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Looking for help with Dead(ish) Lynx 2


deadl0ck

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Hi all,

I picked up a broken Lynx 2 for cheap (15 Euro) and I hoped to repair it. It's my first Lynx so this is all new to me, so please bear with me..

So I've taken it apart and cleaned and I've recapped it fully, and replaced the MOSFET but still no power.

 

I then tried the power trick with the wire from battery -ive to the headphone jack +ive. The screen lights up but that's it (even with a game inserted).

I had lightly soldered the wire to the headphone +ive and it fell off, so I tried it again just to see for sure if anything was on the screen and it actually turned on once and the game started (so it's not totally dead)

Here's the strange bit: when it played I took the wire away to cut out the bypass and it stayed playing. I've tried it a few times more but the game won't start again, however, it seems I can turn on the Lynx and it lights the screen if I just touch the wire to the headphone +ive and then remove - it does not need to have a constant connection.

 

The one thing I did NOT do was clean the little power switch as it was kind of glued to that plastic wire loom, but I'm going to disassemble again and and remove it and give it a clean, that's all I can think of - any advice or suggestion would be great. Thanks all!

 

Another thing that occurred to me was maybe the copper RF shield that I had to partially lift up to get at C3 was touching something, so I may make sure C3 pins are properly insulated with some kapton tape.

 

Here's what I bought (this is the seller pic - I should have take a before pic):

Lynx-Original.jpg

 

Here's the WIP:

Lynx-Now.jpg
Lynx-5.jpg
Lynx-4.jpg
Lynx-3.jpg
Lynx-2.jpg
Lynx1.jpg

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As the game started up at least once it means that most chips are ok.

 

I would probably connect +5 V from a lab power supply directly to the +5V trace and GND on the Lynx PCB to see that it works. If it does, then the fault is in the power on/off circuitry.

 

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Grounding the headphone jack vwith  9v  is the worst thing you could do. If the zener is gone the 9V fries one or more of the chips.

 

If the lynx doesn't start anymore that's what probably happened.

 

Try again powering with only 5v and check if  there is a chip getting hot (you have to remove the metal shield on a lynx 2), this is a hint that the chip is dead.

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Avoid 9v and maybe you could be so lucky to find the problem and fix it without changing the chips.

 

First thing is to clean the pcb with isopropyl alcohol. There could be short circuits for dirty or acid from the capacitors.

 

Also clean the cart and cart connector contacts. A bad cart connection could cause a hame not to start. You can do the cart trick (two pins of the vart connector to short) to make the lynx turn on  without a cart, that should show the Insert cart message on the screen of a working lynx.

 

If the cart trick has no duccess  start checking the single components.

 

The power on circuit is probably broken, but for the moment you can power the circuit with 5v after the ppwer circuit.

 

 

 

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In my opinion - yes. For testing I would solder in a wire between the pins 31 and 33 on the cart connector. Then you don't need to have a cart when starting it up. There is also another solder in some other thread that short circuits the Power On button so that the Lynx starts when you apply power. Then you don't have to mess around with buttons. You just need the main board.

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  • 2 weeks later...

OK - I need to get back to this as I was busy for the last while and left it.

 

Here's the Lynx II schematic off Console5's website ( https://console5.com/wiki/File:Atari-Lynx-II-Schematic-(Hayato)-C104247-6-29-90.png )

 

Basically this part:

 

power-schem.png

 

Do I need to connect +5 to power to try and turn it on without a flex/membrane circuit ?

 Thx !

 

 

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Personally, I would be inclined to use a small piece of wire and touch it between pins 14 & 11 of U6 to switch on and between pins 7 & 11 to switch off, that always works for me.

I think the Power connections shown in that image are for supplying to the flex circuit not for powering the Lynx on/off. 

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No, those pin numbers are incorrect...

Pin1 is Top Left

Pin 7 Bottom Left

Pin 8 Bottom Right

Pin 14 Top Right

 

Often there is a little indentation in the top of the case near one corner or the centre of one end and pin 1 is locate to the left of that, if you cannot see one then on rectangular device with the text horizontal and reading left to right pin 1 should be the bottom left corner and the pin numbers increase in a counterclockwise direction.   

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  • 3 months later...

HI - I eventually got back to looking at my Lynx II today.

 

I have the flex cable totally disconnected as there are so many bad traces on it

 

I can power it on by touching pins 14 & 11 of U6 with a piece of wire, as you suggested @Stephen Moss but all I get is a lit up screen with no game starting.

 

Could the wire from battery -ive to the headphone jack +ive that I did at the start have killed something ?

 

Where can I go from here ?

 

Thanks !

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Unless something is getting very hot it is difficult to know that horrid headphone hack has damaged something or not.

If you have a DMM locate MOSFET Q12 set your DMM to the 20V DC range, the G as S pins should be Marked on the PCB place the com lead of your Meter on the S pin and the other of the large tab on the opposite side to the G and S pins, if using batteries I would expect an reading of 1-2 volts. with an external power source I would expect a reading of about 4 volts, it does not necessarily relate to the nothing happing issue but I does establish if the Zenner is functioning. 

 

I do not recall ever powering up my Lynx without the flex circuit connected and so do not know if that would prevent a game running or not, I would think it unlikely but my Lynx is at work and we are under a national Covid lockdown so it will be at least 8 weeks before I can get to it to verify if that is an issue or not. 

You say your flex circuit have many bad traces, are you basing that on just appearance or have you confirmed via continuity testing? If you have confirmed you can get pens with conductive ink that you could use to try to repair it. Alternatively, you may still be able to purchase a replacement, you might want to try a forums search for a retailer as the question of where to get a replacment has come up before but off the top of my head I think Best Electronics sell them.

 

If you look the the top left corner of the schematic, your will see R1, D1 C3 and TP1, this holds the reset pins of Hayato and Suzy low for a short period of time after power up while the power to stabilizes. If my Lynx was powering up but nothing was happening the first two things I would check are that Suzy and Hayato are getting the correct voltage to their power pins and that the reset circuit is operating correctly.

If you can locate and get easy access to TP1 and have a DMM then set it to the 20V DC range, place the Com lead on either the S pin of Q12 or pin 7 of U6 and the V/Ohm lead to TP1. If you are powering the Lynx from batteries then I would expect you to get a reading of about 6 volts, if powering it form an external supply then I would expect that to be about 9V. Assuming you have a cartridge inserted and that having the flex circuit being disconnected is not an factor. If you are not getting those voltages then depending on what the voltage is it is possible that Hayato and Suzy are being held in reset which would prevent anything from happening.

 

The Lynx II schematic I have is drawing number C104247, but it indicates that is sheet 1 of 2, if anyone knows where I can find a copy of sheet 2 let me know. 

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Thanks so much for the detailed reply @Stephen Moss

I have a DMM so it's time to start tracing stuff - it's a right pain trying to keep the batteries in the holder when it's taken apart (I don't have a power adapter) - time for some sticky tape I think.....

Thanks again - I really appreciate it - we're back in total lockdown here too (Ireland) - stay safe !

Edited by deadl0ck
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If you just want to test the main logics of the lynx you can use a bench power supply or other +5v 1A source to directly power the lynx and essentially bypass the power stage. Solder wires to the leads of capacitor C41 in the upper left of the board. Attach your +5 source to those leads (Paying attention to the polarity of the power supply or adapter you are using and matching them to the polarity of the capacitor!). If you have a game inserted, then as soon as you plug in the adapter, the Lynx will power on and hopefully start the game you inserted. If not, then it it likely one of the main IC chips at that point. If it does power on and work, then you know you can isolate your troubleshooting within the power stage section.

 

On the Lynx 1 is is C39 near the speaker to do the same thing. 

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