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MPU 3 power off/on issues


martinb
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Hi all,

So, have an old MPU3 Lucky Strike clubber which works once you can get the thing powered on. You can sit powering on/off for a while until it finally bursts into life and then you can play for some time until it is powered off (or sometimes when paying £1's). 

The alpha was dead but I swapped (for an MPU4 thanks to the forum) and now working fine. When it is powered on  the reels judder and display is dead, sometimes it will beep other times pulse the solenoid but mostly it just judders the reels once maybe twice - you know when it will work as the display reads resetting or similar message.

I have read most of the old topics about similar faults but the chap I got this from said the board was recently refurbished, which makes sense as there are fly wires for the battery. 

Anything obvious I should check? I have done the basics like cleaned connectors, reseated things etc etc 

I do not have another board to try and when I enquired about one it was £350 which is way more than I paid for the machine lol.

Cheers!

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Posted (edited)
3 hours ago, sulzerned said:

I'd be looking at replacing the main capacitor in the power supply and also the three capacitors underneath the mother board.


As it happens, I have just taken the board out to have a look, those capacitors look to have been replaced, see pic what do you think? Thank goodness those connectors were later replaced with molex type, they are fun to get out! 

I could do the PSU capacitor thanks, visually it looks ok but I appreciate any suggestions. The PSU had badly burnt 12v cable from top of the fuse which I replaced/ cleaned etc but made no difference. 

This morning it started first press but since then I can’t start it - it’s mainly just juddering the reels but can also pulse solenoids, play noises or have random characters on the alpha. It blew the payout fuse too. 

6FF1BA5B-8E13-480D-B260-8ADD2F0CBD7E.jpeg

Edited by martinb
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They've been replaced, Rubycons are a good make too. The original blue ones were LCR and they always need changing.

Post a pic of the whole board, the symptoms for intermittent booting are many fold, too many to guess at.

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Posted (edited)
27 minutes ago, midibob said:

They've been replaced, Rubycons are a good make too. The original blue ones were LCR and they always need changing.

Post a pic of the whole board, the symptoms for intermittent booting are many fold, too many to guess at.

Are these any good as a starter?

The power supply is an LCR cap so I will replace that one thanks 

8C29C01C-1256-44AA-8E04-E1E6FF7900A1.jpeg

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909F59F3-B986-4C18-9682-9B1BB54A416F.jpeg

Edited by martinb
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When I service these I usually swap the four resistors R92-95, C42, T60, 61 and T11. Put IC7 & 8 in 'turned' sockets although 7 looks like it's been done but maybe not 8 which would be odd? Then any other corroded or iffy looking bits, that includes all the transistors in the RESET circuit.

I can't see what diodes are fitted in D44/45 but they should be the P600 type, pic 1 looks a bit on the small side!

Then make sure there's no corroded/dry joints on any of the plugs, all the pins look in good nick which is good.

The big LCR cap in the PSU doesn't appear to suffer like the smaller ones on the board, won't do any harm swapping it but an identical replacement is pricey!!

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55 minutes ago, midibob said:

When I service these I usually swap the four resistors R92-95, C42, T60, 61 and T11. Put IC7 & 8 in 'turned' sockets although 7 looks like it's been done but maybe not 8 which would be odd? Then any other corroded or iffy looking bits, that includes all the transistors in the RESET circuit.

I can't see what diodes are fitted in D44/45 but they should be the P600 type, pic 1 looks a bit on the small side!

Then make sure there's no corroded/dry joints on any of the plugs, all the pins look in good nick which is good.

The big LCR cap in the PSU doesn't appear to suffer like the smaller ones on the board, won't do any harm swapping it but an identical replacement is pricey!!

Thanks Bob, I'd love to have the tools to attempt this so I think I need someone to do it, is this something you can do and if so how much please? if not is there someone who can help?

I managed to get a capacitor for the PSU from RS for £14 delivered, now that I can manage lol. 

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Posted (edited)
24 minutes ago, midibob said:

Used to be able to get these for a few pounds years ago. I've sent you a PM.

Cheers Bob.

I changed the Alpha on this machine as mentioned, here is a school boy error admission for a giggle (at my expense) 🤣

 

IMG_2524.jpg

Edited by martinb
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We’ll as an update I have been busy busy and tried a few things like reseated the IC’s 7 & 8 and thoroughly cleaned everything from the cabling looms/connectors to the boards, re-assembled and methodically reconnected things, all new bulbs and hey presto the thing is only reliably working! 

I had removed the reel deck and cleansed all that too and the reel backboard, in doing so I lost one of the lamps on reel B opto - I shoved that to the end and everything is working just as it should. I’ve ordered some spare opto’s as I suspect they are a point of weakness. 

I have a new £1 coin S10 mech so can use some current ‘real money’, but I decided to leave the 10/20 and 50p’s as old money and have old coins I can use. Payouts tubes for new £1 work fine. 

Very happy at this stage, thanks for input folks, I have no doubt I may need help again as these are no spring chickens! Thank goodness for this forum with these old machines. I want more now lol …. 
 

998F4840-C69A-4614-8627-54A30BF27819.jpeg

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