Amiga 500 keyboard PCB faulty

lioneer · 18 October 2021, 11:24

Hi, i have problem with A500 keyboard. When is inserted to motherboard, amiga is freezed (no kickstart logo) and only caps lock LED is always on. When i unplug it, kickstart appear and amiga is working correctly. Where is problem? What chip is faulty?
Thank you

lesta_smsc · 18 October 2021, 11:31

I had similar issue when I accidentally must have shorted keyboard during testing. However, my caps was flashing rather than solid but after leaving off for 5 mins it worked as normal again. I assume it must have affected something in memory which then reset.

solarmon · 18 October 2021, 12:16

Make sure you have connected the keyboard connector the correct way - the purple wire should be on the right.

If you have connected it in reverse then the A500 with not boot up - like what you have experienced.

Overdoc · 18 October 2021, 12:19

Are you sure you connected it the correct way?
The black wire needs to point to the left side of the A-500.

If that doesn't help, then you can try to exchange the two CIA chips (8520A) against each other (but be sure you insert them in the correct direction!)

If that doesn't solve the issue, then something on your keyboard's pcb probably failed,. (most likely the 6570 chip, unfortunately....)

lioneer · 18 October 2021, 14:13

yes, cable is connected in the correct way. And CIA chips are good, because when i tried another keyboard, it works good. I have problem only with this one keyboard (and i need it, its oldest rare version with "space invaders" keys - early A500, red LED and Caps lock). so maybe, changing the 6570 chip is needed? from working pcb...

solarmon · 18 October 2021, 14:22

Quote:

Originally Posted by lioneer

yes, cable is connected in the correct way. And CIA chips are good, because when i tried another keyboard, it works good. I have problem only with this one keyboard (and i need it, its oldest rare version with "space invaders" keys - early A500, red LED and Caps lock). so maybe, changing the 6570 chip is needed? from working pcb...

Check the pins of the keyboard MCU for dry joints. Also check the 555 reset circuit on the keyboard - if it is kept low then this will stop the A500 from booting (because _KB_RESET is kept low).

18 October 2021, 11:24	#1
lioneer Registered User Join Date: Jul 2021 Location: Ostrava Posts: 58	Amiga 500 keyboard PCB faulty Hi, i have problem with A500 keyboard. When is inserted to motherboard, amiga is freezed (no kickstart logo) and only caps lock LED is always on. When i unplug it, kickstart appear and amiga is working correctly. Where is problem? What chip is faulty? Thank you

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18 October 2021, 11:31	#2
lesta_smsc Registered User Join Date: Feb 2012 Location: United Kingdom Posts: 3,173	I had similar issue when I accidentally must have shorted keyboard during testing. However, my caps was flashing rather than solid but after leaving off for 5 mins it worked as normal again. I assume it must have affected something in memory which then reset.

18 October 2021, 12:16	#3
solarmon Registered User Join Date: Dec 2018 Location: UK Posts: 1,715	Make sure you have connected the keyboard connector the correct way - the purple wire should be on the right. If you have connected it in reverse then the A500 with not boot up - like what you have experienced.

18 October 2021, 12:19	#4
Overdoc Commodore Collector Join Date: Aug 2001 Location: Austria Age: 53 Posts: 944	Are you sure you connected it the correct way? The black wire needs to point to the left side of the A-500. If that doesn't help, then you can try to exchange the two CIA chips (8520A) against each other (but be sure you insert them in the correct direction!) If that doesn't solve the issue, then something on your keyboard's pcb probably failed,. (most likely the 6570 chip, unfortunately....)

18 October 2021, 14:13	#5
lioneer Registered User Join Date: Jul 2021 Location: Ostrava Posts: 58	yes, cable is connected in the correct way. And CIA chips are good, because when i tried another keyboard, it works good. I have problem only with this one keyboard (and i need it, its oldest rare version with "space invaders" keys - early A500, red LED and Caps lock). so maybe, changing the 6570 chip is needed? from working pcb...

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