cowdog360

Fantastic! I just ordered some samples too. I'm still going to see if I can get the original 4069 circuit to work.. but the hard part is finding a good break point for the battery voltage. The Lynx II is probably quite a bit different in that regard. What I'd really love to do is shove a pair of 18650's in parallel to get about 6000mah

The other question is if the Lynx can turn the powerboost off after that system timer cycles out, like in the games we were talking about. I think you still want to have the POWERON/ (PowerOn NOT) signal tied in. Basically, you could tie the POWERON/ right into the the shutdown on the LTC. Overall, looks like a fantastic solution that will allow the buttons to work, no standby power drain. Plenty of safety, load sharing, etc. Very nice work! Super happy with seeing it all work like I thought it would!

Now measure the current draw with it off.. see if it even registers. It should be just a few microamps.

Yes! Awesome news man. I'll have to order up some of those chips to try as well. the STM6601 looks like it does the exact same thing as the LTC2950 at about 1/3rd of the cost. So on the pushbutton, do you have to hold the ON down for a few seconds? Or it it instant off? Definitely want to see your wires on the PCB and schematic so I can translate this to the Lynx II. Also - the easiest way to solder those SMD chips is solder paste and hot air (but you have to have the tools of course). Nice job on the first well documented LiOn Lynx! (Isn't that two animals? lol)

One idea, superglue the chip to the board, and jumper the pins to the pads with some 30 gauge wire.

Aww, it's so cute! Nice work my friend. You're beating me to it. I'll be doing that soon after I get through my backlog of Lynx repairs.

Check your voltages across capacitor C41. Your power supply could be acting up. But.. it's more likely DRAM or a bad Suzy.

Just verified. With the Lynx diagnostic cart, I had it running for 3.5 hours on two identically modded Lynx II's. Then I booted Warbirds and left it on the title screen. Both turned off after an hour. APB does the same thing. So it has to be a game thing.

Yes it's great, and thanks for the shout outs. Glad to help.

I'm actually wondering if this is a game/software issue. APB seems to shut off after an hour or two of idle time. I'm doing comparisons right now with two Lynx IIs and the diagnostic cartridge. So far they've both been on AC for about 1 hour 30 minutes. Any ideas if certain games shut the system down after too much idle time?

I actually need to solve several problems for the lithium circuit: 1. How to seperate out the 3.7V battery rail and 5V boosted output rail if I want to use the 4069 instead of a button controller IC. 2. How to keep the original lynx power jack, but deal with the issue of someone plugging in a real 9V adapter. Since the powerboost and most boost controllers can't take more than 6 volts in. 3. Make it pretty easy to do rather than tons of hacking to the board. #1 is the one I'm working on at the moment. #2 seems like what you might actually have to do is put another 5V buck converter in front of the powerboost. I really want to use the stock jack so we can use the Lynx adapter, or a 5V adapter, but don't have the mod the case.

Yeah I realized that right after I posted it. I'm trying to find a good spot on the board to break the traces to seperate the 5V and battery rails. So far, not finding anything obvious. The schematic and board layout are very different. Regarding the 4069, actually @Mojado did an excellent job talking about how the power supply circuitry works here: http://atariage.com/forums/topic/236279-what-are-the-5v-regulator-mod/page-2 Go to post 37. Lots of info and pictures. But basically, half of the 4069 is used to latch the On/Off button state. The other half if used as a square wave osciallator to run the switching power supply. Pretty slick design really.

Just a quick question here. How long can the Lynx II stay turned on while idle on AC? I swear I've had some that stay on nearly forever, and some that shut off after an hour or so. I know the Lynx I is different than the Lynx II in that regard. Any ideas? Thanks!

Yes, that's true.. this was just to show the odd issue with that. I actually have about 4 Lynxes that won't power on with new MOSFET or 5V directly into C41. So either its more common, or I have really bad luck And you must be buying your MOSFETs in bulk for 50 cents.. not that $1 is a whole lot more.

This is pretty typical of engineers/technical guys dealing with the end user of a product. It sounds great, but we always miss what's really important Let's say we use a lithium battery that is 3400mah, since that's probably what I'm going to use. In a Lynx I, you can fit more. The Lithium battery will be boosted to the voltage needed to run the Lynx, and the conversion is probably around 90% efficient, so you wind up with about 3000mah roughly of usable power. A McWill modded Lynx with new screen probably draws 300-400ma, so a decent guess would be 8-10 hours. And you could recharge it in about 3 hours. So in short, probably 8-10 hours depending on what size battery you pick.

So here's some more ideas for the lithium ion conversion. I'm going to try this on my Lynx II: Basically, the CD4069 inverter can run down to 3V, and its what acts as both the power on circuit and the oscillator for the built in switching DC supply. If you look at all the Red X's, I'm going to chop out all of the DC switching section since we don't need it anymore. Where D11 is, I'll drop in VBAT from the Powerboost 1000c which should allow the 4069 to operate like it used to. Then, take pin 11 off the 4069 and run it into the enable on the powerboost. Then, the 5V output of the powerboost would just be placed across where C41 was. This should work, retain all the original button and shutdown functions from the CPU. I'll try and let you know!

I agree that in most cases re-capping is overrated or not needed. I just offer the service, so most people take me up on it. I do have a few Lynxes that I haven't done it on, just because they work fine (but I still do that MOSFET and zener every time now). On a gamegear, you have to do it, since they all leak and destroy the PCB. On Amiga 600/1200/4000 computers same deal. With vintage audio equipment, in a lot of cases it affects the sound (but you could easily check measuring ESR like you said). In general, Atari seemed to have used good caps on both Lynx models. I will say though, that there are a few revisions of the Lynx II PCB that are terrible in terms of pad and traces lifting.

Actually, it's more likely to the way that McWill implemented the screen buffering on the new screen.

I was talking with another person last night, and it may be possible to use the original CD4069 and power buttons to act as an enable trigger for the powerboost. The CD4009 will work with as low as 3V input, so if you have it tied directly into the battery at 3.7V, that should work. The big issue would be seperating out the power rails, since it is a shared one right now.

So I have an odd one. I have a Lynx II that works, runs, but had some scrambled video on the screen. So after talking to a local fellow Lynx'er and engineer around here, he suggested I replace the Suzy chip. Luckily he had some brand new Suzy and Mikey's in his cache of goods (you can buy them also from Best Electronics). Here's the Original Suzy Chip (also notice the DRAM is SMD on this board revision): After desoldering the Suzy with some chipquick, and resoldering with some solder wicking to fix the bridges, it fires up and works like new! And of course I recapped it, new MOSFET and zener for the rest. Honestly, most Lynx II's can probably fixed with a Suzy, Mikey, and RAM.. too bad the chips cost almost $50.

True, the zener and MOSFET may not fail from storage, but ask Glen about his refuribshed Lynx that popped the zener He's the one who posted the video using the 5V supply to bring it back. Its too cheap and too easy not to do. If I could find a good supply of sub $60 Lynx II's, I'd recap, MOSFET and zener and sell them for $100.

Looks like a solid plan. I can't wait to get some more Lynx II's to try my hand at this as well. I have a powerboost 1000c already, and just need to buy a few LTC2950's. What I'm seriously thinking of doing after this is all figured out is just taking the powerboost 1000c design and building a new PCB that has all the components sorted out, less LED's and make a simple to wire up option for others who want to do it. Soon the Lithium Mod will be the ultimate replacement for the power supply woes! Cuz there's just something about it.. so right.. (Couldn't resist)

Nice work to both of ya. I'm definitely doing the Lipo mod on my Lynx II shortly as well. I want to use the stock power jack for the 5V input.. but I'm worried that someone might stick the Lynx 9V into that and blow the Powerboost 1000c. Making me think about tossing a 5V zener across the input as a crowbar of the Powerboost. What would be cooler is if the powerboost could take up to 12V in... but it can't.

I have one behaving similarly. It was working great, then bam.. nothing. Fires up with the shorted MOSFET as well. I'm going to check the 4069 IC and see if that's the culprit.

Nice! Can't wait to see it all come together. If I really had some time, I'd just design my own PCB/circuit that has the boost controller, charger, and button controller all on the same thing. I was thinking about doing things cheaper and just chaining together a charger and a booster, but the big issue is dealing with using the battery while charging. I imagine if you don't design things right, it could be very bad for the battery. Which is why I figure the powerboost circuit is tried and true, and not too bad..a little expensive, but doable.