A4000 Tips for repair.

[Cosmos]

We must find all togheter a method to check and find the prob(s) on every Classics in 5 minutes...

I'm sure it's possible...

First, I'll picture all ICs and on each of them, take the pins voltage... Can be usefull... I'll begin on a working A4000D revB


Any others ideas ?

[hikey]

Something is messing with the chip-ram data bus for you to get the green screen. Maybe one of the other chips that are connected to the chip ram data bus have a problem (Paula, Lisa, Alice). Check the reset lines, if any are stuck low all the time that may help isolate the problem. Check for normal activity on each of the 16 chip-ram data bus lines on an oscilloscope if you have one. I think they're labeled DRDxx on the schematics.

[psodas]

@Cosmos

If any of the customs is faulty, the FatGary dont start the reset lines.
The same can happen from any point of the machine with any other problem large or small. For example if you go to 74HCT166 one of two ic who is responsible for joy controllers, and cut the MDAT line, the machine doesnt boot at all.

For all this reasons I believe is not possible to make a list for defacto standard problems.

An other example is the RTC. If it is faulty, the machine can doing anything. In a previews repair, any time who I power on the machine, had a different screen. Yellow, green, red!?!?! One other time, was just dark grey.

Confused??

---------- Post added at 01:08 ---------- Previous post was at 01:05 ----------

Also as Hikey said, (and I in previews post) check the reset lines.

[Amiga-Digital]

Originally Posted by Cosmos

We must find all togheter a method to check and find the prob(s) on every Classics in 5 minutes...

I'm sure it's possible...

First, I'll picture all ICs and on each of them, take the pins voltage... Can be usefull... I'll begin on a working A4000D revB


Any others ideas ?

you got still green/gray/green

have u change the video DAC chip U460 , thats a chip that give also a green screen

when i not work , maybe i can check you board , i got 2 roms here to check the memory chip/fast data lines cia ( timer datalines ) audio , video datalines