Electronics > Repair

What more i can do?

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222Lab_Test222:

--- Quote from: 222Lab_Test222 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.

--- End quote ---

Harry did you read this?

222Lab_Test222:

--- Quote from: Harry_22 on November 20, 2024, 06:47:19 pm ---
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.


--- End quote ---
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.

222Lab_Test222:
@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.

Harry_22:

--- Quote from: 222Lab_Test222 on November 20, 2024, 11:15:45 pm ---
--- Quote from: 222Lab_Test222 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.

--- End quote ---

Harry did you read this?

--- End quote ---
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)

Harry_22:
Ring A8 through all the board. Use the broom to speed up the process.
Please make a photo of the bottom PCB side.

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