Electronics > Repair
What more i can do?
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asis:
Hi,

I dare to voice my version.
-
If you look at uPD4990.pdf (p15), you can see uPD4175BC = (IC22 74LS174), inputs (4, 5, 12, 13), which are directly connected to the junior tetrad  DATA BUS D0 ~ D3.

The command procedure is described in detail in the document.

It cannot be ruled out that at the initialization stage (POST) some process occurs related to entering into the shift register and checking the contents.
It is quite possible that uPD4990 are faulty.
-
I suggest studying the document, so as not to fall into euphoria.
222Lab_Test222:

--- Quote from: Harry_22 on December 12, 2024, 05:41:23 am ---Ok, good!

Where the trace?

--- End quote ---
Here,
222Lab_Test222:

--- Quote from: asis on December 13, 2024, 12:17:50 am ---Hi,

I dare to voice my version.
-
If you look at uPD4990.pdf (p15), you can see uPD4175BC = (IC22 74LS174), inputs (4, 5, 12, 13), which are directly connected to the junior tetrad  DATA BUS D0 ~ D3.

The command procedure is described in detail in the document.

It cannot be ruled out that at the initialization stage (POST) some process occurs related to entering into the shift register and checking the contents.
It is quite possible that uPD4990 are faulty.
-
I suggest studying the document, so as not to fall into euphoria.

--- End quote ---

I am buying new RTC, lets see changes when new RTC are swapped.
222Lab_Test222:
Asis,

I am looking your currents comments and you seems to be interested in RTC IC23.
And we have done couple of measurements and observations.
If you need further anything let me know.
By the way you can read past posts, #Reply 109 and #Reply 119-123. It can give some answer you want.
222Lab_Test222:

--- Quote from: Harry_22 on December 12, 2024, 07:34:49 pm ---Possible solution for you:
Check the clamping force of the collets with a some chip leg.
Read the working IC16 EPROM with programmer, compare it and make a copy of new 27C2001 for test.

--- End quote ---
The main things is those Motherboards are so weird. Even in the working boards sometimes the results are not same. I am trying to get on one more motherboard which is good and is not repair by me in the past for further easy comparisons.

The things about BIOS is i ask my friend for programmer, he told me to that he will give BUT still i haven't got it. Looks like i will buy now. And in japan any delivery takes a week time not sure why is that.
And EPROM of non working board works in another board, so i doubt we can find anything on those files BUT i will send as fast as i can.
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