Power but no picture (Atari 800XL)

[inphanta]

Hi, this is my first post here.

 

I did see a similar thread to this (via a Google search which brought me here), but I don't think the problem is the same.

 

OK, I recently picked up an Atari 800XL on eBay. I hooked it up to my TV at home (a flat screen LG) and it worked fine via the RF out/antenna. The only thing I found a bit strange about it was that every time I typed a command into its BASIC, it returned an error which suggested it only read the first two characters. For instance, when I typed in 'RUN' after typing a small program to test, it returned an error saying the command 'RU' wasn't recognised. I'm not too familiar with the Atari setup (I'm traditionally a Commodore guy), so I figured maybe there was some quirk with the UI I wasn't aware of yet. Either way, it powered up and the keyboard worked so that was enough for now.

 

However, I returned this morning to discover that even though the unit powers on, there is now no display on the screen. I have a C64 that is hooked up to the same TV via an RF cable which works fine, and when I first tested the Atari, it was via the same channel and t worked fine, but this appears to not be the case now.

 

I've tried retuning the TV countless times, swapped swapped the C64 and Atari RF leads to eliminate those as the possible cause, but now I get nothing more than a black screen. The only thing I did different the second time around was plug in the RF cable into the back of the XL when the machine was already powered on. Could this have fried it somehow? It seems unlikely to me, but I can't think why it would suddenly develop a problem like this. I am obviously very disappointed as I always wanted a 800XL and was looking forward to playing with it, so either I broke it somehow or I was sold a dud.

 

I would be grateful if anybody on here could offer any suggestions regarding the hardware.

 

Could this be repaired, or should I just give up on it?

 

Thanks in advance.

[russg]

Hi, this is my first post here.

 

I did see a similar thread to this (via a Google search which brought me here), but I don't think the problem is the same.

 

OK, I recently picked up an Atari 800XL on eBay. I hooked it up to my TV at home (a flat screen LG) and it worked fine via the RF out/antenna. The only thing I found a bit strange about it was that every time I typed a command into its BASIC, it returned an error which suggested it only read the first two characters. For instance, when I typed in 'RUN' after typing a small program to test, it returned an error saying the command 'RU' wasn't recognised. I'm not too familiar with the Atari setup (I'm traditionally a Commodore guy), so I figured maybe there was some quirk with the UI I wasn't aware of yet. Either way, it powered up and the keyboard worked so that was enough for now.

 

However, I returned this morning to discover that even though the unit powers on, there is now no display on the screen. I have a C64 that is hooked up to the same TV via an RF cable which works fine, and when I first tested the Atari, it was via the same channel and t worked fine, but this appears to not be the case now.

 

I've tried retuning the TV countless times, swapped swapped the C64 and Atari RF leads to eliminate those as the possible cause, but now I get nothing more than a black screen. The only thing I did different the second time around was plug in the RF cable into the back of the XL when the machine was already powered on. Could this have fried it somehow? It seems unlikely to me, but I can't think why it would suddenly develop a problem like this. I am obviously very disappointed as I always wanted a 800XL and was looking forward to playing with it, so either I broke it somehow or I was sold a dud.

 

I would be grateful if anybody on here could offer any suggestions regarding the hardware.

 

Could this be repaired, or should I just give up on it?

 

Thanks in advance.

No, plugging the RF cable in while powered up won't hurt anything. You get a black screen, so your power supply is probably OK, I guess you get a red led bottom right. It is a shame you got a dud.

I'm not the fix it expert. I would buy another one and swap chips, starting with Antic and GTIA. You're probably going to have to open it up. See if you got one with mostly socketed chips, that would be good for

chip swappihg. Of course, you're not using the same pwr sply for Commodore 64 and the Atari, that would fry things.

[+bob1200xl]

The Atari executes a series of steps when it powers on so you can get some idea as to what's happening by watching the screen and listening to the audio. It is most useful if you use the A/V jack rather than relying on the RF (TV) output.

 

If the CPU/MMU works at all, the system checks memory size. The screen will show a dark, ugly, non-black picture.

 

The system resets all the hardware chips. This will turn the screen black and send a 'pop' to the audio.

 

Does any of this happen? Is the Channel switch set to the proper TV channel? (as I said, best to use the A/V jack - a C64 A/V cable works although the signals are swapped between plugs IIRC)

 

Bob