pb3623
Well-known member
Hello all,
I got a second TAM last week off of one of the Facebook groups and, like the one I bought last fall, it also came well-appointed w/ a Sonnet G3/400. After some machine freezes, I took off the Fat Back and saw the frameless in the HD bracket was not on. I've since been working on certain tests, to the extent of my "trained monkey" abilities.
Here is where it gets interesting. When I measure the voltage in series with one of the fans, the 12V drops to around 1 volt. When I take off the fan the supply goes back up to 12V. So, am be correct in stating that, under load, the voltage is dropping to where it isn't enough to move the fan?
I wouldn't think there is a fan controller or any sort of fan logic since it's a 2-pin header (ground and power). But could something have shorted? If so, why do I still see 12V without load?
Is there another way I can try to tap 12V from another location on the board?
Am I even following the right methodology here?
Thanks very much in advance!
I got a second TAM last week off of one of the Facebook groups and, like the one I bought last fall, it also came well-appointed w/ a Sonnet G3/400. After some machine freezes, I took off the Fat Back and saw the frameless in the HD bracket was not on. I've since been working on certain tests, to the extent of my "trained monkey" abilities.
- Fan header J17 next to the ROM/cache slot measures 12.00 volts across both pins.
- The installed fan, using bridge wires, runs off of a 9V battery.
- I don't have the specs on this stock fan since the label isn't visible but I assume it's 12V, 600-900mA based on its size. I know the amperage needs to be known if a replacement was deemed necessary but the 9V battery should rule that out.
- I've tried a variety of other 12V fans of similar size, and they all work off a 9V battery and their original machines (one of which was a 603e CPU fan on a 6500) but none work on the TAM's fan header.
- The TAM doesn't appear to have another fan header for me to try. There is a 3-pin J7 behind the ADB ports (above the Cuda) that I'm not sure what it does but it measures 4-5V across two pins.
- I've reset the PRAM and CUDA just to say I did but again, J17 measures 12V.
- Seems the secondary fan (up in the upper right of the case, if you are looking at the rear) is connected to the backplane somehow. I can't get to it and it doesn't appear to run either.
- I've swapped out the Bose power supply/sub just in case it was a +12V supply issue.
- No other issues with the hardware that I'm aware of but I haven't gotten very far with it.
- I do know that Accelerator, Ethernet and HD both work without issue.
Here is where it gets interesting. When I measure the voltage in series with one of the fans, the 12V drops to around 1 volt. When I take off the fan the supply goes back up to 12V. So, am be correct in stating that, under load, the voltage is dropping to where it isn't enough to move the fan?
I wouldn't think there is a fan controller or any sort of fan logic since it's a 2-pin header (ground and power). But could something have shorted? If so, why do I still see 12V without load?
Is there another way I can try to tap 12V from another location on the board?
Am I even following the right methodology here?
Thanks very much in advance!