Stern ACDC opto no power

[travk42]

Hi all!
I'm having a power problem. A month ago, our Stern AC/DC pinball machine starting loading two balls at a time. I removed the balls and ran diagnostics. The optos were still detecting balls in the #22 and #23 position which would reflect an opto problem. I replaced both transmitter and receiver opto boards and still no fix. After a call with Stern, they said I should have 5v at the opto transmitter board but only have 0.67v. There are no apparent broken wires, the driver board behind the glass is sending 5 volts, and random tests show 0.67v along the right bank of wires.

Can anyone point me to a common starting point to find my power issue before I cut all the zip ties and trace wire by wire?


https://pinside.com/pinball/forum/topic/ac-dc-premium-opto-5-volt-power-issue#postbox

 

[Moonraker]

A fairly common problem for many modern Sterns. Try looking at your 'Z' connectors first, either the male and/or female one for the feed to the trough. On that era of machine there's probably 2 of them - one right next to the trough (which is to allow it's speedy replacement on site) and then possibly a second one probably bottom (right hand?) corner of the playfield as you look at it in the upright position. The one next to the trough is the most likely culprit. The connector pins (both male and female) can oxidise over time (there by creating resistance on the line) giving the problem you are experiencing. Alternatively, it could be a broken wire at the one of the female connectors. Some people choose to by-pass the connectors altogether by soldering wires together, if you do this remember to put heat shrink over the exposed wires.

Typical female 'Z' connector (example shown is only a 6 way connector):

5791-12235-06 - 6h special *Z* .156 inch

<p> 6-pin male/male *Z* connector used on many solid state electronic pinball machines. </p> <p> Snap apart for smaller number of circuits or combine for larger pin count. </p> <p> 6h special *Z* .156 inch spacing. </p> <p> Reference: </p> <ul><li>Stern Pinball, Inc (SPI)...

www.marcospecialties.com

 

[travk42]

I'll give that a try. Thank you!