Help with installing a mod chip on a VA2.1 board.

[bertmansk]

edit* for the title I meant to say BIOS chip!
edit2* BIOS chip installed professionally (Bad_Ad84). Added more pics.

Hi guys. Making this thread because I need some help on my 2.1 board. It's not the same as the 0 or 1.

Here are photos of my Non-MIL DC.






fell res links: front, back, inside, bottom sticker

I asked Bad_Ad for some instructions, but I'm a noob when it comes to this and basically I need to be spoon fed. Plus, it would be nice to have a sort of official thread for installing the chip on a 2.1 board for everyone to see.

Some nice instructions I found for installing on a V0 and V1 board: http://www.mmmonkey.co.uk/sega-dream...ee-bios/#ic502

Now, some facts:

• This board does not play backups. Not even the data/data burn method.
• The 2.1 board does not seem to have the IC502. If you look at the rear picture, You can see the stamp "IC502", but no chip. I'm not sure why, maybe you do.
• It also doesn't have the alternate solder point RA515.
• Bad_Ad's instructions: The installation is the same, other than the point to solder leg 44 to the existing flash chip. You need to look up the datasheet of the tsop flash chip (just look at the chip and google the part number) then find the WE leg, this is what pin 44 needs connecting to.

I just want to install the chip the easiest way possible. I've thought that piggy backing with no switch is the easiest. Correct me if I'm wrong. Hopefully I don't need resistors for that... If so, then maybe I'll just remove the old bios chip (was trying to avoid this).

Anyway, that's all I can think of for now.

Update 1: BIOS chip installed
Update 2: Testing backups on DC with new BIOS

[RetroJunkie]

Damn that thing has a ton of capacitors compared to the VA1s I have.
Was much else changed on the VA2s apart from the GD-ROM getting that terrible ribbon cable and the removal of MIL CD capabilities?

[Bad_Ad84]

Desolder and lift leg 12 of IC501
Connect that to pin 23 (or any other 3.3v power source) via a 10k resistor (if you dont have resistors, you can do it without - but resistor is preferred), this will disable the on board chip.
Piggyback the chip, also lifting legs 1, 12 and 44
Connect pin 1 to 23 (ideally via a resistor again, but without will work)
Connect pin 12 to ground


Pin 44 needs to connect to /WE on IC503 (pin 9) - you will need to find an alternative point with a multimeter or solder directly to the chips leg.

[fasman]

Why not have a pro fit it for you?

I am sure you can find a forum member in Italy that can help you out, or just post the board to Bad-Ad, and get it done properly.

[Bad_Ad84]

I would fit it for you for free, just pay the shipping back and forth. I can then use it to take pictures and update the mmmonkey guide (I have write access to his wordpress).

Which directly benefits me (no one asks me for instructions), you for a free install and everyone else for the guide.

[bertmansk]

I will take you up on that offer. Will PM you.

[leetuser]

Does anyone know what kind of switch I need if I want to piggyback the bios chip. I would like to retain the ability to switch back to the retail bios. (I like switches)

[Bad_Ad84]

SPDT

[Druid II]

Wow, thanks alot for those full resolution pictures! We need more stuff like that, there are so many different boards out there, and they should be categorized properly so we don't have to hunt around for info.

[bertmansk]

Wow, thanks alot for those full resolution pictures! We need more stuff like that, there are so many different boards out there, and they should be categorized properly so we don't have to hunt around for info.

Well I uploaded them to my dropbox so they're here to stay forever :)

[Bad_Ad84]

If you dont mind, I will put them on the wiki thats in progress

[bertmansk]

If you dont mind, I will put them on the wiki thats in progress

They're all yours

[leetuser]

SPDT

Thank you.

[henderson101]

I'd love to do this mod but I neither have the soldering skills, nor the parts. Being in the UK, how easy is the chip to source and also would it be possible to also take up the offer of fitting? (happy to pay a fee if so.) Never looked at the board, so no idea what revision (it says something about being a model 01 on the bottom sticker and plays burnt discs etc.)

[bertmansk]

Bad_Ad84 sells the BIOS chips: http://www.assemblergames.com/forums...arts-chips-etc
and I'm sure he offers a fitting service, you'll prob have to PM him about that.

[henderson101]

Cool. PM'd him, thanks!

[Bad_Ad84]

Mod done

[bertmansk]

Such a clean job! Looks great. Can't wait to play with it

[Mack702]

Very clean soldering work man , nice job.

[-=FamilyGuy=-]

Mod done

Clean job! But shouldn't you have used the resistors? Also, any way to have an updated schematics, or is it the same as VA1?

Great job!