Glitchy sprites on FDS

[fredJ]

I made a video that explains

"The mysterious famicom disk system glitching"

https://www.youtube.com/watch?v=7qsfqbfB0IU

Sorry about my crappy camera, I'm trying to find a better (for cheap)...

[80sFREAK]

Thanks for the video.
AFAIK famicoms with "FF" have PPU rev G and twins have rev E. What s the difference? Hard to tell until someone decapsulate both, take photos of the silicon and compare.

Why to replace CHRRAM but the other? Because we have chioce of SRAM chips, not PPU, isn't it?

I think this issue related not only to the speed of the chip, but input capacitance, which loading PPU slightly diffrent and shape of controlling signals might change enough to produce glitches.

[fredJ]

I have now tried with an AV Famicom, board hvcn-cpu-02.
And.. it did not glitch.

So that is some good news. Only the 1989 famicom board famicom glitches. It means that high end users don't have to worry and that one could say it is a built in problem with the console model rather than a defective RAM adapter.

[P]

Good, what PPU revision does that AV Famicom have?

[Asprate]

FredJ sent me a glitchy RAM-adapter to test with.
I noticed some flickering sprites when checking the PRG datalines with my Oscilloscope. So I thought there must be some CMOS/TTL mix?

These are pictures from SMB All night Nippon and Mario Golf Without any modification:


If I soldered in a 10Kohm resistor-array on the PRG datalines to Ground, it improved.


Mario had no glitches anymore. Golf however had one sprite not working.



Replacing the 10Kohm resistors with 4.7Kohm solved the problem! I had no resistor-array for 4.7k so i had so make my own Ghetto Style 





Further testing should be done, I don't know if this causes any other problem and damages any components, so it should only be for testing.

[93integraman]

well, this method fixed mine! I had some glitchy sprites on golf, mario, and metroid on my fds and I figured I'd give it a shot... I used a 4.7 array as suggested, and viola! everything looks clearer now! Thanks so much for the suggestion!

Side note: lay the resistor array down against the board before soldering it, and it will sit low enough to put everything back in the case when your done.

[Jaek_3]

I'm not very good with this sort of stuff, does anyone have a more in depth tutorial about the above fix?   

[xwred5]

Sorry for digging this up from the grave.

This is more of an informational post

I am having this problem on my NES front loader. The following values all have shown visual improvement (I don't have O scope). In all cases I am using a resistor array on a -04 ram board. My test condition is the second level of Castlevania, both on a disk and the FDSstick.

3.9k
4.7k
5.6k
5.1k
6.8k
10k

Update 11/21: Tested on a second NES (1st unit is a -08 NES second is a -11), No Change
Tested 10k, no change
Still waiting on the smooth ram adaptor, and I forgot to order a 3.1k. I have a Hi Def NES I need to install, I might install and see if there is a change.

Update 11/27: Hi-Def NES fixed it, however I had the game "crash" in a complete glitch. Could not get the FDStick to work either (audio only, no video). Worked with an actual FDS. Need more time to play around.

Update 12/03: I've bought way too much Nintendo stuff. Glitchy ram adaptor is working on the Hi-Def NES as long as I am using a FDS, not FDSstick. I suspect a power issue. Glitch Ram adaptor is working on a Top Loading NES, and an RetroUSB AVS. My smooth ram adaptor is currently MIA. I may or may not update this post again

[fredJ]

I'm not very good with this sort of stuff, does anyone have a more in depth tutorial about the above fix?   

Finally:



The ground wire is to connect to the resistor pin with a DOT. Important.

[zmaster18]

So I recently got some RAM adapters and I can also confirm that about half of FMR-03's will have glitchy sprites. Out of the 5 I had, 3 of them had the glitch on my 'FF' GPM-02 Famicom. 1 of the 3 RAM adapters had the smooth plastic casing.

I will attempt the 4.7k resistor fix once I get my hands on some.

[Whiteboy]

Just want to add that I am also getting the glitch sprites problem on all my FDS games. I got my FDS today and was so happy to get 15 games in mint condition with it! 14 of the 15 games work, but all of those 14 have the sprites issue and no other issues.

I did thorough cleaning of my RAM adapter pins and console too, like many. Wiggling the RAM adapter around in the console didn't change a thing.

Famicom model: HVC-101
RAM adapter revision: HVC-FMR-03 with a SONY chip, see pic

I also have an FDStick on the way, but If I read this thread correctly, then that alone won't solve the glitches.

I'll be getting a RetroUSB AVS in the next month or so, perhaps my RAM adapter will work on that.

But at the moment since I suck at soldering (and unaware of possible side effects with that resistor array mod fix), I think my solution will be to just buy another RAM adapter - the 04 model from ebay if I can even ask sellers to open the thing to check - and hope that works on my Famicom AV and AVS.

[zmaster18]

Wow, so the RAM adapter isn't working on your AV Famicom toploader? This is a new discovery.

I may be able to help you with getting a new RAM adapter. Message me! 

[Whiteboy]

Messaged you. Am I the only one in the thread with the problem on the revision 03 adapter with an unmodded toploader?

[zmaster18]

I got my resistor arrays in the mail the other day and soldered them into 6 glitchy RAM adapters. They all work perfectly now! This method works  

[skyway1985]

can you send me a link to which array you purchased? i actually want to use this on an fds to NES adapter my friend murmasa made. has the sprite glitch with ram adapters but not an N8, and want to see if installing this on one of my ram adapters will remedy the situation a bit.