Konami Viper RTC dremel and battery replacement

[Mrhide]

well I tried .... and it works ... so for anyone wanting to give it a shot, here's how the battery reveal itself as you dremel your way in



The top tab is ground and is pretty easy to keep a big piece to attach to.

...and then I broke it


.... it's DEEP ... don't afraid to dremel away (wear a mask! lots of small particules)
finally I figured out you can't remove the battery from its holder, you have to insert a screw driver underneath and gently lift it ( cover your pins below as you work)

 

[Mrhide]

underneath is the + tab and it's really hard to keep a big piece of it!


Still was able to use it:



The M48T58 says 5V but the battery is a BR1225, which is 3V.

So I use a 3v 2032 socket, from an old motherboard, burn the U39 on a TL866 II Plus and....




things to do better?

- less wires, glue the battery on top and THEN solder them.

Hoping this helps someone!

 

[stj]

if you want to be really neat, remove *all* the resin.
the chip has 2 contacts at each end, one end is the battery and the other is a 32.768KHz watch crystal.
you can fit a new crystal and glue a holder directly to the chip package after
i may dig one out to show pictures

 

[stj]

btw, is there any info around relating to the row of diagnostic leds?
i have 2 vipers, not dead - leds running patterns, but black screen.

 

[nem]

I soldered a new battery in parallel with the old one. You just need to dremel until you hit the contacts.

https://forum.arcadeotaku.com/viewtopic.php?t=22880

 

[skeletalpeacock]

Hi all. Thanks for the advice on this fix. I'm attempting it myself but I'm stuck. I cant find any evidence of where the positive tab went. I have the battery fully out. Can I please get a clarification of what "underneath is the + tab" means? Do I need to dremel under where the battery was to get that rail? @Mrhide

 

[nem]

Positive tab can actually be seen in your pic.

Or you can just cut off the side entirely and expose the contacts on the edge, like I did in the post above.

EDIT: there's a better pic on Hackaday which shows what it looks like when you remove the whole epoxy top:

https://hackaday.com/2021/05/11/the...ing-a-spent-lithium-cell-in-a-coffee-machine/

 

[skeletalpeacock]

Positive tab can actually be seen in your pic.

Or you can just cut off the side entirely and expose on the contacts on the edge, like I did in the post above.

EDIT: there's a better pic on Hackaday which shows what it looks like when you remove the whole epoxy top:

https://hackaday.com/2021/05/11/the...ing-a-spent-lithium-cell-in-a-coffee-machine/

Ah, so it is that circular region!

I opted to go through the wall, as you did. It was too hard to solder into that little ridge area, and the dremel didn’t expose more.

Thanks for clarifying!

 

[skeletalpeacock]

Hey all, just wanted to say thanks.

This worked first try without a hitch. I did have trouble finding the konami region codes so here they are for the next person -

Jaa = Japanese region version a
Aaa = Asian region version a
Uaa = U.S. region version a
Eaa = Europe region version a
Jab/jba = version b

I unzipped the rom for my game (silent scope ex) from mame and found a file with “uaa” in the name ending in u39 and it was the correct one.

Below is a pic of where I found the positive terminal I had “lost”. If I had to do it again - I would use fine sandpaper, as opposed to the dremel, to get an edge capable of holding solder on the circular area pointed out by nem. Because the dremel was too rough I would always erode any of that edge I touched. Cheers all.