Snow Bros (Toaplan)

[Jacmar]

BOARD 1



In pretty decent physical condition, not even cleaning required, but graphics issues and no sound at all.



Top left quarter of the screen messed up and you can't see it from the pics but the screen was flashing/strobing constantly .... A quick google search and it seems 95% of graphics issues with these pcb's is down to bad dynamic RAMs at IC's 23,24,25,26. Historically it looks like most people just swap out all four but I didn't fancy doing that and got the slice on them to try and identify which one (or ones) were causing the issue.. my thinking was only one of the four was at fault which was why only 1/4 of the screen was messed up.
Sure enough slice identified IC 23 as bad (the others all passed) so whipped it out (if only it was that easy, removing chips from this pcb is a nightmare) and replaced with a new one .....



Graphics fully restored ...



Onto the sound problem ......

 

[qjuk]

Top stuff.
All four of the rams on my board have previously been replaced and socketed by a previous owner.
I believe the ram failure is a common fault with this board.

 

[BubNotBob]

BOARD 1

View attachment 47179

In pretty decent physical condition, not even cleaning required, but graphics issues and no sound at all.

View attachment 47180

Top left quarter of the screen messed up and you can't see it from the pics but the screen was flashing/strobing constantly .... A quick google search and it seems 95% of graphics issues with these pcb's is down to bad dynamic RAMs at IC's 23,24,25,26. Historically it looks like most people just swap out all four but I didn't fancy doing that and got the slice on them to try and identify which one (or ones) were causing the issue.. my thinking was only one of the four was at fault which was why only 1/4 of the screen was messed up.
Sure enough slice identified IC 23 as bad (the others all passed) so whipped it out (if only it was that easy, removing chips from this pcb is a nightmare) and replaced with a new one .....

View attachment 47183

Graphics fully restored ...

View attachment 47187

Onto the sound problem ......

I also have one of these boards with graphics issues, as you discovered a google search says failing RAM is the common fault. So I am prepared with new RAM and thought this was going to be an easy swap out and then I saw your comment 'removing chips from this pcb is a nightmare', now I am a bit wary. On visual inspection I can see the holes in the PCB are smaller than I have come across before and I also notice that some of the pins are bent so they are not going to pop out without a wiggle. My board is nice and tidy like yours so I want to do a good job. Any tips on chip extraction?

 

[Lurch666]

These type of multi layer PCBs have a large ground and +5V layers so when removing chips it's extremely difficult to remove the GND and +5V legs since the large layers absorb all the heat when trying to melt the soulder on those pins.
When working with this type of PCB I now use a heat gun to warm the area where I'm removing the chip so it's easier to get the soulder to melt.

 

[BubNotBob]

These type of multi layer PCBs have a large ground and +5V layers so when removing chips it's extremely difficult to remove the GND and +5V legs since the large layers absorb all the heat when trying to melt the soulder on those pins.
When working with this type of PCB I now use a heat gun to warm the area where I'm removing the chip so it's easier to get the soulder to melt.

So I understand correctly you are talking about adding some heat to the chip area before getting the desolder gun on the chip legs?

 

[Lurch666]

Yes but just for the GND and +5V pins.

 

[BubNotBob]

OK, thank you. That is definitely something I haven't tried before.

 

[Jacmar]

Yes it's the +5v and GND pins that are the problem due to the large layers like @Lurch666 says. They suck so much heat ..... I think this is where one of those soldering heat mats you can get would come in real handy to get some general heat into the pcb. Heat gun can work too but this was even a struggle on this board.
If you know the chip your taking off is knackered then I'd recommend just snipping the leg(s) from the chip and use your iron on max heat on just the leg, making sure you've added some (lead free) solder first! The cut option wasn't a route I wanted to go down on some of the chips during this repair (you'll see in the rest of the repair write up) so had some real fun (not) with this pcb!

 

[BubNotBob]

Thanks to both of you its always best to know what you are in for. I was going to swap out all four chips but now will work out which ones are duff and target them.