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 boardand 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.

 

[MacTech68]

Have you tried disconnecting the hard drive and CDROM drive?

Also, try a minimum RAM on the CPU card and remove the additional VRAM.

Leave all USB devices disconnected.

Though you haven't explicitly stated so, I assume when you held the reset button, it eventually turns on the screen and the amber light turned green.

You may also want to remove the PRAM battery and leave it overnight before testing again.

The most common problem these had was a bad flyback transformer. But that would usually result in the machine powering off about 10 seconds after pushing the front power button.

 

[Rikintosh]

Have you tried disconnecting the hard drive and CDROM drive?

Also, try a minimum RAM on the CPU card and remove the additional VRAM.

Leave all USB devices disconnected.

Though you haven't explicitly stated so, I assume when you held the reset button, it eventually turns on the screen and the amber light turned green.

You may also want to remove the PRAM battery and leave it overnight before testing again.

The most common problem these had was a bad flyback transformer. But that would usually result in the machine powering off about 10 seconds after pushing the front power button.

-Without hd and cdrom
-without any memory (except for a single memory module, and I've tried with others)
-without anything connected to the usb ports
-with or without pram battery
I waited a whole week without battery, with the motherboard out of the computer
I've tried it all. The flyback problem is common in the 2nd generation of imac, but in these first, they do not usually give flyback problem due to having internal cooler for cooling

Right when I bought it, I found that pressing reset it would turn on, after a few weeks, I had to keep reset pressed for 15 seconds, a few more weeks later, I had to press for 30 seconds for it to work, until about a week ago, it was necessary to hold it for 60 seconds. Currently it doesn't work anymore, I can hold the reset button for 5 minutes, it won't get the green light...

When I turned it on, I noticed a certain slowness (I know he's old and I can't expect it to be fast, but I know a g3 233, and he was slower than normal) and sometimes he froze completely.

Another strange thing that I noticed, is that sometimes, it sounded a little distorted "bong", something like a radio not very well tuned, I came to think that the speaker was burst, but at other times that I started it, the bong it sounded normally ... (this model doesn’t usually pop the speaker, like the second generation imac), i took it apart, and the speakers were perfect..