Dead Lynx 1

[naujoks]

I have a Lynx 1, which shows no sign of life whatsoever, neither with batteries nor a PSU.

I replaced the original MOSFET with a 2SK2231, as recommended elsewhere on this site.

I have an original Atari PSU (output 9v) to go with the unit. I measured 13V coming out of it, without load. Is that correct?

I visually inspected the caps, they look good, no bulging, no leakage. I cleaned the buttons/contacts, but they looked good before anyway.

What could I try to find the fault?

[+Stephen Moss]

First, 13V out of the PSU off load is about what you should expect.

Second, I suggest you try levering the search facility as there are may posts already on the site in regard to Lynx's not powering on/off - just ignore those that instruct you to connect the "Headphone" ground to the main power GND. Although a good place to start would be to connect 4.5V - 6V DC across C39 (making sure to get the polarity correct) as that will indicate if the issue lies with the power stage or may be something more serious and difficult to diagnose.

Although before you do that you did have a cartridge inserted didn't you as the Lynx may not power up with it. 

 

You can find Lynx 1 schematics here .

[naujoks]

Aha! Putting +5V across C39 worked and it's come to life. Some cartridges work, others don't, but that's for another thread.

So what's next after this?

[naujoks]

Well, just for giggles I put it all together again, and what do you know, it's working, both with battery and PSU.

Curiously though, it switches on only when I'm putting in a game cartridge. I imagine that's what it would have done in the beginning, I just didn't do that. The off button is super sensitive, and the on button doesn't work after I switched it off. Strange.

[+Stephen Moss]

39 minutes ago, naujoks said:

Does anyone have an idea why my Lynx 1 only switches on when I'm inserting a game cartridge, but not when pressing the ON button?

The OFF button on the other hand is super sensitive and only requires the lightest touch to work.

 

There could be several reasons for this...

1) The ON button is somehow trapped by the case keeping it pressed in the On position.

2) The flex circuit for the buttons (the smaller of the two) is not correctly inserted into its FCC connector resulting in intermittent/bas contact that my affect the initial logic states, try re-inserting it.

3) A problem with U6 and associated components shown to the left of Q11 on the schematic.

 

That is where I would start, in realation to item 3, as I stated above search perform a search for previous forum posts regarding Lynx power and On/Off issues, there should be enough replies to them from me by now to indicate what voltages to expect and what to test to either resolve this particular issue or eliminate some possible causes thereby helping to narrow down what the problem may be.

Note: When searching the forum it may help not to limit you search to Lynx 1, although some of the component references may not be the same (i.e. C12 in a Lynx 1 may be C15 in a Lynx 2) the power circuits are identical.