Author Topic: U13 replacement for Cave CV-1000 PCB repair  (Read 196 times)

Offline buffi

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U13 replacement for Cave CV-1000 PCB repair
« on: March 30, 2021, 03:20:07 PM »
Do you also have a stack of old Cave CV-1000 PCBs, and worry about the internal memory of the undumped CPLD at U13 going bad leaving you with an unusable board? Maybe you have a PCB which is already broken due to this?

The CPLD is programmed with device protection enabled, making it hard to dump its content. Luckily it's just a 44 pin device with not too many buses connected to it, so I went ahead and analyzed its behavior and programmed a compatible bitstream that allows you to burn any EPM7032AE CPLD and use that if the original one goes bad. This should allow you to repair a CV-1000 board where U13 has stopped working!

Information about exactly what the CPLD does, and how to make a compatible one for repair is available in this repo: https://github.com/buffis/cv1k_research/tree/main/U13_Research

The docs should be pretty thorough but let me know if you have questions.

NOTE: !!! THIS IS ONLY MEANT FOR REPAIRS FOR DUMB COLLECTORS LIKE ME.
PLEASE KEEP MULTI TALK AND THAT KIND OF STUFF OUT OF HERE !!!


Offline EOJ

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Re: U13 replacement for Cave CV-1000 PCB repair
« Reply #1 on: March 30, 2021, 03:25:35 PM »
Wow, that's pretty awesome!! Many thanks for your work on this.
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Offline buffi

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Re: U13 replacement for Cave CV-1000 PCB repair
« Reply #2 on: March 30, 2021, 03:40:27 PM »
Thanks.

Pretty big disclaimer that I’m a hobbyist, and I’ve only tested this on a few credits so far, but if your board is busted you dont really have much to lose!

Seems to work well so far, and hopefully all the documentation can help someone.

Offline RandomRetro

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Re: U13 replacement for Cave CV-1000 PCB repair
« Reply #3 on: April 01, 2021, 12:51:12 AM »
Wow, I hope to never have to use this, but nice work and impressive. Thanks for sharing and I enjoyed reading the github details; not that I understand it all, but still like reading it.