Mysterious Famicom Mod

[oon]

Hi guys 

Alright, just signed up to ask you what you thought of this Famicom I've got. I bought it in Japan already modded and the colours are a bit washed out so I opened it up to have a look inside.  The mod installed doesn't look like any others I've seen on this site or anywhere else.  It seems to be comprised of the same components but located in a totally different area of the board.  Also there's a short black wire inside the silver box part of the Famicom that I've not seen on any other mod guide either.  I am thinking of removing this mod, buying new components and installing a new mod following a guide from this website.  I'm not very good with electronics but have used a soldering iron before, do you think that it's a good idea?  Is my Famicom's board different?  Should I install the new mod in the same place as the current one (see the picture below) or stick to the instructions in the guide?

The AV mod


Short black wire in the bottom-left



Any help or information would be greatly appreciated.

[ericj]

I'll defer to others about the mod, but that short black wire is to jump the fuse, which is probably blown.

[Da Bear]

Looks strange, the video is tapped and amplified after the inbuilt transistor (Q1) instead of directly of PPU pin #21. Don't know how much it affects the signal when doing it like that since I have not done so myself, but I think its not the optimal thing to do.

I would have rebuilt it.

[Xious]

Well, on the VCCI models (like this one), I normally attach the A/V modification (which is on a PCB) to the block of four + two connections you see in the second photo, which bridges the FC mainboard with the FC RF board.

I also think there is something odd about the configuration... It's not easy to tell though, as this is one of those free-floating solder jobs. I don't see any caps on the modification--anywhere--and I can't see a part number on that transistor. Please examine it and see if you can find a part number, as that will tell us if it's even the right kind of amplifier.

As a side-note, I've been thinking of building an A/V box for my own use, with one major difference to my usual work: It'll be tube-based.

Anyhow, it would also be useful to have photos of this that illustrate the port configuration that has been added on the side of the case, both from the inside and the outside, to help identify what the intention is of this configuration. I don't recall off-hand what i on the other side of the PCB, to which the white leads are soldered.

In any case, soldering the transistor to the video pin on Q1 isn't a huge problem, however I think the best place to tap the signal if you want to maintain RF and have A/V, is on the bridge to the daughter-board. I'd say that either the resistor value is wrong, it's missing a capacitor, or (most likely) it's using a bad type of transistor for the amplifier. Report back on the part numbers if you can, and please photograph the other areas of this modification. I think the idea here was to simulate stereo sound, but I can't see where those white leads are going, nor am I sure that the place to which they've been soldered is in any way appropriate. I'll need to look at a VCCI mainboard and check that lies at that location.

I can confirm that the black jumper in your second photo is a fuse bypass. I do this as well, from time to time, on my experimental systems.

[jpx72]

I can confirm that the black jumper in your second photo is a fuse bypass. I do this as well, from time to time, on my experimental systems.

Yeah I do that too, I have blown the 7805 lately because of that (understand: recommended to change that to a normal working fuse)