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G3 AIO Molar Macs wont start

NickNick

Well-known member
Hello there. So I recently acquired two G3 Molar macs from a friend. Both were stated as having screen issues. Neither of them work. One will give a mac bong and the other wont. Both will power on and display the green led and I can hear the fans spin up as well as the HDD's on both machines. I have tried the cuda reset on the mobo but am unable to zap the PR ram. Took out the memory sticks and tried one at a time still same effects on both machines. I even swapped out the personality cards to see. Both still work. Unsure what the issue is. Thinking the mobos might be bad. Also I tried hooking up external monitors to both machines and neither would display an image. Will the monitors not turn on if a certain test fails? Any ideas are appreciated. Thank you so much.
 

beachycove

Well-known member
If the original IDE hard drives are still installed, in my experience such drives more or less always need to be tossed. I have seen so many fail that I no longer expect anything else. Beyond that, since you are looking for ideas: Will the machines boot or appear to boot (given the screen question) from an 8.1 emergency floppy? Or from an 8.5/9.1 installer CD?
 

NickNick

Well-known member
Hey thank you for the replies!!
If the original IDE hard drives are still installed, in my experience such drives more or less always need to be tossed. I have seen so many fail that I no longer expect anything else. Beyond that, since you are looking for ideas: Will the machines boot or appear to boot (given the screen question) from an 8.1 emergency floppy? Or from an 8.5/9.1 installer CD?
Yes the original HDD is still in the machine and in fact needs to come out as in both machines they both make noises.
Good point with the CD thing. I have a few installers OS 8.1, OS 9 and OS 9.2.2. I will give that a go.


I'd try checking the power supply voltages
Thank you so much Wayne I also didnt check the voltages. Had to clean them first they were dusty. Speaking of voltages and such, I was wondering if somehow the cables got damaged as there are multiple ribbon cables inside the machine in addition to the HDD and optical drive ones. Thinking about testing those with continuity...
 

NickNick

Well-known member
Update:
So I have been messing about with these machines. Found out that both machines actually do give a boot chime but faintly. I swapped the caddy's out between the machines just to try out different scenarios. In one machine the sound works and gives a boot chime but the other one does not. However upon tinkering with the machines I decided to replace the ram in one of them. What do you know after the boot chime the CRT came to life with some crackles of the tube. The machine fired right up. I guess the ram somehow just became bad, both sticks. Tried the same in the other machine but that one did not boot up.
Didnt think it was the ram as both machines do the exact same thing. Now that one is working I tried that working caddy in the other machine, it too came back to life with the CRT making some crackling noises displaying an image. Who knows how long these machines sat broken. Now I have to figure out what could be causing the other machine not to boot. Would a bad rom dimm cause issues as such, or perhaps the processor as well became fried? Also how do you remove the speaker cover area on these machines. The volume buttons are pushed in on one. I want to fix that. Thank you all for your help.
 

NickNick

Well-known member
I did swap them out to test the other machine. It too does work just there is an issue with the logic board. Kind think perhaps the processor went on it. Would it make a boot chime if the processor was bad?
 

beachycove

Well-known member
If you get a startup sound, the machine has already run a series of low level hardware tests in its POST sequence. I'd eat my hat if that did not include the processor, but others may know better.

If it boots with the other logic board from the internal drive, the drive should be good.

If it were me, I would reseat the logic board several times, since bad contact there may be the problem. That is pretty common in any AIO with a tray logic board. I would also reseat everything on the the board, swapping in known-good RAM (and VRAM, which I think the G3AIO had!). Also, I would look at capacitors, and check to see that the machine has not been overclocked by moving those little jumpers. Trying to make a G3 go too fast will result in a machine that hangs.
 

NickNick

Well-known member
Hmm...I too would have assumed that it would test all components before startup chime. I will try the resetting things with the processor and the cache dimm. I did read about the G3mobos having overclocking ability which I did locate and appears to have been left alone but it could as well need to be reset. I will try that all today as it does appear to be hanging. As for the bong, its very quiet but then again so was the other one and it has full volume when powered on.
 

NickNick

Well-known member
Well I believe you might be onto something as I re-sat everything including the processor and the machine that didnt produce any noise made a bong noise out of both speakers. I know that monitor works as I took the working logic board caddy out of one and tired in the other. I still suspect the processor being the issue but am unsure. What else would cause the machine to not turn the monitor on.
 

beachycove

Well-known member
Leaking capacitor goo would certainly be very common. Ten years ago, machines from the late 1980s mostly needed recapped. Those that didn’t were the exception rather than the rule. Your Molar Mac is from the late 90s, and we are ten years on….

Having said which, a change in behaviour after reseating may indicate dirty contacts. People find that cleaning them with an eraser helps sometimes, or you could maybe try high concentration rubbing alcohol.
 

NickNick

Well-known member
you could maybe try high concentration rubbing alcohol.
Thank you so much. I do need to get some 90 percent as I currently have 70 percent. By the way I did feel it was the processor or surrounding area, as I took everything out and tired each individual component out into a good motherboard. All but the processor as I was afraid of harming a good logicboard. A deal came on eBay for a G3 AIO logicboard. Bought it and it came with a new processor. Works as it should now. I'm still keeping the other logicboard as a backup as I still haven't ruled out it as being bad. However having removed the old logicboard there was an area with severely corroded (like rust) resistors surrounding a crystal oscillator which is near the processor. Those resistors are so small I'm afraid of rubbing one off when attempting to clean as there is rust around the contacts. Thank you so much for all you have done with assisting!!
 
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