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MPU4 Ejects coin when switching on

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Hello All, Happy Christmas. My MPU4 machine has just started paying out a 20p coin when I switch on the power. It has never done this before but has all of a sudden started doing it. 

Any know what might be causing this?

Video of the problem here 

 

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odds on that your battery has leaked you need to check for broken tracks with a meter and replace all of this

Inked20191129_225840_002_LI.jpg

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Oh no I hope not. I have got a new battery and intended to do the battery mod but i've just not had time to get round to it. The machine still works fine and pays out 20p's fine during the game. 

Do you think it might be too late to save this board?

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my advise is warm you rmachine up with a heater

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That's about the best board I think I've ever seen! However it might still be best to swap out all the triac driver transistors T12-19 and also do the 'fingernail test' with C9-16. By that I mean just put your fingernail underneath the caps and apply a tiny bit of lift,  if the cap body comes away from it's wire (on any of them) replace them all. It has to be said there's no visible sign of corrosion so they are probably OK.

Good luck.

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28 minutes ago, riche100 said:

my advise is warm you rmachine up with a heater

The machine is kept in my office next to an 8 foot long radiator. The humidity in the room is around 28-35% 

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14 minutes ago, midibob said:

That's about the best board I think I've ever seen! However it might still be best to swap out all the triac driver transistors T12-19 and also do the 'fingernail test' with C9-16. By that I mean just put your fingernail underneath the caps and apply a tiny bit of lift,  if the cap body comes away from it's wire (on any of them) replace them all. It has to be said there's no visible sign of corrosion so they are probably OK.

Good luck.

Thank you for your input. Do you know what the triac drivers do on the board? Are they to do with the payout or something else? It's nice to know it's the best board you have seen. There is a service sticker on it from 2001 and the battery has been replaced so this must have saved it. The voltage in this battery actually good at 2.57v

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can you snip the legs off  that battery and remove it so i can see the tracks under it 

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28 minutes ago, fruit58 said:

can you snip the legs off  that battery and remove it so i can see the tracks under it 

Yes, just in the process of doing that now 👍

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Have I just killed this good board? I didn't have anything small enough to get in behind the battery to cut it off so I desoldered it. On removing it one of the legs appeared to pull out a track from inside the board. Are these multi layered? 🤔 Have I just killed it??

IMG_20191211_210250.jpg

Edited by Prototype_uk

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No it’s the corrosion and yes it’s hiding under the battery, there’s your issue.

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Track you pulled out is your to the battery easily fixed especially if it’s just ground 

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Get rid of this tho, may short the chip, think that’s part of the trace for the battery 

BF8E73AD-294F-4699-B27A-4C2D0F5C00A1.png

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Diode looks fine. Broken track goes under IC to resistor marked with Red Circle so easy link wire fix. I have tested all 4 of those corroded tracks and they all test fine. Should I get some white vineger on them to see if they are weak?

IMG_20191211_221712.jpg

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i would just use a fiber pen to get the copper clean and put some solder mask paint on them 

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My Nifty 50 did this the other day.

It hadn't been switched on for a few weeks tho.

I find once it's been on a while it stops doing the

one coin payout on boot up.

My mpu4 doesn't have a battery in it either.

 

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