FDS RAM Adaptor Glitching, "PRAM CRAM 00FFH"

Started by JoystickDivision, March 02, 2021, 10:26:53 pm

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JoystickDivision

Hey, I've just signed up today in the hopes that someone more knowledgeable can help me out.
I recently acquired a Disk System with the RAM adaptor and when I boot it, the music plays and sounds great. I can make everything out as Mario and Luigi fight over the light-switch, but everything is covered in glitchy, vertical lines.

I've just tried the self-test and I get "PRAM CRAM 00FFH" and the 'PORT' section underneath does its little cycle.

I can't try out any disks yet though, since the drive has its own problems, but this whole issue still occurs whether the drive is connected or not.

I can confirm that other cartridges work perfectly, the cartridge input is totally clean and the RAM adaptor pins are all making a good connection too.
The Famicom itself is an original, un-modded system.
If I need to, I can de-solder and re-install chips.

Thanks in advance for any help, tips and/or suggestions.

JoystickDivision

Another thing I forgot to mention is that sometimes when I boot it, the snare drum goes a little nuts and keeps playing for a bit after the music is meant to stop.
Also, in case you're curious, it's a 'verion 2' BIOS.

JoystickDivision

UPDATE: I replaced the belt and the drive works really well. Playing Super Mario Bros. 1 & 2 completely fine, but all the vertical glitchy-ness is still present.

Once again I appreciate any sort of feedback.

P

Sounds like something is wrong indeed. I guess you could try reflowing the chips and expansion connector and see if you still get errors in the RAM test.

Some RAM-adapters are prone to strange glitches in games, but it usually doesn't cause any errors in the self-test. In those cases, people have fixed it by adding pull-down resistors (not sure about the values) on the data lines.