II GS starts in diagnostic mode ?

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Joined: Dec 19 2010
Posts: 4

I have two AII GS systems that startup in diagnostic mode. Test reports "system good" and loops endlessly. Wont boot any drive. I swapped all plugin ICs and tried with no cards or peripherals plugged in and keyboard disconnected but no joy. Does anyone have any ideas what may be at fault here ?. Does the nvram need clearing- how do you do it?
Any suggestions would be much appreciated.

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Joined: Apr 11 2006
Posts: 1013
Re: II GS starts in diagnostic mode ?

This is a sign that the second joystick button, or the option key on the keyboard is stuck. If you have either one plugged in, unplug that and see what happens. I doubt both could have bad ADB ports; my money's on the keyboard being bad, and you're moving that from machine to machine.

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Joined: Dec 19 2010
Posts: 4
Re: II GS starts in diagnostic mode ?

Thanks for the reply David.I think youre on the right track here.
I have two keyboards they both allow one GS to boot occasionally after about 5-10 CTRL/Resets. The other just will not boot and stays in diag loop.
After playing around for a bit the one that does sometimes boot I noticed when I run Proterm the menu screen is flashing fast all the time like a key is held. (both kybds) I think ill dismantle the keyboard and remove the Option key on one. (no kybd buffer overflow in Basic)

Im hoping its not faulty ADB. Can you tell me - if you turn on a GS without a keyboard does it go into diagnostic mode automatically ?

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Joined: Apr 11 2006
Posts: 1013
Re: II GS starts in diagnostic mode ?

MK14HAK wrote:

Can you tell me - if you turn on a GS without a keyboard does it go into diagnostic mode automatically ?

It does not. So it could also be the joystick port causing trouble.

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Joined: Dec 19 2010
Posts: 4
Re: II GS starts in diagnostic mode ?

I have no joysticks plugged in. Looks like ADB problem by the way the kybds behave then. I may go looking for dry joints around ADB controller and check joystick ports. Both ROM01.

Thanks for confirming operation without keyboard.
Hope I can fix these, Ive got a scope so I can get low level if I need but I imagine replacing ADB controller is not possible these days...

update: looping peeks to gameport pdl and buttons show random data for both pdl and buttons, cmos buffer poss faulty here. (Faulty Xmas present for the boys till I have time or courage to replace)