Marathon — Rectifier Assembly Check
Testing & diagnosis
From a Marathon service manual — check it applies to your exact model before use.
Procedure
- Test each rectifier with an ohmmeter. Remove the bolted leadwire from one rectifier at the terminal stud.
- Test resistance between the disconnected leadwire and the rectifier base. Make sure you have a good connection.
- Note the reading and reverse the ohmmeter probes. One reading should be high and the other low if the rectifier is good.
- If high and low readings are not achieved, the rectifier is defective and must be replaced with correct polarity.
- Remove the surge protector circuit board from the rectifier assembly.
- Check the surge protector with an ohmmeter by measuring resistance across the terminals. Reverse probes and repeat.
- A high resistance should be measured in both directions. If not, replace the surge protector.
Tools required
- ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- one reading high, one low
- high resistance both directions
Source: Marathon service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.