IMac G3 (DV/SE) 1999
- For more information, see this article's corresponding Wikipedia page: iMac G3.
| Preliminary Information | |
|---|---|
| Release Year | 1999 |
| Leak Risk | Medium |
| Batteries | Lithium 3.8V half-AA cell (removable, rechargeable) |
| Mounting Technology | Through Hole, SMD, BGA, Sockets |
| Capacitor Types | Aluminum Electrolytic, Tantalum, Ceramic, Polymer |
| Destructive Entry | No, but very brittle plastic |
| Hardware Specifications | |
| CPU | PowerPC 750 (G3) @ 233 MHz - 700 MHz |
| Memory Capacity | 128MB up to 1GB |
| Memory Type | PC66 144-Pin (Tray Loading), PC-100 SDRAM (Slot Loading) |
| Storage | 3.5in IDE HDD (4GB-60GB), CD/DVD-ROM |
| Graphics | ATI Rage 128 VR with 8 MB of SDRAM
ATI Rage 128 Pro with 8 MB of SDRAM ATI Rage 128 Ultra with 16 MB of SDRAM |
| Display Interface | VGA |
| Power Requirements | |
| Input Voltage | 100-240V AC |
Announced in October 1999, The iMac (Slot Loading) was the low end of a new "good, better, best" iMac product strategy from Apple. The iMac SL built on the success of the rev. D iMacs, adding a faster processor, more RAM (64 MB base), a better graphics sub-system, an improved speaker system, and a slot-loading CD-ROM drive. With all these new features, the iMac SL was still $200 cheaper than predecessor. At $999 U.S., the blueberry-only iMac SL was the cheapest Apple-branded machine in many years.
Known Issues
No Power, No Life
Causes
- Missing +5V trickle
- PMU error
- IVAD controller does not send DC-ON signal
- General IVAD board failure
Solutions
- On IVAD (CRT) board: Check F101 fuse for continuity.
- On logic board: Check J9 on Pin 3 for +5v trickle.
- On logic board: Check C10 (above GPU near VGA port) for -10v.
- On connector J20: Check pin 6 for +5V trickle.
- On connector J20: Check pin 8 for -10V.
- On connector J20: Check pin 5 for DC-ON (+15v when attempting to turn on)
- On CRT Neck board: Check connector P303 for the following:
- Pin 8: +5V
- Pin 5: -10V
- Pin 9: +6.3V (is unregulated)
- On IVAD (CRT) board: Check IC902 (7805) for 5V.
- On IVAD (CRT) board: Check cathode of D940 for 6.3V.
- On IVAD (CRT) board: Check cathode of ZD904 for +15V (below +11V the PSU will not run).
Powers on for one second
The iMac has a complex start up sequence and if the IVAD controller or the PMU is not happy for whatever reason, the iMac will be shutdown after a second or so. Because the PMU holds the CPU in reset during this process, you won't hear a boot or failure chime, just the power light turning on and then off.
Causes
- PMU error
- General IVAD board failure
- Bad or missing CRT - The iMac will absolutely not boot without a CRT connected!
Blown Speakers
The speaker rubber membrane and glue perishes, causing the speaker to sound awful and without any bass. The only solution is to remove and replace the speakers. Check the Replacement Parts section for speakers to replace with.
CD/DVD drive will not inject or eject
The rubber rollers on the disc mechanism expand over time and won't grip onto the steel bar. A simple fix is to apply a thin amount of glue which will bond between the roller and the steel bar to grip onto the disc, but not thick enough that it distorts the original shape. It should be possible to use different parts to replace these. Some users have reported having success with boiling the rubber rollers, but this doesn't always fix the mechanism. It is also possible to replace the whole CD/DVD drive assembly for a standard slot-loading disc drive from say a MacBook, but this requires a custom bracket as the iMac disc drive is not a standard laptop drive in shape.
CRT convergence is wrong/heavily distorted or shifted
The CRT convergence assembly is made of a plastic that grows exceptionally brittle with age, made worse by the fact it is covering the CRT neck where the heater for the CRT lives. It's possible either the tubular holder for the convergence rings or the retaining screw-on lock is now broken, meaning the convergence rings are now free to move and thus requires calibration. This process is documented in the following subpage:
Adjusting iMac G3 CRT Convergence
Disassembly Notes
Use Apple's service manual to understand how to open the case. The logic board and the down-converter board are easy to access and only require removing the bottom cover and the RFI shielding around the computer.
The IVAD (CRT) board requires full disassembly and involves removing the front bezel. The grey plastic behind the front polycarbonate bezel is notorious for cracking and becoming brittle, as such you must expect it to be fragile and that you will need to order a spare. MacEffects sell a replacement you can use.
General Notes
IDE Compatibility
- The iMac chipset's IDE controller is not compatible with drives above 128GB. Using a 120GB or smaller capacity drive is recommended.
- The iMac is not compatible with most IDE to SATA converters. IDE to SATA converters that are using the JMicron converter chipset will not work. The iMac will not see or use the drive. StarTech IDE to SATA converters, or any converter using the Marvell chipset, should work fine.
VGA Output
- The VGA output on the back of DV models is hardwired to only duplicate the screen of the internal CRT. There is no way to change this behaviour.
USB
- The USB ports on the iMac are only USB 1.1 compliant, with a max speed of 12 M/bits per second.
- Supposedly the iMac is capable of booting from USB, but it can only be done from within the Open Firmware prompt. Not all USB drives will work for this method. Most USB DVD drives will not be able to be used for USB booting.
FireWire 400
- The FireWire 400 ports always supply +15 volts, even at power off.
Original Parts
Down Converter PCB
This PCB is connected to the logic board on the right if looking at the iMac from the bottom with the CRT neck away from the user.
| RefDes | Qty | Capacitance | Voltage | Mount | Diameter/Size | Height | Lead Spacing | Temp | Type | Brand | Series |
|---|---|---|---|---|---|---|---|---|---|---|---|
| C801 | 1 | 2200 µF | 25V | THT | 12.6 mm | 25 mm | 5 mm | 105 °C | Electrolytic | Nippon Chemi-Con/United Chemi-Con | KMG |
| C802 | 1 | 1000 µF | 16V | THT | 10.3 mm | 16.7 mm | 5 mm | 105 °C | Electrolytic | Nippon Chemi-Con/United Chemi-Con | KMG |
| C804
C805 |
2 | 3300 µF | 10V | THT | 12.7 mm | 21 mm | 5 mm | 105 °C | Electrolytic | Nippon Chemi-Con/United Chemi-Con | KMG |
| C809
C810 |
2 | 3300 µF | 10V | THT | 13 mm | 34.5 mm | 5 mm | 105 °C | Electrolytic | SAWWHA | RX |
| C814
C815 |
2 | 470 µF | 35V | THT | 10.3 mm | 17.5 mm | 5 mm | 105 °C | Electrolytic | SAMWHA | RD-M1A |
| C817 | 1 | 6800 µF | 25V | THT | 18.3 mm | 36.8 mm | 7.2 mm | 105 °C | Electrolytic | Nippon Chemi-Con/United Chemi-Con | KMG |
| C818 | 1 | 47 µF Bi-Polar | 35V | THT | 8.2 mm | 11.8 mm | 5 mm | 105 °C | Electrolytic | Teapo | SN-A3 |
Note: The voltage ratings for C809, C810, C814, C815, C817 are over specced on this PCB and can be replaced with lower voltage parts if you must, but it is recommended to keep to the original voltage specifications.
| RefDes | Original Voltage | Minimum Voltage |
|---|---|---|
| C809
C810 |
10V | 6.3V (3.3V nominal) |
| C814
C815 |
35V | 25V (15V nominal) |
| C817 | 25V | 16V (12V nominal) |
Replacement Parts
Stereo Speakers
A close match appears to be made by PUI Audio, the AS03104MR-N50-R. This fits, but the terminals are smaller, and as the unit is half the depth, it requires a bracket or a small amount of hot glue on the bottom speaker shell housing to keep in place. Also, these speakers are much more sensitive than the originals, you will need to put a resistor in line in order to reduce the volume to be in line with the iMac's original speakers.
Resistor spec required: TODO.
Digikey: https://www.digikey.co.uk/en/products/detail/pui-audio-inc/AS03104MR-N50-R/7622243
Mouser: https://www.mouser.com/ProductDetail/PUI-Audio/AS03104MR-N50-R?qs=YCa%2FAAYMW01gA%252BTN1Sb3hw%3D%3D
Inner Bezel
MacEffects sells a replacement inner bezel that fits the iMac G3. It is only sold in the USA however, and international buyers will have to pay for shipping which is quite expensive.
MacEffects: https://maceffects.com/products/inner-bezel-for-slot-loading-imac-g3-w-plastic-tabs
Down Converter PCB
| RefDes | Qty | Compatible Part Number | Order Links |
|---|---|---|---|
| C801 | 1 | 860020478022 | Digikey Mouser |
| C802 | 1 | 860020375017 | Digikey Mouser |
| C804
C805 C809 C810 |
4 | 860020278023 | Digikey Mouser |
| C814
C815 |
2 | 860020575014 | Digikey Mouser |
| C817 | 1 | 25PX6800MEFC16X31.5 | Digikey |
| C818 | 1 | ECE-A1VN470UB | Digikey Mouser |
If parts are not available or different selection is preferred, you can use the values in the Original Parts section to perform a parametric search.
Kits
- Digikey: https://www.digikey.co.uk/en/mylists/list/789KR1QQVM
- Mouser: https://www.mouser.co.uk/api/CrossDomain/GetContext?syncDomains=www&returnUrl=https%3a%2f%2fwww.mouser.com%2fTools%2fProject%2fShare%3fAccessID%3df50c9cc56e&async=False&setPrefSub=False&clearPrefSub=False
Related Links
Miscellaneous Info
LG seems to have designed the chassis components or at least manufactured them as evidenced by their logo on the IVAD and Down Converter PCBs. However their logo is not present on a later revision of the chassis which uses the same rough design but instead of using a LG CRT, it can also use an equivalent spec Chunghwa Picture Tubes model instead. The logo used on these boards looks like a 4 leaf clover like you would see with LG's older logo from the 1980s which is of a 4-leaf clover. The PCB quality is also different, and the casing of the reference iMac was made in Czechia, then known as the Czech Republic. It might be that LG did not want their logo next to one of their main display rivals? The Chunghwa CRT is labelled as such so it is possible.
In the service manual, it says the board manufacturer for the Chunghwa compatible chassis is 'HH'.