Re: Q:Inside a IIC

[Jan <jankro@vip.fi>]

OK, I�ll get the following voltages: 4.94V, -11.33V going in to the 7905, -5.12V
coming out from 7905, 16.10V.
The left front test terminals: left=ground, Middle=16.08V, right=4.94V. Second
supply: 15.99V, 5.01V.

16V comes out from the brick. The power supply inside the IIC gives out only two
voltages 16V and 12V, the -5V is generated by a 7905, but what generates the -12V?
and where does it go to? I could not find it??

Jan
BTW, thanks for your help so far, I appreciate it.

Rubywand wrote:

> Jan writes ...
> >
> > Does anyone have a schematic of an IIC?
> > How about a list of all the different chips and their meaning, like GLU,
> > SPI, MMU? I�m trying tho trace the problem why 3 of my IIC�s don�t work.
> > All have similar problems, strange characters on screen and no boot from
> > disk, disk will spin and try to read. Speed of the disk is ok. Someone
> > suggested the upper memory had a bad chip, but replaced those too with
> > no luck.
>  ....
>
>      Your question (along with the two from Angelo) 'did it'. I just ordered
> the //c Technical Reference from Amazon. So now, if someone talks about an
> "SPI" chip, I'll at least know that it's not the Special Purple Interface.
>
>      For now, a guess relating to the kind of slightly flakey behavior you
> mention is a power supply problem-- like one of your negative voltages (-5V or
> -12V) is messed up. If there are any voltage test points you can identify on
> the motherboard, you could check voltages between the test points and ground.
>
> Rubywand