Hello,
at first I must mention I am just a beginner in 8-bit repairs. I collected few experiences in repairs like changing the capacitors, voltage regulators and building kits like Minstrel 2,3, etc.
I want to play with my Dragon 32 after couple of months again. It was working previously, but now it developed some fatal failure.
I had to power it on and off couple of time to boot in into working state, but after few other tries it died completely. Now I can see only white and black vertical bars on screen.
The processor seems to be live - with scope I see some activity on address and data lines. Couple of time during the probing and restarting the pattern on screen changes, but most of the time I see the vertical bars.
I already removed all the socketed chips and cleaned them with contact cleaner. I am able to remove only memory chips from the daughter board. With removed memory chips the behavior did not changed.
Does anybody has a clue what could the culprit? Where should I start?
M.
Dead Dragon repair - black and white vert.bars on screen
Dead Dragon repair - black and white vert.bars on screen
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Re: Dead Dragon repair - black and white vert.bars on screen
Welcome to the Dragon Archive!
I had a similar problem with a CoCo2, and turn out to be a bad MC6847 video chip.
Other culprits could be the roms. If they have given up their ghost and become corrupted, you could get a bad video initialization.
If you type CLOAD and press Enter, do you hear the relay click?
Do you have any spares, and can we get a picture of your board?
Cheers,
Rob
I had a similar problem with a CoCo2, and turn out to be a bad MC6847 video chip.
Other culprits could be the roms. If they have given up their ghost and become corrupted, you could get a bad video initialization.
If you type CLOAD and press Enter, do you hear the relay click?
Do you have any spares, and can we get a picture of your board?
Cheers,
Rob
Re: Dead Dragon repair - black and white vert.bars on screen
Hello,
unfortunately I am quite busy with my job, so I have only limited time to work on these "fun" projects.
After CLOAD"" I hear no click. I assume the computer is dead. I mean the processor is running, but not doing any reasonable activity.
What kind of picture of the board you mean? Some photos are attached to my previous post.
Michal
unfortunately I am quite busy with my job, so I have only limited time to work on these "fun" projects.
After CLOAD"" I hear no click. I assume the computer is dead. I mean the processor is running, but not doing any reasonable activity.
What kind of picture of the board you mean? Some photos are attached to my previous post.
Michal