Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

eMac 800Mhz -> 1.33GHz conversion

lbodnar said:
Now all that is required for the project like this is eMac logic board with downconverter and PC PSU. There is no need to take anything else from eMac. Both - VGA and power connectors are easy to make.

Hey, is there anybody out there reading this or I'm just blogging!?..
Click to expand...

Reading with great interest! Can you give us more details on making the VGA and power connectors?

I'm trying to dig up details on the 3rd gen emac now without tearing apart my own (since it's my main computer) - hopefully the pinouts are the same, since I would really love to do an ATX conversion and replace the internal CRT.

-vga4life
 
OK I am game

I have an eMac 700 Generation 1 logic board.

I am interested in making this thing work.
I have spent nearly 4 hours of reading all of the forums I can find and looked at all of the iMac conversions that have been done and the g2 eMac conversions but allas none of those help as this board is totally different.

I have ram, HD, CD-RW, ATX case and 400w ATX p/s, and a 17" external monitor.

1) Has anyone figured out the pins for the PSU (mine has 20 pins)
2) Has anyone figured out the blind connector for the video and which one to use? (mine has 2 of them)

BTW congrats IBODNAR very nice work!

Thanks
 
Hello!

I've a 2G eMac-Board (1.25) without the Down Converter Board. Is it possible to get the Mac running without this board?

MrFX
 
MrFX said:
I've a 2G eMac-Board (1.25) without the Down Converter Board. Is it possible to get the Mac running without this board?
Click to expand...
This must be the 3rd generation eMac.

In the 2nd gen eMacs downconverter board produces +5 +12 +3.3 and +2.5V voltages. If the 3rd gen DCB is more or less the same (I assume it is) then it is possible to replace it with ATX PSU and an extra 2.5v linear regulator, I think it is pretty low current source (SDRAM ?) At least in 1st gen DCB 2.5v supply is just a simple linear regulator. Maybe just LM317 and two resistors would do. All other voltages are available as is from PC ATX PSU.

No, I don't know the pinout :D [yet!]
 
Hallo!

OK, it's the Board with the DDR 2700 and the 3 USB 2.0 Ports. I've got the board still not, but can get it.

@lbodnar
Have you the pinout for the internal video connector (as shown in your picture)? How have you connected it to the external Display?

Bye.
MrFX
 
MrFX said:
Have you the pinout for the internal video connector (as shown in your picture)? How have you connected it to the external Display?
Click to expand...
Yes, I have connected my gen 2 eMac but since gen 1 has a different internal video pinout I would assume gen 3 eMac might be different too.
 
Hi,

but someone said, that the Gen 3 Board can used as a replacement for the Gen 2 Board... ok, i'm still waiting for the photos from this board and then we will see...

MrFX
 
Hello again,

i have now some photos from the Gen 3 Board, it looks like a Gen 2.

I think, i will get the whole Digital Assembly as on the picture, so the Down Converter is included.

@lbodnar
Can you post the internal video pinout from the Gen 2 Board and what modifications you made in the OF to get it work?

Best wishes,
MrFX
 

Attachments

  • eMac_gen3.jpg
    eMac_gen3.jpg
    85.2 KB · Views: 384
MrFX said:
Hello again,

i have now some photos from the Gen 3 Board, it looks like a Gen 2.

I think, i will get the whole Digital Assembly as on the picture, so the Down Converter is included.

@lbodnar
Can you post the internal video pinout from the Gen 2 Board and what modifications you made in the OF to get it work?

Best wishes,
MrFX
Click to expand...

Hi MrFX,

Can you take some detailed pics of the motherboard? I have a Gen 3 (I think, is that the current line?) that I want to overclock. However, it seems there is some confusion over where the jumpers are to do this.

My eMac is a 1 GHz edu model, so I would really love to take it to 1.4 or so...

Thanks,
Steve
 
Hi,

sorry, i have the board not yet...

Gen 3 board have DDR-Ram and USB 2.0

MrFX
 
MrFX said:
Hi,

sorry, i have the board not yet...

Gen 3 board have DDR-Ram and USB 2.0

MrFX
Click to expand...

Yeah, that's mine!

If you get the chance whenever, that would be wonderful!! I know topgunn also wants to overclock his Gen 3, but couldn't find the jumpers.

My family uses this eMac a lot, so I'm not able to disassemble and leave it unusable for too long.
 
i just got done overclocking my 1ghz gen 2 emac to 1.4 ghz.. everything is going well, just it took me all evening and almost had a heart attack a couple of times....
i just kinda read a posting about how to dissassemble the emac, which im my opinion was the hardest part, then followed the instructions in the links above. one word of advice, don't mess with putting the same resistors back on, just use some soder to make the "bridge". much easier than the resistors. i knew they were small, but god, they're really tiny.

best of luck to anyone else trying it out!
 
Hello!

@lbodnar

Thanks alot for the fantastic informations... i will try it ASAP.

Bye.
MrFX
 
Hello again!

Does anyone have the Service Manual for the newest eMac-Series (not the one called emac_ati_graphics.pdf)?

I would compare the part numbers with the board i would like to buy.

Bye.
MrFX
 
Hello!

I've received the board yesterday and will take some hi-res photos next days...

So long.
MrFX
 
700mhz Gen1 Bind-mate connectors!!!

Ok I bought a 700mhz mac off of eBay to just get these voltages!!!

Blindmate nearest External Connections:

*pin one is in the upper left corner as you have the RAM sockets facing you and the CPU to the right side!!! Pin two is below pin one. => top row is odds and bottem row is evens.

1 Red Mic (5v)
2 White Mic (Sig)
3 Mic (GND)
4 Mic (GND)
5 Power Light (+)
6 Power Light (GND)
7-10 NC
11 FAN (Speed Sense)
12 NC
13 Left Speaker (-)
14 NC
15 Left Speaker (+)
16 NC
17 Right Speaker (-)
18 FAN (GND)
19 Right Speaker (+)
20 FAN (12v)

Blindmate nearest CPU eMac OFF with Power plugged-in.

*pin one is in the upper left corner as you have the RAM sockets facing you and the CPU to the right side!!! Pin two is below pin one. => top row is oddsand bottem row is evens.

1 12v
2 -0.14v
3 7.3v
4 -0.14v
5 7.3v
6 -0.14v
7 GND
8 GND
9 13.9v
10 GND
11 5v
12 GND
13 GND
14 -0.14v
15 GND
16 -0.14v
17 GND
18 -0.14v
19 11v
10 -0.14v

Down Converter w/eMac powered ON

*Pin out is ACTUAL!
1 20v
2 GND
3 20v
4 GND
5 0.03v
6 0.74v
7 3.3v
8 GND
9 3.3v
10 GND
11 2.5v
12 GND
13 2.5v
14 GND
15 5v
16 GND
17 5v
18 GND
19 5v
20 GND

* All of these voltages were observed with a digital multimeter and were checked 3 times sequentially.
 
guylan said:
Ok I bought a 700mhz mac off of eBay to just get these voltages!!!
Click to expand...
That is terrific! Were power connector voltages measured with logic board detached?

Will you be able to sample few voltages on a logic board with the power on?

I understand it is difficult to get to blindmate connector when eMac is on without fully taking it apart. But I will trace connections to the bottom of the board that is reachable in normal operation.

I hope solutions is near!
 
Hello again!

Leo, have you ever measured the current, which takes the board on 12 and 20 V (with the original PSU)? If not, i will try it today in the evening and measure it.

I want to know this for looking for a little switching supply... i will not use a big ATX... :D

Bye.
MrFX
 
MrFX said:
have you ever measured the current, which takes the board on 12 and 20 V (with the original PSU)?
Click to expand...
I was going to, but got distracted...

CPU 12V should be about 2..2.5A at full CPU load (based on datasheet info) and 20V power around 2A (drives included). All together I guess 100W PSU should be enough.

Are you planning to replace 20V with 12V? 20V is downconverted to 12, 5, 3.3 and 2.5V so if you power drives straight off PSU then 20V can be reduced to 12V that makes very friendly power system with just 12/5v needed. This one is 250W but a nice form-factor.

Just remember that 2A on 20V requirement will become 3A on 12V because downconverter board is a switched PSU. And make sure you look at currents too as most PSUs are not very strong in 12V department. This is why it is beneficial to power drives straight off PSU, not via downconverter.

Even better, I would supply only 5V to CPU12V because it is downconverted on the logic board to 1.55V anyway and on an average PC power supply 5V power has much more current capacity (isn't it on that dedicated 4-pin CPU power connector that was introduced for Pentium 4 ATX CPUs?) I shall try it and report back!

Please post your measurements!
 
lbodnar said:
That is terrific! Were power connector voltages measured with logic board detached?

Will you be able to sample few voltages on a logic board with the power on
Click to expand...

Yes the Blind-Mate power measurements were taken with the logic board detached. I was hoping that with those voltages we could use the info you got on your Gen2 to figure out what was to be connected to 12v and 5v but that -0.14v has got me rather confused. Although the Down Converter shows promise. I think I should be able to provide the 3.3v, 5v and 12v to the Down Converter socket and the board should power right up.

As far as getting measurements with the logic board attached....hummmm....let me put it this way....I have a pair of pliers and an achy tooth and no novacane. The only way it seems that I will be able to get any readings is if I take out the CRT and get teh voltages from the back side of the blind-mate.
 
guylan said:
I was hoping that with those voltages we could use the info you got on your Gen2 to figure out what was to be connected to 12v and 5v but that -0.14v has got me rather confused. Although the Down Converter shows promise. I think I should be able to provide the 3.3v, 5v and 12v to the Down Converter socket and the board should power right up.
Click to expand...
I do have Gen1 700MHz board with downconverter that netjosh_granada kindly sent me for testing. I have fully reverse-engineered the downconverter (don't forget 2.5v) but had no success powering the whole eMac up.
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back