atari lynx II issue

[ddulin]

Hi guys

 

I am news on this forum and just got last week an atari lynx II to complete my collection.

But there is an issue. I can't power up.

So I read many and many post. I allready tried:

bypass the mosfet: no change

 

I read on a thread (don't remember which one) that we can feed direclty 5V on C41 to see if the lynx power on.

So I did that, and I have a "insert game" screen.

so I read another post about this screen, and the game that I used for switch on the lynx is a working one because I allready tried on my lynx 1's I childhood.

I also look at the cartridge port and try to clean it but no change.

 

Is anyone know if a lynx that still displayed "insert game" may be fried?

 

What else can I try/check??

 

thanks for your help

[+Stephen Moss]

The Lynx circuit diagrams are in my opinion a bit of a mess and therefore difficult to understand, if you are getting an "Insert Game" with a known good game cartridge that could just be the Lynx's response to a problem cause by the fact that the way you have bypassed the power circuit means that some part of the system is not getting the correct power it needs thereby creating an error.

 

You may not have considered this thread as the Title refers to a Lynx 1 and you have a Lynx 2 but apart from some components having differing ID numbers i.e. R47 in one might be R56 in another the power circuit is the same in both units so you might find reading it helpful.

[sage]

If the insert game messge pops up, it means that the CPU, memory and graphic chip and display are o.k.

Most likely the cartrisge port or cart has some issue, most like likely dust or dirt.

The message pops up, if the first kb of the cart cannot be decoded (aka read correctly).

[7800fan]

I posted schematic of Lynx II and sent it to console5 site. They are about 90% same as Lynx 1 with wiring and parts, the part number do differ. The sound output has stereo capability on the jack but combined for mono speaker internally. It also has extra circuit that checks the voltage level and power LED that can flash when the battery's low. Lynx 1 doesn't have this.

 

If you are working on Lynx 1, AA has the schematic and console5 as well.

[Mojado]

The Lynx circuit diagrams are in my opinion a bit of a mess and therefore difficult to understand, if you are getting an "Insert Game" with a known good game cartridge that could just be the Lynx's response to a problem cause by the fact that the way you have bypassed the power circuit means that some part of the system is not getting the correct power it needs thereby creating an error.

 

You may not have considered this thread as the Title refers to a Lynx 1 and you have a Lynx 2 but apart from some components having differing ID numbers i.e. R47 in one might be R56 in another the power circuit is the same in both units so you might find reading it helpful.

 

 

Stephen has a point. Looking at Lynx II schematics, the cartridge takes both 5V (Vcc) and 9 volts (PWR4069). When you provide power to only C41, you don't provide power to 4069 chips. Since people butcher their Lynx's with a 5V mod, it seems 5V on 4069 also works, so assuming you don't have batteries on it or ac adapter and only powering C41, also power C39 by also providing the neutral of the 5V to the negative terminal of C39. You shouldn't have to because it should go thru the body-diode of Q12, but if the FET is bad, it won't make it. This would also explain why your Lynx doesn't power.

 

To summarize, also connect the negative of the 5V supply you are using to power C41 to the negative of C39. This will allow you to provide a reference to the other part of the power circuit which may affect how the cart works.

[ddulin]

thank you guys!

 

I will try these things and keep this thread updated soon...

[ddulin]

is someone can tell me where can I check 5V on lyn I or II. Just to be sure that the unit isn't burned (over thatn 5V , 9V...) . I have read we can check on TP15, is that right? So one probe on TP15 and the other on ground?

 

thanks

[Mojado]

is someone can tell me where can I check 5V on lyn I or II. Just to be sure that the unit isn't burned (over thatn 5V , 9V...) . I have read we can check on TP15, is that right? So one probe on TP15 and the other on ground?

 

thanks

You can probe one side of side of C41 against the other side of C41. Depending on polarity you choose, you'd get either 5V or -5V.

[ddulin]

thanks Mojado

so on a fried lynx I should have something like 9v or -9v on C41

and on Lynx 1 there isn't C41. where can I check 5V?

[Mojado]

thanks Mojado

so on a fried lynx I should have something like 9v or -9v on C41

and on Lynx 1 there isn't C41. where can I check 5V?

 

On Lynx I, across c44, should be 5V DC.

[+Stephen Moss]

On Lynx I, across c44, should be 5V DC.

 

I know that is what it looks like it should be on the circuit diagram and perhaps my brain has turned to mush (often happens this time of year) however I am not totally convinced that is the case.

 

If you follow that line it goes directly back to the power socket which would be at 9V and at the TP above the Zenner it says "ZERO", if you subtract the 4.3V Zenner voltage from 9V you would get around 5V and so it is possible that a reading of 9V if you read directly across C44 is fine as you may only get a reading of 5V with regard to the "ZERO" reference point.

What is not clear is if this "ZERO" point is a reference point for making voltage measurements on the rest of the system or if the main circuits are floating at this Zero point in which case their grounds are incorrectly labeled.

 

I really need to take my Lynx II apart and have good look at what is going on (others also find the circuit confusing) although I may have to fix it first as I knew it had been repaired before I brought it but I suspect it may have had the "connect to the headphone ground" bodge rather than a proper repair as with no cartridge inserted it appears to power off after a split second and I think it should stay on and display an "Inset Cart" message or is that just the Lynx 1?.