Looking for help with Dead(ish) Lynx 2

[+-^CrossBow^-]

13 minutes ago, deadl0ck said:

Thanks @-^CrossBow^-

And you reckon I don't need to have the flex circuit attached at all ?

No the flex isn't needed for that. Again if you attach +5 directly in that manner, and have a game plugged into the cartridge slot and the cartridge slot it making good contact with the game, then it will just power on as soon as power is applied to that capacitor. I use a bench supply for this purpose, but an old cell phone charger that puts out +5 could be hacked to do the same thing if you had one handy. It won't tell you exactly where the issue or problem is, but you can at least rule out any major logic chip issues quickly.

 

If you just want to see something legible on the screen, then you do as @karri suggested and you solder a jumper wire on pins 31 and 33. Then when you apply power, you would get the Insert Game message like the Lynx 1 units do.

 

[deadl0ck]

9 minutes ago, -^CrossBow^- said:

No the flex isn't needed for that. Again if you attach +5 directly in that manner, and have a game plugged into the cartridge slot and the cartridge slot it making good contact with the game, then it will just power on as soon as power is applied to that capacitor. I use a bench supply for this purpose, but an old cell phone charger that puts out +5 could be hacked to do the same thing if you had one handy. It won't tell you exactly where the issue or problem is, but you can at least rule out any major logic chip issues quickly.

 

If you just want to see something legible on the screen, then you do as @karri suggested and you solder a jumper wire on pins 31 and 33. Then when you apply power, you would get the Insert Game message like the Lynx 1 units do.

 

Brilliant - thanks for all the help !!

[deadl0ck]

42 minutes ago, -^CrossBow^- said:

No the flex isn't needed for that. Again if you attach +5 directly in that manner, and have a game plugged into the cartridge slot and the cartridge slot it making good contact with the game, then it will just power on as soon as power is applied to that capacitor. I use a bench supply for this purpose, but an old cell phone charger that puts out +5 could be hacked to do the same thing if you had one handy. It won't tell you exactly where the issue or problem is, but you can at least rule out any major logic chip issues quickly.

 

If you just want to see something legible on the screen, then you do as @karri suggested and you solder a jumper wire on pins 31 and 33. Then when you apply power, you would get the Insert Game message like the Lynx 1 units do.

 

Actually @-^CrossBow^-, I have a USB Power bank and an old iphone USB charger that I just striped the wire from and I can get a steady 5.43V out of that - would that be OK ?

[+-^CrossBow^-]

5.43 is on the high side and the closer to +5 you can get the better to be on the safe side. I know the lynx itself will run on as low as 4.8v as I've had many only put out that much when doing the McWill LCD upgrades on them. Find a more modern switching adapter that puts out a solid +5 and you should be okay for testing. 

 

 

[deadl0ck]

Will do - thanks !!

[deadl0ck]

I got a 5.01V Supply and did as you said @-^CrossBow^- and the game started right away !!

So it seems to be a power issue

[+-^CrossBow^-]

Nice! So now you know where to focus your attention on getting it working.

 

Now, try changing out that diode since I can see in the pics it looks like the original is still in place? Unless you have done that since those first pics and I missed it? And yes if the flex is bad, that will need to be replaced. Best Electronics in California does sell them or at least they did. I bought about 6 of them 2 years ago and now that I think about it...I might need to get a few more soon. Hmm...

 

 

[deadl0ck]

It's D13 right ? (The Zener I need to replace)

 

Also - when I just switch back to the batteries (as opposed to 5V on that cap) I should still be able to test without the Flex connector connected  ?

 

Thanks again !

[+-^CrossBow^-]

Nope, batteries and normal DC require the flex to switch the state of the lynx as on/off through the U6 IC chip that was mentioned before.

 

[deadl0ck]

3 hours ago, -^CrossBow^- said:

Nope, batteries and normal DC require the flex to switch the state of the lynx as on/off through the U6 IC chip that was mentioned before.

 

But If I leave it off and use the 11 and 14 on U6 as @Stephen Moss suggested I can turn it on - if I can do that can I leave the flex disconnected as there are a lot of worn/broken traces on it ?

 

And to double-check - It's D13 that I need to replace (as I have a zener replacement I got in a small power kit) ? 

[+-^CrossBow^-]

Yes it is D13 to replace. I see you replaced the mosfet but did you also go ahead and replace the two small SMD 3906 transistors as well at Q7 and Q8 locations?

 

So you are able to get it to turn on/off jumpering the pins off U6? I missed that part I guess. Then it is likely the flex at that point causing your issues, but you should be able to use a DMM in continuity mode to verify if the traces are actually worn through or not from the contact point where the button pressed to the end of the mylar flex where it plugs into the Lynx PCB connector.

 

 

[deadl0ck]

I replaced the mosfet but not the Surface mount ones - they look tricky !! (Although I did get them in my power rebuild kit)

I did the mosfet separately as it came with the cap replacement kit which I also did.

 

I'll start with the zener and see how it goes, but like I said I've never done a surface  mount one before (My hands seems abnormally shaky whenever I try and do delicate work like that !)

 

I'll keep you posted and thanks again for the help and encouragement !

[+-^CrossBow^-]

Luckily the SMDs on the Lynx aren't that bad as there is room around the components at least. To remove the zener you only need to use a chisel tip on the iron, and apply lots of flux and use a lot of solder to essentially have it form around the iron and both sides of the diode. It should basically just move right off the pads at that point. I do the same with SMD resistors. The 3906s actually aren't that difficult either. If you use the same method of just putting a lot of flux and solder, you will find that enough heat builds up for those to come off as well.

 

[deadl0ck]

So replaced the Zener and there are some signs of life... the screen is darker and some flashing image on it

 

Here's the zener replacement (sorry about my terrible soldering skills): 

 

And here's a quick video of the screen now: https://photos.app.goo.gl/yoPgGZaXAHai1bij8

[deadl0ck]

So looks like I'll need to do the transistors at Q7 and Q8 

[+-^CrossBow^-]

7 minutes ago, deadl0ck said:

So looks like I'll need to do the transistors at Q7 and Q8 

Ah, looks like your kit came with the diode for the model 1 lynx as that uses a through hole version. But that will work and I've done it for quick tests.

 

Did you have a game inserted at the time you did that video above? Because what is being shown is you can just make out the portions of where it says Insert Game being displayed. I've only seen that happen when the cartridge isn't making good contact. You might try and jumper pins 31 and 33 to force that to always be on so that you either get a game to load up, or you will always see the Insert Game message. But it looks like an issue with poor contacts on the cartridge and cart slot now.

 

[deadl0ck]

So no joy there with the cartridge - I can wiggle it around and sometimes I can see the complete Insert Game message but that's it - I then checked it with C41 to 5V and the game starts - so it's something else other than a bad connection - I guess I should replace the 2 transistors as a first step anyhow.

 

[deadl0ck]

It lives !!

 

Q7 and Q8 replaced and it lives !

 

The screen looked VERY bad at first:

 

I checked the screen connectors on the flex cable and there were 2 that looked a bit bad, so a little bit of conductive paint and I now I have this:

 

Thank you SO MUCH @Stephen Moss and @-^CrossBow^- !!

 

Another Lynx comes back to life thanks to you both