iMac G3 (Rev A -> C) G4 CPU Upgrade

[LightBulbFun]

So my 7410 chips arrived woo now that I have everything i hope to try and do the G4 CPU upgrade like you have done (as i said in a past post ill be trying first with a 300Mhz G3 ZIF) is there any last things I should know before i try? (im not using a bottom heater i plan to preheat the board with my hot air gun/re work station slowly.) any recommendations on what temp i should use when I put the G4 Chip on and are going to reflow it? I have a good idea but I always check with the experts first also i noticed my chips also i think have .76Mm balls they are defo smaller then whats on the G3 ZIFs chip for example. ill attach a picture and if you can tell me if they are like yours/ready to be soldered that would be very helpful  

 

[max1zzz]

Yeah those are fine to solder, mine all have .76mm balls and work fine.

As for temps, you'll have to do some experimenting to find what works best for you. What you can do is give the chip a tap on he side when you think it is molten, the chip should "wobble" a little ( don't tap it too hard, if you do it will go sliding across the board. I have done that a few times....) if it dosen't move don't try and lift it yet or you will rip pads up

TBH, when i'm not using a bottom heater I just use a heat gun, it's very imprecise, but much more powerful than my atten 858 so make the job easier.

On another note, I should have something cool to show you guys soon, just waiting on a order from CPC for a couple of parts i need.....

 

[LightBulbFun]

very cool! yeah iv seen the wobble thing done a few times I also been doing lots of practicing on dead boards to get a feel for things I also did an EEPROM swap on a GPU I had you can read about it here http://forums.macrumors.com/threads/eeprom-replacement-and-flashing-x850-xt-rom-on-firegl-x3.2016538/ 

Thank you very much for all the help and advice you have given me over this Im looking forward to see what else you have in store (my plan if I get the G3 ZIF upgrade done ill do my G3 Pismo Card and MAYBE my iMac G3 Slot loading FP but thats a bit rare also a much bigger board to handle then a simple CPU card)

 

[LightBulbFun]

well today I gave the first stage a go, removing the old G3 from the board I completely messed up the first ZIF (board pop corned well i think it did. it made a couple muffled cracking noises) but i managed to remove the CPU off the second ZIF card without it pop corning or lifting any pads next step tommrow is to clean all the pads up on the ZIF PCB(easier said then done LOL) and plopping the new 7410 chip down heh. do you have a picture of the Tip you used on your soldering iron you used to clean up the pads on using soldering braid I assume? (and what temp you set your soldering iron to) also the link in the above post is bad so here is the good link  heh EEPROM replacement and flashing X850 XT ROM on FireGL X3

 

[LightBulbFun]

Update time! today I attempted it finally! to cut it long story short I the 7410 Upgraded 750 266Mhz G3 ZIF chimes in the G3 BW but i get no video. I have a couple theories on this big one being I Goofed up somewhere but the fact i get a chime is good the other theories is the 266Mhz ZIFs cache cant run at 300Mhz (ill have to dig out the G3 beige to test at slower speeds) or the stock IBM 750 Ran/runs at too high a voltage for the 7410 to post at I know that the 400-500Mhz motorola G3s run at 2V in the Pismos and such but i dont know what something like an older 266 may run at it might be even higher the heatsink does get quite hot. anyways just figure id post a quick update im quite pleased it even chimes heres a picture (note thats thermal goop on the die) now to plot my next moves *looks at PowerBook G3 Pismo*

 

[max1zzz]

I would assume (although someone can correct me if I am wrong) that the fact you get a chime means the cpu is working, so your soldering should be good.

Have you tried clocking the CPU down? You should be able to do that with jumpers on the B&W's logicboard

 

[rsolberg]

I know the spec for the 7410 is 1.8v vcore. I expect the original 750 is more like 2.2-2.4v, but I can't find the pertinent datasheet right now to be sure.

 

[LightBulbFun]

Yeah thats what im thinking. to test lower speeds I need my G3 beige out as i have not come across a jumper chart that goes bellow 3x multiplier (but giving it some thought i know there is a way to jumper the bus speed down from 100Mhz to 66Mhz should look into that then) otherwise yeah I hope the ZIF is not giving it too much voltage, I should compare a G4 Yikes ZIF card to my one to see the differences as AFAKI the voltage for the CPU is set on the ZIF card

 

[max1zzz]

looking at the datasheets, the 7410 is 1.8v vcore (with the max rating being 2.1v) whereas the 750 is 2v (with a max rating of 2.2v). So as was discussed before voltage modifications may be required to get these running stably at higher frequency's

 

[LightBulbFun]

what specific 750 data sheet are you looking at just wondering as it can vary from chip model to chip model id not be surprised if the early 750s ran at a higher voltage then the later 750s found in Pismos and the like. but yeah looking into how to lower the voltage is always good (because even if it runs fine at stock voltage lowering the voltage will make it run cooler which is always good ) depending on how i feel tommrow i may try upgrading my Pismo I know of reported success for example here http://www.mactech.com/2006/09/19/diy-powerbook-g3-pismo-g4-upgrade my main reluctancy with the Pismo is I dont have a spare card to drop in should I mess up somewhere

 

[rsolberg]

I found the datasheet I was looking for. The 200-266MHz 750 (no suffix) on a 0.29u process has a recommended VCore of 2.6v. There was a litho change to 0.25u for the 300-400MHz parts (still no suffix) and those ran on 1.9v.

 

[LightBulbFun]

2.6v! yikes! (pun intended ) would explain why its not posting luckily i have Pictures of a Yikes ZIF from user Bunnspecial and will be comparing them to my G3 ZIF (and my 300Mhz ZIF that i butchered for that matter). my quick over view of when he sent the pics shows a set of resistors right above the CPU at the end of the zif that are differently placed between all the ZIFs i suspect those may set the voltage.  Edit yeah a quick poke around with a DMM shows  all those resistors as 100 ohms those are prolly it

 

[max1zzz]

I was under the impression that the voltage is set on the logicboard on g3's?

Edit: no, you are right, From trag further back in the thread

in the Beige G3 Apple used a voltage regulator module on a seperate plug-in card. It was a little complex because it received a signal from the ZIF CPU module telling it what voltage to set. The signal was just controlled by resistors installed or not installed on the ZIF module

 

[bibilit]

Not wanting to be rude, but on your picture some components on the bottom are no longer where they used to be, too much heat ?

 

[LightBulbFun]

yeah just a couple what i assume by pass caps. I have a mild case of CP so my hands can get a bit shaky when you dont want em to. and i knocked a couple caps lose lifting the old chip. i made sure all where connected still (well apart from one that looks decidedly dodgy ill try reworking that last one if my voltage adjustments dont solve the chime but no video issue but i doubt its the issue)

 

[LightBulbFun]

Hmm just tried jumping the supposed Vreg pads on the 266Mhz 7410 ZIF (I used small copper strands to do so and made sure there was continuity) to match the ones on the 300Mhz. I still only get a chime and no video but i THINK the heatsink stays cooler for longer and i noticed that i can now do command ctrl power and reset the Machine, before after the initial chime the machine would hard lock up ie i could not reset it via the ADB keyboard I should drag the G3 beige down and see what it does. (tho some times it still hard locks up so yeah)

 

[LightBulbFun]

another report just set the G3 BWs FSB to 66Mhz still the same thing. shame theres no visible/known test points on the ZIF to measure voltage. (the G3 Beige is in bits and needs a PSU fitted as the old one blew up so I dont want to drag that down plus being a DT id have to clear off a bunch of stuff off my desk to fit it in LOL)

 

[LightBulbFun]

just wanna report some great news! i decided to try this on my PowerBook G3 Pismo CPU card. and it worked! i removed the old CPU soldered on the new one put it in the Machine and it booted right up. the only thing wrong is the L2 cache does not work (on uninorth machines it should show up with a G4 CPU and installing a cache enabler just panics the machine) but otherwise it runs fine! passed geek bench with no issues (got a score of 178 but thats due to the lack of L2) im really stoked about it! going to try run leo on it heh. (attached are some pictures ill prolly leave it at 400Mhz because screw trying to mess with those SMD pads to over clock it, it will run cooler under clocked at 400Mhz and finally its my proof that it is a home grown G4 Upgrade as no company sold a 400Mhz G4 Pismo upgrade AFAIK) so Yeah Wooo!

 

[CC_333]

I have some spare Pismo CPU cards, one of which has a bad L2 cache. Would you like to experiment with them?

They're just sitting in my drawer, wasting space.

My only request is that, after perfecting your technique, I'd like to have one back, with the G4 chip installed, so I can upgrade my Pismo with it

You can keep the rest of them if you want, though.

c

 

[max1zzz]

Been haveing some late night electronics fun tonight.....



I'll have to have a play around with the jumpers tomorrow to see how fast the cpu will clock up to on the iBook