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hexcor

Second Lynx 1 no power post in 1 day?

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Hi all,

Just got a Lynx 1 that doesn't power on (with batteries or using the power cord, working game is in). When plugged in, I tested the voltage across the Mosfet and see it's about 8.7V on the source and gate, zero on the drain. If I push power while doing that, still no change. I ordered the power regulator refresh kit from console5 and replaced the mosfet (the diode was not included, they'll resend it) and see the same issue.

 

Would a dead zener diode contribute to this? I would think that since the drain is reading at zero, there;s an issue before the diode, no?

 

I've seen the bypass, where exactly should i solder the wire for a Lynx 1 to test this out?

 

 

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Hi all,

Just got a Lynx 1 that doesn't power on (with batteries or using the power cord, working game is in). When plugged in, I tested the voltage across the Mosfet and see it's about 8.7V on the source and gate, zero on the drain. If I push power while doing that, still no change. I ordered the power regulator refresh kit from console5 and replaced the mosfet (the diode was not included, they'll resend it) and see the same issue.

 

Would a dead zener diode contribute to this? I would think that since the drain is reading at zero, there;s an issue before the diode, no?

Before messing around with the Zenner and MOSFET you should first establish the basics which are is power in getting to key points in the circuit and is the power on/off latch (U6 and support components) working because if one or the other of those is not correct replacing the zenner and MOSFET may not make any difference as there may be nothing wrong with them.

 

 

I've seen the bypass, where exactly should i solder the wire for a Lynx 1 to test this out?

 

 

DO not do that, you are connecting voltages that should not be connected together.

There have been many posts here regarding Lynx's that do not turn on/off, I suggest using the search facility to find them as they will at least get you started and may already contain the solution to your problem.

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Thanks, I found an old post of yours after posting this. I will look into it this week. Appreciate it.

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OK,

 

Before messing around with the Zenner and MOSFET you should first establish the basics which are is power in getting to key points in the circuit and is the power on/off latch (U6 and support components) working because if one or the other of those is not correct replacing the zenner and MOSFET may not make any difference as there may be nothing wrong with them.

 

 

DO not do that, you are connecting voltages that should not be connected together.

There have been many posts here regarding Lynx's that do not turn on/off, I suggest using the search facility to find them as they will at least get you started and may already contain the solution to your problem.

 

 

 

Stephen,

I opened the system and started probing around. One comment you made was to check the power on U6 on the off and on state. You said to put the com (black) cord to TP16, I am not seeing TP16 on my MB looking at the image ere (https://upload.wikimedia.org/wikipedia/commons/9/98/Atari-Lynx-Motherboard-Bottom.jpg) it looks like TP16 should be just right of the black power wire... on my Lynx (1), that section is covered by other components, I MIGHT be able to see TP16, but it's not accessible, so I used TP18.

 

Back to U6, I probed the legs and i'm getting negative voltage readings and then when I press on (I wish I had a helper if I have to hold!), i'm getting some changes... here's what I have

 

OFF

1 0

2 -9V

3 0

4 0

5 0

6 -9V

7 -9V

8 -9V

9 0

10 0

11 -9V

12 -9V

13 0

14 0

 

I rounded to the nearest whole number

 

ON

1 8v

2 0

3 0

4 9V

5 9

6 0

7 0

8 0

9 9

10 still 0

11 now 9

12 Now 9

13 0

14 9

 

Just to be clear, the numbering is 1 at the circle, then it goes counter clockwise (so #2 is to the left of 1 and then #8 is across from #7, right?)

 

 

Also, looking at this site:http://www.learningaboutelectronics.com/Articles/How-to-test-a-zener-diode it describes how to test a zenner diode. I'm seeing about 385 ohms either way...

Edited by hexcor

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I said TP16 as it should be a convenient place to pick up 0V from, it should not be covered by other components, it should be accessible as it is a key test point. That aside you can also pick up 0V from the negative battery terminal or pin 7 of U6.

You must of had you meter probes connected the wrong way round to be reading a negative voltage, either you black lead was not in the COM terminal of your meter or had your red lead to 0V.

 

You are correct in the pin order of U6, pin 1 is to the left of the circle (or top right is it is orientated in the image you linked to) and then go in sequence anticlockwise. Could to retake the measurements just to confirm they are correct, you do not need to hold the on/off buttons in place, U6 is a latch so an on/off button press and when working correctly it should stay on the respective on/off state.

 

The link for the Zenner testing did not work for me so I do not know what you are being told but your measurement will not be accurate if you are measuring it in circuit and I do not have a Lynx one to compare it with.

Edited by Stephen Moss

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I said TP16 as it should be a convenient place to pick up 0V from, it should not be covered by other components, it should be accessible as it is a key test point. That aside you can also pick up 0V from the negative battery terminal or pin 7 of U6.

You must of had you meter probes connected the wrong way round to be reading a negative voltage, either you black lead was not in the COM terminal of your meter or had your red lead to 0V.

 

 

Hi Stephen,

I retested again this time by putting com on pin #7 and got readings..

 

when "off" (plugged in and game cart in) 1,4,5,9,10,13, and 14 all have between 8 and 9V

When I press "on" 1,4,5, 9, and 14 stay between 8-9V. 10 and 13 read 0. 11 and 12 read between 8 and 9V.

 

This means U6 is working correctly, no?

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That makes a bit more sense, the On/Off latch (pins 10 -13) appears to be operating correctly but the power oscillator (pin 1-6 & ancillary componets) is not running, hence it is not turning on. I did help someone diagnose a blown Q13 once so it may be useful if you can find that in case I cannot remember how to.

 

In the meantime with the power disconnected try measuring the resistance between pins 1 & 10 of U6 and between pin 10 of U6 and the Collector of Q13 (if you cannot identify the collector then measure to all three pins).

Also doing each pin in turn measure between one pin of Q13 and the other two, take one measurement with the black lead on the pin fixed pin and the red lead on the other two and another with the red lead on the fixed pin.

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In the meantime with the power disconnected try measuring the resistance between pins 1 & 10 of U6 and between pin 10 of U6 and the Collector of Q13 (if you cannot identify the collector then measure to all three pins).

Also doing each pin in turn measure between one pin of Q13 and the other two, take one measurement with the black lead on the pin fixed pin and the red lead on the other two and another with the red lead on the fixed pin.

 

 

OK, here's what I got:

between 1 and 10 of U^ I measured 10.12k ohms

Between 10 and Q13 I got the following..

for the bottom (again, using this image https://upload.wikimedia.org/wikipedia/commons/9/98/Atari-Lynx-Motherboard-Bottom.jpg)Igot 10.12k ohms

for the left and right I got 1.8m ohms (this is mega 1e6, not milli 1e-3, correct?)

 

When measuring the components of Q13

 

Black fixed on the top left pin, I got 120 ohms on the right pin, 0.36 m Ohms on the bottom

Black fixed on the top left pin, I got 120 ohms on the right pin, 0.36 m Ohms on the bottom

Black fixed on the bottom pin, I got 1.7 m Ohms on both pins

 

now, with the readings, mostly they were increasing, so I let it go up and just stopped taking the readings.

 

 

I do have a cap and power kit from console5 (i've only replaced the mosfet, and the zener diode was not included, it should be delivered tomorrow to me), it did come with two transistors (one for Q13). Are you thinking Q13 is shot?

 

I appreciate all the help, my son's been bugging me to have it working so we can play 2 player California games!

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I would think the M on your meter should be Mega (1e6), most meters do no have a milliohm range.

I cannot be entirely certain with measuring it out of circuit but I think Q13 is probably OK, it definitely does not appear to be short or open.

 

Measure the resistance between the big (bottom) pin and the left pin right of Q11, measure with your meter leads both ways round.

 

Measure the resistance between U6, pin 2 and the Left side of R54, between the Left side of R54 and the Left side of C73 and between the right side of C73 and the top right pin of Q13. I would expect 0, 4.7K and 0 respectively.

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Woah, q13:

 

 

Black fixed on the top left pin, I got 120 ohms on the right pin, 0.36 m Ohms on the bottom

Black fixed on the top right pin, I got 120 ohms on the left pin, 0.36 m Ohms on the bottom

Black fixed on the bottom pin, I got 1.7 m Ohms on both pins

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I would think the M on your meter should be Mega (1e6), most meters do no have a milliohm range.

I cannot be entirely certain with measuring it out of circuit but I think Q13 is probably OK, it definitely does not appear to be short or open.

 

Measure the resistance between the big (bottom) pin and the left pin right of Q11, measure with your meter leads both ways round.

 

Measure the resistance between U6, pin 2 and the Left side of R54, between the Left side of R54 and the Left side of C73 and between the right side of C73 and the top right pin of Q13. I would expect 0, 4.7K and 0 respectively.

 

 

Ok, resistance measurements on Q11

With the red lead on the bottom and black on the top left, I got 0.L

With the red lead on the top and the black lead on the bottom, I got about 10M ohms

 

with regards to C73, did you mean C37? If so, I measured 0, 4.7K, and 0 as you expected.

 

My zener diode came in today, should I install it, or hold off? I won't be able to do it until this weekend.

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My zener diode came in today, should I install it, or hold off? I won't be able to do it until this weekend.

 

 

Here's something... I tested the resistance of the diode on the Lynx, in both directions it was OL. When I tested the one I got in the mail in one direction I got OL, and in the other I got 20 Mohms... I wonder if the zener diode on the Lynx is broken (it is still connected to the system, so I don't know if that plays any role).

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Gosh, I wish I could edit/delete posts! Sorry for the overposting.

 

I ended up replacing the Zener diode and nothing changed. I then tested the old one for resistance off the Lynx and it had similar readings as the new one.. so as far as I can tell, it's still good

 

so, back to where we were. I did the measurements and posted them above.

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Well I'm stumped, it's possible I am missing something as my brain always gets a little fatigued by the end of term, I would have like to have been able to track it down to a specific component but...

the readings you are giving are not quite what I would expect but do not clearly indicate that Q11, Q13 or the Zenner is completely short or open.

 

I was initially suspicious of you Zenner reading, 300 ohms both ways was not what I was expecting but I wanted to see if anything else may have been contributing to that/gone and you appear to have shown that the Zenner is not the problem providing you are looking at the correct diode which appear to be D12 on the schematic but ZD1 on the PCB and that you have it connected the correct way around.

 

I only have a Lynx 2, although the power stage appears to be the same and so I would expect similar measurements when reading both the Zenner and MOSTFET. I get changing values like my meter is charging/discharging a capacitor.

 

I think Q11 may be blown as 10M is very high, I would expect the body diode to be less than that but the only way to know for sure is to replace it although I cannot see why that would stop the power oscillator running, I would think that Q13 the more likely culprit for that.

The other possibility is that there is a bad connection somewhere which your meter probes bridged thereby providing an erroneous reading.

 

I have not tried it but you could you could try testing to see if Q1 is blown by bridging the Drain & Source pins with a 39 ohm, 0.6W resistor, solder it in place as it will get hot and only turn the lynx on only for a second or two, it may not allow the screen to light but you should hear the speaker click if it comes on. But you may just have to try changing Q11 and Q13 as I cannot think of anything else to try and if that does not get you anywhere because they are OK that is progress of a kind and at least you have some spare parts should you eventually need them.

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Thanks. I did replace Q11 already, ill try Q13 tonight.

 

The caps look ok(nothing bulging) I would like to not recap if something else is shot! Ill replace q13 and if it doesnt work, I still have my lynx 2 that works!

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But you may just have to try changing Q11 and Q13 as I cannot think of anything else to try and if that does not get you anywhere because they are OK that is progress of a kind and at least you have some spare parts should you eventually need them.

 

OMG OMG OMG OMG OMG OMG OMG

 

I replaced the transistors at Q4 and Q13 and then reattached the speaker and it turns on! I don't know if the speaker needs to be connected or not, I just decided to do it.

 

Anyways, it powered on with a game, but the screen shows nothing and no sound is coming out of speaker/headphones

 

I'll recap this weekend and see if it does anything.

 

Thanks for all your help, I really appreciate it

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I would be surprised if the speaker needs to be connected for it to turn on as it has nothing to do with the power stage.

If you now measure U6 pins 1 to 6, 8 & 9 with the lynx on you should read something around 3 - 4.5v - just to confirm the power oscillator it is operating as it should.

 

I presume you tried adjusting the volume and brightness controls and the backlight was on.

 

Check the flex circuits are correctly inserted into the FCC connectors and that they have not cracked/torn as your were testing/replacing parts.

 

If all that checks out you may not be getting any video or sound because the reset line to Mikey and Suzy is being held low. Measure the voltage across R65 and C7 with the Lynx on, you should get 0 and 5V respectively,

if that is correct then measure between pins 1 & 4 of Suzy and pins 57 & 61 of Mikey (both should read 5V) to ensure the reset signal is correctly reaching them.

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If all that checks out you may not be getting any video or sound because the reset line to Mikey and Suzy is being held low. Measure the voltage across R65 and C7 with the Lynx on, you should get 0 and 5V respectively,

if that is correct then measure between pins 1 & 4 of Suzy and pins 57 & 61 of Mikey (both should read 5V) to ensure the reset signal is correctly reaching them.

 

 

To get to Mikey and Suzy I had to remove a metal shielding, which I just did. I cannot check voltage since the cart needs to be in the system and that covers the chips!

 

Here is what I found:

U6 off 1,4,5,9,10,13m and 14 all read 9V, on 2,3,6,8,11,12,14 7.8ish

 

Measure the voltage across R65 and C7 with the Lynx on, you should get 0 and 5V respectively.... got 7.39V

 

Also, Mikey was very very hot to the touch... could this be a failure? At one point, the speaker kicked on and was loud and staticy, but I was able to lower the volume. I do have a parts Lynx 2 motherboard, I could remove mikey from that, but i'd like to avoid using hot air (never did it before, although I do have a hot air gun, lol)

Edited by hexcor

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I think you might have to concede defeat.

I think you will find Mikey difficult at best to desolder with hot air, you have to heat a relatively large area to about 300c and it has to be focused heat so as not to desolder adjacent components which are then blown everywhere if your heat source has a high airflow rate.

 

Additionally, without knowing if Mikey is getting hot due to failure in and of itself or if something else is causing it to get hot you may just end up cooking the replacement. That is assuming Mikey feeling hot is a problem as I have never felt it on a working unit, 40c could feel hot to the touch but most semiconductors operate up to 80c so 40c is well within spec and that may just be the way Mikey is under normal operation, if you can boil water off it then there is defiantly something wrong.

 

If U3, Y4 and Suzy feel OK and Mikey still gets hot with the flex circuit for the LCD disconnected that could suggest there might be a problem with Mikey but I am by no means certain, the only way to be sure would be to replace it..

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I cant really remove the LCD flex circuit on the lynx 1, can I? At this point (and searching at other posts in here), 7V going thru those components would dry them, Im going to toss in the towel.

 

My thought is someone put the power cord into the headphone or comlynx jack and fried the system.

 

 

Ill clean it up and make a display out of it. Oh well. Thanks again for all the help

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The cart connector is a rare thing today. I had one Lynx where I removed Suzy and Mikey and turned it into a Raspberry Pi RetroPie unit with an extra cart connector for reading/burning carts.

StoneAgeRetroPie.jpg

 

The nice thing is that all buttons are on the main pcb so it is not difficult to rewire them for a RaspberryPi. The screen here is a 5" analog car monitor. At ebay for €12.

Edited by karri

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StoneAgeRetroPie.jpg

 

 

 

 

 

Wow, that's nice looking. I have a broken Lynx2 that im tossing a Raspberry pi zero into. I connected the controller to a teensy and have the rest of the parts.. I just need to have some time to connect everything. Got pictures of the inside of that?

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Wow, that's nice looking. I have a broken Lynx2 that im tossing a Raspberry pi zero into. I connected the controller to a teensy and have the rest of the parts.. I just need to have some time to connect everything. Got pictures of the inside of that?

 

I should take some pictures. My wiring is a bit tight inside as I bought a large Raspberry Pi 3B+ to get some extra power in it. But I also added some extra electronics to map the cart connector to the Pi, wired the sound to go through Lynx I amplifier, wired the serial UART to go to ComLynx. The idea was to be able to insert a cart and use ComLynx for multiplay. So I would need to document everything at some point.

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I should take some pictures. My wiring is a bit tight inside as I bought a large Raspberry Pi 3B+ to get some extra power in it. But I also added some extra electronics to map the cart connector to the Pi, wired the sound to go through Lynx I amplifier, wired the serial UART to go to ComLynx. The idea was to be able to insert a cart and use ComLynx for multiplay. So I would need to document everything at some point.

This would be great, I'm working on something similar but there is a lot to do.

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