Hello everyone,
I'm working on an 1967 MCI 5A with an 8v71 and a 4 speed. From what I see the electrical system is stock.
Has anyone had to replace the selenium rectifier diode that is in the auto shut down and lamp circuit? I've attached photos of the faulty component. Basically I need a diode to replace this older style selenium unit. Just not sure how big I need. Perhaps newer MCI's had silicon diodes that might fit my application.
basically the component is a check valve to let electricity trigger the same warning buzzer but not feed back to the other circuits. One of three circuits can trigger the buzzer, low air pressure, low oil pressure and engine over heat. Low oil pressure and engine overheat also trigger shut down.
The component failed and isn't acting like a check valve. Its acting like a short between all three circuits. So if any circuit is active the shut down is triggered. With low air pressure active on startup the signal is backfeeding into the auto shut down circuit. When I disconnect the low air pressure circuit the bus runs as normal and build air as normal. once aired up if I reconnect the low air pressure circuit the bus continues running normally.
Anyways if anyone has an idea of a superseded part I could use that would be very helpfull info. Unfortunatly the manual doesn't give a part number for this little piece, it only has a number for the entire buzzer harness
Thanks for any help, Alex
