brandorf.com The everyday ramblings of one nerd.

26Apr/13

Making the Retron3 a little better.

Were I live now, I'm fortunate to have what I'm beginning to assume is a shop of a dying breed: the independent video game store. This seems especially true now that GameStop owns pretty much every other game store chain. While poking my head into the one closest to me, I uncovered a little gem from my youth: , the resulting nostalgia bomb was irresistible, but now I needed a console to play on, I haven't owned a Sega Genesis since I regrettably gave mine away to a relative years ago.

While the little shop did have a Genesis in stock (and even a 32x to go with it), this thing caught my eye. The Retron 3 is a clone system that can play NES, SNES, and Genesis games, just the thing for a retrogamer who is running out of A/V inputs on his TV (and it was on sale!). I took the little thing home, with a Sega controller (good, because the "wireless" controllers that came with it were pretty awful) and was shortly afterwards playing a cyborg kick-boxer punching a caveman in the face, awesome.

Eternal Champions for Sega Genesis, at a bargain!

Eternal Champions for Sega Genesis, at a bargain!

The system seemed to work great, for my NES and Sega collections, but things went sour when I tried out one of my few SNES carts; the sound was horribly distorted as can be heard here. It sounds like some serious clipping, like the volume was cranked up too high. Turns out I was right, this was exactly the case: a little more research revealed a flaw with the assembly of the unit's SNES side. For the SNES's audio amp, they used 2.7kOhm resistors, when something like 33kOhm would have been appropriate. Perhaps this was a typo on the data sheet or similar because the resistors in question are SMD, the don't have the traditional color bands a 2.7K Ohm resister is simply marked '272' where as a closer 27k Ohm would be marked '273'. Enough of the electronic lesson, it's clear that the solution is to crack the beast open and give it a transplant.

See the little black rectangles with '272' printed on them?  They are the ones that have to go!

See the little black rectangles with '272' printed on them? They are the ones that have to go!

It's not easy, but you CAN mount standard 1/4" resistors as surface mount.

It's not easy, but you CAN mount standard 1/4" resistors as surface mount.

This seemed like a fantastic opportunity excuse to use my fancy new tool toy : SainSmart DSO203 Nano I'd wanted an oscilloscope for a long time, but being at best a hobbyist, could never justify having a full expensive bench unit. This little beauty is smaller than my cellphone, and let me trace the audio signal to the spot on the board. (In theory anyway, I was pretty new at using an oscilloscope.)

Poking around on the Retron with the scope in analog mode, to try and see where the audio signal is coming from.

Poking around on the Retron with the scope in analog mode, to try and see where the audio signal is coming from.

An example of what the scope was showing while the SNES was running.

An example of what the scope was showing while the SNES was running.

Special thanks to Benheck.com user Ace_1, who seems to be the resident expert on clone systems, for pointing me in the right direction as to which resistors to replace, as I'm still a rookie to using an oscilloscope, it was taking me a while to trace the audio out on the board.

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