Author Topic: What more i can do?  (Read 36967 times)

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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #250 on: November 20, 2024, 01:43:22 am »

@222Lab_Test222, could you take out both EPROMS from working board and track the beep signal as usual. Reduce the time/div to detailed view the delay between reset release and beep stop. First with EPROMs and next without.

Here it is BUT after EPROMs removed, beep doesn't stop so, how to watch delay?
--With EPROMs
--Delay with beep stop
--Without EPROMs
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #251 on: November 20, 2024, 01:43:51 am »
....
« Last Edit: November 20, 2024, 01:46:24 am by 222Lab_Test222 »
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #252 on: November 20, 2024, 05:16:39 am »
2. Check the signal on OSC3 quartz near the chipset.

It seems good, BUT if i change more divisions, i couldn't get frequency maybe because it was too dense..
OSC3 is connected to R28 and then to TORNADO Pin 115
« Last Edit: November 20, 2024, 05:38:16 am by 222Lab_Test222 »
 

Offline Harry_22

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Re: What more i can do?
« Reply #253 on: November 20, 2024, 06:26:51 am »
Check the signal Output Enable on working machine with EPROMs at 500us/div.
« Last Edit: November 20, 2024, 06:33:38 am by Harry_22 »
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #254 on: November 20, 2024, 07:21:56 am »
Here
 

Offline Harry_22

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Re: What more i can do?
« Reply #255 on: November 20, 2024, 07:56:03 am »
Here
Could you reduce time/div to see the pulses
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #256 on: November 20, 2024, 08:04:38 am »
One thing I do not understand, Please Clarify this..

Regarding the RTC ICs,
Here Red color are Inputs and we done lots of check on it, Its all good, same in working and non working board.

Yellow color are Outputs, This should be Ok as All inputs are ok right?
Then why Outputs are not going as exception,
-The Data Out should be constant High voltage BUT it Keeps Fluctuating.
-The TP should be 64Hz But it doesnt give frequency sometimes and sometimes it give 72Hz.
-The XTAL inverter seems good.

Why is this happening? Is RTC bad?
Or I miss something on the input of this RTC?

Image is below:
 

Offline Harry_22

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Re: What more i can do?
« Reply #257 on: November 20, 2024, 10:30:27 am »
Follow the logic, it is the most important thing here:
First we found where the Bios itself is located. It turned out that it is in EPROM together with MS-DOS system.
We checked whether it loads - it turned out that it doesn't. It doesn't even try.

It became clear that the malfunction occurs at the very start. In modern machines, when the machine is turned on, a special Power On Sequence testing procedure occurs and it is quite complex (see the picture). We also have some events from this procedure.

On the other hand, we approached it from the other side, not head-on. We tried to understand which elements can cause such a multiple malfunction.
These are capacitors. CMOS with power supply that could run down and "spoil the data". Such cases have repeatedly occurred when the computer refused to start with a black screen due to a dead battery.

We checked the RTC that is the only one powered here. We found that the working one board has no pulses at the output, but the faulty one does.
Here. The faulty one starts from zero. The C0, C1, C2 pins have a low level, the output frequency is 64 Hz according to the datasheet (Correction: C2 should be high!)
RTC on the working one board does not start from the zero. Now it stores the C'(0...3) settings recorded during the previous work cycle. Therefore TP (Timing Pulse) outputs are different.
But when you unsoldered the TP pin from the line, we were convinced that the TP signal does not affect the start.

Now about the important thing. I missed your message that "DATA OUT pin (Pin 10) is unstable in non working board", most likely this is interference on the bus in the Z state (high impedance). But the absence of CLK on pin 9 needs to be studied in more detail. Where does it come from?

PS
I remind everyone that we can't work faster because of the big time difference. It's like driving a Mars rover. From 3 to 20 minutes, radio waves fly in only one direction.
« Last Edit: November 20, 2024, 08:53:18 pm by Harry_22 »
 

Offline Harry_22

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Re: What more i can do?
« Reply #258 on: November 20, 2024, 06:03:29 pm »
Here you can see Beep behavior on working board as well as EPROM Output Enable.
« Last Edit: November 20, 2024, 08:58:38 pm by Harry_22 »
 

Offline Harry_22

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Re: What more i can do?
« Reply #259 on: November 20, 2024, 06:47:19 pm »
@222Lab_Test222, could you take out both EPROMS from working board and track the beep signal as usual.

I wonder if it might be an idea to scope the OE and CE pins of the EPROMs? The OP has reported that there is activity on all the address lines other than the high order A16 and A17. I'm wondering whether the pre-BIOS beeping is non-fatal and still allows the BIOS to POST, at least until it encounters a problem?

This is how I imagine the two EPROM layouts (the high order address space is occupied by MS-DOS):

Code: [Select]
256K .--------. A17  .--------. 0x3FFFF
     |        |      |        |
     |        |      |        |
     |        |      |        |
     | MS-DOS |      | MS-DOS |
     |        |      |        |
     | v3.21  |      | v3.21  |
     |        |      |        |
     |        | A16  |        | 0x10000
 64K |--------|      |--------|
     |        | A15  |        | 0xFFFF
     |  BIOS  |      |  BIOS  |
     |        |      |        |
     |KDX 1.34|      |KDX 1.34|
  0K '--------' A0   '--------' 0x0000

      High byte       Low byte

      D15 - 8         D7 - 0

Please check OE, CE, Address and Data busses on the non-working board with the same 500us/div. Attach here only meaningful ones.
All the lines are paralleled except Data bus.

Recheck CLK signal at Pin9 IC23 RTC.
« Last Edit: November 20, 2024, 09:32:29 pm by Harry_22 »
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #260 on: November 20, 2024, 11:15:45 pm »
There are some more ICs under BIOS MSDOS, You guys noticed or not?
IC5 74LS07
IC17 74F32
IC71 74HC125A

Green LED is connected to IC5 via resistance.R26
Red LED is connected to IC5 via resistance.R6

Buzzer is connected to SWITCH SW4, the 4th pin is used to toggle sound on or off. Then it is on IC21 Pin 2, and that is near Tornado IC.

Harry did you read this?
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #261 on: November 21, 2024, 12:26:41 am »

Please check OE, CE, Address and Data busses on the non-working board with the same 500us/div. Attach here only meaningful ones.
All the lines are paralleled except Data bus.

Every Pins are different, shall i send all here?
I only send and compare some of them, check it..
I do not understand any signals.

No is Non Working Board and Another is working board, I compare images and edit in 1 picture.
« Last Edit: November 21, 2024, 01:20:17 am by 222Lab_Test222 »
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #262 on: November 21, 2024, 01:25:50 am »
@Harry_22, @fzabkar

Is there a way to know what triggers the IC9 TORNADO IC, Every input of the ICs as well as BIOS pins seems to be getting inputs from the IC9.
Even the LEDs seems to be the same case.

This TORNADO IC is playing a crucial role in our troubleshooting.
 

Offline Harry_22

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Re: What more i can do?
« Reply #263 on: November 21, 2024, 03:30:57 am »
There are some more ICs under BIOS MSDOS, You guys noticed or not?
IC5 74LS07
IC17 74F32
IC71 74HC125A

Green LED is connected to IC5 via resistance.R26
Red LED is connected to IC5 via resistance.R6

Buzzer is connected to SWITCH SW4, the 4th pin is used to toggle sound on or off. Then it is on IC21 Pin 2, and that is near Tornado IC.

Harry did you read this?
Yes.

Please check the LED signals on both boards. And attach them here if they are different.
Also check and compare the CLK IC 23 RTC (pin9)
« Last Edit: November 21, 2024, 03:47:19 am by Harry_22 »
 

Offline Harry_22

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Re: What more i can do?
« Reply #264 on: November 21, 2024, 03:45:30 am »
Ring A8 through all the board. Use the broom to speed up the process.
Please make a photo of the bottom PCB side.
 

Offline Harry_22

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Re: What more i can do?
« Reply #265 on: November 21, 2024, 03:56:32 am »
Tornado-T is like North and South bridge in one. This is beginning of computer fairy tail.
Unfortunately we have no info on it but only on analogs. See my post #244
 
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Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #266 on: November 21, 2024, 04:07:42 am »


Please check the LED signals on both boards. And attach them here if they are different.
Also check and compare the CLK IC 23 RTC (pin9)

The CLK IC 23 RTC seems good, Its low signal, BUT same as we done previous.
The RED LED seems good BUT Not sure about Green LED. It sometimes glow and sometimes doesn't, so not sure how to compare.
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #267 on: November 21, 2024, 04:16:03 am »
Tornado-T is like North and South bridge in one. This is beginning of computer fairy tail.
Unfortunately we have no info on it but only on analogs. See my post #244

Can you send me Pin Diagram or Datasheets if you have?
 

Offline Harry_22

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Re: What more i can do?
« Reply #268 on: November 21, 2024, 04:24:08 am »


Please check the LED signals on both boards. And attach them here if they are different.
Also check and compare the CLK IC 23 RTC (pin9)

The CLK IC 23 RTC seems good, Its low signal, BUT same as we done previous.
The RED LED seems good BUT Not sure about Green LED. It sometimes glow and sometimes doesn't, so not sure how to compare.
Just print the picture from non-working machine.
Is it behavior different time to time?
 

Offline Harry_22

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Re: What more i can do?
« Reply #269 on: November 21, 2024, 04:25:38 am »
Tornado-T is like North and South bridge in one. This is beginning of computer fairy tail.
Unfortunately we have no info on it but only on analogs. See my post #244

Can you send me Pin Diagram or Datasheets if you have?

I don't have Tornado itself. Only analogs.
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #270 on: November 21, 2024, 04:28:47 am »
Ring A8 through all the board. Use the broom to speed up the process.
Please make a photo of the bottom PCB side.

A8 is connected to IC9 Tornado pin 23.
Here is back side..

Top left is Power supply then there is CPU then BIOS.
« Last Edit: November 21, 2024, 04:34:09 am by 222Lab_Test222 »
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #271 on: November 21, 2024, 04:30:15 am »
.
Is it behavior different time to time?

Yeah sometimes it glows, sometime it doesn't...

For working it should be dim glow continuous.
 

Offline Harry_22

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Re: What more i can do?
« Reply #272 on: November 21, 2024, 06:12:48 am »
.
Is it behavior different time to time?

Yeah sometimes it glows, sometime it doesn't...

For working it should be dim glow continuous.
What is a signal monitored here? CLK?
 

Offline Harry_22

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Re: What more i can do?
« Reply #273 on: November 21, 2024, 06:26:20 am »
Ring A8 through all the board. Use the broom to speed up the process.
Please make a photo of the bottom PCB side.

A8 is connected to IC9 Tornado pin 23.
Here is back side..

... back side of the Moon.

Please make a broom from the wire, connect it to the multimter with fast short ring responce and "clean" all the back side.
We have to know all the points with A8 address.
Could you check also the data bus. For instance Q1.

It would be good to ring All the Data and Address busses for short to +5V and Gnd. Just to be shure.

It would be very good to know the chip names from the back side.
« Last Edit: November 21, 2024, 06:51:43 am by Harry_22 »
 

Offline 222Lab_Test222Topic starter

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Re: What more i can do?
« Reply #274 on: November 21, 2024, 07:07:40 am »

What is a signal monitored here? CLK?
[/quote]

As it is connected to the IC5 IC, i guess the output of IC5 leads to this, not sure though
 


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