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Irem M72 Legend of Hero Tonma, no sprites

Tailsnic Retroworks

Tailsnic Retroworks

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Hi. I'm trying to repair a Legend of Hero Tonma origi al board. When booting, I have "RAM NG" error with no number associated and the game doesn't visualize good the sprites.

PXL_20250818_220734893.jpg


PXL_20250818_220749225.jpg


PXL_20250818_220758841.jpg


PXL_20250818_220809054.jpg


I have full checked the 4x sprites rams, 2xLS245, 2xLS244 and Nanao Custom 12 (this last one is even exchanged with one of another board and the same result).

PXL_20250818_221107584_1.jpg


Also followed the schematics and all the LS244-245, rams and Nanao Custom 12 are well connected between them. For anyone who knows more about this hardware. Where should I look?
 
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Your sprites are showing up solid white, which indicates a Palette issue to me. Palette signals are labeled as COL0 through COL3 in the schematics. Look in the lower-right corner of this page of the schematics for those signals and start probing and tracing them:
rtype_Page_11.png

I believe D0 - D3 on IC23 - IC26 should correspond to those signals.
 
ShootTheCore said:
Your sprites are showing up solid white, which indicates a Palette issue to me. Palette signals are labeled as COL0 through COL3 in the schematics. Look in the lower-right corner of this page of the schematics for those signals and start probing and tracing them:
rtype_Page_11.png

I believe D0 - D3 on IC23 - IC26 should correspond to those signals.
Click to expand...
I'm going to check the board today, but reading you, I have noticed you mention "COL 0A", " COL 1A", "COL 2A" and "COL 3A" in the 4/8 page of M72-B-D board you show.

But reading further the schematics I also see "COL 00", " COL 01", "COL 02" and "COL 03" on pages 7/10 and 9/10 of M72-A-C board. Could be probably those signals the ones you're referring really? Only asking
 
I did mean COL 0A, COL 1A, COL 2A and COL 3A on page 4/8 - which then are relabeled as D0, D1, D2 and D3 on page 5/8. Sorry for the confusion.

I'm not sure on the accuracy of the schematics. The schematics show IC19 as being a 74LS174 while it looks like a PAL/GAL on the real board. They show the COL signals emerging from Pins 2, 5, 7 and 10 on that IC .

You may want to just try programming and installing a fresh GAL:
https://wiki.pldarchive.co.uk/index.php?title=R-Type
 
@ShootTheCore I have seen in page 9/10 of M72A-C that there are COL 00-01-02-03 and COL 11-12-13-14 signals directly related to 4xALS374 in the sprites zone (RAMs IC36, IC37, IC38, IC39)

PXL_20250819_212314158.jpg


I have tried to quit 1 of those 4 rams and the sprites lose graphical info. Probably is the real final palette section of sprites zone.

Tomorrow I'll test those 74ALS374.
 
As said, I think the problem is one of the 'KNA91H014', this custom IC often goes bad because it has RAM blocks inside.Years ago I reversed it from a bootleg but the circuit is quite large so a reproduction is hard to think about.

P.S.

I fixed a Ken-Go PCB with similar issue time ago :

https://jammarcade.net/ken-go-repair-log/
 
Nothing, I have exchanged IC79 QFP custom, even IC62 Nanao 17 custom. Desoldered and tested externally IC61 74LS74 and IC67 74LS38. Also tested 4x rams IC36-37-38-39 and 74LS374 on IC25-26-27-28. Exchanged also IC10 Nanao 13 custom and IC9 Nanao 14 custom.

Is the same issue. The only culprit that is probably making this is IC2 Nanao 15 custom, but I haven't any replacement for testing.
 
Maybe I wasn't clear enough. You shouldn't replace chips randomly.
What I was suggesting is probing the QFP custom chip, looking for activity coming in and going out.
White sprites should show all colour signals being high (logical 1). You need to find where it originates.

[EDIT]
I found the schematics for R-Type.

1755730754253.png


Is there activity on the Rx, Gx and Bx signals?
What about the input signals? CAx, Dx, etc?
Could be the logic around it too, like something wrong (only speculation here) with the CBLK signal (Colour Blanking?).
 
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74LS74 in IC61 is in charge of CBLK and DCKL. That's why I desoldered it yesterday and tested it externally, with 74LS38 in IC67 which is involved too.

In the first photo you can see "RAM NG" error, which is a general RAM error as far as I know.

Also in the second photo you can see in the bottom left corner that not only the sprites are shown in white, it is drawing "square" garbage.

And in the gameplay, on concrete Tonma animations when jumping, also there are glitches. I'm going to try to get a NANAO 15 custom and see if this is the main culprit.
 
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