Cummins/Onan — Replacement of Diodes
Repair & overhaul
From a Cummins/Onan operator's manual covering: 250DFT-57R8, 300DFT-4R8, 300DFT-4XR8, 300DFT-5DR8, 300DFT-6DR8, 300DFT-7XR8, 300DFT-9XR8. Check it applies to your exact model before use.
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Before you start
- Excessive heat can damage a diode.
Procedure
- Unsolder leadwires from diode terminal.
- Use proper size wrenches to hold body of diode while removing nut attaching diode to heat sink.
- Push diode free of its mounting hole in heat sink.
- Install new diode in same position (or direction) as defective diode.
- Insert new diode into mounting hole in heat sink or bracket. Secure with nut and washer.
- Connect leadwires to appropriate terminals.
- Solder leadwires removed from defective diode to terminal of new diode. Use needle nose pliers to absorb heat.
- Replace access cover.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Parts have directional arrows marked
Source: Cummins/Onan operator's 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.