Problem SMD advice help needed?

[Ronnie Dent]

This is a long shot on here, I have a Barcrest MPU5 Star Wars fruit machine that fails to boot up due to the security pic chip, this is mounted on the games flash card the pic chip is PIC16LF84A this chip needs to run constantly and is powered by a varta 2.4v battery. Now I can get it to boot by leaving machine powered usually for hours! and recycle the power it will come on, but if it's left off for any lenght of time it will error no characteriser no chip iD, I think an oscillator chip may be the problem, the only thing I can see is a 4 legged smd device close to the pic chip, it's marked 32C75 I think it might be a crystal to run the chips clock? But no idea, google never helped me find what this chip is, I have 2 cards for the game both doing the same thing? I will post a pic shortly.

Thanks for any help or advice

Ronnie

 

[Ronnie Dent]

Here is a couple pictures, the smd chip is just in front of the pic chip

 

[Ace`]

What makes you think it's the crystal/oscillator? sounds more like the battery needs to be replaced to me.

 

[Ronnie Dent]

What makes you think it's the crystal/oscillator? sounds more like the battery needs to be replaced to me.

The battery on both cards have just been replaced, thanks for your input

 

[Ace`]

I'd be looking at those surfe mount capacitors next then, they always fail in that type of smd package.

 

[Ronnie Dent]

I'd be looking at those surfe mount capacitors next then, they always fail in that type of smd package.

Thanks Ace, trouble is I have no idea what they are value wise, no schematic that I know of on this board

Thanks Ronnie

 

[Ace`]

They're labelled, 2x 10uf 1x 220uf 16v I'd use standard radials and bend the legs, much easier to install and they're usually better quality too.

 

[Ronnie Dent]

They're labelled, 2x 10uf 1x 220uf 16v I'd use standard radials and bend the legs, much easier to install and they're usually better quality too.

Wow you were able to see the values? There are also a few under the CHR chip would not get radials in there, thanks for your help Ace will post a pic with CHR removed

 

[Ronnie Dent]

Sorry I picked that up wrong, you meant the can type caps, I was thinking the little tiny one's lol

 

[Ace`]

Yeah just the three can type need replacing, can't be sure that's your issue but I cannot see much else it could be either.

 

[Ronnie Dent]

I will replace them for sure, willing to try anything
Thanks again
Some say the chip could be bad! But 2 doing the same thing!
Ronnie

 

[Ace`]

I think if the chip were bad it would never boot no matter how long you left it on for.

 

[Ronnie Dent]

Well I changed the 3 caps on the first card and it booted straight up! Result I thought! So switched it off for an hour and it failed, no chip ID

So I did the 2nd card and again booted straight up! Not got any further yet, will leave it on for a while, normally it would never boot right away, only after being left on for some time.

Thanks Ronnie

 

[Georgian2]

You could meassure the voltage on that battery. Write it down the voltage when the thing boots first time and the voltage when it dosen't and you need to let it "to charge" .
Is it possible that the battery is soldered the wrong way?

 

[Ronnie Dent]

You could meassure the voltage on that battery. Write it down the voltage when the thing boots first time and the voltage when it dosen't and you need to let it "to charge" .
Is it possible that the battery is soldered the wrong way?

Thanks for your input, I have been checking the battery but it never dips below 2.6v

The 2nd card has booted everytime so far, fingers crossed it will survive overnight

Thanks Ronnie

 

[Ronnie Dent]

Ok this morning after an overnight at power on it alarmed again! It took a long time to decide usually it alarms fairly quick, when it takes a long time it usually boots! But I right away cycled the power and it booted, so the caps have made it much much better, so we are getting closer to resolving it, thanks very much Ace for your advise, I would never have even considered those caps!

Thanks Ronnie

 

[Ronnie Dent]

Just for clarity here is a pic of the card we are talking about now, with new caps fitted the correct value but higher volts

 

[Ronnie Dent]

Well both cards failed to boot this morning! Given changing the caps improved things I'm now wondering if it could be a psu issue? Barcrest mpu5 seem to be bullet proof psu wise but you never know!

Thanks Ronnie

 

[Ace`]

Are there any of those can type caps on the other pcbs?

 

[Ronnie Dent]

Are there any of those can type caps on the other pcbs?

Probably on the main cpu but I have tried 2 mpu's but before changing these 3 caps! Maybe worth swapping again?
Thanks Ronnie