Amiga 3000 black screen -- caps lock test?

mattsoft · 15 February 2018, 17:58

Hi all - recently picked up an Amiga 3000 in rough shape. It had been stored in a damp location and looked terrible. When plugged in, I get the green LED and a black screen.

I removed the battery which had leaked and sprouted a green forest. I've removed the forest and cleaned the board. Damage is minimal and no traces appear damaged.

All socketed chips have been removed, sockets cleaned, and chips re-inserted.

PSU is outputting proper voltages.

I've also cleaned the system top to bottom and she looks wonderful now. But yeah, she doesn't work...

What happens is the machine powers on, green LED comes on, caps lock flashes on then off. The screen is always black. It does not color cycle or anything. If I press the caps lock multiple times, it stays off on the 6th press. I believe this is something wrong with the CPU from everything I have read.

Anyways, that's all a preamble to my question. I've read something about the "caps lock test" but cannot find any info on this. It sounds like the number of caps lock presses until failure gives more information about exactly what the problem might be (for example, stopping at press #6 instead of 10) -- but maybe I'm not understanding that correctly. I've seen many references to http://amiga.serveftp.net for more info, but the site appears down.

My next step is to double-check all jumpers and make sure they're set correctly. I assume they are, but never assume anything...

If nothing, thanks for listening.

Hedeon · 15 February 2018, 18:28

A quick test regarding cpu could be to install a 3630.

alexh · 15 February 2018, 18:31

Which video output are you using?

mattsoft · 15 February 2018, 19:36

I've tried both RGB (15KHz) and VGA (30KHz) video outputs -- same results.

Yeah, if I had a CPU card like a 3630 I would try that, but I don't...

ajk · 15 February 2018, 19:55

If you have the capability to burn a diagnostic ROM, it might be worth a try. Although if the CPU doesn't manage to start up, it won't run the diagnostic code either...

I don't think the caps lock tells much about the state of the computer, except that it's not taking in the key presses.

My suspicion would be that there is damage to the traces after all, it may just be hidden from view. Could you get a very detailed photo of the board around that area?

mattsoft · 15 February 2018, 21:30

I'll take a picture of the damaged area when I get home this evening. I'll also double-check any jumper settings on the board.

mattsoft · 16 February 2018, 02:44

Checked all jumpers and they are set to default. No love.

Attached are pictures of the battery damage.

ajk · 16 February 2018, 05:40

Thanks, good photo. It doesn't look too bad indeed but there are some traces that appear somewhat suspect. I have marked a few in the photo below, would be worth checking out with a multimeter. Anything with a dark spot may be compromised and it only takes one to mess up the system, if it carries an important signal.

amigasith · 16 February 2018, 09:21

In many cases, it's not just bad traces that cause problems. Vias can also be a major source of issues.

While they look okay from the outside, they might be broken from the inside and don't actually connect their traces from the upper to the lower layer / from one layer to GND / from one layer to VCC, etc. On the A2000 for example, this is often the root cause of a black screen. There are countless examples for this over on a1k.org.

In most cases, however, this can be fixed easily by soldering "bridges" with small wires that you stick through the vias. Or in the case of a via that connects to GND (or VCC, respectively), searching for the next best possibility to connect the loose trace to GND (or VCC, respectively).

Your best bet is to check every single trace and every single via in a large area around the battery damage. It's a lot of work and very time-consuming, but in the end it's the best possible approach.

mattsoft · 17 February 2018, 08:55

Wow,thanks for all the great help! I’ve got some work to do obviously. First step, pull out the multi and start testing.

ajk · 17 February 2018, 10:11

Yes, this is the kind of thing that requires patience and attention to detail. Still, the board is relatively speaking in good shape and can almost certainly be brought back to working condition. You could have it much worse!

15 February 2018, 17:58	#1
mattsoft Registered User Join Date: Dec 2016 Location: Seattle, WA Posts: 89	Amiga 3000 black screen -- caps lock test? Hi all - recently picked up an Amiga 3000 in rough shape. It had been stored in a damp location and looked terrible. When plugged in, I get the green LED and a black screen. I removed the battery which had leaked and sprouted a green forest. I've removed the forest and cleaned the board. Damage is minimal and no traces appear damaged. All socketed chips have been removed, sockets cleaned, and chips re-inserted. PSU is outputting proper voltages. I've also cleaned the system top to bottom and she looks wonderful now. But yeah, she doesn't work... What happens is the machine powers on, green LED comes on, caps lock flashes on then off. The screen is always black. It does not color cycle or anything. If I press the caps lock multiple times, it stays off on the 6th press. I believe this is something wrong with the CPU from everything I have read. Anyways, that's all a preamble to my question. I've read something about the "caps lock test" but cannot find any info on this. It sounds like the number of caps lock presses until failure gives more information about exactly what the problem might be (for example, stopping at press #6 instead of 10) -- but maybe I'm not understanding that correctly. I've seen many references to http://amiga.serveftp.net for more info, but the site appears down. My next step is to double-check all jumpers and make sure they're set correctly. I assume they are, but never assume anything... If nothing, thanks for listening.

16 February 2018, 02:44	#7
mattsoft Registered User Join Date: Dec 2016 Location: Seattle, WA Posts: 89	Checked all jumpers and they are set to default. No love. Attached are pictures of the battery damage. Attached Thumbnails

16 February 2018, 05:40	#8
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	Thanks, good photo. It doesn't look too bad indeed but there are some traces that appear somewhat suspect. I have marked a few in the photo below, would be worth checking out with a multimeter. Anything with a dark spot may be compromised and it only takes one to mess up the system, if it carries an important signal. Attached Thumbnails

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Amiga 1000 Keyboard unresponsive, Caps Lock solid on	Matthias1231	support.Hardware	8	06 December 2019 16:39
Amiga 500 non working keyboard with extra ram attached, Gary, 2 blinks caps lock.	CoCan	support.Hardware	16	26 February 2017 20:14
Amiga600 boot problem: black screen + caps lock on	fpmpaolo	support.Hardware	12	16 May 2016 23:36
Flashing Caps Lock	Nobby_UK	support.Hardware	8	06 December 2014 20:58
A3000 boots black screen after A3640 test install	Brosol	support.Hardware	35	20 February 2010 18:16

15 February 2018, 18:28	#2
Hedeon Semi-Retired Join Date: Mar 2012 Location: Leiden / The Netherlands Posts: 1,993	A quick test regarding cpu could be to install a 3630.

15 February 2018, 18:31	#3
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,330	Which video output are you using?

15 February 2018, 19:36	#4
mattsoft Registered User Join Date: Dec 2016 Location: Seattle, WA Posts: 89	I've tried both RGB (15KHz) and VGA (30KHz) video outputs -- same results. Yeah, if I had a CPU card like a 3630 I would try that, but I don't...

15 February 2018, 19:55	#5
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	If you have the capability to burn a diagnostic ROM, it might be worth a try. Although if the CPU doesn't manage to start up, it won't run the diagnostic code either... I don't think the caps lock tells much about the state of the computer, except that it's not taking in the key presses. My suspicion would be that there is damage to the traces after all, it may just be hidden from view. Could you get a very detailed photo of the board around that area?

15 February 2018, 21:30	#6
mattsoft Registered User Join Date: Dec 2016 Location: Seattle, WA Posts: 89	I'll take a picture of the damaged area when I get home this evening. I'll also double-check any jumper settings on the board.

16 February 2018, 09:21	#9
amigasith Registered User Join Date: Jan 2013 Location: Wild South / Germany Age: 48 Posts: 271	In many cases, it's not just bad traces that cause problems. Vias can also be a major source of issues. While they look okay from the outside, they might be broken from the inside and don't actually connect their traces from the upper to the lower layer / from one layer to GND / from one layer to VCC, etc. On the A2000 for example, this is often the root cause of a black screen. There are countless examples for this over on a1k.org. In most cases, however, this can be fixed easily by soldering "bridges" with small wires that you stick through the vias. Or in the case of a via that connects to GND (or VCC, respectively), searching for the next best possibility to connect the loose trace to GND (or VCC, respectively). Your best bet is to check every single trace and every single via in a large area around the battery damage. It's a lot of work and very time-consuming, but in the end it's the best possible approach.

17 February 2018, 08:55	#10
mattsoft Registered User Join Date: Dec 2016 Location: Seattle, WA Posts: 89	Wow,thanks for all the great help! I’ve got some work to do obviously. First step, pull out the multi and start testing.

17 February 2018, 10:11	#11
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	Yes, this is the kind of thing that requires patience and attention to detail. Still, the board is relatively speaking in good shape and can almost certainly be brought back to working condition. You could have it much worse!

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)