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Barcrest MPU4 machine - dead

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#1 ant2110



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Posted 29 September 2020 - 02:01 PM

Hi guys, 


Have a Rocky Horror machine, when turned on the ONLY thing that is visible is the red 5v LED on the MPU4. Absolutely nothing else, not one bulb, the reels aren't energized, nothing. 


So far I have:

- Checked the fuses in the power supply 

- Checked the fuses on the two sub boards in the cabinet


These are all okay. 


I have replaced the MPU4 processor board with another known working one. Just the same. 


I feel like this is power related, where are the best test points to check the voltage rails? 


Or does anyone recognise this  description and able to suggest something more?



Many thanks !


#2 No1Stoney


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Posted 01 October 2020 - 09:17 AM

Are the fuses making good contact inside the PSU? I know old MPU4 PSU's black fuse holders can be a problem sometimes. Does sound PSU related if you've swapped out the MPU4 for another board and exactly the same issues.


It's been a while since I last worked on an MPU4 machine so my memory is a bit rusty

#3 ant2110



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Posted 04 October 2020 - 02:57 PM

Thanks for the advise. The fuses are making good contact. The outputs are correct on the output connector of the PSU.
I think I'll need to check the voltages at other places around the machine but do not know where the test points are. Apart from the main reel board where 5v is marked.

Do you know if any lamps are directly connected to power and not controlled by the MPU4 processor board? Coin slot maybe?

Like I said nothing is lit.

Any further suggestions appreciated


#4 barcrest junky

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Posted 06 October 2020 - 08:48 PM

Back again

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