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Lynx II will not "turn off"


richa_chan
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Hello all,

 

I have an Atari Lynx II that has the opposite problem from what I usually read on here. Whenever it is connected to a power source (wall adapter or batteries) it immediately turns on and never turns off. It will drain batteries completely if I leave them in it. Without a game it just shows the "Insert Game" message. With a game it plays fine, good display, good sound, but the Power and Off buttons do not do anything.

 

I have replaced the D13 Zenner and the Q12 MOSFET and it continues. Happens with or without the flex ribbon for the buttons attached.

 

I guess it is a more fortunate issue then "will not turn on", but has anyone ever run into this or have any ideas?

 

Thanks!

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There could be a number of things wrong with your Lynx. Since you ruled out the flex and contacts, there must be something less trivial wrong with it.

 

The schematics for the power section can be found here. From here you see that pressing the off button uses a phalanx of components, since the "latch effect" is not trivial at all. Capacitors are old enough to be replaced as a preventive measure if you haven't done that alreadyy. I've seen the power section explained here, and as a software engineer I can say that it's complicated and I will not be bothered with it :)

 

Seriously though, I'm scared to death of the 9V using the same rail as the downstepped 5V, so I converted two out of my three Lyxes to USB using Powerboost and a li-po battery. Third is sitting on the desk waiting for the soldering iron to heat up. I'm still hopeful that I'll be able to persuade my father (who is a hardware engineer) to help me design a replacement for all the parts used which woud handle the on/off buttons too, but that's a summer project...

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Thanks for the info! I won't have time to dig into it this week but I'll update again if I get it working or not.

 

I've been reading on here about the 9v/5v thing, but those schematics are crazy. This is my 2nd Lynx, the other does not display anything at all but the power LED comes on and the power on/off button works. :)

 

If I can get them back in shape I want to keep one "original" and one with an LCD mod/lipo to actually play on. Fun to show people the difference.

 

Trying to keep these old electronics working is a task!

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So... after replacing all of the caps, diodes D9,10 and 11, and the D13 Zenner I still had the same MOSFET issues. It would not power off. So I decided screw it, removed the power circuitry and did the 5V mod with a lipo battery. Also did McWills's screen upgrade which is amazing! Added a hard on/off switch for now until I can mod the soft on/off.

 

Unfortunately... I lost sound. Sound used to work fine on this. I've double checked all the caps I replaced and the speaker. I do not get sound via the speaker or headphone jack.

 

Does anyone know the specific caps that are used for sound on a Lynx II so I can troubleshoot a bit more effectively? I'm not sure how anything else I replaced could have broken the sound.

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I had a sudden dead sound problem, turned out to be a dry solder joint on the power to the sound board, see here for the saga: http://atariage.com/forums/topic/262448-lynx-ii-tracing-a-sound-problem/ skip to the end for the update.

 

Unbelievably it was the same exact issue, but It took me a while to find it. The voltage checked out so I just randomly started re-soldering the components in that region while the Lynx was on. Soon as the iron touched the top of L21 sound came through. Unfortunately the metallic part on the inductor also fell off immediately. I was able to get the connection to work by putting a large solder blob there but I'd like to replace that if I can find the part I need.

 

Thanks for the help!

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