Powerbook overheats - no fan

Hi, slavik. What leads you to believe the Powerbook is overheating? Is it going to sleep while you use it? Shutting down unexpectedly? Misbehaving in other ways? If the temperature sensing and fan control system is working properly, the PB should go to sleep before it gets hot enough for serious damage to be done. If those systems aren't working properly, it might really overheat, and then other misbehaviors would probably appear.

I don't know for certain, but I assume there should be no voltage at the fan contacts unless the temperature sensors in the Powerbook detect excess heat that needs to be removed — that is, I suspect there should be no voltage to the fan when the Powerbook is running at an acceptable temperature. There is no published documentation of the temperature at which the fan should come on, or where — at which sensor(s) — that temperature must be reached to trigger the fan. You've already determined that your fan works when you give it power, so I can think of only two possible explanations for its not running in the Powerbook: either the PB isn't hot enough for the sensors to turn the fan on, or the sensor and fan control system isn't working properly. In the former case, there's no problem at all, and in the latter, the logic board probably needs to be replaced, since that's where most of the sensors and the control system are located.

http://node123.cit.geneseo.edu/~stratton/ServiceManuals/PowerBooks/

This manual might have detailed diagrams.

Apple has never published schematic diagrams of its circuit boards — those are proprietary information. And they don't need to appear in service manuals because service technicians never try to repair a board. Doing so would be too risky, and the cost would be too high. Bad boards are always just replaced: with new ones if available, or refurbished ones if the stock of new ones has been exhausted.

Afterthoughts, too late for editing:

I suspect there are sensors integrated into several of the Powerbook's major components. There is certainly at least one in the G4 processor itself, and there may be others elsewhere on the logic board, probably including one in the video processor. Some Powerbooks — I'm not sure about yours — have heat sensors in their trackpads and perhaps in other components that aren't on the logic board. I wouldn't be surprised if the PMU, which is separate from the LB in your PB, contained a sensor. But there has to be a control center to which all the sensors report, and that decides when to turn the fan on. Without schematics, great soldering skill, and an unlimited supply of replacement parts and components to experiment with at no cost, you aren't likely to be able to make any headway on your problem except by replacing whole circuit boards.

Search for G4FanControl and TemperatureMonitor.

I thought the temperatures were WAY too high also, just from experience with electronics for some 30 years, and the fan never seemed to run when I thought it should, as a result I have run the TemperatureMonitor software for over a year, and will see how the G4FanControl does when I am not using the PBG4 at home.

I had to run two updates on the JAVA before I could get the G4FanControl to work, but the author of the software has a reference to the actual controller chip on her(?) www site, which impressed me enough to give it a shot without doing a LOT more "due dilligence" before trying unfamiliar software.

I have NOT looked into any of the commercially available cooling pads, but considering that notebook "computers" are in general a bad combination of tradeoffs in the physical architecture to achieve a "portable" design, the overheating problem is NOT unexpected. I note that even my Apple IIc has its problems when I added the ZipChips and 1MB expansion cards. Oh yes, I DO run a small auxiliary 4" 120V AC external fan blowing under my PBG4 on my desk where I have some small 1/2" blocks permanently installed to raise it up to allow good flow of cooling underneath it.

Hi, Boson Engineer. Temperature Monitor and other temp monitoring utilities detect no heat sensors in any Tibook other than a hard drive temp sensor. That sensor seldom or never reflects the temperatures reached in other parts of the Powerbook that routinely get much hotter than the HD. So while temperature monitoring software can be valuable with an Aluminum PB G4, it's nearly or completely useless with a Tibook. If your PB G4 is Titanium, I'd be interested to hear whether G4FanControl functions with it.

Here's a useful explanation of the sensor-detection issue quoted from the Help files for Hardware Monitor.

Q: I am using the latest release of the application which should support my computer, but still no sensor at all, or only a S.M.A.R.T. hard drive temperature sensor is found. Is this normal?

A: Unfortunately there are some specific Macintosh systems which don't allow that sensor values can be read out by a normal application program. There are two different cases:

1 - The computer uses a self-contained cooling control system. The hardware itself controls its own monitoring. No transfer of data from the sensor to the operating system is possible because there is no bus connection between the sensor and the actual computer.

2 - The computer contains sensors accessible via a data bus, but cooling control is independent of Mac OS X. Apple does not provide any device drivers which would allow application programs to get data from the sensor. Only the firmware or a closed part of the operating system core has access to sensor data.

In both cases, it is not possible to develop an application program which could read out sensor values. The following Macintosh systems are affected by this problem:

- PowerBook G4 Titanium (all models)
- eMac (all models)
- iMac G4 (all models)
- Mac mini (all PowerPC-based models

Hello,
Just a note from my experience on 3 similar powerbooks: changing the thermal paste between the processor and the copper heat conductors (excuse my French) will help _a lot_.
After a couple of years, this paste is actually not working any more, and the processor heats up. But with new paste (that is 1 hour work + 1 € tube), the fan never starts anymore, except in real warm days.

Message was edited by: Sylvain M

Interesting post, Sylvain, and a good tip. I was in a Circuit City store yesterday shopping for something else, and noticed little tubes of thermal paste for sale. Maybe I'll pick one up and see whether changing the paste makes any noticeable difference in my four-year-old Tibook's running temperatures. I have no concerns about overheating, but it would be nice to have my fans run less often.

Hi Sylvain,
I have often wondered if scraping the old paste and adding new would make a difference in how much heat is generated and how often the fans would run in my 867MHz & 1ghz Titaniums.
Last year I bought an emergency 1GHz logic board from ebay since parts are not available where I am, but it came with the paste completely burned black so I figured that the board was toast also---maybe not?
Next time in the states I will also pick up a tube of paste and try your trick.

Thanks a bunch for this little tidbit of info!!
PB

I decided to try to install the emergency logic board with the burnt looking microchip(mentioned in my last post) yesterday after I found a tiny tube of thermo paste that I had stashed away for emergency purposes.
The microchip was seriously discolored from heat, and although I had doubts about its usefulness I installed it in a what was previously an 867MHz DVI Titanium.
It started up and has performed perfectly for me these past two days, but with the same 40gb 7200 hard drive and the same two 512 ram sticks installed and working, it seems to actually be slightly slower than it was with the 867 processor??

My question is: could the burnt face on the microchip cause it to run slower than when it was new?

Oh Yeah, one more question: what exactly is thermal paste and is there a common substitute (for those of us who live in remote areas where thermal paste is not available)?
Thx
PB

PBookie: If your 1GHz LB has damaged cache memory, it might well be slower in processor-intensive tasks than an 867MHz board whose cache is intact. See what System Profiler says about your L2 and L3 cache. You should have 256KB of L2 and 1MB of L3 on a 1GHz Ti LB. The computer might run normally in other respects without all of its cache memory, whose function is specifically to speed up the processor's access to needed data. The cache is part of the processor, unfortunately, so you can't replace it except by replacing the LB.

Thanks for your reply eww,

The L2 & L3 cache were the first things that I checked when it didn't seem faster.
Perhaps the way that I am checking it is faulty.

While it still had the 867 chip in it I tried starting it up at exactly the same time with a 1GHz Titanium. Then I opened up iPhoto on both, then iTunes on both, then Adobe PS2 on both, then a Bible program that always takes quite a while to initiate.
In nearly every one the 867 was slightly faster.
I always believed that it was because of the smaller faster hard drive in the 867, but now I try the same tests with the new 1GHz chip and the two are nearly identical in speed??

Could it have something to do with the 64mb as opposed to the 32mb video chip taking longer to pop up? (I guess I thought it would be the other way around.)
PB