Sinclair SCV-750EB Service Manual page 132

5.28 F4 Troubleshooting
Digital display output
Description
 1F4 module A L0 or L1 protection occurs for 3 times in 60 minutes.
 2F4 module B L0 or L1 protection occurs for 3 times in 60 minutes.
When F4 displays, a manual system restart is required before the system can resume operation.
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Possible causes
Refer to L0 or L1 error troubleshooting.
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Procedure
Refer to L0 or L1 error troubleshooting.
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