iMac G3 issues

[Theretrogamingroom]

Of the four iMac G3s that I bought, 2 of them do not work. The first broken one (A BB model) doesn't power on at all. The second one (Blue Berry) powers on but usually doesn't do anything beyond that (No startup noise, no logo on the screen, nothing.) I got it to work once, but after about 15 minutes, it gave me a "You need to restart!" crash message.

Obviously the first needs a new power supply, but I am not sure if the second one is facing a software or hardware issue. What does it need?

Thanks

 

[phreakout]

1.) Check the P-RAM battery. Voltage must be at 3.67V up to 3.8V at maximum. If not, replace the battery and don't forget to press the PMU reset button once for about a second.

2.) One thing to keep in mind is that all models of iMac G3s across the board will suffer (or have suffered) the death of their P.A.V. (Power Analog Video) Board. When this happens, successful power up or normal startup is one-in-a-million to nill. In your case, the symptoms you describe warrant the need to check if it's bad. In more severe cases, you will hear a single zap or click, followed by the power button turning either orange or lighting up for a second and shutting off. You'll need to match part for part, when it comes to PAV Boards. Apple had 2 different part numbers for this part: one with a toggle switch and one without. This was due to Apple using 2 different companies making CRTs: LG and CPT.

3.) Check the Down Convertor board, attached to the logic board. Sometimes these go bad and throw off the rest of the iMac.

Here is a link for where to get the service manual and tear-down procedures. They should cover Rev. A through Rev. C and D (iMac G3 Summer 2001). You can also go to http://www.ifixit.com and they post take apart steps for these iMacs as well, but may not go as far as access to the PAV Board and CRT.

So, go grab a multimeter and start narrowing down where your trouble is. Use the Troubleshooting section within the service manuals in the first link to help navigate what to test and where. Let us know what you find. We'll be here to help.

73s de Phreakout. :rambo:

 

[bibilit]

I agree with Phreakout,

With G3 imac series, the main failure is with the PAV board (often the Flyback transformer is the culprit)

If the two units are of the same type (ie tray or slot loading) you can try swaping logic boards.

The message is a kernel panic, can be hard or soft issue.

try swaping ram, i had a lot of issues with sticks on G3 Imacs.(you will probably get an unusual chime, but this is not always the case)

Concerning the P-RAM battery, you can have a try without, and press the reset (only once)anyway.

Never had any issue with Down Convertor Board, but swaping boards is a logical path, and the easy one... the PAV board is hard to reach.

 

[phreakout]

I agree with Phreakout,
If the two units are of the same type (ie tray or slot loading) you can try swaping logic boards.

The message is a kernel panic, can be hard or soft issue.

try swaping ram, i had a lot of issues with sticks on G3 Imacs. (you will probably get an unusual chime, but this is not always the case)

Concerning the P-RAM battery, you can have a try without, and press the reset (only once) anyway.

Not necessarily. The logic boards for the G3 iMacs are different. The original 1998 model has a different shaped and pinout logic board compared to the 2000 or late 2001 models. The tray-loading models 1998 through late 1999 (which are Rev. A through Rev. D) not only had their CD-ROMs as a tray-loading drive, but the logic boards as well, were fitted inside a tray-like metal/plastic cage. To access the logic board, you simply undo a few screws, pry apart some plastic panels, unplug 2 cables and pull the assembly out.

The next generation of G3 iMac models had the logic boards screwed in underneath the high voltage and CRT assembly. A little more screws and panels to take off before you can gain access to the logic board. Usually these models had CPU speeds starting at 350 Mhz through 700 Mhz and their CD-ROMs (some with DVD-ROMs and Combo Drives; CD-RW and DVD-ROM) were of the slot-loading nature (Instead of a tray that pops out when you eject the disc, you had a slot that you fed the disc into. The drive's mechanism will automatically pull the disc in and eject it out for you.)

Although swapping out RAM is a good suggestion, be careful you match the right type of memory sticks with your iMac. The Rev. A through D G3 iMacs used sticks of memory similar to that found in a laptop computer and were rated as PC-66 or PC-100 standard. You will have to pull out the logic board cage assembly in order to change out the RAM on these models. The 350 Mhz through 700 Mhz G3 iMac models all used desktop memory of PC-66, PC-100 and PC-133 standards. For these models, you only have to unlock a door underneath the case and pull it open to get to the RAM; it's that easy.

You can run your iMac without a PRAM battery, but in some cases, running without a battery will also present the same symptoms of the problem you've been having. I would only run without a battery if I knew that the cell was dead.

73s de Phreakout. :rambo:

 

[bibilit]

A through D G3 iMacs used sticks of memory similar to that found in a laptop computer and were rated as PC-66 or PC-100 standard. You will have to pull out the logic board cage assembly in order to change out the RAM on these models. The 350 Mhz through 700 Mhz G3 iMac models all used desktop memory of PC-66, PC-100 and PC-133 standards. For these models, you only have to unlock a door underneath the case and pull it open to get to the RAM; it's that easy.

Right, i only got the slot-in type to play with.

Concerning ram, you cannot make any mystake as they are quite different in size and shape, effectively the very first generation of Imacs came with so-dimm sticks (found on ibooks and powerbooks of the same generation) where slot-in imacs used the common Sd-ram found on dekstops and on pc's (even if not always a 100% compatible)

another try is to leave only 1 stick and try to boot (if several fitted)

you only have to unlock a door underneath the case and pull it open to get to the RAM

Right again, you just need a coin to release the latch and have access to ram and airport slot.

Another tip, just above that door, you should have a perforated blanking plate, to gain access to a vga output (if available, as not all are supplied with)

try to connect a screen and fire the Imac, an upgrade to Mac Os X without loading the proper firmware tends to disable the inner screen.

A firmware upgrade (from a HD and 9.2 Os) solves the problem.

 

[phreakout]

A couple of things I forgot to mention regarding logic boards. If you have a Rev. A through Rev. D G3 iMac logic board, theoretically you can mix and match the boards. For example, a Rev. D board could be installed in a Rev. A model, boosting the speed by 50 to 100 Mhz. Somebody correct me if that is accurate. The slot loading G3 iMacs (350 to 700 Mhz) I'm 100 percent sure they can be mix and matched. But make sure the models you are swapping logic boards out of use the same P.A.V. board.

Another tip, just above that door, you should have a perforated blanking plate, to gain access to a vga output (if available, as not all are supplied with)
try to connect a screen and fire the Imac, an upgrade to Mac Os X without loading the proper firmware tends to disable the inner screen.

A firmware upgrade (from a HD and 9.2 Os) solves the problem.

Not all slot-loading G3 iMac logic boards have external VGA out. I have a 400 Mhz board that came with an MPEG codec card, but no VGA out, whereas the 500 Mhz board that replaced it had the opposite (1 VGA out, no MPEG board). It would've been nice to add that MPEG card, but the new board didn't have the connector soldered on. I would have to desolder it from the old board and resolder to the new board.

I agree with regards to installing OS X without the right firmware upgrade applied. Double check that you have version 4.1.8f4 installed. If not, boot into OS 9.x, download the firmware update from Apple and you should be good to go. You may have to reinstall OS X as well, but you don't have to lose anything. Do a clean install and it will still retain the users and user data; it will only install a clean system folder and your old folder will be turned into the "Previous System Folder". From there, reinstall the software updates, move the preference files into the new System folder and you're good.

73s de Phreakout. :rambo:

 

[waynestewart]

With the slot loading iMac, the boards should all physically interchange but different ones had the processor in different spots which may raise a heat sink issue. A few iMacs had a raised spot on the metal divider panel so that it would touch the processor. Most of the iMacs I swapped motherboards on had a small piece of aluminum that screwed onto the divider panel so that it touched the processor. When I was swapping motherboards, I used to move that heat sink to the appropriate spot if the processor was in a different location

 

[bibilit]

I used to move that heat sink to the appropriate spot if the processor was in a different location

I agree,

Unfortunately, i had several issues with PAV / FBT and not so with logic boards, i resigned recently to throw 2 units i could not repair (i kept some parts anyway)

one of FBT was so bad that sparks were everywhere.

You can still use the Logic board and convert it to a sort of "hackimac" loosing the all in one aspect:

http://www.applefritter.com/node/858