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djglish

800XL not firing up

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I haven't had my trusty 800XL out for about a year now.  Plugged it in and it appears to be dead.  No power light and nothing on the screen.  I tried it with both a cartridge in the slot and with a floppy drive hooked up.  It's not the power supply since my XEGS starts up just fine (the PS is the tan type that looks like it's made for the XL series).  

 

Any thoughts on what I should check first?  I don't have an oscilloscope but do have a multimeter.  

 

The XL does have the Rambo 256meg upgrade but is stock otherwise.

 

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Posted (edited)

Power is always the first thing you check. 

Edited by Gavin1968

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There isn't much to go bad if you don't have any power.  Like _The Doctor_ said, check the switch and make sure you don't have a corroded power connector.

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Posted (edited)

@djglish  Where has the machine been kept whilst inactive incidentally?

 

Would be worth checking the DIN power socket itself to make sure it's ok and the pins are conducting/there is continuity/current.

 

Aside the power supply or some internal components possibly being to blame, the issue maybe down to a bad connection in the socket itself. The DIN sockets are pretty hardy but perhaps pushing in the cable in after a long time has caused something to break this time around. Did there seem to be any resistance plugging it in? Have you opened it up yet to look inside?

 

I had this the other week with an 800XL which amongst other things powered up once the socket was replaced with an identical one from a donor board.

 

 

Edited by Beeblebrox

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Can't really add much, but power is one issue so make sure you are getting 5V actually entering the machine, so check the switch and the DIN for the PSU. More a case of follow the lines here..

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I'll try and check out the switch and make sure that the socket on the computer hasn't gone bad.  Beyond that I don't have much experience.  I did open it up and I don't see any obviously bad caps.  At least I have the XEGS to use for trouble shooting the power supply and other peripherals that I am using.  

 

 

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Posted (edited)

@djglish  Yup defo check those out first.

 

Perhaps snap some hi def images of the pcb and post em up.

 

As part of the investigation process I guess also run through the last thing you recall doing when you last used it as you said it was a while. Where it was stored too? Does the power switch feel OK mechanically?

 

If you were getting signs of life on the monitor or a power light we could suggest the usual initial things like bad ram, etc if there was still an issue. 

 

Is the pcb socketed at all btw? 

 

Do you have a meter you can check for continuity for re power socket and switch?

 

 

Edited by Beeblebrox

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 Sorry for the delay.  I was sucked in to a Campaign in my favorite old game (Panzer General for the PC). I did check and am getting power to the backside of the power plug.  I also checked the switch and it appears to be working.  When in the on position it is getting power, when off it isn't.

 

Here are a couple of shots of the motherboard. 

 

 

P1050465.thumb.JPG.2c3cbdbdfe771fe229a11dc0bac621ec.JPG

P1050472.JPG

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Posted (edited)

Push down on all chips firmly a few times and push down on the add on boards at the location where they join to the socket of the main board as well.

apply power

C2 looks a little funky.... check the power on the positive side of the electrolytic capacitors.

at power on describe if there are any pops and clicks. or any response from the display device....

 

what are you using for a display and how is it connected.

Edited by _The Doctor__

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C2 actually looks good. The picture seemed to have a shadow that made it look bad.  I have a Video cable with composite, sound and two other RCA plugs (probably chroma and luma).  I've checked the pinouts and am using the correct ones.  I'll try reseating the chips and give it another go.

 

I'll also double check the motherboard connection.  I remember swapping out the motherboard to test another project that I was working on.  I do  have another dead 800XL board that I can swap chips with if needed.  Any idea which ones should be swapped out first?  

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Forgot to add that both this motherboard and the dead one have fully socketed chips (Yay!!!)

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can we get specifics like what voltages you see, can we see the power supply you are using...

does the monitor cord you are using work with any Atari?

Have you powered on holding option down while doing so, pressed select once and then start key? was there any sound?

again I ask if there is any indication the machine is trying to output video at all, you can have a black screen because that's what the tv does on no signal or you can have a black screen because the Atari puts it out...

are their any distortions traveling in that screen? any humming noises or wavy imperfection rolling around in the displayed screen?

I have a Vizio TV that won't display any Atari RF or Line level (composite/l-c) but all other TV's in the house have no issues what so ever...

 

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If your power LED used to work and now doesn't, and you didn't disturb the keyboard connection, then it sounds like the power circuit has gone open somewhere, or completely shorted.

 

It isn't normal in an 800XL, but if you take out the system board and check the bottom side for cracks in the solder joints around the power plug and the switch.  When they crack, they can form a hairline circle in the solder joint and that can be all it takes.

 

If you are getting power measured before and after the switch when it is in the on position, then it is not a short, you would then want to pick one of the smaller TTL chips in the center of the board and measure between 5V and GND on one of those chips (on a 14 pin chip, pins 7 and 14, on a 16 pin chip, pints 8 and 16.  google the 74LS series chip you pick to verify the position of the power legs.  I'm guessing you will find less than 5V, or even 0V.  The power in an 800XL is simple, so other than a cracked solder joint or trace near the input/switch, I'm at a loss at the moment to think of what could go open.

 

 

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I decided to reconnect everything after having pushed down all of the chips.  The XL is working again.  Not sure if that was it or if I might have not connected the keyboard ribbon cable tight enough earlier.  I did have the keyboard off since using it last to check out another project (put a mini-PC in an Atari case).  That could have been the problem all along.

 

Thanks to everyone for all of the suggestions.

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