Sega MSF Lamp Row

[Eddie Twadds]

Almost there with my 'sold as fully working' MSF but one particular problem is still bugging me before I throw in the towel.

Lamp row 7 works intermittently (more often not working ). I have connectivity throughout the chain all the way back to CN6 - 8 (red violet). Changed the TIP 102 at Q78 and the 2N5060 at Q87. TIP creates path to ground and lights the row when I short the tab to ground but refuses to work during attract or test mode. Resistors all test within tolerance and when compared to all the others.

Connector and pins buzz out OK so presume continuity is OK. I don't have a logic probe but am OK with a DMM - what next?

Thanks

Martin

 

[astyy]

Have you tried this procedure to t/shoot, the example used is conveniently MSF and isolates the loom by testing directly on the PCB connectors.
http://techniek.flipperwinkel.nl/desega/index3.htm#lamp

I'm trying to trace a similar problem albeit coll related on my Hook and whatever is causing it is repeatedly blowing the new transistor I'm replacing, so it could be something elsewhere such as a fault diode on one of the lamps in that row. I guess what I'm saying is if replacing the Transistors didn't fix the problem you might be back to square one.

Trust that's of some help....someone knowledgeable will be along shortly I'm sure!

 

[chris b]

i would suspect its the chip that controls the row

 

[astyy]

I should read my own advice! I currently have all feature lamps permanently lit (not flashing) on my Hook, I'm going to follow the testing procedure across MPU CN6 and CN7 to see if the problem is off the board.