I started off using this page: https://circuit-board.de/forum/inde...e/?s=57e20125a860dd0b9153c2a4c85b17ebf0b8a076
It's in German but you can translate it to English. basically it's a hack to make better 5v regulation for Atari Lynx handheld systems. The current factory design is a zener diode and a transistor in emitter-follower design and it is somewhat hazardous. Because there is nothing to separate unregulated voltage from 5v regulated voltage, if one of the 2 part failed it will dump unregulated voltage (around 9v) and that can fry other component. Obviously the factory warranty expired some 25 years ago and replacement working Lynx isn't cheap. So preemptive measure would be needed to keep my old game systems working for another 25 years.
The Germans at the forum changed the circuit and used either 7805 regulator or smaller switching chip like LD1117S50TR
I have modded 3 of my Lynxes with the LD1117 series chip. It is small and its form factor fits exactly where the 2 SMD diodes used to be. But I did find one oddity: The Lynx that has original LCD are working fine. The one Lynx I have with new LCD from (https://atariage.com/forums/topic/233632-lynx-lcd-replacementvga-out-by-mcwill/) does not work.
I was probing and I noticed when Lynx powers up, I got 5v on the output for a few seconds then it dropped to around 3.5v before it shut down due to power failure. I swapped for another LD1117 to rule out defective chip, I still got the same result, and I even tried a known good one from my other Lynx. The one I took off my LCD modded system was installed in other Lynx and it worked fine so all the LD1117's I have are working fine. I swapped it for a less efficient 7805 and this time the LCD modded system worked fine. The 5v output never went below 4.95v.
The original Lynx I have with the volt mod draws about 280mA at most. The new LCD peaked at 170mA (the absence of original CCFL is a big factor) so it is not due to over-current or heat. LD1117 series is rated to 800mA which is more than 4 times needed power for my Lynx with new LCD (and regular 7805 is good to 1 amp). So I am confused why LD1117 is not working with new LCD.
PS would I need a heat sink for the standard 7805 regulator when it doesn't go past 200mA? There's no vent and no internal air circulation inside Lynx so it would get a bit warm. Lynx can run off batteries, up to 9v, or off AC adapter. The one I have has 8.5v when plugged in.
Or is there another 5v regulator that won't get warm, won't drop voltage at measly 200mA, and if possible, something that fits SOT-223 package size? For Atari Lynx, this pinout would work well for SMD soldering to keep things small and neat:
The LD1117 has V-in and GND reversed from the picture and the chip needed to be soldered upside-down to match the pads on the Lynx.
It's in German but you can translate it to English. basically it's a hack to make better 5v regulation for Atari Lynx handheld systems. The current factory design is a zener diode and a transistor in emitter-follower design and it is somewhat hazardous. Because there is nothing to separate unregulated voltage from 5v regulated voltage, if one of the 2 part failed it will dump unregulated voltage (around 9v) and that can fry other component. Obviously the factory warranty expired some 25 years ago and replacement working Lynx isn't cheap. So preemptive measure would be needed to keep my old game systems working for another 25 years.
The Germans at the forum changed the circuit and used either 7805 regulator or smaller switching chip like LD1117S50TR
I have modded 3 of my Lynxes with the LD1117 series chip. It is small and its form factor fits exactly where the 2 SMD diodes used to be. But I did find one oddity: The Lynx that has original LCD are working fine. The one Lynx I have with new LCD from (https://atariage.com/forums/topic/233632-lynx-lcd-replacementvga-out-by-mcwill/) does not work.
I was probing and I noticed when Lynx powers up, I got 5v on the output for a few seconds then it dropped to around 3.5v before it shut down due to power failure. I swapped for another LD1117 to rule out defective chip, I still got the same result, and I even tried a known good one from my other Lynx. The one I took off my LCD modded system was installed in other Lynx and it worked fine so all the LD1117's I have are working fine. I swapped it for a less efficient 7805 and this time the LCD modded system worked fine. The 5v output never went below 4.95v.
The original Lynx I have with the volt mod draws about 280mA at most. The new LCD peaked at 170mA (the absence of original CCFL is a big factor) so it is not due to over-current or heat. LD1117 series is rated to 800mA which is more than 4 times needed power for my Lynx with new LCD (and regular 7805 is good to 1 amp). So I am confused why LD1117 is not working with new LCD.
PS would I need a heat sink for the standard 7805 regulator when it doesn't go past 200mA? There's no vent and no internal air circulation inside Lynx so it would get a bit warm. Lynx can run off batteries, up to 9v, or off AC adapter. The one I have has 8.5v when plugged in.
Or is there another 5v regulator that won't get warm, won't drop voltage at measly 200mA, and if possible, something that fits SOT-223 package size? For Atari Lynx, this pinout would work well for SMD soldering to keep things small and neat:
The LD1117 has V-in and GND reversed from the picture and the chip needed to be soldered upside-down to match the pads on the Lynx.
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