Early Stern pinouts

[Retropin]

Does anyone know which pin on the MPU supplies the +5V to a stern SB100 sound board?

Its supposed to enter the sound board via pin 30. There are 2 X 16 pin connectors here to make up the 32 pin input. Seems to me they cross and may even flip over

[Mr Pinbologist]

I just checked on my Stern Dracula for you, pin 30 on the mpu is the +5v to the sound board

[Retropin]

Bizarre!!!!

So its 30 to 30??


MMMMM. Something very strange going on with my machine - thanks for the help!

[Mr Pinbologist]

Yes definitely pin 30 to pin 30. As far as i can tell all the pins on both ends should match up 1 to 32... i checked a few at random with a meter.you have to be careful with pins 1 to 16 (first connector) with the orientation of the plugs .. its easy as to get it up side down! the plug from 17 to 32 (second connector)should have a locating key on both ends of the lead so its inpossible to get that one wrong... unless someone has removed it... as was the case on my Lectronamo when i got it.. and it had wires removed!!

[Retropin]

LOL- Locating pins removed also. Problem is with pins 17 - 32 - power input. Having this connector in place drags the MPU down. Also drags the Alltek MPU down if i put that in.
But with no connector there i DONT have +5v on Pin30 MPU.

Ill dive into it later and see what ive actually got. Bloody hell - theres only a few of the pins used!

[Mr Pinbologist]

let me know how you go... ALL of the pins in the connector (except pin 29.. key pin should have a wire going to it). If the plugs are mixed up on the sound board end it can put a short across the 5v line. Also it might be worth checking between pin 30 and ground with an ohm meter on the soundboard incase its shorted.. could be a shorted cap C1, or a shorted logic chip U1 to U6.

[Retropin]

Will dive in later, but U1 - U6 all replaced as have associated caps, inc filter cap C1

[Retropin]

6.4V at pin 30 MPU and theres a short to ground alright, not on the sound board though - i just got a tickle off the legs!!!

[Pinball Fixers]

6.4V at pin 30 MPU and theres a short to ground alright, not on the sound board though - i just got a tickle off the legs!!!

That usually means that earth is NOT wired properly... Make sure the earth strap is connected to the Earth pin on the mains plug.

[Strangeways]

Is that a "tickle" off the PINBALL legs ??

Sounds a bit like a floating ground there mate ! As suggested - check the ground braid right around the cab..

[Retropin]

Yep - off the legs.

I immediately screwed down tight the braid in the header and ensured a good connection, but didnt have time to go any further.
 Floating ground was my thought too - get a nip off all grounding wires inc lamps etc. I couldnt feel it at first cos the skin on my finger tips is pretty thick. Was only when my forearm touched the leg that i got bitten. Skin there is like a babies bum. LOL- gave me a start!

[Strangeways]

Keep us posted on this one.. i might have a spare board I can send you if you need it.