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tlgrooms

Posted Fri Aug 21, 2020 7:25 pm

Got the v1.2.1 Diagroms and installed them. I can run some of the tests now that I couldn't before. Posted a video on YouTube, see link below.

https://youtu.be/r9p2CtPoVgU

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dalek

Posted Sat Aug 22, 2020 6:32 am

Looks similar to the bus buffers issue I was having on my A3000D. I had to replace two faulty 74F245's that do the chip ram (4 in total). If you've already swapped out chip ram I'd be looking in that area next.

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tlgrooms

Posted Tue Aug 25, 2020 9:36 am

I have removed the socketed chip ram but not the soldered on chip ram. I guess that's the next step if I can find someone to do it for me. I am shaky and would not be comfortable attempting it myself.

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tlgrooms

Posted Tue Aug 25, 2020 9:49 am

Dalek, what would your machine do when you had this problem? Mine just comes up with a black screen and alternates between 2 different shades of black and will go no further in the startup process.

Also, will any 74F245PC chip work? Do the other numbers on the chip need to match? Mine for instance show MP9112. Some of those offered on ebay show P9024Y.

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dalek

Posted Tue Aug 25, 2020 6:34 pm

tlgrooms wrote:
Tue Aug 25, 2020 9:49 am
Dalek, what would your machine do when you had this problem? Mine just comes up with a black screen and alternates between 2 different shades of black and will go no further in the startup process.

Also, will any 74F245PC chip work? Do the other numbers on the chip need to match? Mine for instance show MP9112. Some of those offered on ebay show P9024Y.
It would do lots of weird things, not always consistent. I would get a yellow screen even with the daughterboard in place, sometimes black screen.

Usually corrupt graphics in diagrom, memory tests failing in different areas and different patterns of memory failures depending on where I placed known good ram chips. Also failures depended on temperature too, so some freeze spray might have helped me isolate the problem chips.

Any old dip 74F245 from any manufacturer will be fine. Steer clear of Chinese suppliers/ebay as they could be rebadged slower parts. Get new from digikey or mouser they are cheap enough.

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Christian

Posted Fri Aug 28, 2020 6:53 pm

I have an A3000 that was flaky. I also changed all chips and did a lot of troubleshooting. Turns out that the Agnus socket needed to be cleaned. I used a Chemtronics Goldguard Pen and it works perfectly now.

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tlgrooms

Posted Mon Aug 31, 2020 12:50 am

Attached is the link to the serial output from Diagrom 1.2.1. The 3000T only has the onboard ram in it, all other socketed memory has been removed.


https://drive.google.com/file/d/1pmnlP3 ... sp=sharing

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Christian

Posted Mon Aug 31, 2020 1:00 pm

First of all - your A3000T is more working than it is not. I had a similar issue where a missing tick signal jumper (either power supply or vsync signal) caused the same black/dark grey cycling issue.

Try swapping the two CIAs with each other. Be careful not to pry underneath the socket.

Also, maybe the tick signal from the Power Supply is gone (broken). Switch the appropriate jumper on the A3000T to vsync to test. I'll see if I can dig that info up.
The deinterlacer won't work well if that jumper is switched to vsync, but it's good enough for testing.

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Christian

Posted Mon Aug 31, 2020 2:37 pm

A3000T tick source jumper is J350. Switch and see if Kickstart gets to boot menu.





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