low.
If the panel is determined to be shorted, the left and right side of the panel can be isolated by disconnecting
the connector C20/C10. Furthermore, the ribbon cables of the panel data electrodes can be disconnected
one at a time until the short is no longer present.
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