What is wrong?

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By MSX_Dan

Supporter (12)

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07-04-2018, 22:07

Just switches my msx on and the screen is like this.

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By MSX_Dan

Supporter (12)

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07-04-2018, 22:19

Also when i press numbers and symbols keys they show as letters.

By hamlet

Scribe (3660)

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07-04-2018, 22:47

Your Canon V20, I guess?

By MSX_Dan

Supporter (12)

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07-04-2018, 22:47

Yes

By sd_snatcher

Prophet (3471)

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07-04-2018, 22:50

It seems that you have a bad VRAM chip. But bit1 is always stuck to 1, and the bits 2 and 3 sometimes are stuck to 1 too.

By Grauw

Ascended (10056)

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07-04-2018, 22:55

One of the VRAM chips is bad, always returns 1. The second of eight.

Looking at the board, the VRAM is the 4116’s I think.

@sd_snatcher Nothing wrong with bits 2 & 3, it’s just showing the backtick instead of the space (20H -> 60H).

By MSX_Dan

Supporter (12)

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07-04-2018, 22:53

I have no idea what you guys are saying here lol

By hit9918

Prophet (2905)

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07-04-2018, 22:54

it looks like data bus pin 6 always goes high

By Grauw

Ascended (10056)

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07-04-2018, 23:01

MSX_Dan: One of the chips marked U31-U38 on the board is bad and needs to be replaced.

Looking at the service manual, U32 or U37 is the problem.

By sd_snatcher

Prophet (3471)

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07-04-2018, 23:04

@sd_snatcher Nothing wrong with bits 2 & 3, it’s just showing the backtick instead of the space (20H -> 60H).

You're right. I counted the bits from the wrong side. So its 7-n, where n is the number I mentioned. Wink

By MSX_Dan

Supporter (12)

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07-04-2018, 23:02

i have no idea of how to go about solving this. this is beyond any knowledge of mine.

it's strange because i booted it up and it was fine. then like a minute after those lines appeared.

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