Leaderboard

I seem to have had some of the worst of the worst boards that others have not seen anywhere near the problems I have had with them! but they all get fixed but it can take weeks! there is not one I have scrapped yet!

sunlight works well, if you can find it!!!

very common for chips to fail, battery rot vapours kills a lot of the chips too, if you have a very clean board with no rot then you can find loads of chips that don't work like this one!! everything with a white paint dot on it was faulty and was changed, then the circled in green chip worked at first then failed soon afterwards about a hour later once the board worked and then there was some weird lamp problem on that board too where lamps would not turn off properly but stay on a bit!! only way to cure it was to cut away between the tracks as it appeared the voltages on the transistors was leaking and keeping the gate of the transistors turned on!! very odd as others are very forceful in saying boards cannot become slightly conductive! but this did cure the problem once it was determined which transistors was causing it and that they were not actually faulty by changing them and the chips that drove them!!!!

This Makes more sense now, #thanks to booze.net website for parts list. Im being sent the parts, but im sure anyone reading this will find this list useful. MPU 4 - PARTS LIST IC1 = EF68B09P IC2 = EF68B40P IC3/4/5/6/7/8 = EF68B21P IC9 = GM76C28A-10 (Little diode) IC33/34 = CD4049UBCN OR MC14049UBCPG (payout failure) IC10 = AY38912A/P IC13/14 = ULN2803A IC15 = SN74LS541N IC16 = SN74LS541N IC19 - SN74LS22N IC20 = SN7425N IC21 = SN74LS04N IC22 = SN74LS08N IC23 = SN74lS138 (de-multiplexer) or 74hct138 IC27 - ULN2803A IC28 - ULN2803A IC29 - ULN2803A IC30 - ULN2803A TR8-TR1 = BT137-500G BTB08-600B - RS COMPONENTS (payout Triacs) T1-T8 - BC327-25 (display selects) IC19 = SN74LS22N + T20 + T21 (BC328) + IC21 = SN74LS04N (+ T40 ZTX500 - T41 ZTX300) 6116 RAM T9 - BC328 ZD21 - BZY88 - 7.5V D66 - IN4148 T12-T19 = BC338 (transistor pre-drives for payout triacs) C1-C8 = ,1uf poly caps rapid 4p each (1000pf) C9-C15 1000pf (1000pF 100V X7R Axial...Lot of 100) http://myworld.ebay.co.uk/dannell.4you/ C47 - 104Z CERAMIC CAP LEDS - common anode

yup capacitors, there marked Cxx rather than Rxx, replace all the transistors, capacitors, and zener diodes making sure especially the zener diodes are connected and are protecting the inputs on the 68b21 chip, they are there to stop the inputs rising above 4.7v as the zeners pull it to that should they try and rise above that which would likely damage the chip.

capacitors,resisters they aint,would pay you to strip the lot and the diodes

stripped off the solder resist now back to copper that's remaining! looks good around the ram but it is a good job I did remove the ram as this would have not been spotted at all! if the track had of worked I don't think it would have worked for long!! look how neat the rot has rotted round the pad disconnecting the supply to the ram!!

Reckon I have an unwanted mpu4 case if you need one Rich. PM me if you do.

Good work rich .nice thread

Bought from the Same seller 👍

yup instant destruction of the rom, always check twice it is right way round, then once more before power is added so most likely the new rom is not for that machine as things are wired differently, so stick with the old one when you can get it sorted