Re: IIe faulty RAM ?

[Stephen Shaw <stephen@apple2.org.za>]

Very likely!

On Sun, 10 Jun 2001 23:30:03 +1000, Mark Cummings wrote:

> I have an extra Platinum IIe International NTSC motherboard that WAS
> working and now NOT working.
> IIe has known good power supply, and 5.25 controller in slot 6 with a 5.25
> drive connected and a 80col/64K card. Except for the motherboard all the
> other parts are known good.
>
> These are the symptoms:
>
> 1. Power on produces No beep, a display full of random text/or graphics
> which appears to be flickering, and the disk fails to boot. All voltages
> measured on the motherboard are good.
> 2. Attempt to Ctrl-Reset freezes display until RESET is released, but then
> returns to previous condition but usually with a slightly different screen
> of garbage.
> 3. Attempt at Ctrl-OA-Reset, is pretty similar to Reset, although
> occasionally I get a noise from the speaker or the disk light goes on
> (forever, until Reset again). I guess this is just the drive motor I/O
> location getting some garbage.
> 4. Attempt at Ctrl-Option-Reset gets treated similarly, occasionally the
> 80-col display comes on, or a graphics page with similar flickering
> graphics.
> 5. Attempt to use freexe spray or my thermonuclear device (hair dryer) has
> failed to alter the state of the fault. This was an old trick that I
> remember using years ago on a II+.
>
> I have swapped all the socketed IC's out with another identical working
> unit, and the result is the same. The chips placed into the other IIe work
> fine.
>
> I am suspicious of the soldered in RAM, which is 2 of 41464C-10. Before I
> go desoldering, can anyone shed any experience with RAM faults and the
> symptoms.
>
> Would the inbuilt diagnostics (Ctrl-Option-Reset) run correctly if the RAM
> was faulty, if so how would it display the result, since the text screen is
> memory mapped. Also, should it still make any sounds, as this would be
> addressed outside of RAM space ?
>
> One thing I have noticed is that there appears to be some message in the
> middle of the screen occasionally that looks like R?M something or other,
> which I think is a call for help ! :O
>
> Mark

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