(SOLVED) Sprite ram NG 24000000

[Shakunetsu]

Hi!

My cps3 was working perfectly very recently. I moved, it sat in a box for about a month unused, and I bought one of TRFightStick's metal enclosures to put it in. I don't know if I damaged something while putting it in the enclosure or if it suffered some damage during the move, wish I tested it between those two things.

The board runs but the display is mostly black with some thin garbled lines. Things like insert coin, press start, copyright text, healthbars, timer, meters all display fine. Sound is fine, gameplay seems to be totally normal, just can't see much.

I ran the memory test and get SPRITE RAM NG 24000000, SIMM1 NG, SIMM2 NG.
When I run the simm test I get the usual darksoft SIMM1 NG but SIMM2 reports OK.

I found that the sprite ram is located at 1D and checked around that as well as the PPU and couldn't see any obvious damage but i'm no expert.
There is a mounting hole near the PPU with some wear from screws around it but the traces appear to be in tact.

Anyone have any ideas?
Any insight greatly appreciated, thank you kindly for your time.

 

[xodaraP]

Have you tried rewriting the game onto the SIMMS?

 

[Shakunetsu]

I have, it ran successfully but result was the same

 

[GoldenGlover]

I’ve had this error before and fixed it. Based on my experience it’s one or a combination of the following:

• The sprite ram chip located at 1D is on its way out
• There is a broken trace between this sprite ram chip and PPU pins somewhere between 200-228 (this is the side facing the left edge of the motherboard PCB, or
• The PPU is corroding & giving off a sprite ram error

My sprite ram on a former CPS3 motherboard I had was getting warm when operating & failing the memory test - it was not displaying sprites correctly while the game was running. I found a combination of patching a corroded trace running alongside the edge of the motherboard between the sprite ram & PPU & replacing the sprite ram with a Hitachi HM514260DJ7 fixed the board’s issues. Another motherboard I had that also failed a sprite ram test had a corroded PPU (somehow corrosion developed underneath the PPU on all four sides) & I had to junk that motherboard.

Can you provide pictures of the traces along the left edge of your motherboard where the PPU is & a close up of the sprite ram at 1D?

 

[Shakunetsu]

Thanks so much for the information!

I hope these pictures are good enough. I've tried to find any traces that might be damaged and I haven't seen anything yet.
It's great to know the part I can replace the sprite ram with!

The sprite ram feels very slightly warm after letting the game run the demo for a little while. No warmer than the chips in 2D - 5D, I assume that's normal?

I can follow up later with a video of the display if it helps at all - would be nice to know if it looks similar to the one you were able to recover.

 

[GoldenGlover]

Thanks so much for the information!

I hope these pictures are good enough. I've tried to find any traces that might be damaged and I haven't seen anything yet.
It's great to know the part I can replace the sprite ram with!

The sprite ram feels very slightly warm after letting the game run the demo for a little while. No warmer than the chips in 2D - 5D, I assume that's normal?

I can follow up later with a video of the display if it helps at all - would be nice to know if it looks similar to the one you were able to recover.

No problem; those traces look OK to me from these pictures but I’d take a closer look at the two traces above the screw hole near the PPU (I can’t tell if they are dirty or if some of the laminate is worn away). Maybe check those two for continuity?

I’d also inspect the solder side of the board in the same area (edge closest to motherboard) as there are some traces from the sprite ram that are also underneath the motherboard. If you post a pic of the same area underneath the board that’d be helpful. If you leave the board on 15 minutes does the sprite ram get any hotter to the touch? The one I had that failed almost felt like it was burning.

Replacing the sprite ram isn’t difficult but be careful to take your time desoldering it with a hot air gun - those pad traces underneath are delicate.

 

[Shakunetsu]

Here's a photo of the back!

Noted - I may or may not actually attempt that myself, SMD soldering is not something I'm experienced with...

I let it run about 15-20 minutes and it never got alarmingly hot - stayed about the same temp as the other 4 chips around it!

 

[GoldenGlover]

I would clean the traces on the bottom of the board between F & G and G & H and make sure those traces don’t have any corrosion (I can’t tell if there’s leftover flux on some of those traces or if it’s something else). If all looks good there, replacing the sprite ram (it’s only a several dollar part) is going to be your best bet. Good luck!

 

[Shakunetsu]

Fingers crossed, thank you very much!

 

[Shakunetsu]

Necroing a very old post, but just wanted to update that the problem was some of the PPU legs had lifted and after soldering them back into place the board is working great!

Thanks again GoldenGlover, your comments here were a big help in understanding the issue.