Imac 27 2009 unsuccessfully flashed bootrom.

[torsapbro]

Imac 27 2009 unsuccessfully flashed bootrom.
I had a working imac, but decided to flash the bootrom, first connected to different chips (the lm393 chip and the chip that is under the video card), until I found the right one.It failed to flash, because the old bootrom could not erase the flashrom. When turning on the imac, several problems were detected.
1) A total of 2 diagnostic LEDs are lit.
2) There is no sound at all, although there is no RAM in the imac.
3)The fans are spinning, the imac does not reboot.
4) For some reason, the imac began to turn on when I insert the network cable, bypassing the button.
Checked 14 pins
When the imac is turned on, 2 - 3.27v, 3 - 5.02 m, 4 - 11.9v, 9 - 3.27v, 10 - 11.8, 11 - 11.8 , the remaining pins are 0 volts.
The Lm393 chip that I wanted to flash has 2 earths on legs 2 and 7.Maybe the problem is in him?
I will be incredibly grateful for the help, first of all, I'm all thumbs when it comes to computers.Secondly, I want to learn.

 

[Nguyen Duc Hieu]

May I ask what is the purpose of bootrom flashing in this case?

 

[torsapbro]

May I ask what is the purpose of bootrom flashing in this case?

• May I ask.Does your question benefit?
  
  
  

 

[Nguyen Duc Hieu]

• May I ask.Does your question benefit?
  
  
  

Yes, it benefits me. That's why I used "May" in my question.

 

[DeltaMac]

"flashing a bootrom" is quite unusual on a Mac, and there is usually a purpose for that.
I "think" that Nguyen Duc Hieu was trying to find out what your goal was, when you said first that you had a working iMac, but "decided to flash the bootrom". There's usually a purpose, or a goal when doing such a procedure.
Were you following some steps to do that?

 

[torsapbro]

May I ask what is the purpose of bootrom flashing in this case?

you know a lot and are a respected person on the forum.I will try to describe my problem.I decided to flash the Bootrom because I wanted to install it on imac 27 2009 rx470 4gb.When installing the rx470, a cyclic gong occurred.And I thought I should flash the bootrom.But still could not flash the data was not deleted.​

 

[Nguyen Duc Hieu]

you know a lot and are a respected person on the forum.I will try to describe my problem.I decided to flash the Bootrom because I wanted to install it on imac 27 2009 rx470 4gb.When installing the rx470, a cyclic gong occurred.And I thought I should flash the bootrom. But still could not flash the data was not deleted.​

Your description made me guess a lot.
- You tried to flash the graphic card with a CH341a programmer, using its clip?
If in that case, the process should be
1. Read the original rom
2. Erase the original rom (on the chip)
3. Program the new rom
When you miss step 2, you will not be able to write the rom on it.
With the original rom still persist, your iMac can not boot properly.

So the solution is to reflash the ROM.

 

[torsapbro]

Your description made me guess a lot.
- You tried to flash the graphic card with a CH341a programmer, using its clip?
If in that case, the process should be
1. Read the original rom
2. Erase the original rom (on the chip)
3. Program the new rom
When you miss step 2, you will not be able to write the rom on it.
With the original rom still persist, your iMac can not boot properly.

So the solution is to reflash the ROM.

All right.I flashed the correct vbios, but the card does not start.Two LEDs are lit, and when turned on, a cyclic gong.I suspect that the video card is probably not working.Thank you for your help.