Repair Log: Irem M72 - Legend of Hero Tonma

JohnRambo'sKnife · Jun 6, 2021

Wish I had your troubleshooting knowledge. Impressive to say the least.

ShootTheCore · Jun 6, 2021

Thchardcore said:
Wish I had your troubleshooting knowledge. Impressive to say the least.

Thank you for the compliment. I learned a TON from reading the PCB repair logs that @caius , @yavuzg , Porchy, Bryan McPhail and others have written - I'm just trying to follow in their footsteps and document everything publicly as best I can. :thumbsup:

stj · Jun 8, 2021

something i learned early on - dont trust ribbon-cables.

ShootTheCore · Jun 8, 2021

stj said:
something i learned early on - dont trust ribbon-cables.

Absolutely! I didn’t mention it in my write up, but I tried swapping the two ribbon cables between the malfunctioning M72 board set and my working board set early on. The cables are good in this case. :thumbsup:

ShootTheCore · Jun 22, 2021

The KNA6034201 reproductions from @caius arrived and FINALLY the board set is working 100% with no jailbars!

I ran the board for 24 hours as a "soak test" just to make sure that everything was solid. For good measure, I tried swapping in each of the original KN customs one at a time just to see if one of them was good, but unfortunately both custom chips have issues.

In the end, I ended up replacing 14 failed chips across both the middle and bottom boards.

One more update to come after I program, install and test the M72 Multi! :thumbsup:

kikaso · Jun 22, 2021

Nice job! What could have caused all of those bad chips?

ShootTheCore · Jun 23, 2021

My assumption is that either the power supply got turned up way too high, the power supply failed catastrophically, or the JAMMA harness was plugged in upside down.

kikaso · Jun 23, 2021

ShootTheCore said:
My assumption is that either the power supply got turned up way too high, the power supply failed catastrophically, or the JAMMA harness was plugged in upside down.

Yeah that makes sense. Glad you brought it back to life.

Neodogg · Jun 23, 2021

ShootTheCore said:
The KNA6034201 reproductions from @caius arrived and FINALLY the board set is working 100% with no jailbars!

I ran the board for 24 hours as a "soak test" just to make sure that everything was solid. For good measure, I tried swapping in each of the original KN customs one at a time just to see if one of them was good, but unfortunately both custom chips have issues.

In the end, I ended up replacing 14 failed chips across both the middle and bottom boards.

One more update to come after I program, install and test the M72 Multi!

Fantastic work!

kuze · Jun 23, 2021

Very nice work, props to you for sticking it through to the end. I know it can get pretty disheartening once you’ve replaced so many chips! Thanks for sharing the journey through pics :thumbup:

Apocalypse · Jun 23, 2021

ShootTheCore said:
Thank you for the compliment. I learned a TON from reading the PCB repair logs that @caius , @yavuzg , Porchy, Bryan McPhail and others have written - I'm just trying to follow in their footsteps and document everything publicly as best I can.

There's also that awesome blog:
http://arcadefixer.blogspot.com/

AlxUnderBase · Jun 23, 2021

Alot of good lessons there too !

@ShootTheCore ... Awesome achievment here sir !

ShootTheCore · Jun 27, 2021

Last update on this board!

I've replaced all the electrolytic capacitors and fitted the Apocalypse M72 Multi. Playing a round on each of the games now and everything is working 100%.