If you have an Amiga 500+, and have a trapdoor expansion that has a real-time clock on it, you may need to disable the onboard clock on the A500+ to use the one that is on the trapdoor expansion. This is useful if you have an A500+ board that has has damage to the clock circuitry due to battery corrosion, or an A500+ motherboard that never had the clock circuitry.

To do this, locate the JP9 jumper pads on the A500+ motherboard which is on the right side below the GARY chip (shown by the red box in the photo below)

Simply place a blob of solder between the two pads on JP9, and your A500+ will use the clock on your expansion instead.