bobmoo79

Yes I bought my faulty Lynx II on Ebay, expecting to sell it on when it was working...but I still have it. I replaced the caps, the zener, the MOSFET. Had issues with it so started swapping out other bits and then once they were resolved had to change the LCD - I bought an original working screen from Ebay and it was so much better than the one I had (terrible colour bleed). After all that work I had sunk so many hours, and far more money then I expected into it that I couldn't part with it (plus I've built a small library of games), so I think I'll keep it a while longer ?

Did you manage to fix it?

please keep this thread updated with progress. im interested!

Have you managed to look into this yet?? One word of caution if not...be very careful with the flex membrane that connects the buttons to the mainboard. It has graphite (I think) contacts, rather than the more usual standard metal contacts and they wear off VERY easily if you disconnect/reconnect it, and then you'll need to buy a new membrane from the USA (or a good used one on Ebay if you can find one). At a stretch you could cut off a few mm before you reconnect it but it's not ideal. When I worked on my latest Lynx project i did all I could to make sure I didn't unplug the membrane at all to avoid damaging it.

I use eneloop batteries because they have great battery life, and they fit fine, but I know what you mean. I found that Rechargeable Duracell Ultra (AA) batteries have a slightly longer body than a standard AA battery and wouldn't fit in my baby monitor. Before that I thought they were all a standard size but they're not.

yes 40mm is the one to go for. you have to desolder the wires from the old one and solder them onto the new one. the old one is clipped in to place so you may need to use a small flat screwdriver to remove it. the new one just clips in place. I assume it's the same for Atari lynx 1, mine is lynx ii.

So in the end I ordered a replacement LCD from a guy in Italy (via Ebay) and that arrived yesterday. After letting the system run for a quite a while I didn't see any of the horrendous ghosting or colour bleed that blighted my old LCD, so I'm going to consider this unit fixed now. Perhaps not quite as good as getting new old stock from Best Electronics but it was certainly cheaper and did the job brilliantly. Oh and I also ordered a new speaker from Ebay too, so the sound is now much clearer too! https://www.ebay.co.uk/itm/6-Sizes-Small-Speakers-8-Ohm-0-5W-Metal-Frame-Mini/233227469203?ssPageName=STRK%3AMEBIDX%3AIT&var=532726494967&_trksid=p2057872.m2749.l2649 This one is the right size (40mm) and clips into the case just like the original. As it's not a paper cone it should last longer with a cleaner sound - better than buying new old stock, and probably no worse than the one Best now recommend instead of the original. Can't wait to spend some time properly putting this old machine through its paces now.

that looks nice. the only 3d printed things I've seen come out of my mate's 3d printer has that spaghetti effect where you can see the filament in the finished product. yours looks nice and smooth! random question: there used to be a website where you could upload an stl and get quotes from people who owned a printer and would sell you a print. any idea what that site was? I wanted to use it a few months ago. the sites I found were all corporate and charged far too much.

I changed to a 1w zener and it's working brilliantly.

thank you for all you help. I checked the voltage on pin7 and pin 14 of U11 and it was 4.8v so this appears to be working perfectly well now. I will consider changing the Zener Diode for a miniMELF 1W variety at some point but for now this one is working well enough.

It works with the DC jack, but not all with batteries? The schematic is here and it doesn't look as though there's much to go wrong. Maybe start by checking the soldering on the battery connections to the PCB, and also the PCB traces from those connections to the relevant points? https://atariage.com/Lynx/archives/schematics/index.html?SystemID=LYNX I'm sure somebody else will come along to offer better technical support. ?

so I removed the links and the lynx now appears to be working correctly(yay!) but I'm wondering why d13 failed. obviously d13 failure is BAD because it can kill the lynx and I want this to live for many years. so I wonder whether the components i selected when i did the mosfet and diode replacement are correct. I thin they are but can somebody check for me?? here is a list of components I used during this repair. do they look ok to you? or d13 I used 1N5229BTR. https://uk.rs-online.com/mobile/p/zener-diodes/8050126/ for q12 i used AOD514 https://alltransistors.com/pdfview.php?doc=aod514.pdf&dire=_aosemi thanks

yes d13 didn't seem right to me so i took it off the pcb and it was definitely faulty! I hadn't checked it in a while but I'm sure when this thing went wrong it was fine, so I'm confused. maybe I didn't check it after all. anyway, I put a new one on the pcb and now with the wire jumpers in place it shows 'insert cartridge', which is fantastic news. I inserted a cartridge and the game loads. I haven't had time to remove the wire jumpers yet but will do later. if it doesn't power on then, my guess is it will be a faulty flex circuit. thanks again for your help and I'll post again as soon as I have removed the jumpers.

hello again, DVM in diode mode: d13 reads 47 in both directions. d12 reads 152 with COM in the left pin (red on the centre pin) d12 reads 147 with red on the left pin (COM on the centre pin) DVM set to resistance mode: r74 reads 108 ohm. u1 pin 7 and 14 reads 153ohm.

you were correct, that jumper wasn't connected. i checked and needed to resolder one of the links on because it had come loose! I checked r67 and it measures 260k in circuit. close enough? so once again I measure u6 voltages with the Atari psu connected and BOTH wire links connected as you requested. DVM COM connected to d11. 1- 9V 2- 0.3V 3- 0.3V 4- 11.8V 5- 11.8v 6- 0.1V 7- 0V (GND) 8- 0.1V 9- 11.8v 10- 0.1V 11- 10.9v 12- 12.V 13- 0.1V 14- 12V (VCC) im not sure what you're asking me to do with u6 pin13 and tp17. I've connected those together now so perhaps that request is no longer required. thanks for your patience

almost forgot the photo. please ignore the red test wires. they're only connected at one end. the white wire connects c52 to c11.

sorry for any misunderstanding. to avoid removing the metal shield I connected positive side of c11 to c52 (nearest side to c38). this is the same as shorting pins 31 and 33 of cart connector and easier too ? without a cart inserted I still get these: (com connected to d11, then without black band): 1- 12V 2- 0V 3- 0V 4- 12V 5- 12v 6- 0V 7- 0V (GND) 8- 0V 9- 12v 10- 12V 11- 0v 12- 0V 13- 12V 14- 12V (VCC)

ok so here are the voltages I get now: 1- 12V 2- 0V 3- 0V 4- 12V 5- 12v 6- 0V 7- 0V (GND) 8- 0V 9- 12v 10- 12V 11- 0v 12- 0V 13- 12V 14- 12V (VCC) Check R72, R73 and C43 are not short circuit r72 is 4.7k r73 is 10k. thanks

thanks for help! with the jumper installed as shown in your photo, with cartridge removed, and with the atari lynx psu connected, I get 0v on all pins of u6. i tested r72, r73, c43 and none are short circuit. what's next? ?

I think I need some kind soul to walk me through this step by step as I'm getting nowhere fast.

so I have now replaced u6, q7, q8, q12, d13 and the unit still doesn't power on with either batteries or official Atari lynx psi. for u6 i used CD4069UBM96. for q7 and q8 i used "40V 200mA SOT-23 2N3906 SMD PNP Transistor" for q12 i used AOD514 for d13 I used 1N5229BTR do these all look acceptable? I have checked all resistors in the power circuit and they appear to be ok. I have checked all caps and none are short circuit, so i assume are ok. i have checked L15 and it is a short across its terminals, so i assume it's ok. 1) with the COM lead of the multi-meter on the end of D11 without the black line (furthest from C39/C41) i measure approximately the following voltages on U6... Pin 1 = 12V Pin 2 = 0V Pin 3 = 0V Pin 4 = 12V Pin 5 = 12V Pin 6 = 0V Pin 7 = 0V (Supply) Pin 8 = 0V Pin 9 = 12V Pin 10 = 12V Pin 11 = 0V Pin 12 = 0V Pin 13 = 12V Pin 14 = 12V (Supply) 2) connecting the top end (nearest to R70) of C38 to pin 14 of U6 for a second, the Lynx stays off when it should switch on. i now measure approximately the following voltages on U6... Pin 1 = 8.3V Pin 2 = 0.5V Pin 3 = 0.5v Pin 4 = 12 Pin 5 = 12V Pin 6 = 0.13V Pin 7 = 0V (Supply) Pin 8 = 0V Pin 9 = 12V Pin 10 = 0.1V Pin 11 = 11V Pin 12 = 12V Pin 13 = 0V Pin 14 = 12V (Supply) so something happens but clearly this is not correct. 3) if I use a piece of wire to connect the top end (nearest to R70) of C38 to the other end of C38 (or pin 7 of U6) for a second, the voltages revert back to those I measured in step 1.

rj1307 I DID measure the voltages, they didn't change so I replaced Q8 as you suggested above. it didn't fix the problem so will check those voltages again tonight. my new transistors turned up today so I will replace q7 and q8 if I need to. I will also follow Stephens advice, and then if I'm still stuck I'll try the flex as suggested by Crossbow. I've been trying to avoid disconnecting the flex as it is SO fragile. I'll probably remove it, cut off a couple of MJ and reconnect it. it's a last resort for me because it's expensive to get a replacement from the USA. thanks for your help everyone

I followed the advice given by rj1307 above which suggested I need to change q8, so I used a q8 from a spare faulty motherboard but that didn't help. I also fitted a CD4069UBM96 for u6 but it didn't fix my problem either so im a little confused now. I have ordered brand new replacements for q8 and q7 so I'll try those once they've arrived. if they don't fix it then I'm at a loss.

excellent post Stephen, thank you! im sure this will help many people.

got some funny readings on Q7/Q8 but they're in circuit and I didn't have time to take them out to measure them properly. im just going to replace q7, q8 and u6 and see what happens. the components are cheap so seems like a good plan. should be here in a few days.