AES - Blue screen and reset loop

[jcoelho]

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For anyone interested in the solution, in my case it was trace A16 from the cart slot to the CPU. This is a screenshot from a different board revision but it shows the offending trace:



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Hi all!

I hope you are well. Here I am again, the AES I repaired a while ago is giving me trouble again. It is an early NEO-AES 5V revision with a daughter board.

This time it gets into a reset loop with original carts or with my NeoSD pro. It was giving me a blue screen with or without a cart but, after reflowing and cleaning the card slot, power switch and carts, that seems to be gone and now it only gives me a beautiful blue screen when no cart is present or a reset loop when there is a cart. I can see the console seems to get into a reset loop since the led in my scart switch blinks rapidly, so looks like it tries to sync, resets and repeat.

I measured voltage on the cart slot and all 5v pins get exactly 4.79v according to my multimeter. I'm using a Triad 5V 4A PSU.

A while ago a did a full recap, replaced the power and video connectors and the resistors on the video output.

Any suggestion on what to look for?

Thanks!

 

[jcoelho]

Quick update: Reflowed cart slot and, after tying many times, my only original cart gives me a blue screen like there was no cart at all. My neosd pro still causes the console to reset over and over...

 

[neoslacker]

Hmm, if you really want to chase it down you will need to continuity check the traces to the cart socket to the CPU- WRAM - the console is probably 99% but there’s a bad trace somewhere - probably take a couple of hours but you’d be surprised what you’ll find.

 

[neoslacker]

Oh and if you want an easy way to know all the traces. Download the “BoardFollk” schematic and open it in KiCAD. Then just use highlight nets to see all the connections - it’s amazing

 

[jcoelho]

Oh and if you want an easy way to know all the traces. Download the “BoardFollk” schematic and open it in KiCAD. Then just use highlight nets to see all the connections - it’s amazing

Thanks for the suggestions! Just had a look at the Board-Folk schematic and yeah, it's amazing! My board is a Neo-AES but, besides the components being in different places around the board, I should be able to extract valuable information from it.

 

[neoslacker]

Thanks for the suggestions! Just had a look at the Board-Folk schematic and yeah, it's amazing! My board is a Neo-AES but, besides the components being in different places around the board, I should be able to extract valuable information from it.

I have not uploaded it to YouTube yet but I literally fixed an AES-6 with blue screen with cart inserted last night.

It was trace A7 from the CPU to the cart. Looked dirty in one place, wiped it and the trace just flaked off - it was eaten. Bridged it and fixed it in 5 mins.

I was surprised that a single bad address line would give blue screen with a cart but I guess it makes sense.

Hope this gives you an idea of how this is probably a tiny trace break if you are lucky.

 

[mariotaotao]

same problem here, and after I check the tracks and clean the board between the cartridge slot and Z80 chips, the screen become red with no cart insert

 

[neoslacker]

same problem here, and after I check the tracks and clean the board between the cartridge slot and Z80 chips, the screen become red with no cart insert

That is usually an error with work ram connecting to the 68000 cpu

 

[neoslacker]

same problem here, and after I check the tracks and clean the board between the cartridge slot and Z80 chips, the screen become red with no cart insert

High quality pics of board would also help if you have them

 

[mariotaotao]

High quality pics of board would also help if you have them

OK, I'll take a photo and post here later

 

[mariotaotao]

High quality pics of board would also help if you have them

Hi, update some pics here, I can enter memory card managment menu on boot by pressing A+B+C+D，and it works like normal.
The graphic and sound also seems good, any suggestion on what to check next? thanks

 

[Neo Alec]

same problem here, and after I check the tracks and clean the board between the cartridge slot and Z80 chips, the screen become red with no cart insert

Usually the diag bios would be the next step. If you're not comfortable desoldering, you should get help.

 

[mariotaotao]

Usually the diag bios would be the next step. If you're not comfortable desoldering, you should get help.

Do you mean I need to desolder the bios chip and replace something to debug? Is there a tutorial? Thanks

 

[Dr. Jigglin]

Do you mean I need to desolder the bios chip and replace something to debug? Is there a tutorial? Thanks

There is a custom diag bios you install in place of the original bios chip. Desoldering it without issue takes experience.

 

[jcoelho]

Oh and if you want an easy way to know all the traces. Download the “BoardFollk” schematic and open it in KiCAD. Then just use highlight nets to see all the connections - it’s amazing

Hey @neoslacker

Just wanted to thank you for this info. I was able to fix my AES today, it was trace A16 from the cart to the CPU. The BoardFolk schematic proved to be an invaluable resource, my board is not the same revision but the schematic helped me find the problem easily.

Thanks again!

 

[Neo Alec]

Wow. @neoslacker's suggestion kind of came out of nowhere for me. I remember troubleshooting traces on boards without tools like this. It's amazing what's available now. I'll have to look into Boardfolk next time!