MAG251 Board Opening Map

This is the fast internal opening map for MAG251 once gun, spool-gun, and drive-roll branches are already bounded.

Open Only After Proving

base plain-steel MIG baseline has been proven or ruled out
spool-gun complaints are already separated from the base gun
clamp, polarity, and current path are already clean
correct feed direction is already confirmed before any deeper blame

First Internal Targets

Board or internal group	Open first when...	Key connector or checkpoint	Best local file to open first
Capacitor or output-smoothing branch	the arc feels ripple-heavy or unstable under otherwise healthy setup	output smoothness and capacitor condition	workbook sheet `MAG251`
Motor direction or post-board service branch	feed direction is wrong after internal work	motor direction and board-install logic	workbook sheet `MAG251`
Gas-valve or control branch	trigger feed is present but gas behavior is abnormal	gas-valve branch around trigger action	`mag251manualweb.pdf` and workbook

Connector and Board-Family Reminders

Do not treat a wrong feed direction after repair as a random new fault. The workbook already names that branch.
Keep spool-gun-only complaints outside the chassis until base MIG is proven healthy.
Keep ripple complaints separate from pure feed complaints. They are not the same branch on this model.
Do not open the machine while chart-correct plain-steel base MIG is healthy and only the spool-gun branch still fails.

External Parts Exit Paths

If the opening pass shows the complaint still follows the external gun, spool gun, or drive-roll branch, leave the board path and use the official ordering flow instead.
MAG251 parts category: official parts path
SpoolKing24D spool gun 07NS1000: official product page
MAG251 drive-roll family including 072611011 and 07NS1005: official category page

Stop Rules

Stop and go back to the external path if base MIG is healthy and only the spool gun still fails.
Stop and correct motor direction first if it is obviously wrong after board work.
Stop and return to the full guide if ripple, gas, and feed evidence still overlap after the first opening pass.

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