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Andrew96_

Maygay EPOCH MPU repair

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On 9/13/2018 at 10:37 PM, Homer_1209 said:

Hi Andrew, I’ll check the difference in timing on the rest LED from the v6 to the v8 tomorrow for you and let you know!!

I’m guessing you’d like my v8 boot chip then....

Believe it or not the first cpu board I picked up had the v8 chip in!! On checking the others I had v4, v5, v6 and the one v8!

Let me know!!

Sorry I thought I had answered but I haven't! yes I think the V8 is the latest! and yep I would be interested in a V8 chip to mess with, I do have a V6 I can let you have until I can crack the V8 so you would not be without one! cheers , many thanks!

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I do have another epoch mpu board to do, but is it worth me spending the time to document it here? is anyone still interested now one has been done?

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10 minutes ago, Andrew96_ said:

I do have another epoch mpu board to do, but is it worth me spending the time to document it here? is anyone still interested now one has been done?

I'd be interested. I always enjoy seeing other people's handy work, in the hope that it inspires me to do something similar!

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I'd also be interested to see another repair thread, I find them fascinating, I just don't have the dexterity, patience or know how to even start repairing boards.

 

Which is a shame as I have been given another Fruit Machine (Full Moon Fever) which looks like it might have a dead Epoch board. The hit and miss nature of the spare boards I have seen makes getting a replacement a bit of a risk.

 

Pete

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ok so the next one! I had a new one that was perfect and new! a friend at that time wanted to 'borrow' a good board, trouble was it was fitted to a machine and I never got it back! I got back one that looked ok but in actual fact the dips didn't work!

did not remember to takes a pic of it before I started (was fuming to find out it didn't work LOL)

so the first move is to remove all the components in the affected area! here is the start of that and then remembered to take a pic!!

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more close up of the area of rot! does not look bad but it's enough to cause problems!

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so ram now removed and all the smd components in the spark protection and ram supply removed!

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scrape it all clean to see the remaining copper tracks!

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bit of track measuring and studying of the tracks to see any damage on them, ones that was damaged replaced with 0.25mm wire over the tracks, I think there was about 12 in the end that looked like they needed doing

 

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not forgetting the underside too where they go through the board!

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then the solder resist, being careful not to get it on the smd solder pads!

Ram and 2 smd capacitors put back on also!

IMG_2166.JPG.0ce7d2558f106e9610d3886ea7defb8a.JPG

 

SMD components in the spark protection and ram supply tested, yup one resistor was open circuit and nice and crusty at its ends!

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I changed a few bits as they did not look that good! looks better now!! coming along nicely!

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finished!!!!

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yep all works now! closer view of the repaired area now complete

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I have since doing this put in pcb eyelets where the battery goes, but at the time this was done I did not have any that size!

 

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least now it works! but sadly the soldering skills needed to do this sort of repair are not basic ones, this took me about a week to complete and this only had the dips not working!

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That is insane,  how do u solder the tiny pads? whats your setup?

 

Those unpopulated battery area picks are very useful as you can clearly see/follow the dips shift reg clk/data/latch(i think) traces back to cpu and they go straight under the battery. So that must be where mine are damaged!

Hopefully can get my dips working again :)

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8 hours ago, midibob said:

Nice job Andrew. Bit of a busman's holiday for you now.;)

lol it is the same sequence every time! you just got to stick with it and plough through not thinking about the time spent on it as it is a hobby, then hope it all works in the end!

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Awesome job do you bend you repair wires first or tape them down or anything? I've tried the odd few...lots running together is hard though!

Next question lol- Ram chips... If you wanted to replace ram chips do they need any programming or are they blank and storage only?

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solder the first bit on then follow the track and bend round the corner, then solder that bit then move on to the next corner and solder that down, trick is to have the iron no hotter than 380 deg C and only on long enough to solder the wire with extra flux of course on a cleaned track, preferably pre-tinned first.

no, ram is blank and only retains its data when it has power, remove power like the battery and all data is lost and you then (like on barcrest erio) have to put thousands back through the machine for it to settle own and pay good as some really don't like a ram clear!

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You make it sound so easy mate lol! I will keep trying and practicing my soldering... I don't think I will ever be able to fix an epoch!

Yeah thanks I've seen you mention about replacing ram chips and different boards having differently manufactured chips so that's handy to know.

With the other types of chips like say a Pal chip that you sometimes need to reproduce -do you lift and copy the data that's stored on a working version and just program it straight on? I saw you was after a fast boot chip a while ago is it the same as programming Eproms? I can manage that ok so far.

Edited by MattyL

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Depends, if the pal chip is protected you cannot read out any data then if you can get the data it has to be converted for the later gal chips, if the data cannot be read but just contains logic then there are ways to find out what the chip does and reproduce it, but takes time! 

Pic security chips are harder! I have managed it but it is not easy and takes months!

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