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Discussing the Open Source FPGA Amiga Project
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 Post subject: Only empty blue screen and no text
PostPosted: Sun Sep 21, 2014 10:40 am 
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Joined: Fri Sep 19, 2014 11:25 am
Posts: 6
My Minimig give me only empty blue screen and sometimes it might flash red screen before that blue. I am already flash new arm firmware using SAM-BA so I think that my arm board is okay. Where and how to try find what is broken?


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 Post subject: Re: Only empty blue screen and no text
PostPosted: Sun Sep 21, 2014 4:42 pm 
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Joined: Mon Dec 01, 2008 9:58 pm
Posts: 1568
Location: .de
Is your Minimig board a self-made one or build by ACube?
Some self made has soldering trouble at FPGA or S-RAM chips.

In your case the 68SEC000 cpu seems to work and at least can access the FPGA internal bootloader program to set the background color.
For bootloader text print the S-RAM/Chipram bus need to work properly and this may be the problem of your board. Possibly a RAM chip is damaged.

For general FPGA test, some other core like the "PacMan Core" is a good point to start.
If this works with graphics and sound, the RAM or CPU bus has a problem.

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 Post subject: Re: Only empty blue screen and no text
PostPosted: Sun Sep 21, 2014 4:56 pm 
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Joined: Fri Sep 19, 2014 11:25 am
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My board is ACube's 4 MB version. They are used some sort of black glue securing wires that are soldered upper memory chips. I am not so sure how easy it is replace the chips because of that clue... :cry:

I will test that "PacMan Core" and report here. :)


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 Post subject: Re: Only empty blue screen and no text
PostPosted: Sun Sep 21, 2014 5:38 pm 
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I found core named MiniPong2 and it work! :mrgreen:
So I need replace RAM chips or just play ping pong? :(


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 Post subject: Re: Only empty blue screen and no text
PostPosted: Sun Sep 21, 2014 7:36 pm 
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Joined: Mon Dec 01, 2008 9:58 pm
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Location: .de
Did this board ever work with a normal Minimig (Amiga) core by now?
If not, it may suffer a damage by some transport or ESD.
If there still is warranty, you should contact dealer or even ACube for repair service.

If its not possible to send it back:
By now there is no core with a test routine for the whole 4MB memory existing.
It may be possible to write a bootloader test routine and show different screen color as result.
But this need to be done by somewone else, currently Im too much out of ASM coding to do this.

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 Post subject: Re: Only empty blue screen and no text
PostPosted: Sun Sep 21, 2014 7:57 pm 
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I buy it february 2013 and it stopped working last friday so no warranty anymore I think. :(


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 Post subject: Re: Only empty blue screen and no text
PostPosted: Mon Sep 22, 2014 9:18 am 
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Is it possible for you to messure the lead contact of this black wires?
Maybe one is teared off which cause a RAM bus conflict and very well can produce such a problem.
Also make a visual check of the soldering points of the S-RAM chips. Perhaps there is some kind of foreign material between the pins causing a similar error.

If all did not help, somebody need to tech-check your board and possibly replace the RAM or even the 68SEC000 chips.

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 Post subject: Re: Only empty blue screen and no text
PostPosted: Mon Sep 22, 2014 6:54 pm 
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Joined: Fri Sep 19, 2014 11:25 am
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Any idea how I remove that black clue? It is very hard and there is no way measure those black wires or remove chips before that is removed. I have rework station so at least in theory I can remove those chips without damaging board and solder new chips in place.

Picture:

http://kuvaton.com/k/yW36.jpg


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 Post subject: Re: Only empty blue screen and no text
PostPosted: Mon Sep 22, 2014 8:26 pm 
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Location: .de
There is many different glue material to fix a wire. Some type are weak like gum, others are hard as stone.
One has to be very careful in removing it and not to break off the IC leg where the wire is soldered on.
Possibly some heat may help.

The soldering points of the S-RAM chips looks, sorry, horrible. Seems to be done pin by pin and not as usually with solder flux and dragging methode.

Also there seems to be an FPGA pin not in its place (right side on your picture), this is part of the RAM access pin for address or data bus.
Maybe this pin has bad contact to its pad or the next pin and therefor no RAM is available any more.
Its not an easy task to solder on a 208 pin QFP chip, so please be careful in trying to fix it by yourself.

According to your picture, the memory chips could still be OK but only has some communication trouble with the FPGA.
A pin by pin check of good contact between the components would be a good start.

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 Post subject: Re: Only empty blue screen and no text
PostPosted: Mon Sep 22, 2014 8:33 pm 
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This glue seems to be some sort of Hot melt adhesive. I tried isopropyl alcohol and it does not help but heat melts it. I try to check that FPGA pin.


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