Author Topic: What more i can do?  (Read 36972 times)

0 Members and 1 Guest are viewing this topic.

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #225 on: November 19, 2024, 02:30:45 am »
Ok, cut the trace at the leg.
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #226 on: November 19, 2024, 03:01:20 am »
Ok, cut the trace at the leg.

The two TPs are shorted, TP of RTC and TP of Motherboard is shorted.

If that what you want from desoldering?
 

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #227 on: November 19, 2024, 03:56:04 am »
Is it possible to desolder RTC chip?

Don't forget to remove the battery.
« Last Edit: November 19, 2024, 04:00:06 am by Harry_22 »
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #228 on: November 19, 2024, 04:02:10 am »
Is it possible to desolder RTC chip?

Don't forget to remove the battery.

I can try to desolder it, BUT if incase there is issues then i need to buy new RTC.
 

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #229 on: November 19, 2024, 04:07:05 am »
Yes, check it please.
But your board don't work anyway.
You nothing to break down.
 

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #230 on: November 19, 2024, 04:09:26 am »
 While you have a time check TP1 signal at other non working boards.
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #231 on: November 19, 2024, 04:14:28 am »
Yes, check it please.
But your board don't work anyway.
You nothing to break down.

I dont think RTC has issues as Other similar non working board shows same results.

what shall i do after desolder?
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #232 on: November 19, 2024, 04:27:26 am »
While you have a time check TP1 signal at other non working boards.

I checked 2 more Non Working Motherboard , with TP1 and there are similar.
 

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #233 on: November 19, 2024, 06:33:21 am »

I checked 2 more Non Working Motherboard , with TP1 and there are similar.

Perfect!

So try to unsolder RTC chip.
Thus we disconnect Pin 11 which generates pulses with 64 Hz frequency.
There are a lot of D4990A on Ali.
Just raise 11 pin as I wrote but literally by half a millimeter.

I have another one approach to your problem from Beeper side. More on this later on.
« Last Edit: November 19, 2024, 06:35:09 am by Harry_22 »
 

Online Sorama

  • Regular Contributor
  • *
  • Posts: 208
  • Country: be
Re: What more i can do?
« Reply #234 on: November 19, 2024, 06:52:52 am »
Maybe you can follow the beeper signal to know what it triggers and thus understand the conditions and analyze those conditions ?
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #235 on: November 19, 2024, 07:03:35 am »

So try to unsolder RTC chip.
Thus we disconnect Pin 11 which generates pulses with 64 Hz frequency.
There are a lot of D4990A on Ali.
Just raise 11 pin as I wrote but literally by half a millimeter.

The thing is i do not understand what will happen if i desolder, will it only not send signals to TP?
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #236 on: November 19, 2024, 07:07:07 am »
Maybe you can follow the beeper signal to know what it triggers and thus understand the conditions and analyze those conditions ?

Can you give some hints and explanations?
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #237 on: November 19, 2024, 07:30:28 am »
Just raise 11 pin as I wrote but literally by half a millimeter.

Here it is,
The Pin is raised
The second image is the signal of TP1 non working board after RTC TP raised...
 

Online Sorama

  • Regular Contributor
  • *
  • Posts: 208
  • Country: be
Re: What more i can do?
« Reply #238 on: November 19, 2024, 07:33:03 am »
Maybe you can follow the beeper signal to know what it triggers and thus understand the conditions and analyze those conditions ?

Can you give some hints and explanations?

If you know (electrically) what drives the beeper and in the end which transistor/ processor pin, it may help you understand the prerequisites/conditions for the beeper and thus why it is beeper. Just follow the signal of the beeper.
 

Offline fzabkar

  • Super Contributor
  • ***
  • Posts: 2807
  • Country: au
Re: What more i can do?
« Reply #239 on: November 19, 2024, 07:34:00 am »
Thus we disconnect Pin 11 which generates pulses with 64 Hz frequency.
There are a lot of D4990A on Ali.
Just raise 11 pin as I wrote but literally by half a millimeter.

Pin 11 of the RTC is open drain, so it can be safely shorted to ground. Will this do what you want?
 
The following users thanked this post: 222Lab_Test222

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #240 on: November 19, 2024, 07:34:53 am »

If you know (electrically) what drives the beeper and in the end which transistor/ processor pin, it may help you understand the prerequisites/conditions for the beeper and thus why it is beeper. Just follow the signal of the beeper.
So i should track the beeper pin to where they are connected you mean?
 

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #241 on: November 19, 2024, 11:48:30 am »
Just raise 11 pin as I wrote but literally by half a millimeter.

Here it is,
The Pin is raised
The second image is the signal of TP1 non working board after RTC TP raised...

So we have got the same High level signal on Pin 11 RTC.
No reaction? The same continuous beep? Seems so.

@fzabkar, we tried to get High level as on working board. Now we got it. Nothing has changed.
The timer does not cause a malfunction, although I wanted to believe it so much.


That's it, we forgot about RTC.
 

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #242 on: November 19, 2024, 04:15:36 pm »
It seems you said that the beeper is connected to the Tornado-T chipset.
As we can see from the picture, the beeper signal is generated immediately upon power supply.
When Reset is released it disappears.
In our case either the Reset signal does not reach the chipset or it is held, for example, by the video card, ISA bus. Or there is another signal in the system, some Hardware Ready.

1. Ring that the Reset signal reaches the chipset. Remember the pin.
Make a broom out of a stranded wire (see the picture). You will find the connections in the board much faster (especially on boards with many small SMD parts).
2. Check the signal on OSC3 quartz near the chipset.
3. Measure and compare traces from both LEDs on both machines.
« Last Edit: November 19, 2024, 07:27:15 pm by Harry_22 »
 

Offline fzabkar

  • Super Contributor
  • ***
  • Posts: 2807
  • Country: au
« Last Edit: November 19, 2024, 09:03:57 pm by fzabkar »
 

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #244 on: November 19, 2024, 09:38:37 pm »
WACOM Tornado-T chipset should be similar with other 80486 Green PC ISA-VESA Systems.

The task is for you to trace the main signals along the path of the processor, chipset, and small logic.

Reset#
CLK, including 66 MHz quartz and logic around it.
Track pin3 MB3771 (Power Good?) and pin2 (Gnd or not)
Try to find 14 MHz clock signal.

« Last Edit: November 19, 2024, 09:59:21 pm by Harry_22 »
 

Offline fzabkar

  • Super Contributor
  • ***
  • Posts: 2807
  • Country: au
Re: What more i can do?
« Reply #245 on: November 19, 2024, 09:54:55 pm »
The scope traces suggest that the beeping stops as soon as Reset is released. This in turn suggests that this is happening well before BIOS starts executing. However, the OP has reported that the beeping continues on a good motherboard if the EPROMs are not present. This would suggest that BIOS code is switching off the beeping. I don't get it. :-?
 

Offline Harry_22

  • Frequent Contributor
  • **
  • Posts: 603
  • Country: 00
Re: What more i can do?
« Reply #246 on: November 19, 2024, 10:07:15 pm »
The scope traces suggest that the beeping stops as soon as Reset is released. This in turn suggests that this is happening well before BIOS starts executing. However, the OP has reported that the beeping continues on a good motherboard if the EPROMs are not present. This would suggest that BIOS code is switching off the beeping. I don't get it. :-?
Yes, you are right. Something looks strange.

@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.
« Last Edit: November 19, 2024, 10:23:03 pm by Harry_22 »
 

Offline fzabkar

  • Super Contributor
  • ***
  • Posts: 2807
  • Country: au
Re: What more i can do?
« Reply #247 on: November 19, 2024, 10:26:16 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
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #248 on: November 20, 2024, 12:04:46 am »

Reset#
IC1 reset signal is connected to IC2 Pin 1, IC5 Pin 1, IC23 Pin 6, TORNADO IC Pin 77.

CLK, including 66 MHz quartz and logic around it.
It is connected to IC6 Pin 3, IC7 Pin 2

Track pin3 MB3771 (Power Good?) and pin2 (Gnd or not)
Pin 3 doesnt have any power, Pin 2 is not GND, there is some voltage, it is connected to Resistance and then VCC.
« Last Edit: November 20, 2024, 04:36:19 am by 222Lab_Test222 »
 

Offline 222Lab_Test222Topic starter

  • Frequent Contributor
  • **
  • Posts: 287
  • Country: jp
Re: What more i can do?
« Reply #249 on: November 20, 2024, 12:41:19 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.
« Last Edit: November 20, 2024, 04:51:06 am by 222Lab_Test222 »
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf