Micro Trainer Faults: Solutions
For instructors. This page is not linked from anywhere on the site. Keep the card with the trainer, not with the students.
Board: Ten-fault production board (wire codes A1, F1, L1-L12, Z1-Z8 on the silkscreen)
Which switch sets which fault
| Switch | Fault | Circuit | Where it sits | Correct answer |
|---|---|---|---|---|
| 1 | High resistance | Left Front | Ground leg, between the load and C4 | 4.7k in series in the Left Front ground return |
| 2 | Open circuit | Right Rear | At the load, on its feed terminal | Right Rear load open on its feed side — C7 stays live, the load has nothing on either side of it |
| 3 | Short to V+ | Left Rear | C6 feed, taken straight off the fuse output | Left Rear feed shorted to V+, bypassing the circuit switch |
| 4 | Short to ground | Right Front | C3 feed side, through 1 ohm | Right Front feed shorted to ground |
| 5 | Open circuit | Left Front | At the load, on its ground terminal | Left Front load open on its ground side |
| 6 | Short to ground | Right Rear | C7 feed side, through 1 ohm | Right Rear feed shorted to ground |
| 7 | Short to V+ | Right Front | C3 feed, taken straight off the fuse output | Right Front feed shorted to V+, bypassing the circuit switch |
| 8 | High resistance | Left Rear | C6 feed leg | 4.7k in series in the Left Rear feed |
| 9 | Open at the switch | Power distribution | Between the circuit switch and C1, the master feed | Master feed open at the switch — every circuit dies, no single circuit is at fault |
| 10 | Open in the rear feed | Power distribution | The +5F to +5R tie, at C10 | Rear rail feed open at C10 — both rear circuits die, both front circuits keep working |
How the ten faults are distributed
Every lighting circuit can be faulted two ways, and two more faults sit in the power distribution itself — so a dead board is not automatically a dead circuit.
| Circuit | Fault A | Fault B |
|---|---|---|
| Left Front | High resistance | Open circuit |
| Right Front | Short to ground | Short to V+ |
| Left Rear | Short to V+ | High resistance |
| Right Rear | Open circuit | Short to ground |
| Power distribution | Open at the switch | Open in the rear feed |
Clearing a short to ground
A short to ground drops the whole board: the eFuse shuts off, every light goes out and every reading past the fuse is 0 V. Measuring alone will not find it, and the fuse latches — disconnecting the short does not bring the board back on its own.
- Pull one feed jumper.
- Press RESET.
- If the fuse stays up and the other lights return, the fault is in the section just disconnected. If it trips straight back off, reconnect and try the next one.
Worth letting a student find on their own: pulling the return jumper of the shorted circuit does nothing. The short is on the feed side, upstream of the load, so opening the ground leg leaves it connected.
Generated by website/deploy_solutions.py. Edit the table there and re-run; changes made in the Shopify admin are overwritten.