oski_98

Hi @Rollinpizza, It's been a while since I've been on the forum, but I was very happy to hear that you were able to fix your Lynx. I think we made you try just about everything under the sun! As a silver lining this is now a great blank screen troubleshooting thread. Wishing you many hours of enjoyment on your newly fixed, hard earned Lynx.

There's a lot of information on this forum about how to troubleshoot issues like that. You just have to go find it and be persistent.

I think you tried just about everything you could. I'm really impressed by your tenacity but it's probably not worth pursuing further. I wouldn't blame you for giving up. It's probably best to just save up and buy a new one. I would put this one away, maybe some day you'll come back to it and figure it out. Maybe in the future they'll figure out how to make Mikey and Suzy clones. Who knows.

Answer to Q1: I would try positioning the socket and see if it gets in the way. Answer to Q2: Should be fine. Kapton tape is not conductive. You can use a continuity tester to be sure. Answer to Q3: It shouldn't matter if the cartridge port is not attached. It's just connectors, there are no components in the cartridge port.

There is no startup sound. The only thing I can think of is to replace all the cheap ICs on the board, including the DRAM and see what happens. Seems like a long shot though.

@Igorpossibly I have an older revision? I downloaded it last week though. Could it also be that the presence of other files affect it? Or even the quality of the SD card?

Yeah, I had issues with the following names for the ROM: 1. "Super Asteroids, Missile Command (USA, Europe).lnx" 2. "super_asteroids_missle_command.lnx" It works fine if I just name it: astero.lnx

It didn't have an ampersand, but it was a long name. I think the firmware, or maybe the boot image, don't handle long names and also certain characters well. For example I noticed that for some file names, ones that have only letter characters, it doesn't show the extension. But if the file has an underscore it shows the file extension.

On a hunch I just shorted the rom name to astro.lnx and somehow that fixed the issue.

Does anyone else have trouble playing the "Super Asteroids and Missile Command" ROM on their ElCheapoSD? I'm using the atari gamer boot.bin and when I select the room it fails to load, there's some text the flashes in front of my eyes too quickly for me to read (could be an error). Subsequent attempts to load the ROM seem to just hang. If I remove the associated .SAV file seems to go back to quickly failing with flashing text too quick for me to read then back to freezing on load. I searched the forum but couldn't find any specific mention of this.

It seems unlikely that Hayato is the issue given the level of activity you are describing. I think it's strange that the chip would fail in such a targeted way rather than fail catastrophically. At this point I'd wait and see what happens after you replace the audio amplifier. The random behavior you are describing could be due to the audio amp chip being faulty or possibly a cold solder joint that is sometimes not properly conducting. You could test continuity between components and leads and their pads or nearby vias. Alternatively just reflow every solder joint. Exhausting work to be sure but it's an option to consider.

For reference, here's the measurements I took from a PAG-300 Lynx II (a more rare Lynx II variant with a Mikey instead of Hayato chip). I took these with an oscilloscope, and I also included the mean voltage computed by the oscilloscope. I think the mean voltage should match what you would expect to see with a digital multimeter. The HI&LO on RAS when the game cart is inserted is a good sign that there's some activity on the ICs. However, I'm concerned about your measurements on the LCD pins. Especially that none are reading HI&LO. Pins 22-25 are for powering the backlight. Don't test these with the logic probe. The voltages are outside the range of what that device would expect. I don't think it would damage the logic probe, but just to be safe I wouldn't use the logic probe on this. Measure these with a DMM instead. Pins 17-20 are the data lines I would definitely expect HI&LO reading on those pins. Strange also that 14 is reading HI, I would expect 13 to read LO and 14 to read HI. Pins 3-7 are square waves I would expect HI&LO readings there as well. Unfortunately, I'm not sure what the reading for all the test points should be on a Hayato Lynx II so I can't help much there. Maybe collecting that data would be a good future project. I do know that TP26 (DBL) on the PAG-300 Lynx II should NOT read 0V, it's a 50% duty cycle 3.15kHz square wave with a crest of 4.9V and a trough of 0V - it should read ~2.4V with a DMM. What happens if you try to measure with the logic probe directly from the Hayato pins? See the pin layout for Hayato here, the data lines are pins 2-5 or Hayato, DBL is pin 63, the display clock signals are pins 13, 15, 16. See if you get the same measurements with the logic probe if you take the measurement directly from those pins.

@ChildOfCv the test circuit approach also turned up during my research on the topic. It seems like that's the best way to test it. I confess I was simply too lazy to build a test circuit. I wonder if one of these ATmega328-based component testers sold on Amazon for $15 would do the job just as well.

Thanks for the reply. I was looking for a more specific explanation of how the circuit works that would explain the difference. I understand that the surrounding components would affect the measurements I take with my multimeter when the component is installed vs. uninstalled. The reason I provided the measurements in my previous posts was precisely to quantify what the effect is when I take measurements with my DMM (Fluke 117). Though I guess I could be making some bad assumptions about the consistency of these measurements across different boards and different DMMs. I'm 100% confident the diode was installed in the correct direction: with the black stripe towards the RF shield. Here's a WIP picture I took while re-capping the board. I think more likely explanations are that the diode was defective or that I damaged it during installation.

I recently had an interesting experience refreshing the power circuit of an Atari Lynx II and learned some things that might help others. I had just replaced Q12 (MOSFET), Q8, Q7, and D13 (zener diode) of the power circuit. I had done four of these before and inspected the work closely so I just put the unit back together and powered it on. Immediately I noticed that the screen was very bright, much brighter than I had ever seen it before - so bright that even at the lowest brightness setting I could barely see the game splash screen. I immediately powered it down and suspected that too much voltage/power was issue. I turned it back on one more time and measured the voltage across C41 at 8.5V, much higher than the 4.8-4.9V I would expect. I thought about turning it back on and troubleshooting, but decided instead to just go to bed and come back to it tomorrow with a fresh mind - I didn't want to risk turning it on more. So the next day I best guessed that probably the issue was the zener diode, since that is the component responsible for stepping down the voltage and so I decided to remove it and test it. So I fired up the hot-air rework station and as soon as I saw the solder start to melt I gently tried to move it with my tweezers and it came apart. It just shattered into two pieces in my tweezers. First time that's ever happened to me. I'm positive I was handling it gently. So I grab a new zener diode and decide to test this one with my multimeter before installing it. Forward bias reads .71V and reverse is 0L (open circuit) as expected. Then I install it and remember that I had taken forward and reverse bias measurements of the diode when installed from another unit: forward biased .29V and reverse bias .94V. I have no idea why those are the measurements when installed, I just know that they are for another Lynx II that works fine (if anyone can explain it I would love to know). The newly installed diode is close enough to these measurements (.29V forward biased .82V reverse biased) so I fire it up and finally get 4.8V across C41 Moral of the story: test your zener before you install it. And if you want, test it after you install it using the measurements provided in this post. Who knows it might even save a Lynx or two.

Also if you're testing with pin 31&33 of the game cart port jumpered you might instead want to test RAS with a game cart inserted. It should be always HI&LO.

If the RAS is showing HI&LO that's probably a good sign that Hayato is fine. So maybe the issue is Suzy or the DRAM. I would immediately replace the audio amplifier. Reason why: if you hear audio with a game cart inserted that means both chips are working. So I would replace the audio amplifier insert a working game cart and listen. If you hear sound then do a little dance because that means Hayato and Suzy are OK. If in that situation you don't hear audio I would replace the DRAM first, since that is an easy and cheap part to find. Also, what about the LCD header? Have you tried probing the clock and data lines?

That IC is an LM386 audio amplifier. A replacement part is probably less than $1. In fact I would just buy replacements for all of the ICs (except Mikey/Hayato and Suzy which are difficult to source) just in case. Probably won't cost you more than $10.

WRT the logic probe, I think the cheaper one you linked should work fine.

You don't need anything fancy. The Elenco LP-560 is cheap and plentiful. There's some posts here on how to use one. Generally what I look for is activity on the RAS/CAS of the memory chips. I've found that to be an indicator that both Mikey and Suzy are working. I would then check the LCD header. I have a post on this forums with a table of the measurements I took on my board. Not sure what to conclude from Hayato being slightly warm at startup I've never noticed any warmth at all from Mikey at startup. A few other thoughts. 1) It's easy enough to check the VCC of the RAM and other ICs on the board. I would do that as well. If the data and address buses are active maybe it's possible that the DRAM chips are faulty and not responding appropriately. This is just a theory, I've never experienced this, nor am I knowledgeable enough of those aspects of the circuit to say so with any certainty. 2) Where did you get the capacitor replacement kit? Are you sure the voltage rating as well as the capacitance for each capacitor are suitable?

Hayato doesn't "send" reset. Other circuits can use the reset pin to turn processing on/off. Setting that pin low turns Hayato off setting it high (e.g. 4.9V) turns it on. R1 and C3 just delay when Hayato turns on after you press the Lyn on button. In other words, it seems like there's nothing wrong with the reset circuit or the power to Hayato. You should also check the voltage of the Suzy VCC pins as well. If there aren't any obvious signs of a short such as warm chips or VCC pins pulled low. I think you'll have to at least buy a logic probe to test whether the ICs are working properly. Like I said earlier, they are cheap $10-30.

A few observations from staring at the pictures. * Nothing looks obviously wrong with Q12, Q8, Q7, and D13 though I can't quite tell the part number for Q12. * What happened to C58? It's gone and there's just two wires, what are they connected to? * It looks like the electrolytic capacitors were replaced? If this is true, I would double check the polarity and specs for every one. Finally what kind of multimeter are you using to test voltage and on what setting? Make sure you're not using a DMM in any auto-sensing low-Z mode as that will not provide accurate measurements for this application.

I think you're counting the pins wrong because pin 6 does not connect to C83, that's actually pin 15. For reference, pin 1 is labeled by the "1" that's by the bottom middle of the chip. It's next to the right side of D1. Also WRT to Hayato pin 6, it seems like the traces on the board don't match the schematic exactly. The schematic shows pin 6 connected to a 5V source and and an inductor. But if you look at the traces on the board that pin connects to two "104" SMD resistors. This is unlike some of the other pins connected to a power source. For example, if you look at pins 18, 29, 49 they connect to an SMD inductor which matches the schematic. I guess what I'm trying to say is that I wouldn't trust the schematic implicitly, there were multiple board revisions and does anyone really know the source of these schematics? Instead I would try to visually follow the traces and use the continuity tester on your multimeter to figure out what's connecting to that pin. But do make sure you're testing the right pins

WRT TP1, I'm not sure if TP16 is the right ground point but I'm pretty sure you can just use the negative terminal of C3 as your ground point to measure the voltage on the reset pin. R1, D1, and C3 form a power-on-reset circuit that delays when the Hayato RESET pin goes high long enough for other components to "get ready". When C3 is charged the pin will go high, so you can just measure the voltage across C3. R1 provides resistance to delay charging of C3 and D1 provides a path for discharge on power-off. Actually, if you look at the board carefully there are many ground points (small vias onto the ground plane) for using an oscilloscope probe with a ground clip. There's one to the right of R11 and one immediately to the right of pin 1 of Hayato. You could use either off those as grounds as well. +1 to what @Stephen Moss said, if you can confirm that C3 is a short then the RESET pin will never go high and this Hayato will never "turn on". You should be able to do this with a continuity tester. You should get a short beep across C3 but not a solid tone. BTW if you can't afford an oscilloscope, you can still troubleshoot a lot with a logic probe, and that only costs $10. If you do get a logic probe I can help suggest what pins to probe for activity. I'll spend more time this evening looking at your pictures and let you know if I see anything out of place.

I have a Mikey and Suzy chip that *may* be OK and that I'd like to tinker with. I've been thinking about hacking together some kind of improvised circuit to test these, but before I go that route I thought I'd ask here if anyone has a Lynx I or Lynx II C104129-001 motherboard (the kind that's compatible with Mikey instead of Hayato) lying around that they'd be willing to part with. They don't have to be in great (or even good) shape as long as the traces connecting Mikey and Suzy are OK. I'd be be willing to pay something reasonable for it. If there's any interest please DM me.