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Amiga 2500 video

billdeg

billdeg

Technician
Joined
Nov 18, 2003
Messages
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Location
Landenberg, PA USA
I have an Amiga 2500 with the video toaster and a bunch of cards. Here is the directory with pictures
http://www.vintagecomputer.net/commodore/amiga_2500/

I don't know much about the Amiga 2500, in particular the ins and outs of videotoaster-ing.

On a more basic level, I cannot get any video output, at least to the two monitors I tried, the Commodore 1950 and Magnavox Professional Series Color Display. I don't even think the "Video" port is active. I can use these monitors with a stock 2000, 500, or 600 so I know they work.

I replaced the battery and inspected the cards for shorts and such, I don't know if a dead battery prevents the entire system from working. Everything is in nice shape, nothing obviously wrong, hardly and dust or signs of problems. When I power on the system I can hear the hard drive loading something, it seems like the system is booting to the hard drive.

I am thinking of taking out all of the cards and making it a 2000, if it's as easy as just taking out the video processing cards to do so. Anyone here been down the Amiga 2500 like to suggest anything? I plan to read up on the cards and such, I am in new territory here and will need to study up.

If I find anything I will post it here.

Thanks.

Bill
 
The Amiga 2500 is just a 2000 with a bundled 020/030 accelerator card. (You'll know it, it's in its own port, the farthest-right card slot.) You do have the monitor plugged into the 23-pin D-shell "Video" connector on the back? You might try removing all the cards from the machine and adding them back in to isolate any bad ones.

I'm no expert on video-toaster usage, but it shouldn't be anything that interferes with normal system video. What might give you problems is if there's a high-resolution graphics card plugged in, and the video output is going to that instead of to the chipset video (whence the "Video" connector derives its signal.)
 
Basically yah. Tear down the system to an Amiga 2000, test, and add cards to find out what fails. It has a full complement of the Toaster cards, Flicker Fixer, Sunrize sound card, and 3 DPS Digital processing cards. The Flicker Fixer has a video port, you can plug a VGA monitor into it (with an adapter). It may indeed be true that the video signal to the "video" port is suppressed.



Bill
 
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Try the flicker fixer with a VGA monitor first. Once you get computer video, then try the toaster.

To use the toaster, you need two NTSC monitors (one for preview, the other for program out). Hooking up video inputs isn't straight forward, all four need to to be gen-locked (synchronized) to the same master clock. The DPS IV card does that job but only takes one video source. To use additional inputs, you will need additional genlockable TBCs/frame syncs.
 
I already have the 1950 with adapter plugged into the Flicker Fixer. After reading up on the way the card works, I think it's possiblE that there's a bad RAM chip or two on the flicker flixer. The card samples the video in RAM and converts it on its way to the VGA display. Bad RAM may cause nothing to be sent. I do get a light blue screen on the display at least.

I should have replacement RAM someplace, and/or another flicker fixer card. Hopefully my RAM tester can handle this type of RAM.

Another possible issue would be the connection of the Fixer to the motherboard. There is a cable that goes from the adapter (used to attach the card to the motherboard) which travels across the board under the power supply to a daughter board with various electronics. I have pics on my site from the link above of the daughterbd.. At some point along the way something may be not attached corectly. The fuse on the daughterboard is ok. I'd hate to re-disassemble the system to get at the daughterboard so I will test the RAM first.

Last possible issue could be the CMOS battery, not sure if it's preventing the system from booting properly. I hear the hard drive making normal sounds when the system is powered on.

Merry Christmas everyone!
 
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The battery on the Amiga doesn't affect system boot in any way of which I'm aware. Though if it is the original battery, you ought to remove it and put in a socket - those things can be the death of a board if they leak.
 
I am pretty sure the battery on the 3000 keeps the HD information so a dead battery means you won't be able to boot from the HD. On the 2000/2500 this is not an issue.
 
I moved on to two other Amigas, this time two A2000's. Both had little issues that were resolved and now I know a lot more about how these machines work. I learned that the accelerator card of the 2500 was the problem, bad fan if not other things. I removed this card and the system comes to life (albiet as a single drive A2000). The Flicker Fixer is fine/works.

Keeping with the Amiga theme I am blowing through all of these systems I have, the last one left is an A3000. The 3000 has the worst battery damage, clean up will take a while. I have to replace diodes and nearby components damaged by battery acid.
 
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