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Atari 520ST Black Screen


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#1 Binarygeek OFFLINE  

Binarygeek

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Posted Thu Dec 28, 2017 10:24 PM

Hi folks

 

I just got hold of an Atari 520ST, not STM or anything else.  Turn it on, and I get a black screen without any video out whatsoever.  However, 9 1/2 seconds after I turn it on, I get a very audible single "ding" bell sound.  And I do mean 9 1/2 seconds.  Timed it a dozen times, and about the only time difference was probably my stopwatch on/off reaction time.

 

Anybody ever heard of this or have any ideas?  Maybe it means nothing, but could it be one of those red bombs, but in an audio format?  My knowledge of the ST is about 20 years old, so who knows.

 

Thanks for any help.

 

Rick



#2 Zogging Hell OFFLINE  

Zogging Hell

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Posted Fri Dec 29, 2017 7:12 PM

Never heard of that happening (sounds more like something the Mac would do..!). Are you using a disk to boot from or is it just switching it on? The ST does have a bell sound, usually for error messages, but it would have to come through the monitor speakers, which would suggest the monitor is getting something. When you hold down the keys does the key click make a noise?

 

I suspect that your tv (I'm presuming your not using a monitor) isn't liking the output from the ST. The vanilla ST (and the STF) lack a TV modulator, and really need an RGB monitor (or something that can handle that signal).

 



#3 Binarygeek OFFLINE  

Binarygeek

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Posted Fri Dec 29, 2017 10:48 PM

Hi Zogging Hell

 

Thanks for the input.  I am just switching it on as I don't have an external floppy.  The computer does not have a modulator and the TV is connected via the ST video cable composite in.  The TV and cable work fine with another 520ST computer.  Normally when getting this seemingly dead computer I would just pack it up, but the bell chime really made me dig around some and post here.  Hell, I thought somebody would reply within 15 minutes saying "...and I suspect there is an issue with solder ball number 78 on the Blitter chip..."  Or something like that.

 

Rick



#4 Zogging Hell OFFLINE  

Zogging Hell

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Posted Sat Dec 30, 2017 7:10 PM

You'd probably need to go on Atari forum for the 'solder ball 78' stuff ;)

 

I might be wrong but I didn't think the composite works with STs without a modulator, but if you have another original ST without one and it does then I probably am! If you are getting key clicks when you press the keys the problem is not the ST. If not then it may well be 'solder ball 78'. It may be a memory issue, is it an expanded one? I would also pop the top and try reseating all the chips in sockets (take them out, put them back in - check orientations are the same, sometimes a press on the top might be enough)



#5 mellis OFFLINE  

mellis

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Posted Thu Jan 11, 2018 7:06 AM

Hi Zogging Hell
 
Thanks for the input.  I am just switching it on as I don't have an external floppy.  The computer does not have a modulator and the TV is connected via the ST video cable composite in.  The TV and cable work fine with another 520ST computer.  Normally when getting this seemingly dead computer I would just pack it up, but the bell chime really made me dig around some and post here.  Hell, I thought somebody would reply within 15 minutes saying "...and I suspect there is an issue with solder ball number 78 on the Blitter chip..."  Or something like that.
 
Rick


If your ST does not have an RF modulator (which you say it does not), then there is no composite signal on the video jack. Presumably the other ST with which the cable works does have a modulator, and therefore the composite signal is present on the monitor jack.

You will need a monitor for the original 520ST.




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