In switch test the clock's minute optos (00 and 45 minute positions) sometimes fail to register as the hand sweeps past, and the clock misbehaves in its modes. New reproduction clock boards don't cure it, and they make it worse in some cases.
Clock minute optos miss now and then: repin the plug at the 10-opto board
Cause: A bad IDC plug on the 10-opto board: some of the wires had been split at the insulation-displacement contacts, giving an intermittent connection. The clock's hour gearing had also been set about an hour out.
Checks
- Inspect and wiggle the clock's opto connectors at the 10-opto board and at the clock while watching switch test.
- Set the hour gear correctly, using the alignment mark in the manual, so both hands read 12 together.
- Check the minute hand's interrupter passes fully through the opto slot; if replacement clock boards use different optos, they must be the right type.
Fix
- Repin the plug at the 10-opto board with new crimp pins and housing.
- Correct the hour gear timing.
Systems
Games
Related tips
- Gumball enter opto (switch 87) never registers: replace the LM339
- New lock optos fitted: those and other optos on the same plug stop working
- Check opto power supply message with good fuses: reseat the opto board plug
- Opto still dead after replacing both sides: the new transmitter can be bad
- Eddy sensors: electronic ball switches under the playfield
- How WPC opto switches work and which half fails
- Opto does not work: check 12 V at the transmitter connector
- Opto switches dead or intermittent: check the 12 volt supplies
Source: Pinball Repair help group!! (Facebook group)