Everything works except the controlled (feature) lamps, which are all dark. The lamp supply reads about 19 V with its connector unplugged from the CPU board but only a fraction of a volt when plugged in.

All controlled lamps out, 18 V collapses under load: bad lamp fuse on replacement supply

Cause: The game had been fitted with a replacement power supply whose lamp-supply fuse (F4 on that supply) had failed. It measured fine with an ohmmeter but could not pass current.

Checks

• Measure the lamp supply voltage with the CPU connector plugged in, under load, not just unplugged.
• Check voltage on both sides of each lamp fuse while the game runs; a big drop across a fuse means it is bad even if it reads OK on resistance.
• If the supply has been swapped for another make's board, check which fuse feeds the lamps on that board.

Fix

• Replace the lamp fuse with the value and type the schematic calls for.

Systems

• Williams System 11

Games

• High Speed

Related tips

• Pops and slings dead after fitting a replacement power supply: check its fuse map
• Every switch shows active, even with the switch plugs removed: failed PIA at U38
• Right sling locks on at power-up and a pop is dead: bad 7402 at U45
• Pops and slings fire in coil test but not from their switches: ground wire pulled out
• Special solenoid fuse blows at power-up: a pop bumper switch held closed
• Whole lamp column works only intermittently: reflow the board header
• System 11 CPU board connectors
• System 11 CPU board part numbers and spotting features

Source: Pinball Repair help group!! (Facebook group)