Electronics > Repair
What more i can do?
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222Lab_Test222:
Everything is good BUT Look that E15 HOLD PIN.
1st Pic is Not Working.
2nd Pic is Working.
Poroit:
G'day Harry_22,

Is the OP focusing on the correct points for the signals you need to see?

It seems to me that you want him to focus on the D4990A.

I see there is a Test Pont near that IC.

BTW
My contact a Komatsu Australia can not find any details on these machines ever been brought into Australia.
222Lab_Test222:

--- Quote from: Poroit on November 14, 2024, 06:33:55 am ---
It seems to me that you want him to focus on the D4990A.

--- End quote ---

The RTC D4990A Is not performing as it should be, Everything is fine except Output. The output should be constant HIGH But It keeps fluctuating between HIGH and LOW.
222Lab_Test222:

--- Quote from: Poroit on November 14, 2024, 06:33:55 am ---BTW
My contact a Komatsu Australia can not find any details on these machines ever been brought into Australia.

--- End quote ---

Maybe it is only in JAPAN, or could be in TAIWAN And CHINA too. BUT not sure.
Harry_22:

--- Quote from: 222Lab_Test222 on November 14, 2024, 04:18:38 am ---This is Picture of CPU CLOCK and RESET PIN.
The working board and non working board is same.

1st is CLOCK  and 2nd is RESET.

--- End quote ---
Well done and going in the right direction!
But the CLK and Reset# signals must be present on the working board. Check the pinout.

 You will find here the Databook on 486DX2 processor
https://bitsavers.trailing-edge.com/components/intel/80486/Intel486_DX2_Microprocessor_Data_Book_Jul92.pdf
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