AES : Intro screen garbled and looping

Hello Everyone

This is the first time visiting this forum for me, I hope i didn't missed any presentations topic or anything like that

Anyway, I need the point of view of experts, I played all my cards from my side.

So, I have an AES for almost 20 years, about 4 years ago, it stopped working with this symptom:



(it seems that youtube integration doesn't work : https://youtu.be/s9PA5KkYumk

The boot jingle loops, and as you can see, the graphics are totaly out of sync.

Without game, i got this :



Links to video : https://youtu.be/_aRLw9szLtM

Pretty much the same.

4 years ago, i couldnt do anything, had not any material to work with chips, nowaday I have more to work with, and I got myself the very good Neo Diag Bios, which I installed, and got this results :



Link to video : https://youtu.be/UDZL3gGtykg

I could see that it was trying to tell me something, but the console is not able to display anything properly, so I had to go further, and install the M1 chip in a cartridge

The sound code that it make is clearly 001100 :

So according to the official Neo Bios site means :

Z80<->68k COMM. ERROR (DATA) 001100

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A quick look at the possible solutions give this :

Z80 isn't receiving the expected data from the 68k communication I/O port. Most likely an issue with the Z80 data bus or control signal trace to the chips that control the port (NEO-C1, NEO-D0).

Z80 D0~D7 → NEO-C1 SD0~SD7
Z80 IORQ (20) → NEO-D0 IORQ (37)
NEO-D0 SDZ80R (41), SDZ80W (43) → NEO-C1 SDZ80R (84), SDZ80W (85)

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I checked all the tracks that are listed here, all good (the board is very clean and looks almost like new)

I might send my AES to a professional repaire shop, but maybe someone here already had that kind of exact symptoms and error codes?

Thanks anyway for reading, regards

F

I'd probably attack the C1 and D0 first, if all traces check out as you say then one or both may be bad.

lachlan said:

I'd probably attack the C1 and D0 first, if all traces check out as you say then one or both may be bad.

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Thank you, that's a bit what a feared, I dont think I have the competences to change that kind of chips :/

F Destroyer said:

Thank you, that's a bit what a feared, I dont think I have the competences to change that kind of chips :/

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Well I've never tried either but thankfully the legs on those chips aren't too small. Might have some luck with a desolder braid and patience.

Make sure sync is getting to the TV, AV socket or cable connector could be worn out. Also recap the output, bad cap on sync can do that as well.

Xian Xi said:

Make sure sync is getting to the TV, AV socket or cable connector could be worn out. Also recap the output, bad cap on sync can do that as well.

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Sup James?

Video can fool you, but audio cannot.

Check the distortion on the intro jingle. There must be something else too.

Atro said:

Sup James?

Video can fool you, but audio cannot.

Check the distortion on the intro jingle. There must be something else too.

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Probably the whole board could use a recap. But Xian Xi's av socket or cart slot suggestion are valid as well. It sounded like it could have had a bad connection or bad grounding

DasiyAge said:

Probably the whole board could use a recap. But Xian Xi's av socket or cart slot suggestion are valid as well. It sounded like it could have had a bad connection or bad grounding

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Indeed. But the sound is not only distorted. The speed is slower. Hardly a grounding issue in my book.

Without a cart, the garbled screen is blue. I take this as the hardware self test is passed, but whatever is wrong is something the self test doesn’t/wouldn’t check.

Digmac said:

Without a cart, the garbled screen is blue. I take this as the hardware self test is passed, but whatever is wrong is something the self test doesn’t/wouldn’t check.

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I know the Z80 isn't tested on the AES and the C1/D0 both interact with it.