What each card does
The sending card takes the video signal from the player and turns it into data that runs down a cable. The receiving cards sit inside the cabinets and distribute that data to the modules. One sending card usually feeds many receiving cards in a daisy chain.
Symptom one: the whole screen is dark
If every cabinet is dark but the processor shows a signal, the sending card is the first suspect. Check its status LED. Most sending cards flash a green light when they have input and a red or off light when they do not. No light and no output is a strong sign.
Symptom two: one cabinet or one row is dark
That is almost always a receiving card, or the cable feeding it. If the cabinets after it in the daisy chain are also dark, the problem is upstream of that card. If the chain continues normally after the dark cabinet, the fault is in that cabinet's card or its power.
Symptom three: random blocks flicker
Scattered modules flashing on and off across several cabinets usually means a cable, not a card. Wiggle the cable between the cabinets while watching the screen. If the pattern changes, you found it.
The ten-minute test
- Look at the sending card LED: input present or not.
- Look at the first receiving card's LED in the chain: is it receiving data.
- Swap the cable between cabinet one and two with a known good one.
- If the darkness moves with the cable, the cable is bad.
- If it stays with the cabinet, the card is bad.
The mistake that costs money
Replacing the sending card because the screen is dark, when the actual fault is a 3-dollar cable. We see this about once a month. Always swap the cable first, because it is cheaper and faster than any card.
What to keep as a spare
One sending card, two receiving cards, and four short cables. That covers almost every failure pattern, and the whole kit costs less than one site visit.