Jump to content
Sign in to follow this  
cn817166

Atari Lynx 1 not turning on

Recommended Posts

Interesting day today with this thing.

 

It's a recapped, new Q11 mosfet, with ZD1 replaced as well as the Q13, and Q4 replaced, and McWill modded,   was working fine for months never a problem, when i first got it however, it was beat down bad.   Revived it from hell.  Never had an issue with it after cleaning it up.  Haven't turned it on in a month, and now nothing when I hit the power button.   There were Eneloops left in with no corrosion at the posts etc.

 

Checked mosfet showing 8.72V on the Source and Gate,  turn ON and no Voltes on the Drain.  Checked for damage at the power button, none.   Cart is working in another Atari Lynx (V2), and batteries are working good in it as well.

 

Spent all day going through the schematic just to see what I can find that might seem off.  Only thing that seems weird to me is R79 i showing 10K ohms and is right next to Q13.

 

Is there some power trick someone could share on a version 1 Lynx to see if it still boots up? Audio to Ground? I can't seem to find it with a search. 

 

I am at a complete loss on this thing.  No signs of anything blown, Caps are relatively new, only a handful of hours on them in total.   No obvious ground shorts just won't flip the gate to the drain on this mosfet.

 

I know this has been asked 100's of times as it's a common issue.  I did go ahead and swap the Mosfet, Q4 and Q13 again just because I have a ton of them.

 

Any help to try to get this booting again would be appreciated.  Thank you.

 

 

Share this post


Link to post
Share on other sites

Ah damnit.   R78 showing 1K instead of 4.7K.   Gonna swap this and see if it works.

Share this post


Link to post
Share on other sites

Personally I would not do the Audio to Ground hack as that puts 9V on the entire system, I am sure there is a reason why some parts are running at 5V, so do you really want to run them at 9V.

To power it while bypassing the whole internal power stage connect 5V to (assuming you are using the schematic here on AA) to either D14, C50 or C39 ensuring the correct polarity, but ensure it is a regulated (stabilised) 5V if using a power supply that output 5V when not connected to anything. Otherwise 3 AA batteries in series for 4.5V or 4 for 6V.

 

I think you may have mixed up Source, Gate and Drain in your first post as is not the MTD3055E N channel in which case when Off I would expect 9-14V on the Drain and around 0V on the Source & Gate, when On around 0V on the Source, around 4V on the drain and something like 3-5V on the Gate but it depends on your meter. A steady 0V, or 9-14V on the gate when it should be on (U6, pin 10 = 0V) is definitely wrong as U6A, Q13, R54 & C37 combine to make an oscillator.

 

R79 should be 10K, but resistors do not always measure there true value when measured in circuit as it depends on what other components may be in parallel with it, depending on which way round you had you meter probes it is possible the Zenner was forward conducting which would put both it and R56 in addition to C44 parallel with R78 which could explain your reading of 1K. 

Share this post


Link to post
Share on other sites

Killed your Lynx? :(

Was it a mod on a I or II?

 

I'm having some Lynx I problems myself. I have two that I have not used in a while (almost only use my McWill model II) and when I tried to power them on from battery, I got nothing but both worked through power jack. Batteries were good, tested in Lynx II and opened up a Lynx I to make sure I had good connections with the batteries and all looked well. Didn't prod around with a meter yet but I just found it strange that both my Lynx I's after sitting for a while will not power on from battery.

Share this post


Link to post
Share on other sites
13 hours ago, PapaFists said:

when I tried to power them on from battery, I got nothing but both worked through power jack

Sound like it could be a bad power connector, that is where I would start.

If you look inside the socket there is the centre pin and on one side a little piece of sprung metal. When you insert the power jack it moves that piece of metal away disconnecting the batteries, when you remove the power jack it should spring back reconnecting the batteries. It suspect that either it is not happen or at least not enough to reconnect the batteries.

 

If you look at the power connector in this schematic you will see that pins 2 & 3 create a switch that is opened when the power jack is inserted and should close when it is not. With both the batteries removed and the external power unit disconnected measure the resistance between TP16 and either Pin 7 of U6 or the Anode of D18/D19.

If the switch in the power connector is working you should read almost 0 resistance, if it measures infinite resistance (open circuit) then you may need to replace the power connector if you want it to run from batteries, but you could just try reheating the power connectors solders joint first and remeasure in case it is bad solder joint rather than the power connector. 

Share this post


Link to post
Share on other sites
On 5/4/2020 at 7:36 AM, gilsaluki said:

a McWill mod killed one of my Lynxes.  Never do that again. 

Can you be more specific about this? What happened when it died? Were you using AC or batteries at the time?

Share this post


Link to post
Share on other sites

I had a member on this site mod the Lynx McWill.  It took him forever, said he was having probs with ground (or some such junk).  When I finally received it, it worked for about a week or so, then the screen formed massive lines and half the screen wouldn't display.  Then it just fried the motherboard, nothing, dead as a door nail.  It probably was the modders fault.  However, it was an expensive affair. I will just leave my remaining units alone.

Share this post


Link to post
Share on other sites

Thanks for the reply's guys.

 

I did the mod myself, have a bench at work where we do random repairs all day, and these are just fun. 

 

This just happen to be on my personal unit so i'm kinda like wow.

 

Has probably been this way for 6 months without a single issue,  then one day it just stopped turning on.

 

I wonder if it has to do with leaving the batteries in, but at this point it's too late to tell.

 

I'm going to re-read what Stephen said and take it from there.   Really appreciate you guys.   

 

 

Share this post


Link to post
Share on other sites
Posted (edited)
On 5/4/2020 at 5:09 AM, Stephen Moss said:

Personally I would not do the Audio to Ground hack as that puts 9V on the entire system, I am sure there is a reason why some parts are running at 5V, so do you really want to run them at 9V.

To power it while bypassing the whole internal power stage connect 5V to (assuming you are using the schematic here on AA) to either D14, C50 or C39 ensuring the correct polarity, but ensure it is a regulated (stabilised) 5V if using a power supply that output 5V when not connected to anything. Otherwise 3 AA batteries in series for 4.5V or 4 for 6V.

 

I think you may have mixed up Source, Gate and Drain in your first post as is not the MTD3055E N channel in which case when Off I would expect 9-14V on the Drain and around 0V on the Source & Gate, when On around 0V on the Source, around 4V on the drain and something like 3-5V on the Gate but it depends on your meter. A steady 0V, or 9-14V on the gate when it should be on (U6, pin 10 = 0V) is definitely wrong as U6A, Q13, R54 & C37 combine to make an oscillator.

 

R79 should be 10K, but resistors do not always measure there true value when measured in circuit as it depends on what other components may be in parallel with it, depending on which way round you had you meter probes it is possible the Zenner was forward conducting which would put both it and R56 in addition to C44 parallel with R78 which could explain your reading of 1K. 

 

 

So on my Gate and Source i show the 8.7V, nothing on Drain.  Flip power on and nothing switches over.

 

You're saying there should be a load on Drain when in off state?

 

Yeah R79 is 10K and correct on the parrallel,   wonder if my U6 is trashed then.   If that's what kick starts the oscillator function there has to be something off with it.

 

Even went through the whole McWill Install again just to see if something was off, shorted to ground, not connected, or scorched,  Nothing.

 

On button has good connection as well.

 

I fixed another scrap Lynx 1 here while diagnosing this thing and am tempted to remove the install from one and transplant it to the other.

 

Going to swap power jack first and try it on a power adapter as well before I do the transplant.

 

Something is way off though from the sounds of it.  

 

Either way, my system would be different slightly than a reference board as I have removed components from the McWill install requires

 

I'll report back.  Posts like these can maybe help someone else if anything.  I know i've read 3-4 here on this forum regarding other systems and issues that cleared it up really fast.   

 

 

MOSFETS | RIG NITC

Edited by cn817166

Share this post


Link to post
Share on other sites
Posted (edited)

Interestingly enough, i flipped the unit over and notice the screen flash as I put in the 6th battery.   Nothing happens when I hit on or off though.

 

Doesn't seem normal at all,  same remains, without turning ON or OFF 8.7V present at source and gate.    Unsure why.  Something blown or shorted somewhere.

Edited by cn817166

Share this post


Link to post
Share on other sites

First did you try attaching bypassing the internal power unit by attaching 5V to D14 (0V to the L6 end), and if so what happened, because if nothing happened then you may have a more serious problem than just the power stage.

8 hours ago, cn817166 said:

So on my Gate and Source i show the 8.7V, nothing on Drain.  Flip power on and nothing switches over.

 

That reading make no sense to me, certainly the Source if correctly soldered to the PCB it should be at 0V as it should be directly connected to the power in Ground. Remove all power sources then attached the power what you put the lynx in its off state so...

1) What voltage do you measure across R84(?), the one across the Q11 Gate Source junction (Measure with your probes directly on the resistor itself).

2) What voltage do you get on Pins 6, 8 & 10 of U6, ensure the Com lead of your meter is on the main power Ground, i.e. pin 7 of U6. 

 

If you are getting power to U6 (measure voltage across pins 7 & 14) then when power is initially applied the capacitor connected to the input of U6e holds the input low to establish the initial logic states and the output goes to the main supply voltage (Vs) of 9-14 volts and the Lynx should be off.

So with the Lynx off...

3) Voltage for pins 10 to 13 of U6 respectively should be Vs, 0, 0 & Vs.

4) The MOSFET should be off, so no current should flow through it and you should measure VS across the Source (connected to main power ground/U6, pin 7) & Drain (connected to L6/D14) pins.

 

When the power On button is pressed the On/Off latch should switch to the lynx on state and...

5) Voltage for pins 10 to 13 of U6 respectively should be 0, Vs, Vs & 0

6) The MOSFET should be on, current should flow though it, the Zenner should conduct dropping the supply voltage for the rest of the system to 5V (relative to the positive Vs rail, not Vs GND) and so you should measure the remaining VS (about 4volts) across the Q11 Source & Drain pins.

 

Make sure that for items 2, 3 & 5 you measure those voltages with Com lead of your Meter to the main power (Vs) ground, i.e. pin 7 of U6 and the other lead directly onto the IC pins (be careful not to short out adjacent pins). For items 4 & 6 the  Com lead of your Meter should be to the main power (Vs) ground and the other lead to L6.  

 

If pressing the On/Off buttons does not change voltages on pin 10 - 13 of U6 there may be a problem with switches/flex circuit, you can manually toggle the on/off status by touching a wire for a second between U6 pins 11 & 14 (On) and between U6 Pins 11 & 7 (Off).

      

Share this post


Link to post
Share on other sites
On 5/5/2020 at 12:58 AM, Stephen Moss said:

Sound like it could be a bad power connector, that is where I would start.

If you look inside the socket there is the centre pin and on one side a little piece of sprung metal. When you insert the power jack it moves that piece of metal away disconnecting the batteries, when you remove the power jack it should spring back reconnecting the batteries. It suspect that either it is not happen or at least not enough to reconnect the batteries.

 

If you look at the power connector in this schematic you will see that pins 2 & 3 create a switch that is opened when the power jack is inserted and should close when it is not. With both the batteries removed and the external power unit disconnected measure the resistance between TP16 and either Pin 7 of U6 or the Anode of D18/D19.

If the switch in the power connector is working you should read almost 0 resistance, if it measures infinite resistance (open circuit) then you may need to replace the power connector if you want it to run from batteries, but you could just try reheating the power connectors solders joint first and remeasure in case it is bad solder joint rather than the power connector. 

Awesome stuff man! thanks for responding- this will give me a good spot to start, and I also ordered some power refresh kits from Console5 to have on hand so this will be a great check to narrow down on the problem. 

Thanks Stephen, I'll respond with the results-

Share this post


Link to post
Share on other sites
Posted (edited)

Just a suggestion try checking the ribbon cable. I had that problem and had to trim a couple of millimetres off of it.

Just noticed  this is for a lynx 1 mine was a lynx 2. But might be worth a look.

Edited by IronWorks

Share this post


Link to post
Share on other sites
Posted (edited)
15 hours ago, Stephen Moss said:

First did you try attaching bypassing the internal power unit by attaching 5V to D14 (0V to the L6 end), and if so what happened, because if nothing happened then you may have a more serious problem than just the power stage.

 

That reading make no sense to me, certainly the Source if correctly soldered to the PCB it should be at 0V as it should be directly connected to the power in Ground. Remove all power sources then attached the power what you put the lynx in its off state so...

1) What voltage do you measure across R84(?), the one across the Q11 Gate Source junction (Measure with your probes directly on the resistor itself).

2) What voltage do you get on Pins 6, 8 & 10 of U6, ensure the Com lead of your meter is on the main power Ground, i.e. pin 7 of U6. 

 

If you are getting power to U6 (measure voltage across pins 7 & 14) then when power is initially applied the capacitor connected to the input of U6e holds the input low to establish the initial logic states and the output goes to the main supply voltage (Vs) of 9-14 volts and the Lynx should be off.

So with the Lynx off...

3) Voltage for pins 10 to 13 of U6 respectively should be Vs, 0, 0 & Vs.

4) The MOSFET should be off, so no current should flow through it and you should measure VS across the Source (connected to main power ground/U6, pin 7) & Drain (connected to L6/D14) pins.

 

When the power On button is pressed the On/Off latch should switch to the lynx on state and...

5) Voltage for pins 10 to 13 of U6 respectively should be 0, Vs, Vs & 0

6) The MOSFET should be on, current should flow though it, the Zenner should conduct dropping the supply voltage for the rest of the system to 5V (relative to the positive Vs rail, not Vs GND) and so you should measure the remaining VS (about 4volts) across the Q11 Source & Drain pins.

 

Make sure that for items 2, 3 & 5 you measure those voltages with Com lead of your Meter to the main power (Vs) ground, i.e. pin 7 of U6 and the other lead directly onto the IC pins (be careful not to short out adjacent pins). For items 4 & 6 the  Com lead of your Meter should be to the main power (Vs) ground and the other lead to L6.  

 

If pressing the On/Off buttons does not change voltages on pin 10 - 13 of U6 there may be a problem with switches/flex circuit, you can manually toggle the on/off status by touching a wire for a second between U6 pins 11 & 14 (On) and between U6 Pins 11 & 7 (Off).

      

 

 

 

1)  R84 0V

 

2)  With the Q11 to the left of U6, pin numbers i show as:

 

 

7         1

|||||||
 

|||||||

8      14

 

 

2)  on U6 With Lynx 1 in OFF state Using Pin 7 as ground it's   

Pin 6:  0V 

Pin 8: 0V 

Pin 10: 8.2V

Pin 11: 0

Pin 12: 0

Pin 13: 8.1V

Pin 14: 8.2V

 

Will Test more and edit this post

 

 

 

 

Edited by cn817166

Share this post


Link to post
Share on other sites

Not sure why it didn't save my edit's, disregard last post, that was my reference Lynx.

 

Bad Lynx is as follows:

 

1)  R84 0V

 

2)  With the Q11 to the left of U6, pin numbers i show as:

 

 

7         1

|||||||
 

|||||||

8      14

 

 

2)  on U6 With Lynx 1 in OFF state Using Pin 7 as ground it's   

Pin 6:  0V 

Pin 8:  0V 

Pin 10: 0V

Pin 11: 0

Pin 12: 0

Pin 13: 0V

Pin 14: 8.2V

 

Something is off,

Share this post


Link to post
Share on other sites

Yes, definitely something off there.

I presume you used the same power unit when testing both lynx's if not try that, I doubt it will make any difference but at least it will illuminate the possibility of a bad power unit.

 

If I was fault finding this my next test would be to place the Com lead of my meter on the Anode of either D18 or D19 (if you are not sure which end that is perform a continuity check until to the combination of ends the produces a reading of 0 Ohms) and measure the voltage on all pins of U6 and at each end of R84. 

 

Share this post


Link to post
Share on other sites
On 5/9/2020 at 6:25 AM, Stephen Moss said:

Yes, definitely something off there.

I presume you used the same power unit when testing both lynx's if not try that, I doubt it will make any difference but at least it will illuminate the possibility of a bad power unit.

 

If I was fault finding this my next test would be to place the Com lead of my meter on the Anode of either D18 or D19 (if you are not sure which end that is perform a continuity check until to the combination of ends the produces a reading of 0 Ohms) and measure the voltage on all pins of U6 and at each end of R84. 

 

Thanks for all of your input.  So far I haven't been able to find any oddity.  I feel it's something so stupid i'm overlooking or a corroded lead/via inside the board that I can't seem to find.

 

I have a new power supply coming this week instead of battery to see if that yields different results, which it possibly won't but i wanted one anyways.   I'll see what I can find.

Share this post


Link to post
Share on other sites

No luck with a power adapter.    Something is shorted or broken somewhere, the screen flashes briefly and unable to track where the issue is.   Very odd.

C77 showing odd Ohm on ESR meter and my tester, but replaced it with the working one and nothing changed,  surprising the Lynx doesn't need this capacitor to power on (tested it).  it's some sort of filter but has a rating of 2200pF according to schematic.  I'll replace it, no big deal.

 

I'm going to replace U6 from a working Lynx and see what happens.  Will report back.

Share this post


Link to post
Share on other sites

Swapped Bad Lynx U6 into working Lynx U6 spot and the same thing is happening.   I think i've got a bad U6.  Going to swap working U6 now.

Share this post


Link to post
Share on other sites
Posted (edited)

It was U6.    Crazy.   Just turned on.   

 

So turns out it this fix was to replace Q13 (was replaced a few months ago) and U6.  

 

I replaced a few of the resistors and capacitor just as I have them in spares but unbelievable. 

 

Thanks for your help Stephen in helping me diagnose the chip originally.   Should have done this weeks ago.  Gonna grab a few spare U6 from somewhere.  Have to replace the bad one i have now.

 

Under U6 on both units was a legit disaster and one of the traces had rotted through as well.   Both of mine had to be cleaned.   

Edited by cn817166

Share this post


Link to post
Share on other sites

With all those pins on U6 reading 0V, I was thinking that it was either blown completely or a bad connection power connection.

I suspected the connection to pin 14, as although you measured voltage there it could have been the introduction of the meter probe during testing that re-established the connection, if it was a solder rather than an internal issue. If the voltages had been at VCC I would have been looking at the ground pin instead. 

 

If you had re-tested with the COM lead on D18 and had the same result of all pins at 0V then I would have suggested it was blown and from your swapping them between units it sounds like U6 is blown, perhaps someone applied too much voltage or the wrong polarity voltage at some point. Good to hear it is working again.   

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...