2009 iMac 21in need to hold these four keys together: Option, Command, P, and R in order to start or restart.

[zhoubolin]

hey guy

Question

I have a old 2009 iMac 21in that has a problem of showing black screen after press the power bottom behind when starting or restart , therefore the only way i found out to fix this everytime is to hold these four keys many times together on the keyboard: Option+Command+P+R after press the power bottom behind in order to start or restart avoid the black screen.

is there a better fix for this?

 

[Nguyen Duc Hieu]

hey guy

Question

I have a old 2009 iMac 21in that has a problem of showing black screen after press the power bottom behind when starting or restart , therefore the only way i found out to fix this everytime is to hold these four keys many times together on the keyboard: Option+Command+P+R after press the power bottom behind in order to start or restart avoid the black screen.

is there a better fix for this?

I would suggest you to open the iMac and replace the coin battery on the logic board.
If it couldn't help with the problem, maybe you would need to replace the EFI chip on the logic board.

 

[zhoubolin]

I just went checked the "what is coin battery on the logic board?" and what it does?
this seem difficult to operate!

iMac Intel 21.5" EMC 2389 PRAM Battery Replacement

Use this guide to replace the PRAM battery.

www.ifixit.com

 

[zhoubolin]

I would suggest you to open the iMac and replace the coin battery on the logic board.
If it couldn't help with the problem, maybe you would need to replace the EFI chip on the logic board.

I just went checked the "what is coin battery on the logic board?" and what it does?
this seem pretty complicated to operate this

iMac Intel 21.5" EMC 2389 PRAM Battery Replacement

Use this guide to replace the PRAM battery.

www.ifixit.com

 

[Nguyen Duc Hieu]

I just went checked the "what is coin battery on the logic board?" and what it does?
this seem pretty complicated to operate this

iMac Intel 21.5" EMC 2389 PRAM Battery Replacement

Use this guide to replace the PRAM battery.

www.ifixit.com

The coin battery help retain the basic information necessary to boot the iMac inside the EFI chip (basic input-output system).
When it is drained out, the information stored inside the EFI chip is partly missing, therefore, when you start the iMac, it confused about the devices (CPU, RAM, GPU, etc) connected to the logic board and you had to do PRAM reset (Option+Command+P+R ) several time to flush the EFI memory and let the iMac rescan the whole system again.
A typical coin battery has 10 year of operating time. Your iMac is already 13.

The above is just my guess from your description. It may not be correct, but it give you an option to try and test. a new battery doesn't cost much.

 

[CooperBox]

I just went checked the "what is coin battery on the logic board?" and what it does?
this seem pretty complicated to operate this

iMac Intel 21.5" EMC 2389 PRAM Battery Replacement

Use this guide to replace the PRAM battery.

www.ifixit.com

Yes, to acheive this the operation is rather 'complicated' (as you put it). You'll note that even the iFixit tutorial indicates a red 'DIFFICULT' level. This is because a major tear-down is required to remove the logic board.
Apple in their wisdom....no I'll rephrase that........Apple in their obsession to make things as dificult as possible for third parties, placed an expendable item with a life of approx 10 years on the rear of the logic board. This was a planned decision and certainly not an oversight. With my many years experience in engineering, from a maintenance viewpoint it was a definite no-no. And Apple engineers (and any others) would have known that but would have had other strict instructions from their management. Planned obsolescence is unfortuntately a major problem within many industries.
Having said that, changing the PRAM 'coin' battery on a 21" or 27" iMac is doable, and as a keen Apple/Mac collector I've performed this several times, in addition to changing CPU's and GPU's on similar machines. But it's definitely not a task that one should perform without having some past experience, either on other laptops or desktop computers. Just the removal of some of the small electrical connectors can create problems if one doesn't understand exactly how they are retained.
I would suggest you get a knowledgeable friend to change the Pram battery - the cost is approx $4 for the battery. Obviously any Apple store wouldn't want to know, and asking a 3rd party repairer would hardly be cost effective if one adds the labour charge involved.
I also have a 2009 27" iMac10,1 and with an SSD and 16GB memory they are still very capable machines for basic bureaucratic and also internet use under High Sierra and FireFox (Tip: Forget about Safari).

 

[zhoubolin]

I would suggest you to open the iMac and replace the coin battery on the logic board.
If it couldn't help with the problem, maybe you would need to replace the EFI chip on the logic board.

okay so today I finally open my iMac 2009 and take out the logic board, woh..that was hell lot of work, then I replace the coin battery and it problem still remain the same, guess I will replace the EFI chip if I have to.

 

[zhoubolin]

The coin battery help retain the basic information necessary to boot the iMac inside the EFI chip (basic input-output system).
When it is drained out, the information stored inside the EFI chip is partly missing, therefore, when you start the iMac, it confused about the devices (CPU, RAM, GPU, etc) connected to the logic board and you had to do PRAM reset (Option+Command+P+R ) several time to flush the EFI memory and let the iMac rescan the whole system again.
A typical coin battery has 10 year of operating time. Your iMac is already 13.

The above is just my guess from your description. It may not be correct, but it give you an option to try and test. a new battery doesn't cost much.

so today I finally replace the coin battery of my 2009 iMac, that was hell lots of work to take out the logic board, but I am proud that I finally did, however the problem still remain, and funny thing is that it turn out the old coin battery still works and has electricity in it because I test on other thing such as weight measure tools.