Famicom av mod instructions?

[2A03]

I also redid the AV mod on my Famicom with this method and it didn't reduce the vertical lines one bit. I got better quality video like with my top loader, but I'm still getting jailbars. Unlike my top loader, I did what Da Bear did and cut the trace going from the PPU video pin to the 2SA937, and I also used shielded cable for the line going from the PPU to the base pin.

[Da Bear]

Did you desolder 2SA937? Where have you placed the new circuit?

If you can, take a picture of the board and one of your TV with the game running.

[2A03]

Did you desolder 2SA937? Where have you placed the new circuit?

If you can, take a picture of the board and one of your TV with the game running.

I desoldered the 2SA937 from the motherboard just like I did with my top loader. Right now I've got the circuit wedged in the gap between the RF modulator board (which no longer has the RF modulator) and the motherboard. I'll see about getting pics for you later this week as I'm busy for most of the week.

[cmv2]

if you cut and up carefuly the leg 21 and solder of top separate to the motherboard, reduced the jailbars to minimun

[jpx72]

if you cut and up carefully the leg 21 and solder of top separate to the motherboard, reduced the jailbars to minimun

Yeah but if you break the leg (highly possible!), you can throw your PPU to garbage... just a warning.

[cmv2]

almost everything can be fixed

example
http://www.elotrolado.net/hilo_tutorial-reparar-patas-del-chip-snes_1633122

[jpx72]

Haha brutal force applied! Nice!
But be real, not everybody can do such a thing... and by using a drill/ angle grinder to remove part of the chip, everything can happen. It may also cause too much heat so it destroys the chip by overheating it.

[cmv2]

I only said it if you want to avoid jailbars, if someone had better lower their own risk

[Da Bear]

I have a theory I would like to share.
Right now I'm av modding several Famicoms and it works out just fine doing the way I have described. ie cutting traces and moving Q1.
But one machine didn't respond to my mod. Heavy jailbars and a buzzing sound coming out the speakers of my TV.

I measured the voltage regulator and I only got ~4.8v from it. The ones that don't give me vertical lines are those who have ~4.9- 5.1v from the voltage regulator.

If you want to measure the voltage and reply here how much it outputs and how bad your lines are I would be happy. I suspect that underpowered boards gives more interference.

[jpx72]

Nice find, when I get to it I will measure my current modded Famicom and report here. Also, what revision board are you talking about (the one with heavy jailbars)?
When I find myself some time, I can also try to exchange the "classic" 7805 with one of local manufacturer alternatives, just to see the diference.
http://www.iowaind.com/Manufacturing-Equipment-/Lathes-/Needing-Repair-/New-MA7805-tesla-ic-MC7805CK-7805-photo_example.jpg

[Da Bear]

The one that has got bad lines is a HVC-CPU-GPM-02.
The other GPM-02's I tried this on works great, also does the HVC-CPU-07 boards. The older boards have slightly more visible jailbars then the newer ones.
But this faulty GPM-02 is the worst I have seen so far.
I'll try to change the voltage regulator with one I know is giving proper voltage to see what happends. Could be some other component that's faulty to. Don't know yet.
Post Merge: October 25, 2011, 09:10:46 am
Anyone knows if the components in the Famicom would handle 6v? If so I could try to change 7805 to a 7806 to se if more power means less jailbars.

[mamejay]

I have a theory I would like to share.
Right now I'm av modding several Famicoms and it works out just fine doing the way I have described. ie cutting traces and moving Q1.
But one machine didn't respond to my mod. Heavy jailbars and a buzzing sound coming out the speakers of my TV.

I measured the voltage regulator and I only got ~4.8v from it. The ones that don't give me vertical lines are those who have ~4.9- 5.1v from the voltage regulator.

If you want to measure the voltage and reply here how much it outputs and how bad your lines are I would be happy. I suspect that underpowered boards gives more interference.

Hey Da bear,
I have a model that is doing the same thing.  One thing I did find is that the buzzing would totally disappear when controller 2 was not attached.  As soon as it was attached it came back.  I know it was not the controller as I have a few spares and they all did it.  Try this and let me know if the buzzing goes away.

[Pikkon]

I had the same problem with the annoying buzzing and I found a fix for mine.

Just open up the player 2 controller and solder a wire just like in my pic.


Once I did this the buzzing went away and the controller and the mic work fine.

[jpx72]

Anyone knows if the components in the Famicom would handle 6v?

I believe it will. That increase is insignificant. I have famiclones that run on 9V without any voltage regulator (they run fine on 5V too).

I have measured my current modded FC, but I haven't desoldered the original transistor. It had strong jailbars so I attached the capacitor on the PPU and they dissapeared. The voltage on 7805 is 5,01 - 5,02V. My setup (it's HVC-CPU-GPM-02C)

[mamejay]

I had the same problem with the annoying buzzing and I found a fix for mine.

Just open up the player 2 controller and solder a wire just like in my pic.


Once I did this the buzzing went away and the controller and the mic work fine.

Thanks for that one!!  Something to think about.  I actually think I Flucked that console right up trying to work out what was happening.  Just shows a blue screen now