u/StrangeRetroRob

I'm trying to piece together a timeline on early board revs. To do this, I need as many examples of those motherboards as possible so I can start to note the date codes of the chips on the board and correlate it with other publicly available information

Many links are unfortunately dead when I research on older websites and forums and blogs. And when the links are not dead often the pics themselves are

To read the date codes on the CPU and ppu, generally you just need to see the first number and the second character

3M3 = 1983, December (M is the 13th letter of alphabet, I is skipped), 3rd week

We know the square button recall happened sometime around early 1984 but we don't know how many boards were already manufactured before the recall occurred. Also the recall was voluntary.

The first known E revision cpu chips were released around October of 1984. (https://www.nesdev.org/wiki/CPU_variants) While then first known E rev ppu were released December of 1984 (https://www.nesdev.org/wiki/PPU_variants)

By that time, hvc-cpu-07 boards were already in production with the earliest 07 boards having D rev PPU and often with Rockwell produced e rev cpus

But i have heard rumors of 06 boards with E rev chips, so it would be interesting to know how much overlap there is or isn't on this as well

Here are boards I have or can find online, but I am hoping some of you are able and willing to share your pics in this thread also.

This is an Asder nt-102. The NoaC was no longer working properly, so I decided to swap the motherboard to this brand new one with discrete components

The swap wasn't too difficult. I had to desolder the RCA and DC jack off the new motherboard and put them on the extender board, then desolder the 15pin connector from the original motherboard to install on this one. I added the power led to the rear panel and plugged the controllers in and soldered the power switch and it was done

Video output is very good. Audio is clear. However these are clone chips still, not authentic Nintendo ones. Still it makes for a much better clone than it was.

Almost CIB DY-636-190, the original 72pin cart is missing but everything else is here

Reminder in the last photo, don't store your cables without a plastic bag or some newspaper or something

I bought this nes-101 top loader recently as I got a good price since it was untested. As it is RF output only, I had no way to test it with my European television and I basically knew I was going to composite mod it anyway

It now has a few nice mods. The [squeeki kleen video mod](https://github.com/Gumball2415/squeeki-kleen-Video-FC) and [squeeki kleen audio mod](https://github.com/Gumball2415/squeeki-kleen-Audio-FC) are doing most of the heavy lifting here

While the stock console isn't known for producing the best video, the mod board I am using really clears up most of the visual issues caused on the stock boards bad signal routing. The result is a noise free jailbar free image.

On the audio side, I could have simply tapped the 3rd pin of the original RF module and gotten audio that way, and you can even patch in expansion audio by bridging cart pin 51 to that same audio pad using a 1.2k resistor and a 100ohm pulldown. However, I went a completely different route because there is no on board amplifier on the nes-101, and the board routing isn't very good and thus has a lot of noise that comes across in the audio. This audio mod taps the CPU pins 1 and 2 directly, and uses the same 12k/100ohm + 20k/100ohm setup the original Famicom does, but sends it through an actual opamp rather than a hex inverter that's also processing inputs like the Famicom does. This results in a very noise free audio output. However, the mod is designed with famicom in mind, and thus expansion audio was not a consideration with it.

the way I patched in expansion audio was by mimicking the way the NES front loader patches it in, and I am using 67k resistor (47k+20k, 68k would also work well) and a 1k pulldown resistor and sending that to where the CPU1/CPU2 audio channels merge, just before the 1uf capacitor before amplification. I tried outputting directly to the RCA jack like standard top loader mods do, but it just didn't work with the squeeki kleen for some reason. Even though we call the normal NES mod, 47k mod, on the normal signal path of a front loader that 47k resistor bridges the expansion audio output from the cartridge into the "audio IN" circuit, which has a 20k resistor in it already. So by mimicking this configuration using 67-68k resistance, I can use the Everdrive N8 Pro "47k mod" preset for "correct" audio mixing without adjusting mappers for different games

I swapped the capacitors for solid polymer and ceramic ones, as well as I added the following extra filtering and bulk

C6, C12, C27-38 - 100nf. The stock caps here are 10nf radial ceramics, I added MLCC to the bottom of these existing caps. They are all 5v decoupling caps for the different ICs

C33=10uf x7r mlcc. This is the primary decoupling cap for the CPU (was not done for ppu since the mod board does this already)

Output is via 2 RCA connectors, like the front loader, red and yellow. To route my coax wire I used the empty holes from the RF module, which I had to open up a little bit with a file to fit my wires.

The console was also completely cleaned up with all the elbow grease I could find. Literally just rubbing the grease off it with my thumb, a toothbrush, and a tiny bit of dish soap. And the RF shield shined up a bit with "scratch less steel wool" not scratchless, but just scratch *less* hehe

The install photo is missing the SL3/SR3 outputs for passthrough Sega CD audio as that was installed afterwards and I forgot a pic

The sound is incredible and I'm glad to finally have the full tower of power with perfect audio

The video is also really good from this Sony cxa2075

The only thing it's really missing now is my card support which I can play off my new Trifffcart anyway :)

Encoder is a bh7236, basically my favorite encoder since it was officially used by Sega and it's still easy to obtain (a lot of cxa2075 are fake)

I don't know why I didn't take before pics since this is a rare console, but I will describe to you a few issues it had

When I first powered it on, the TMSS screen had obvious rainbow coloring in the white text, with a slight push towards yellow which I've never seen on any other mega drive before. The yellow push ended up being related to capacitor c24 being bad, the primary decoupling cap for the stock mb3514 encoder. Second, the cap is only 10uf and it should be 220uf

Now the mod

I removed the mb3514 and replaced it with my favorite encoder, the bh7236. This encoder is a cxa2075 clone, however it is an encoder which was actually used in some official mega drives. Some pal MD va4, made in Philippines, use this encoder. Whereas the cxa1645 was the best Sony encoder used in a MD, that encoder is more complicated to set up and doesn't provide as good of results as a cxa2075/bh7236 does. Also cxa2075 doesn't have a sync out and bh7236 does

To set up the bh7236 it really only needs a few things.

1. This encoder does not provide a 2v vref, which is required by the power on reset circuit or the system will not be stable. Therefore, you must recreate 2v at capacitor c38. To do this, I used a 150k and a 100k resistor to make a voltage divider and connected its output to the positive pin of c38. (Pin 24->100k, pin 12->150k, then connect pin 14 to both of the resistors)

2. I lifted the unnecessary/not connected pins to prevent any possible nterference by the existing board components, because sometimes NC means internally not connected while other times it can actually be test pins.

3. I set up a new external ytrap. This is what this post shows. Each picture is a 29pf/68uH ytrap followed by a 24pf/82uH ytrap. These two values provide color frequency cutoffs just barely above the NTSC sub carrier frequency. For pal you would want different values (see below). For the best results, I needed to add these components completely off board, so the first image you see isn't actually the final setup of how I did this. When I tried adding the capacitor and inductor on the motherboard directly I still ended up with a lot of rainbow coloring, which was gone once I put the components directly on the encoder instead of mainboard

The images I used are meant to highlight the differences in rainbow/fringing, sharpness/edge crunch, and text legibility

The pics aren't perfect because I took them in the daytime, using a phone that loves to mess with the pics after I take them, and don't have proper screen cap capabilities

Overall I generally prefer the 29pf/68uH combo, but other people prefer the 24/82 setup. And it also depends on the game you are playing

I have played this game way more than I thought I would trying to beat just a single path. It's way harder on sms than it is on other platforms. Way harder

I went all left and beat it with literally no time left on the clock

It was my 2nd of 3 runs for the night. Any time I play I just do one round of each song. This was magical sound shower when I beat it tonight for my first time. Now I need to 100% the remaining parts of the course for true champion status 🍀

Sorry for the repost but I felt like I really needed this title pic rather than the high score pic

This is an old, good quality md2 clone. Technically it is a MD1 va5 clone with MD2 mimicry, because it uses the chipset of TA-04 05 06 07

The shell is good quality fake without many give aways that it isn't authentic

The TA chipset is a good chipset

Video output was ok

But by God the trace layout is bad. They really struggled to make it work and you can tell by the time they added the edge connector they ran out of room for stuff.

Audio circuit was a mess

I added the mega av which mostly fixed the issues with audio but I also found additional issues with the audio circuit. The expansion port was missing 75ohm pulldown on CDL. And the 5v pin of the din connector is supper noisy and was not a good choice for powering the mega av. So I ended up pulling power from another source and adding a 10u+220nf cap for filtering and that helped.

I added 10uf ceramic caps for decoupling all the IC chips since there was a lot of digital noise. That also helped

System was also converted to region free using a manual switch. I actually modded this in december 2025 so I forget for sure which jumper was which

My camera does something slightly funky tintje blue sky which makes it look like clouds appear that aren't there in person. But I think you get the idea. Also my phone may have thrown off the color balance a little

These images were taken yesterday after I added the multi out connector to the system

Today I further improved the ytrap which made it even sharper

This is running at true NTSC clock rate but with a separate 4.43Mhz colorburst clock with the encoder set to PAL and output at 60hz. I could have used NTSC clock but pal provides better color representation.

I picked up this clone which was supposed to be " working perfectly " and long story short it required some work

I did the repairs and then upgraded it with better composite video encoder and added the RGB and svideo output to a newly installed multi-our connector

I bought this Mega Drive clone which was listed as "works perfectly"

It didn't power on when I got it :(

Thankfully it was a few quick fixes. Bad solder joints on the power connector, the din 5 connector, and the entire main board<->sub board interconnector all 16 pins were bad.

After adding fresh solder to all of them the console booted

I added a touch of chrome paint to the 16-BIT logo

I bought this "excellent condition, fully functional" clone and it arrived and didn't power on.

Cracked/bad power connector, bad voltage regulator, bad/blown 1000uf capacitor at the input, dirty 50/60hz switch (distorted video), and a dead cxa1145. 😭.

I fixed it all only to still have a black and white image. I ended up removing and replacing the entire encoder circuit and installed a much better encoder, bh7236. Images are composite output. I haven't yet found the sub carrier pin of the clones PPU chip, so I'm using a separate 4pin osc for 4.43Mhz pal 50 and pal60 output. The console base clock runs at accurate NTSC timing.

Console has pretty good game/cart compatibility. The built in 50/60hz switch is labeled correct inside but the outside shell is for an older model which says stereo/mono

One very annoying thing about the motherboard is everything is reversed. Including the capacitor indicators for negative vs positive, they are all wrong, lol. And the power and reset buttons are in the opposite side of the Mobo from where the actual switches are mounted

Also function restore, but MEGA AV

This shows pretty much everything you need to know about installing it on a G3 va1z although removal of the original encoder isn't necessary, you could move it to the mega av board since the cxa1645 it came with is already really nice. Actually overall the video on this model is nice but now it's better still :)

Original PCEngine, turbonanza mod, and custom made shell printed by jlcpcb

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I left the original blue rubycon installed

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The turbonanza kit is a really nice simple install

I added a Nintendo multiout on this Atari 2600 junior because it was the best way I could think of to fit composite+svid+audio on the shell. The alternative was sticking a dongle or running wires out the back.

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I was originally planning to just run long wires from the leftover RF hole, since the kit shipped with the wires. But unfortunately (or fortunately I guess?) I misplaced them. And I found an SNES svideo+composite combined cable first. Then remembered I had some 3d printed multi-outs available.

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I'm pretty happy with how it turned out

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The cables insert and remove with very little force

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The only difference to account for with the audio on this mod versus the audio setup with 3bp is that you can also fix pass through cd audio by doing the following

On the front of the board near the power switch remove TR1 and TR2. Then run the SL3 and SR3 to pins B27 (Left) and A27 (right) channels of the expansion connector. There are accessible Vias for this

Audio is pretty much perfect now for everything

Also this is a Fujitsu asic, so i set only the jumpers in [ ]