Author Topic: What more i can do?  (Read 36989 times)

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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #175 on: November 14, 2024, 07:39:01 am »
1st is CLOCK  and 2nd is RESET.
 

Offline Harry_22

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Re: What more i can do?
« Reply #176 on: November 14, 2024, 08:00:39 am »
Perfect now!
 

Offline Harry_22

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Re: What more i can do?
« Reply #177 on: November 14, 2024, 09:30:43 am »
1st is CLOCK  and 2nd is RESET.

Just pictures for a complete understanding.
 

Offline Harry_22

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Re: What more i can do?
« Reply #178 on: November 14, 2024, 08:24:56 pm »
Hi!

Could you check the following CPU signals as usual with Reset# trigger at power up.

A17  AHOLD
B17  EADS#
C15  FLUSH#
A3    TCK
D17  BOFF#
C14  FERR#

Chech also the signals in green cirles (please see the picture).
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #179 on: November 15, 2024, 12:02:18 am »
Images
-A17  AHOLD
-B17  EADS#
-C15  FLUSH#
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #180 on: November 15, 2024, 12:03:23 am »
Images
-A3    TCK
-D17  BOFF#
-C14  FERR#
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #181 on: November 15, 2024, 12:30:00 am »
Kindly read images name,
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #182 on: November 15, 2024, 12:31:20 am »
continued
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #183 on: November 15, 2024, 12:32:23 am »
continued
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #184 on: November 15, 2024, 12:34:29 am »
continued
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #185 on: November 15, 2024, 12:56:21 am »
These above all are working board images.

Now below are non working board images.

Only 3 of them are different so i am sending only 3 of them.
They are
-74ls174 1 pin
-74ls174 9 pin
-74f74 9 pin
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #186 on: November 15, 2024, 04:30:32 am »
Ring the Reset signal from CPU to D1 Power supply monitor. It passes via some 74... logic

Also ring the path of CLK CPU signal.
Draw the scheme or mark them on the top PCB layer picture.


The CLK and RESET signals as well as many pins of CPU and other RTC ICs, 74LS ICs, EPROMS all connected to the WACOM IC WE001BF.
 

Offline Harry_22

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Re: What more i can do?
« Reply #187 on: November 15, 2024, 10:15:16 pm »
Thank you very much for your careful measurements!
The summary in pictures you will find below.

You have found a small thread in the processor control logic (see the last screen in the second picture). The main thing is that this thread leads to the root cause.

Please measure the other signals on the pins of this D-type flip-flop.
« Last Edit: November 16, 2024, 01:39:56 pm by Harry_22 »
 

Offline Doctorandus_P

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Re: What more i can do?
« Reply #188 on: November 16, 2024, 01:34:48 am »
My guess is they may have "hidden" some kind of key in the CMOS ram.

And for the rest, what sort of thing is that? It looks like a regular old PC board with some extra I/O. Maybe it's feasible to just replace it with more modern hardware. Maybe you can put it on a modern board, put the thing in a VM and redirect I/O. Modern hardware is so gianormous more faster then the old stuff that you have gazillions of cpu cycles to play with.
 
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Offline Poroit

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Re: What more i can do?
« Reply #189 on: November 16, 2024, 05:32:19 am »
G'day Doctorandus_P,

Brochure attached of the system.

This PC board is part of the controller for the Underground Drilling Machine.

Over 30 years old so if you can think of a method of modernising it, I am sure the OP would be interested.
 

Offline Harry_22

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Re: What more i can do?
« Reply #190 on: November 16, 2024, 09:22:38 am »
My guess is they may have "hidden" some kind of key in the CMOS ram.

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.
 

Offline Harry_22

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Re: What more i can do?
« Reply #191 on: November 16, 2024, 09:44:04 am »
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.
« Last Edit: November 16, 2024, 09:56:10 am by Harry_22 »
 
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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #192 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.

Thanks Again for all help Harry_22
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #193 on: November 16, 2024, 01:46:34 pm »

By the way, we should try to remove the battery and short-circuit the pins for a while.

Can you explain this more?
 

Offline Harry_22

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Re: What more i can do?
« Reply #194 on: November 16, 2024, 01:57:10 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.
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.


By the way, we should try to remove the battery and short-circuit the pins for a while.

Can you explain this more?
Just remove the battery and short the pins in battery holder. For five minutes. It should be done on non working switched off machine.
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #195 on: November 18, 2024, 12:27:18 am »
After some cleaning and resetting the CMOS Battery and shorting it, I get D Flip Flop same in Both Working and Not working one.

 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #196 on: November 18, 2024, 12:28:03 am »
...
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #197 on: November 18, 2024, 12:30:20 am »
...
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #198 on: November 18, 2024, 12:31:29 am »

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

I tried and shorted BUT did not see any changes in beep, Its still beeping...
 

Offline Poroit

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Re: What more i can do?
« Reply #199 on: November 18, 2024, 05:37:34 am »
G'day Test 222,

I just read through all the posts again and problems with capacitors are mentioned a number of times by various members.

"I checked all capacitor, no sign of short, the IC looking good, no burn marks as well as any damages."

How are you testing the caps, are you removing from the PCB and using an ESR Meter?

Someone also thought IC7 could be the fault.

Has this been ruled out?





 


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