Atari Lynx 2 no DC power

[Eyeball]

Hi everyone,

 

I received a Lynx 2 at Christmas and it was working, upon opening up to service the mosfet and capacitor above looked aged so I decided to do a full refresh.

 

I replaced all capacitors, mosfet, zener diode d13, transistors and dc barrel.

 

on rebuild the console would not power on via the switch on front.

 

I checked the flex ribbons were seated correctly and they were.

 

I then measured the dc barrel and center pin only showed 9v when the leg itself was probed but 0v when probing the solder. After a reflow 9v was present at the circuit, however still no power on.

 

my next action was to bypass the 9v rail and I soldered a 5v supply to capacitor C41, when power sent through this wire the console showed insert game even though a cartridge was inserted, a quick remove, blow and re insert got the game to load and I was able to play in its disassembled state ruling out a faulty membrane.

 

I checked the voltages on the mosfet and d13 and the left leg of the fet was 0v, the middle grounded and the right leg 4.7v. D13 showed OL and 4.7 on the cathode.

 

I know this is quite clearly a power issue but I’m not to great at following a schematic to find the fault and have traced it as far as I can from the dc barrel to the left leg of the mosfet with continuity without finding any faults.

 

could someone please help me to bring my Lynx back to life via the mains.

 

thanks in advance

[+-^CrossBow^-]

Check the ends of the ribbon cable from the flex circuit. Just removing that cable after 30years of age is enough to strip off enough of the trace to make them not connect properly anymore. So that is the next thing to check since you know the Lynx is able to live doing the power bypass test.

 

 

[Eyeball]

The ribbon is ok. With the inject I had the ribbon connected and all worked as it should, so I don’t believe it’s at fault. When the jack is plugged in the 9v trail stops at the cathode of D9 and I can’t seem to find it anywhere else when probing. This was done without flex cables or game inserted

[+karri]

20 minutes ago, Eyeball said:

without flex cables or game inserted

The system does not power up without a game.

[Eyeball]

I’m aware. I was just trying to trace the 9v with that test. I’ve just tried with batteries and it works fine. I’m now suspecting the new jack at fault. Could I remove it and use a bench supply to power it up through the jacks connections? If so which holes would I solder to connect the red and black wires from the supply at 9V 3W 1.7A? 

1 hour ago, karri said:

The system does not power up without a game.

 

[+karri]

The Lynx design is a bit strange. Try to check the schematics and find out what is wrong. Soldering 9 V directly somewhere can fry the Lynx.

[+Stephen Moss]

On 1/13/2023 at 7:27 PM, Eyeball said:

I checked the voltages on the mosfet and d13 and the left leg of the fet was 0v, the middle grounded and the right leg 4.7v.

Was that with a 5V supply connected to 9V, if 5V then it is probably OK but if 9V then assuming you are referencing the FET legs with the PCB orientated so that the power socket, volume and brightness controls were along the edge furthest from you then with Lynx off I would expect 0V, 9V , 0V.  

 

On 1/14/2023 at 10:45 AM, Eyeball said:

When the jack is plugged in the 9v trail stops at the cathode of D9 and I can’t seem to find it anywhere else when probing.

If true that would suggest a broken track, likely caused by not following the tried and trust rule of "if it ain't broke, don't fix it".

 

With a cartridge in and an external supply connected you should be able to measure the output voltage of the power unit (likely around 14V DC) across D11 and pins 7 (GND) & 14 (VCC) of U6 (On/Off power latch). If you cannot pick it up at either of those points, unplug the power unit and perform the following continuity checks...

Cathode of D9 to both the Cathode of D11 and pin 14 of U6.

Anode of D11 to both the negative battery connection (may get a reading higher than 0 due to L14 & L16) and pin 7 of U6.