Cummins/Onan — Testing Rectifier Bridge Assembly (CR21)
Testing & diagnosis · Rectifier bridge CR21
From a Cummins/Onan service manual covering: 300.0 DFT, 350.0 DFU, 350.0 WF, 400.0 DFV, 400.0 WK, 450.0 DFW, 500.0 DFY, 600.0 DWV. Check it applies to your exact model before use.
Applies to: Cummins/Onan YB series
Procedure
- Rectifier bridge located in control cabinet, below voltage regulator.
- Contains 3 diodes CR1, CR2, CR3 and two SCRs CR4, CR5 encapsulated in hermetically sealed box.
- Failure of any diode or SCR means entire unit must be replaced.
- Disconnect wires from rectifier unit prior to testing.
- Test unit in order shown in Table 2.
- Refer to Figure 24 for CR4 and CR5 test circuit.
- When test is complete and satisfactory, reconnect unit observing correct wiring hook-up.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- See Table 2
Full service-parts list: Cummins/Onan YB series →
Source: Cummins/Onan 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.