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Atari Lynx II codename Hayato schematic


7800fan
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Finally got my mitts on the real Lynx II schematic and it's code named Hayato. The 2 main chips are: Suzy and Hayato. So there's more than cosmetic and size difference from the Mikey and Suzy pair of the earlier Lynx system.

 

I scanned the schematic in, it was a bit of effort to line up large paper on my cheap letter sized scanner, keeping each section straight as possible. There's a bit of skew in the power supply section, I think my scanner is skewed a bit. I've done only minimal cleaning up to preserve as much as possible. There's a few handwritten notes around Hayato chip, probably late revision? The circuit that handles power LED is on the far right side above the mid section. Basically LED gets 5v from the controller panel, the cathode goes to a 1k resistor and a transistor to ground. Also stereo support,. there's extra circuit in the audio section. LCD looks a bit different as well.

 

The biggest difference are in part labeling. I had a hard time matching Lynx 1 schematic with my Lynx II because the part reference has different number such as a transistor that handles power on, they are marked Q11 on one model and Q12 on other.

 

AA is free to take my schematic and add it to archive section alongside Lynx 1 schematic.

TFqVSmL.jpg

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This is a very good find. The schematics has a few lines that end in thin air. A long time ago I started to enter the schematics into a CAD. But I was never able to complete it. With this new find it would be a good idea to enter it into KiCad and create both the schematics and the board layout.

 

There are many 0 ohm resistors that help pinpointing problems at the factory. These could be clearly marked on the pcb with some troubleshooting instructions.

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Update I was looking at the schismatic to do minor cleaning such as repairing faded line and hard to read number. I think the schematic has earlier version of sound circuit that wasn't used in 3 of my Lynx II's (my 4th one with new LCD is not coming apart for now)

 

I was at R17 and R18 (by stereo headphone jack), it seems to look like both are 50k on schematic but when I looked at the board, both resistors have code 103 which is 10k and those 2 did not go to headphone jack. The 2 resistors that did connect to headphone jacks are 50k and numbere+-d R22 and R23. Also my board has 2 LM396 op amps U5 and U12, when the schematic shows U12 has NJM2073 dual op amp. So far it seems only the audio section are different on my board than from schematic. It appears that both LM396 are used for stereo sound to the headphone jack, and are fed directly to the speaker when there's no plug. No additional op amp are used, which would explain a lot why all Lynx 2 I've heard has shit sounding speaker. Maybe I'll grab an extra LM386 and wire it according to original schematic then to the speaker to see if I can make it sound more like older Lynx.

 

On my board which has model number C104424-001 is slightly different than schematic C104247 so heads up if you have different revisions. From what I can tell, C104424 only differs in the sound section.

 

Going to see if I can draw the alternate sound circuit with 2 op amps.

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tjilniF.jpg

 

I couldn't find out if anything connected to pin 2 of either op amp without removing the chip and I don't have a dead Lynx to "ruin" so the schematic may be off but I got most of the parts identified and connected. As I suspected in my versions the speakers are directly connected to the headphone jack with no additional boosting. When I get the time and money I'll get parts and duplicate the missing op amp circuit and see if I can make my Lynx rock.

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