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Amiga 500 blank screen


nd2003grad
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Once again, I need help. My a 500 unit has worked fine while I've had it, but now since I have tried to have hook up a gotek to the external floppy drive port I can no longer boot the computer. It is switchable between 1.2 and 2.0 ROMs, with 1.2 the power light comes on and nothing happens. With two point no the same thing happens but the power light flashes. I have no idea what I could have done wrong, and I have yet to get the go tech to work correctly although it powers on. Have I fried my machine? Does anyone know how to fix this? It was working fine two days ago. I am posting this on the lemon forum as well. All I want is my Amiga to work!

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By blank, do you mean the computer generates a black image or no image at all so you get whatever the TV defaults to display without a signal? The Amiga has the ability to display various errors with different colours, so if it indeed displays a black image, it can be looked up what it means.

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Seems like the site has had some issues today. Well, I'd say it gives a "grey" image before the screen says "no signal." However, it definitely shows some level of signal prior to that happening. I do hope this is at least somewhat easily fixable. It doesn't matter if the Gotek is plugged in or not.

 

 

post-44799-0-13602900-1471639844_thumb.jpg

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I meant someone else asked you the same question. :)

 

So you get some kind of gray/white image for a short while, before the screen goes out of sync? I'm not sure what you can do. Does the kickswitch consist of two discrete ROM chips, in such way that you would be able to lift one and insert into the Kickstart ROM socket without going through the switch, or is that one entire, larger EPROM which uses a DIP switch or software to select ROM version?

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I'm guessing it's the first one. I've only taken the cover off once, and it's all buried under major rf shielding. Is Amiga like a Bally, where that is not really necessary any longer? Anyway, there's a tiny switch in the back that shows 1.2 and 2.0. That would indicate to me that they are separate?

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I'm not sure if I'm barking down the wrong tree though. An image search for Amiga kickswitch tells me most have two chips, but I think there may be ones with just one bigger chip and the switch will select which address lines to use.

 

A little about colours and blinks, in case it applies to your situation:

http://wiki.classicamiga.com/Amiga_boot_error_code_colours

http://www.amicue.org/TechStuff/amigaboot.html

Edited by carlsson
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OK, here's what I found...

 

I took the machine apart. I'm not so familiar with everything, so one of the chips was slighly loose. I also saw what appears to be the 1.3/2.0 chips in a really strange configuration quite loose from the board in there. I did get it to fire up again after moving it around, but as soon as the Gotek goes in it's back to nothing. Does this look like a normal setup?

 

post-44799-0-50585200-1471801289_thumb.jpg

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Some Kickstart switches come with that ribbon cable, others slap a daughter board straight onto the socket. I doubt that is your problem, but if you like to, you can carefully pry one of the two chips from the daughter board and put it into the motherboard instead of the ribbon cable. It would lock you into either OS version, but if it would make the Amiga boot, it might be one of the causes.

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Ouch! I have at least once soldered some metal onto a chip to replace a pin and made it to work, but it is very hard to get something to stick and not sure it will work. Sorry to hear you got into that much trouble, and we don't even know if that is the likely problem.

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Yeah, I think I may have lucked out and it may be pin 31 which should be bent anyway in this case...but I am still at a loss as to what is happening. I can always upgrade the chip if necessary--I'm used to dealing with Bally where the custom chips are not replaceable/able to be sourced.

 

I wish I knew what was causing this BS and making my Amiga adventure into a nightmare!

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I just installed a GoTek. No issues here. What you might want to do is get yourself the usb to ttl adapter so you can reflash the rom on the GoTek. You can get the files and instructions here:

 

https://cortexamigafloppydrive.wordpress.com

Edited by Sinphaltimus
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Nothing about this has gone well, and I'm about to give up. This system worked great until a few days ago. Now I play around with the ROM chips as that seemed to be some level of problem. I broke my 2.1 Kickstart chip (prong) and subequently my ROM switcher caught fire. I have no idea what to do; I don't even know (or know how to tell/orient the chip) whether my 1.3 rom works (fire was underneath, but brief--no idea what happened). I'm PISSED...this was my prized possession of my collection. Bad thing is I'm 90% sure it could be fixed if I knew more.

 

Now that my switcher is toasted, here's a question--does upgrading to Kickstart 3.1 make compatability issues? I really am at a loss and I'm about ready to throw it out the window and buy an Atari ST. No, I'm not to that point yet.

 

Did I mention that I got stabbed by the 1.3 ROM as well? Great night...

 

post-44799-0-19798500-1471920014_thumb.jpgpost-44799-0-39407300-1471920030_thumb.jpgpost-44799-0-32411300-1471920138_thumb.jpgpost-44799-0-40849700-1471920365_thumb.jpgpost-44799-0-66627800-1471920406_thumb.jpg

Edited by nd2003grad
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A number of early games won't run with 3.1, mainly because they make calls straight into the ROM which has other content at the exact same location. But if you would be able to get the Amiga itself to boot every time, it would be a win. The damage to the kickswitch was unexpected, it looks like the 74LS04 has taken a beating?

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