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eMac 800Mhz -> 1.33GHz conversion

Audio problem for headless emac mod

I have a 1.42G eMac mother board, set up with a LCD monitor following Ibodnar's expert instructions. The unit works well except there is no audio out(internal speaker or external line out). I am running 10.4.8 and later upgrade to 10.4.11, both case no sound, no boot up chime, no sound whatsoever.
On the other hand I use a USB speaker (polycom) and the sound work fine.
Anyone has similar problem? Pls advise.
Thanks
 
Hmmm... Never happened to me before, nor have I heard of it. Did you remember to plug the speaker wire back into the motherboard when re-assembling your computer? I recall it's in the lower left hand side...
 
Re: Audio problem

I had the exact same problem with a 1.25ghz board in an atx case. All attempts to get it to work failed (reset PRAM, reset PMU). I assumed there was some hardware problem with the motherboard, but I happened to hook up a different down converter and the sound started working. So, that's something to try, but usb sound cards are only a couple bucks on ebay.
 
emac audio problem

Thank you for your comments. Speaker cables are ok, in any case the headphone jack did not have any sound too. For the DCB, I did find that DCB may not generate 12V output (I suppose when I used 12V from ATX power supply as input it may be too low for the converter to work.) I believe the DCB 12V out is going to audio circuit. To overcome this I supply the audio 12V from ATX power supply. Still no sound. I suppose the logic bd audio circuit is somehow damaged.
 
All voltages are present since I am using the DCB (except the 12V audio I connect direct from the ATX), so don't understand why no sound. USB audio is ok except I will not hear the boot up chime, so it does not feel quite right.
I did not overclock. LCD is connected via the external display adaptor, ie I did not try to fit the LCD into the eMac chassis. I am using a 24" LCD monitor.
 
emac audio problem

I I'll try to some more testing, but I have gotten audio working with an ATX power supply connected, even with the reduced voltage on 12v line (but maybe it's glitchy or hit or miss). You might also check for swollen capacitors on the down converter board.
 
Thanks. Any additional is welcome.
I suspect your audio problem may be due to DCB 12V. I know that the 12V from DCB supply to audio and the hard disk. When you supply the DCB input from ATX 12V, it may not be high enough for DCB to produce a 12V out. If you power the hard disk from ATX, then the only circuit affected is the audio. When you change another DCB it may have more margin and 12V for audio now becomes available.
12V input to the DCB is probably the threshold(it expect 18V). I measured my ATX and got about 11.8V on the 12V line. Most of the time there is no 12V out from the DCB but I did see a couple of times DCB 12V fired up. To overcome this, I connected the ATX 12V to the logic bd 12V. Unfortunately still no luck. I do not have logic bd schematic so could not trace the audio circuit. So I am stuck.:mad:
 
emac audio problem

The audio chip on the emac,TAS3004, has two 3.3v power supply pins-one digital, one analog. The digital 3.3v is supplied from the down converter 3.3v line. (I'm guessing the analog power supply is provided by the dcb 12v line, since audio doesnt work if you disconnect it.) I believe my sound problem might have been caused by bad/swollen capacitors on the down converter 3.3v line. So, if you're determined to get if working, you might try using ATX 3.3v to power the DCB 3.3v line and see if that makes any difference.
 
one year later

666sheep said:
Bumped Vcore to 1.350 and it booted with 1.92 GHz. It was little unstable (some software unexpectly quit). So I made next step up with Vcore - to 1.375 - and it was enough for CPU to stay stable.
Click to expand...

Hi there!
Could you please tell me if your mac has been working stable since you bumped it up? How many KPs have you had since then?
Thanks in advance!
 
I found my way here through an article on upgrading an original emac. I have a the latter edition with a 1.42ghz cpu. I like this computer and wouldnt mind getting some extra performance out of it. I assume 1.42ghz is the most these motherboards could handle? I want to replace cdrw /dvd drive with a one that writes dvd's, upgrade the hard drive and if I could overclock the cpu that would be great. any advice?
 
Hi...

I´m new in here. This is my first post.
I´m a brazilian mac user.

First I want to say thanks for the high information level of this thread.
Very enlightenment!

I recovered a eMac G4 logic board from a dead analogic board eMac 17".

After put the board in the ATX case I tried some overclock.
I had only success with 900Mhz and 100Mhz fsb.

Other settings I get aways no sound and no video or start sound but no video.

The board is from a 800Mhz NVIDIA eMac. Second version, I belive.

Next week I will try to upgrade the 384Mb RAM to 1Gb.
The first 2x 512Mb PC133 that I brought does not work (double side memory).

Thanks again guys and sorry about my english. You rocks.
 
OC gen3 emac

Could anyone please help me with overcloking my gen3 1.42GHz emac?
As you can see from the picture above there are two pairs of R270 pads on J11 side of eMac board but I don't know which one to choose. I've already soldered a resistor on the right R270 pads (see pic), but mac doesn't want to start up after that. I can hear apple startup sound, but nothing goes on a screen. Shell I put resistors on both R270s or it should be R270 pads on the left?
Any help would be very much appreciated.
 

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ravik said:
Could anyone please help me with overcloking my gen3 1.42GHz emac?
As you can see from the picture above there are two pairs of R270 pads on J11 side of eMac board but I don't know which one to choose. I've already soldered a resistor on the right R270 pads (see pic), but mac doesn't want to start up after that. I can hear apple startup sound, but nothing goes on a screen. Shell I put resistors on both R270s or it should be R270 pads on the left?
Any help would be very much appreciated.
Click to expand...

What clock speed you want to reach? IIRC it should be these pads one on the right (but I can check tomorrow in mine :)).
Now you've underclocked CPU to 1.25 GHz (see below).


Code: 
                          1.25  1.33  1.42  1.50  1.58  1.67  1.75  1.83 1.92GHz
R658 (reverse side)        +     -     +     +     +     -     -     -     +
R270 (J11 side)            +     -     -     -     -     +     +     +     +
R673 (reverse side)        +     +     -     -     -     -     +     +     +
R275 (J11 side)            -     +     +     -     -     +     +     -     +
R689 (reverse side)        +     +     +     -     +     -     -     -     +
 
still no luck

666sheep said:
What clock speed you want to reach? IIRC it should be these pads one on the right (but I can check tomorrow in mine :)).
Now you've underclocked CPU to 1.25 GHz (see below).
Click to expand...

Hi!
The aim was 1.92Ghz, but I must admit I have almost given up:(
I replaced the transistor from the left R270 to the right one (I believe there is a misprint on the motherboard. See pads numbers R275, R270, R277 - seems like R276 is missing; also it could not be two identical pads) and it did help but didn't last long enough.

The machine boots up 2 times out of 5, but freezes after 15 seconds. 3 times out 5 it freezes at startup (KP or see the pic above). I have changed the thermal paste so it couldn't have happened because of overheating.

So now I'm wondering if I changed Vcore in the right way. The original Vcore was set to 1.325V so using Leo's post and voltage controller datasheet I bumped Vcore up to 1.55V (could you be so kind to check if I did it in a proper way, see pic).
Also I'm wondering if I used the right datasheet as pads numbers on my MB are different to the ones in Leo's post (see pics. I believe he has gen2 emac and mine is gen3). However, the voltage controllers are the same.

Any ideas about that?
 
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log on startup after KP

I've had it couple of times so far. It's always the same.
 

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voltage controller

gen2 and gen3 voltage controller
 

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emac gen3 1.42 vcore settings

can anyone send me a pin out to change the voltage setting
i want to over clock it to 1.92
 
ravik said:
Could anyone please help me with overcloking my gen3 1.42GHz emac?
As you can see from the picture above there are two pairs of R270 pads on J11 side of eMac board but I don't know which one to choose. I've already soldered a resistor on the right R270 pads (see pic), but mac doesn't want to start up after that. I can hear apple startup sound, but nothing goes on a screen. Shell I put resistors on both R270s or it should be R270 pads on the left?
Any help would be very much appreciated.
Click to expand...

the one on the right should be r276 the one on the left r270
 
Hi !
i got 1.42Ghz emac.
removed 275 resistor to get 1.58Ghz.
now system profile shows 750Mhz :(
 
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