Electronics > Repair
What more i can do?
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Harry_22:

--- Quote from: Doctorandus_P on November 16, 2024, 01:34:48 am ---My guess is they may have "hidden" some kind of key in the CMOS ram.

--- End quote ---

Theoretically this is possible, but then the CMOS would be in TORNADO-T chipset. Intel later did just that, co-locating the CMOS with the RTC and powering them from a battery.

By the way, we should try to remove the battery and short-circuit the pins for a while.
Harry_22:
Hello everyone!

There are still four pages left. It's time to sum up the interim results.

We have already noticed that the signals on a faulty machine are different from those that are working immediately after Reset line is released.
Chips with BIOS are not readable. They do not receive Output Enable level. But this is just a result of our problem.
By the way, the block diagram of the BIOS organization on two EPROM chips can be seen in the picture below.

We have now compared CPU signals to make sure they are 100% correct.
The difference was found only in the logic; more precisely, the D-type flip-flop is in the wrong state immediately after Reset.
Judging by the location of these chips, obviously they provide basic signal services for processor/chipset.

There must be something very simple if this fault is present on multiple boards.
222Lab_Test222:
If one of the chips goes wrong, does it contains issues in multiple components of the board?
I mean if we suppose D Flip Flop IC 6 74F74  is indeed in fault, then can this causes multiple problem in a board.

By the way I am trying to buy a T48 (tl866-3g) programmer for reading BIOS MSDOS, will arrive in a week.
I will drop BIOS contains here, maybe it will give us some rough idea what to do next.

And i will drop D Flip Flop contains tomorrow, I am taking a break, my mind is being hectic watching and reading this motherboards signals. I indeed need some fresh air.

Thanks Again for all help Harry_22
222Lab_Test222:

--- Quote from: Harry_22 on November 16, 2024, 09:22:38 am ---
By the way, we should try to remove the battery and short-circuit the pins for a while.

--- End quote ---

Can you explain this more?
Harry_22:

--- Quote from: 222Lab_Test222 on November 16, 2024, 01:42:41 pm ---If one of the chips goes wrong, does it contains issues in multiple components of the board?
I mean if we suppose D Flip Flop IC 6 74F74  is indeed in fault, then can this causes multiple problem in a board.

By the way I am trying to buy a T48 (tl866-3g) programmer for reading BIOS MSDOS, will arrive in a week.
I will drop BIOS contains here, maybe it will give us some rough idea what to do next.

And i will drop D Flip Flop contains tomorrow, I am taking a break, my mind is being hectic watching and reading this motherboards signals. I indeed need some fresh air.

--- End quote ---
Incorrect operation of any component will result in operational problems. But in digital technology, as a rule, it will not cause another malfunction. Just like you can’t break the computer’s hardware using the keyboard.

XGeku has never let me down so far. We took a little more for BGA chips. But the software is the same.


--- Quote from: 222Lab_Test222 on November 16, 2024, 01:46:34 pm ---
--- Quote from: Harry_22 on November 16, 2024, 09:22:38 am ---
By the way, we should try to remove the battery and short-circuit the pins for a while.

--- End quote ---

Can you explain this more?

--- End quote ---
Just remove the battery and short the pins in battery holder. For five minutes. It should be done on non working switched off machine.
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