Glitchy sprites on FDS

[P]

There are really some truly nice people on nesdev. To think they would ask you to send it to them and see if they could fix it for free like that. I hope you thanked Koitsu properly.

It was a strange problem though that we still don't exactly know the cause of (I'm Pokun in that thread btw). Anyway I'm glad that it was solved. Have fun with your Disk System!

[80sFREAK]

Why not to replace CHR RAM chip, which is Sony made in mid 86? It also might be latch ('373) degraded over the time. This explains, why same FDS have no issues on different famicom/twin

added
Just read thread on nesdev. Dunno, if you guys like to go to the post office to send boxes, or ebay disputes/claims, but easiest solution at moment is to replace CHR RAM chip with 100ns or faster. I would strictly recommend to ALL resellers, who charging $20+ for FDS, do this procedure. You have to open RAM adaptor for cleaning anyway. 15 minutes and $1 chip might save you losts of time(and money) later.

Still not sure, why some code is so critical to hardware or chips are degraded so badly.

[P]

So you think it's bad CHR RAM chips after all? May I ask what kind of 100ns chips I should look for if I don't know much about chips? My local electronics store only has SRAM. 100+ ns SRAM chips are like 15$ a pieace there, so the RAM adapter will end up costing a lot more. Also how do you know if the RAM chips are pin-compatible with the board?

[80sFREAK]

With current staistic i can say yes, degraded(?) CHRRAM chip is an issue. You can use SFC/SNES cart as a donor for 8kb SRAM. These days chips are JEDEC compatible. If you are not sure, you always can download datasheets and compare pinouts.

[P]

I see, thanks. The local store doesn't seem to have any 18 pin SRAM chips that works anyway, so I guess looking for loose SNES sports games is the way to go.

[80sFREAK]

28pin, 0.6" and 0.3" are fine since layout of PCB designed to fit both. Just don't solder 0.3" chip over the shortcuts 

[P]

Thanks.

[fredJ]

So I've spent a couple of hours now with this problem too...

Glitchy problems happens with:
FDS RAM adapter HVC-FMR-03 (copyright 1985)
AND
A famicom of later revision (the one with FF on the logo)...
Tried with three such consoles, two AV-modded and one not modded, and all were glitchy..

It doesn't happen with:
HVC-FMR-04 (copyright 1986), on any model famicom..

also doesn't happen with a famicom of earlier revision (no FF on front logo) or twin famicom, even with RAM adapter HVC-FMR-03...

I tried the glitchy HVC-FMR-03 with FOUR earlier revision famicoms (all AV modded), and no glitching...

Maybe it is a bug with the HVC-FMR-03 ? One would need to try more RAM adapters. It seems to be a constant problem with this model...
I will add the the later revision famicom (FF logo) has a 1989 motherboard and was released after the FDS which could explain why they are incompatible.
I will try with the AV famicom (HVC-101) when I get another.

[P]

Now when you say it, all faulty units have been HVC-FMR-03. My non-faulty RAM adapter is 04 (the one with the older BIOS version).

[80sFREAK]

@fredJ reuesting photos of every PCB you used for test.

[fredJ]

Famicom PCBs? I don't know if I have time for that right now, that would be a lot of consoles to open.

But I can say that the RAM adapter had the Sony chip.

Also, today I tried a different -03 RAM adapter that has a "noname" sram chip (? no brand name anyways) and there were no glitching...

The D-Ram chips are different too.



The one to the left is the glitchy one...

[Zycrow]

I'll jump in here to say that I picked up a non-modded FC as well as a junker FDS with a working RAM adapter from Senseiman last month.
My prior RAM adapters worked perfectly on the FC, and the adapter worked with my modded FC. So my problems are all solved, but it still remains to be seen what causes all of this nonsense...

[oare]

Glitchy problems happens with:
FDS RAM adapter HVC-FMR-03 (copyright 1985)
AND
A famicom of later revision (the one with FF on the logo)...
Tried with three such consoles, two AV-modded and one not modded, and all were glitchy..

It doesn't happen with:
HVC-FMR-04 (copyright 1986), on any model famicom..

also doesn't happen with a famicom of earlier revision (no FF on front logo) or twin famicom, even with RAM adapter HVC-FMR-03...

I tried the glitchy HVC-FMR-03 with FOUR earlier revision famicoms (all AV modded), and no glitching...

I can report the same behavior here.
The glitches seem to happen when combining an early RAM adapter (HVC-FMR-03) with a later revision Famicom (HVC-CPU-GPM-02).

No problem when using the same FMR-03 with two different HVC-CPU-07 boards, or with an AN-505 Twin Famicom.
No problems either on any Famicom with an FMR-04.

My FMR-03s units both have a smooth plastic top enclosure, whereas my FMR-04s have a rough plastic top enclosure. I'm not sure how precise a visual clue that is, since there might be some overslap between the revisions. But if others can confirm this observation, it might be safer to try and avoid smooth plastic RAM adapters in general, especially if you own a Famicom that has the "FF" logo on the front panel.

Edit: a little update, I tried replacing the Sony S-RAM chip with a Hitachi chip (the "no-name" chip on FredJ's pic), and the glitches are still present.
I'll try replacing the D-RAM chips when I have some free time and see how that goes.
After all, those D-RAM pieces are the main difference between FMR-03 and FMR-04, so those might as well be the real culprit here.

[80sFREAK]

Famicom PCBs? I don't know if I have time for that right now, that would be a lot of consoles to open.

But I can say that the RAM adapter had the Sony chip.

Also, today I tried a different -03 RAM adapter that has a "noname" sram chip (? no brand name anyways) and there were no glitching...

64S20?

By the way, there is a RAM test in the BIOS, you can try to perform it on glitchy adaptors, but i very doubt it is accurate.

[fredJ]

64S20

I'm not sure what you are referring to... but the picture shows the chips http://i.imgur.com/vyKsOgq.jpg
I have sent the adapter to my colleague now so I can't look at it more.

Yes I tried the RAM testing on the glitching one (Start + Select or whatever it is) and it showed ALL OK.

So, next thing to test, per oare, is to replace the DRAM chips, possibly S-RAM, and I also want try it on an AV Famicom.

But if you check the thread: "Re: ATTENTION!!! FDS users, SNROM, UNROM etc might be affected as well." http://www.famicomworld.com/forum/index.php?topic=8512.msg150032, I think someone tried replaced DRAM without success. (or what does "socketed" mean?).