flashing power lights mean something?

[da9000]

I've seen some mentions for this, but not clear response, so I have to ask again. Here's my situation:

A500 rev.6a motherboard, KS 1.2, Agnus 8372A (1MB). All custom chips work fine: placed them on an A500 rev.5 and they worked. Also placed all the rev.5 chips on the rev.6a and same problem:

Green screen and power light blinks.

I know the Agnus is fine, so the green screen is for bad Chip RAM, BUT what the heck is the power light blinking?
Also, what is the "U2 trick" ? I did the re-seating (even remove and replace), but I heard/read something about soldering the base of the Fat Agnus... Any docs on this?

I will double check the RAM chips to see if they're going crazy hot, but I think they had nominal temperatures.

Also of note: when I add a A501 RAM expansion board, it shows a dark gray screen for a split second before the green screen (which otherwise is immediate).

Thanks for any help and hints!

PS. I've been consulting these links:
http://home.arcor.de/kickstart/TKA/Tutorials/troubleshooter/trouble1.html
http://home.arcor.de/kickstart/TKA/Tutorials/troubleshooter/trouble2.html
http://wuarchive.wustl.edu/pub/aminet/hard/misc/Trouble.txt

[motrucker]

The green screen means that there is RAM problem. It should mean chip RAM, not fast RAM. I hate to tell ya, but these chips can be bad without getting hot.
On the power LED flashing - how many times does it flash? This is also a code to tell you what's wrong, but you must get the number of times it flashes.
Hope you track it down..........

[da9000]

Ok, I verified: they don't get warm, so it's possible that they're dead and no short inside. I will have to find some chips to test against. I heard piggy-backing works fine.

Now, as for the power LED, it flashes 11 times, the last being a little longer, and then the same again. Does it mean something other than re-seat the Agnus?

[_ThEcRoW]

I think that there is something wrong with the kickstart. Rev 6a boards was supplied with 1.3. And i can verify that, as i have a rev 6a a500 with kick 1.3.
How a kick 1.2 has ended on a rev 6a board?.

[motrucker]

da9000 wrote:

Now, as for the power LED, it flashes 11 times, the last being a little longer, and then the same again. Does it mean something other re-seat the Agnus?

I just ram across an old thread here that says 10 short, one long flash means something wrong with Agnus; to try cleaning contacts and re-seating. It may mean a bad chip too.

[da9000]

Motrucker, I already did the Agnus re-seating stuff. No changes.

As for the kickstarts, I'm not 100% sure if it is 1.2, but I can try to swap a 2.04 in it (I don't think I have a 1.3). Is there a page that lists the chip numbers that correspond to the various KS versions? Because this ROM doesn't actually say 1.x on it... (unlike my 2.04 KS)

[da9000]

I will just recap my findings, just in case others have stumbled across similar issues:

1) The green screen + 10 short keyboard flashes plus 1 long one, was not an Agnus reseating issue. In fact, it wasn't any custom chip issue, as I replaced every single chip and it still happened. The real reason was: bad CHIP RAM. I did the "piggy-backing" trick described here: http://wuarchive.wustl.edu/pub/aminet/hard/misc/Trouble.txt and was able to narrow down the problem to the first 2 (256kb) CHIP RAM chips. This method works! Use it if you dare One other small note: the "bad" chips were barely warm, while the good ones were colder. What the hell happened to these chips, I know not. Next I will unsolder all chips (I put some tape around the chips and with a canister of compressed air I was able to unsolder them, although it's more messy than other methods, but if that's all you've got...), and solder 20pin sockets and replace with good ones and finally have a working rev.6a A500!

2) For those interested in finding good replacement RAM: I got mine from old PC hardware. The original A500 RAM was four *4256* chips, meaning 4 x 256k x 4bit = 4 x 128kbyte per chip = 512kbyte. Now, the 4bit chips were commonly used in old PC VGA cards (ISA and VLBUS) and PC sound cards (Gravis Ultrasound). Of course I didn't want to mess with my Gravis (ultimate demo music card!), so I grabbed 4 70nanosecond chips from a VGA card. A question for the hardware gurus: I know that VGA cards have "dual ported" video RAM, for concurrent CPU access and RAMDAC access. Does this functionality rest within the *4256* chips or their "memory controller" hardware?

3) rev. 6a works fine with KS 1.3 (I only tested it as far as the boot screen, not in AmigaDOS/WB), and of course KS 2.04


And finally I have a question for the hardware gurus: so the first 2 chips of Chip RAM were bad, does that mean there might be a problem elsewhere in the motherboard that caused them to fail, or is it pretty normal for them to fail like that? I ask because I don't want the new ones to fry in a matter of hours.

[Piru]

BTW, if the very lowest chip memory adresses were corrupt it surely explains the crash (led blinking): The low memory is used for some early system initialization.

[_ThEcRoW]

Also i heard that some blinkings could be a keyboard related problem. Check www.amigahistory.co.uk in the section of troubleshooting for more information on explanation about error codes on amigas.

[FrankBrana]

And i can verify that, as i have a rev 6a a500 with kick 1.3.
How a kick 1.2 has ended on a rev 6a board?.

Not 100% true since not all rev6a were delivered with 1.3 roms but 1.2

[motrucker]

da9000 wrote:
Motrucker, I already did the Agnus re-seating stuff. No changes.
A

If the chip is bad, you can re-seat it forever with no changes.......

[da9000]

Piru:
Thanks for that useful tid bit of information! I didn't know, but it makes perfect sense. I will see if I can narrow it down to the 1st vs 2nd chip. So far I had to piggy-back both to boot the beast.

TheCrow:
I found the problem, but I'll check out that page too. Thanks.

FrankBrana:
Interesting! So it IS possible to have a KS1.2 on rev.6a boards. Thanks for clearing this up.

motrucker:
Obvisouly That's why I was asking for tips and searching elsewhere.


For everyone: do the hardware gurus on the board want to take a stab at answering the 2 questions in my previous post on this thread? (1. Are *4256 chips dual ported and 2. What's the most usual/common method for on-board CHIP RAMs to fry/die? I don't want my new ones to end up the same way)