SNES Deck Testers
From what I have gathered, these Deck Testers were rarely used by most repair centers, if at all. The Repair centers were required to purchase this as it was part of a stipulation in their contract. These testers could be used to test if the console board was functioning properly...if it was not, it would fail the test. It individually tests a variety of the innerworkings of the system.
If the SNES console failed the test, the board was bad and the console might not work properly. By the time the Super Nintendo had come about, Nintendo was already offering service centers a chance to become part of Nintendo's power swap program, so a majority of the centers never did any actual repairs on the units themselves.
As you can see from the pictures, there are at least two variations of this Deck Tester. The original has plain label with a sky blue background and black lettering that says:
WORLD CLASS SERVICE
SNES Tester Deck