Twin Famicom. Nothing on disk mode. Gray screen

[Lavos1999]

Hello Famicom World. I'm a long time reader. I almost always find the information regarding these consoles when I need it.

I have a AN505 Twin Famicom that will not boot on disk mode. I don't even get the Disk System start up screen. The cassette mode works fine.  I was wondering if anyone would shed some insight on what could be the issue with this. Thanks. 

[Byron]

Bad caps, maybe? I would open it up and try to find any capacitors that are bulging or leaking or obviously damaged in some way.

[Lavos1999]

I took it apart and cleaned it a bit. I don't see anything really obvious. All the caps look ok. There seems to be some type of dried on residue all over the board though. Kinda of like resin? Maybe soda or something was spilled on it in the past.

[Byron]

If something was spilled on it, a trace or two on the PCB could be corroded. I've seen soda spills do that to cartridges before.

[Lavos1999]

I'll take a good look at the board! I"ll have to go over it with 90% Alcohol.

[jpx72]

The dried residue is the liquid from leaked capacitors. Inmediately pull all of them out and clean the board! Put new ones in and hope everything will be ok.

[Lavos1999]

The dried residue is the liquid from leaked capacitors. Inmediately pull all of them out and clean the board! Put new ones in and hope everything will be ok.

I'll look at them again. Thanks!
Post Merge: April 19, 2015, 03:42:03 pm
I've been going over the board and it looks like maybe the caps have been replaced? They look a lot newer than the rest of the components. Is this diode setup on the back original? Maybe someone has been in here trying to get the disk system to boot.







Here's the power board. Is that 105C cap new? Did Nintendo use 105c caps?




Disk board

[fredJ]

They look replaced, yes.

If you get a grey screen, are you sure the lever (or switch or whatever you call it) works as it should? The grey screen sounds like the cart mode is activated.

[HokusaiXL]

The caps on the main bored have no flux residue and look cleanly wave soldered.  SO they're likely original.  
The diod bodge is probably a mod nintendo had to do to fix a hardware glitch, considering how crusty the pad beneath them looks.  Most people (not pointing fingers) leave those components floating when they do something DIY like.  
Flip the power board and take another picture so we can see the solder job on it too. o: