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AuthorTopic: A500 video trouble  (Read 799 times)

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Offline tmulicz

A500 video trouble
« on: January 26, 2013, 09:58:17 PM »
Hello people

Here I am, addressing the community with one good question: my A500 is in trouble, what could it be?

Got one A500, Revision 6A, Kick 1.3, green power LED, working great until one given day when it ceased working properly.

I made two videos about it:
http://youtu.be/SAUozKBpS4s (showing the "hand" boot logo)
http://youtu.be/0-PI-1Vgako (a demo called "Copper Master" by Angels, 1991)

As you can see, there is a boot image but it comes and goes, with garbled pix in between
The system actually boots (of course no image, or weird pixels, mostly black) and most of the time ends with the power LED dimming 6 times + reboot (i think)

Now the second video is really charming. The copper bars actually show up absolutely perfect but everything else is garbled. Even sound is working although, when there is garbled video data on the screen, the music also sounds weird. Finally the demo stops when it comes to the copper wiggle.

Now the 1000 point question: what's wrong?
Copper bars working but other graphics no...

Did all these test with the 512KB expansion board removed.
Generally it behaves the same with 1MB RAM, although I must say the the hand boot logo no longer shows up like in first video. The screen remains white almost all the time.

Finally, thanks for patience reading this long story and looking forward for a helping hand.


Offline Oldsmobile_Mike

Re: A500 video trouble
« Reply #1 on: January 27, 2013, 01:22:36 AM »
Re-seat the socketed chips on your motherboard?
Amiga 500: 2MB Chip|16MB Fast|30MHz 68030+68882|3.9|Indivision ECS|GVP A500HD+|Mechware card reader + 8GB CF|Cocolino|SCSI DVD-RAM
Amiga 2000: 2MB Chip|136MB Fast|50MHz 68060|3.9|Indivision ECS + GVP Spectrum|Mechware card reader + 8GB CF|AD516|X-Surf 100|RapidRoad|Cocolino|SCSI CD-RW
 Amiga videos and other misc. stuff at https://www.youtube.com/CompTechMike/videos

Offline TjLaZer

Re: A500 video trouble
« Reply #2 on: January 27, 2013, 01:33:46 AM »
Yeah do the Universal Atari 4 inch drop on that biatch. lol
Going Bananas over AMIGAs since 1987...

Looking for Fusion Fourty PNG ROMs V3.4?

:flame: :banana: :banana: :banana:

Offline AmigaClassicRule

Re: A500 video trouble
« Reply #3 on: January 27, 2013, 01:55:58 AM »
Why do I find the whole concept of classic Amiga crashing either software or hardware wise to be so hot and sexy? I mean just watching that video clip in youtube showing Amiga 500 video problem is so hot...I don't know. There is something about the way the Amiga deals with problems in such a classy way that I like it.....completely reminds me of consoles....:)

Offline tmulicz

Re: A500 video trouble
« Reply #4 on: January 27, 2013, 01:00:58 PM »
Thanks so far for advices.
Right now I'm beyond re-seating... but will try it maybe again.
About hotness and sexyness of such video, I can only agree so far it's someone else-es Amiga :laugh1: :laugh1:  (although I wish well to all amigas out there)

I did try the logical approach, but do not know the hardware that good.

Since the copper bar colors are perfect I surely can consider all the analogic video part OK (hybrid chip and all around)

Remains Denise or Agnus ... I would vote for Agnus ... just waiting for opinions before going on the hunt for a replacement chip.


Offline tmulicz

Re: A500 video trouble
« Reply #5 on: February 01, 2013, 06:48:04 PM »
Final verdict ... the Agnus is not working. Replaced it and now everything's ok.

Although the PLCC socket was and is not in really good shape.


Offline Zac67

Re: A500 video trouble
« Reply #6 on: February 01, 2013, 07:06:01 PM »
Since Chip RAM does work (otherwise the machine wouldn't ever boot up w/o Fast RAM) and Copper graphics as well, I'd guess a problem with the chipset (internal) address bus - either on the Agnus or on the Denise side (so Denise' requests get garbled). The PLCC socket may be a very good candidate - possibly just swapping Agnus improved a bad contact, but if the socket isn't looking too well it may not hold for long...

Did Paula sound work? Disk DMA seemed to be working, too - so in theory it could only be the Denise socket, the Denise chip or a trace leading there.

Offline tmulicz

Re: A500 video trouble
« Reply #7 on: February 01, 2013, 07:16:10 PM »
With a new Agnus, it works fine (for now).
Definitely will replace the socket one day.