The Aussie Pinball Arcade
Aussie Pinball Forums => Technical Matters => Pinball Repairs / Problems & Assistance => Topic started by: Retropin on October 04, 2008, 11:57:15 PM
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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
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I just checked on my Stern Dracula for you, pin 30 on the mpu is the +5v to the sound board
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Bizarre!!!!
So its 30 to 30??
MMMMM. Something very strange going on with my machine - thanks for the help!
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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!!
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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!
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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.
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Will dive in later, but U1 - U6 all replaced as have associated caps, inc filter cap C1
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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!!!
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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.
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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..
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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!
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Keep us posted on this one.. i might have a spare board I can send you if you need it.