Help with iMac G3 '98 (only orange light)

[Rikintosh]

I have a 1998 imac, and it has a motherboard problem. From what I saw on the internet, this problem is very common in this model, but I don't want to change the board, I want to find out what is causing the problem and fix it. Does anyone have a tip?

Problem: When you turn it on, the light turns amber, never turns green, the coolers turn, and sometimes I hear the "bong", but incomplete, it starts to play the sound and halves. The problem is definitely in the motherboard, because I bought another imac, and inverted the cards to find out if there was a problem in the primary source.

What I've tried:

- Change the processor
- Change memory
- Cleaning
- pram Battery replacement
- Reset PMU

Until some time ago, if I held the reset button for 60 seconds (which is on the side next to the USB connector), it would start up and function normally (until I shut down or restarted). I suspected that this could be some capacitor, because I thought, if it turns on when holding the reset for some time, it may be the time needed to charge some capacitor that is not very good. I looked at the board and found nothing visually damaged, and before leaving unsoldering everything from the board, I decided to create this post.

I also have a lombard powerbook WITH THE SAME SYMPTOM, so I believe that the defect of one is the same as the other.

 

[davisdelo]

I would take a look at the power supply next.

 

[Rikintosh]

I would take a look at the power supply next.

It's not a problem with the power supply, since I bought another imac and changed the board. The problem manifested itself in the other unit as well.

 

[philgxxd]

I would post at the collectors section of this forum. There is a great technician who is probably willing to chime in...

 

[Rikintosh]

I would post at the collectors section of this forum. There is a great technician who is probably willing to chime in...

Thanks philgxxd, I didn't even know this forum section existed, lol

 

[bobesch]

There's that magic CUDA button on the early iMacG3, that might help ...?
@TheShortTimer did mention it in his latest thread about resurrecting an early Blueberry iMacG3.
And there has been discussion / recommendations about it in this thread some time ago ...

 

[DeltaMac]

There are 2 versions of both the Analog/Video board, and the power supply.
You need to make sure that the A/V board and the power supply are the same version.
(if you replace a version 2 A/V board with a version 1 board, you have to also swap in a version 1 power supply. The two parts are not interchangeable - both must be the same version.)

Question: You referred to a "plate". What is that?

 

[Rikintosh]

There's that magic CUDA button on the early iMacG3, that might help ...?
@TheShortTimer did mention it in his latest thread about resurrecting an early Blueberry iMacG3.
And there has been discussion / recommendations about it in this thread some time ago ...

There is a small button on the board, in the repair manual it says that you must tighten it when changing the battery, I tried, and I was not lucky

 

[Rikintosh]

There are 2 versions of both the Analog/Video board, and the power supply.
You need to make sure that the A/V board and the power supply are the same version.
(if you replace a version 2 A/V board with a version 1 board, you have to also swap in a version 1 power supply. The two parts are not interchangeable - both must be the same version.)

Question: You referred to a "plate". What is that?

For some reason the broker on my cell phone changed from board to plate. I mean board.

My machine has no problems at the top (part of the main power supply and crt), the problem is at the bottom, on the motherboard, that drawer that we pulled out of the computer, I tested it with a good board, and it worked perfectly, so I'm sure this is a problem on the motherboard


the good card I put on it for testing, was from another imac 98, exactly the same model, and with the same configuration (g3 233mhz, 64mb, 8GB ...)

Here.

 

[davisdelo]

the good card I put on it for testing

Just to be clear, when you say "card" you mean motherboard, correct? Clarification on any non-specific terms would make understanding your problem easier to everyone. Also, is there corrosion on the motherboard? I circled the area in the attached image on where there looks to be some issue, could you provide a better view of the area?

 

[Rikintosh]

Just to be clear, when you say "card" you mean motherboard, correct? Clarification on any non-specific terms would make understanding your problem easier to everyone. Also, is there corrosion on the motherboard? I circled the area in the attached image on where there looks to be some issue, could you provide a better view of the area?
View attachment 953274

Yep, motherbaord.

I took some pictures of different points on the motherboard. I found no signs of corrosion or leakage

 

[swamprock]

Nevermind... you already tried what I was going to suggest...