NOS Canon V20 black screen

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By tilatax

Rookie (22)

tilatax's picture

09-09-2018, 17:22

Yest this makes sense. Thank you. I will swap the VDP first, if it does not help I will replace the CPU. I wait for the solder sucker to ensure nice clean work. I really appreciate your help guys. This resuscitation turned into major operation, but gave me good opportunity to read and learn about the Z80. Despite being unsuccessful I am actually really enjoying it.

By tilatax

Rookie (22)

tilatax's picture

15-09-2018, 21:41

I have replaced VDP, Z80 and VRAM (all socketed now) . Same problem.
I am about to giving up. Crying
Any ideas?
The solder sucker is amazing though.

By Alexey

Guardian (1752)

Alexey's picture

15-09-2018, 22:45

Did you test all those chips in a working computer? If not, please make sure you test them before giving up. As the last resort you can send the computer to RepairBas. He will fix it for you for a reasonable price.

By tilatax

Rookie (22)

tilatax's picture

18-09-2018, 18:19

Yes, all good. I was wondering if the ROM might be the issue, not being able to load and so getting into a boot loop. All the components are considerably hotter than the Yashica YC64's. Does the MSX1 ROM tend to fail with time. It is a proper ROM not eprom, right? The other, and last, option is that the RAM is bad, so the ROM can't be copied into RAM and gets into boot loop?
What do you think?

By RetroTechie

Paragon (1462)

RetroTechie's picture

19-09-2018, 00:05

This would be the time to plug in a RAM cartridge - as suggested in my very first post in this thread. If you don't have one, go buy / borrow / steal one. LOL! It's an essential help for fault finding in dead MSXes. And dead / bad RAM chips inside the machine don't (usually!) interfere with a RAM cart that's plugged in.

Bad RAM is MUCH more common than bad ROM chips. Not the least because main RAM is usually divided over several IC's (like 2 or 8 pcs), where only 1 has to go bad for the RAM to not work.

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