NESRGB board available now

[RGB32E]

Tim addressed several items on page 57:

http://shmups.system11.org/viewtopic.ph ... 46#p992446 - Mentioning to add an electrolytic capacitor ~100uF to the 3.3V regulator circuit. Anyone tried this to improve the stability of the 3.3V regulation?

http://shmups.system11.org/viewtopic.ph ... 81#p992481 - A number of items. He mentions already having a series resistor in place on CS# for compatibility with 75ohm inputs. The SYNC input pin on the XRGB-mini's RGB input has a 75 ohm resistor to ground. Sounds like increasing the series resistance might improve CS# compatibility with certain NES HW when using with the XRGB-mini.

[keropi]

@pasky

thanks again, I'll wait for someone to calculate the R1,R2 values and give it a try , I lack the knowledge to find them on my own

@RGB32E

I did try adding a cap on the 3.3v regulator, made no difference for me

[lettuce]

I also only have Akumajo Densetsu.

After some tuning by ear, I found that I like to run the NES audio through a 1k ohm resistor and the Famicom audio through a 150 ohm resistor. I don't know what mvsfan is talking about. I don't think you'd be able to hear anything from the famicom audio if you ran it through a 41k resistor.

Artemio, I'd be interested to see what you find from your scope tests.

I did a test a while back, with a 22k and also a 47k resistor....

https://www.youtube.com/watch?v=1GUygyhNw-Y

[Artemio]

Edited to add easier access to ths information

I decided to test the 100kohm resistor as recommended by Tim, here are the results. I soldered the resistor directly to the capacitor, as indicated by the diagram.



I then covered it with thermofit, and after listening to Akumajo Densetsu in both systems, I was quite pleased with the results. I tried games without the extra channels and they had no extra noise I could notice.



Here are line level recordings of the first 2 minutes from my Famicom and my NESRGB. The famicom has lower volume, but they are unaltered raw recordings.

Famicom: https://dl.dropboxusercontent.com/u/140 ... level.flac

NESRGB via 100kohm resistor: https://dl.dropboxusercontent.com/u/140 ... level.flac

Here are both signals zoomed in, their phase is inverted but as you can see they are very close to each other. The relative levels seem to be quite close to me.



This is what you get if you invert the phase of one and compare them:

[Pasky]

Now that's some proper experimentation. Awesome, thanks for the information.

[rCadeGaming]

BTW, did you read Villetim's response? http://shmups.system11.org/viewtopic.ph ... 57#p964957 he recommends a 100k resistor and then mix it to C31 in the NESRGB (not the O point), based in the theory and differences between systems.

No, I either didn't see that or it was months ago and I forgot, thanks for pointing it out.

I get it now; there are two methods of mixing in the extra audio, before and after amplification. The method I tried mixes after amplification, whereas mixing it in before requires dropping the extra audio down to line level, hence the much higher value resistors used.

On p.20, Tim says to run the extra audio through a 100k resistor, dropping it to line level, and then mix it in prior to amplification at the point identified by Artemio. In this post, he also mentions that the key to reducing noise is to keep the resistors physically as close to the mixing point as possible, so that the signal doesn't travel through a long high-impedance path which can act as an antenna. That should probably apply to either mixing method.

Then on p.23 cr4zymanz0r says that he's found a better method, that mixing the audio after the amplification eliminates noise because the noise in the extra audio doesn't get amplified. Then on p.28, Skips says that post-amp mixing doesn't actually eliminate the noise, and that we should just follow Tim's original instructions (maybe cr4zymanz0r missed the point about keeping the resistors close to the mixing point?).

Also, the alternate suggestions for resistance in pre-amp mixing (like 22k or 47k from Skips and Lettuce) seem to come from users with NES or Famicom Everdrives, which don't put out as strong of a signal as a real Famicom cart (although I still don't understand mvsfan's post on the previous page, which seems to suggest running the extra audio through a 41k resistor for post-amp mixing. That would result in the extra audio being... inaudible).

Anyhow, I'm going to try pre-amp mixing now and compare noise between the two methods. Artemio, I'll use 100k as a starting point, and see how adjustments sound from there. It certainly seems to be the correct resistance for an equal mix based on your proof. I'm just going to see if I prefer an equal mix or biasing it toward one channel or the other. Thanks for your work.

Artemio and Pasky, how much did your scopes cost you? I could really use something like that for video work.

[Ed Oscuro]

My guess was that Pasky has a Rigol DS2072...maybe. Artemio is using a software program on soundcard capture, I think. But I still second the question!

[Artemio]

I have a Tektronix TBS 1024, shame on me. If I had done some research I'd bought a Rigol, but in my defense I jumped at the opportunity when I had the chance to get one from the US brought by a friend. I had little time and jumped by the brand I used to know.

But yes, the images from my previous post are screenshots of Goldwave, an audio editor. Due to the limited memory in my scope and the nature of this case - audio - I rather digitized the sound with my old M-Audio192.

The scope has served me well though, I've been able to repair a few dozen PCBs thanks to it. Not to mention, learned a lot in the process.

[Pasky]

I've got one of the first revisions of the DS2072. It's firmware updated (keygen'd) to a DS2202. It's a 200MHZ scope with all the trigger modules enabled. I don't have 200MHZ probes though, although considering getting some. Had I known about Hameg's when I was looking for a scope, I'd have gotten one of those instead. Definitely not disappointed with the rigol though.

[darcagn]

I decided to do another NESRGB install, this time with a multi-out connector on a front loader NES. I used the 3D printed multiout connectors for sale at AssemblerGames by Helder/BuffaloWing. Here are pics of my new install. The audio setup is a little weird, because the 20k and 12k resistors on this board got damaged a few months back, so I actually have wires with 20k, 12k, and 47k resistors connected together, heatshrinked, and connected directly to the capacitor at the beginning of the audio circuit. I have also removed the expansion slot connector to make the install cleaner, and upgraded the voltage regulator to a 1.5amp regulator. All I can say is my recent Hakko 808 purchase was very much worth it.

To-do: Find a suitable spot I like for the palette switch, and remove the caps on the NESRGB board that are in my SCART cable already...

Spoiler

While doing the installation, I also temporarily soldered a small wire from the output to an RCA jack, which I used to connect my receiver temporarily to do some experimentation.

I disconnected the jumper from the NESRGB to turn it off, and I played with composite from the standard NES output, but used the RCA jack I connected to the NESRGB for audio. I also disconnected all the wires from the NESRGB except the audio wire to the RCA jack. I did this to eliminate the possibility of noise related to the video hookups during the experiment.

While the system was running, I had it open, and I manually connected and disconnected the expansion audio wire to the pin 9 point.

While using the Everdrive N8, there is terrible amounts of noise when expansion audio is connected, whether the game being played uses expansion audio or not. When expansion audio is disconnected, there is still noise, but not that bad unless my receiver is turned way up.

When playing an NES game (none of which have expansion audio, of course) on an original cartridge, there is absolutely no audible difference in connecting or disconnecting the expansion audio wire. There's some buzz, but it's not bad unless my receiver is cranked up high.

So basically, if you're using an Everdrive N8, there's going to be a lot of noise with expansion audio, and from what I can tell, there's nothing you can do about it. What I may do is cut the trace to the expansion audio inside of the Everdrive N8 cartridge, and rig it up to a switch so that I can turn expansion audio on/off on the actual Everdrive cartridge itself, since it's actually the Everdrive that's causing so much noise, at least in my setup. That way, I won't have to mod the console further and I can only turn on expansion audio when I really want it (which is only really when playing Akumajou Densetsu). It seems like overkill but honestly I like playing games loud and the buzz at high volumes is pretty annoying.

[ApolloBoy]

Why are the screws for the multiout glued in? You're supposed to use nuts for securing them.

[darcagn]

Why are the screws for the multiout glued in? You're supposed to use nuts for securing them.

They aren't glued in, the connector is just epoxied to the case for reinforcement, and the screws actually thread into the holes.

[Voultar]

Why are the screws for the multiout glued in? You're supposed to use nuts for securing them.

They aren't glued in, the connector is just epoxied to the case for reinforcement, and the screws actually thread into the holes.

Sigh.. That's a fine install. The epoxy is a nice touch, as long as you never intend on removing the Multi-Out. It will keep the flexing down.

Well done!

[CkRtech]

Finally got around to fixing all of my minor issues.

This board truly is jaw-droppingly awesome. Suddenly all of my NES cartridges are in danger of being loaded up and gawked at on the big screen.

[ms06fz]

Finally got around to fixing all of my minor issues.

This board truly is jaw-droppingly awesome. Suddenly all of my NES cartridges are in danger of being loaded up and gawked at on the big screen.

I am jealous. I'm still waiting for more boards to be available so I can get in on this...

...And hopefully not wreck the circuit traces on my AV Famicom when I remove the PPU...

(I guess I could play it safe and cut out the PPU from the Famicom, and desolder the one from my NES to replace it... But I dunno, I just think I'm better than that.)

[darcagn]

Why are the screws for the multiout glued in? You're supposed to use nuts for securing them.

They aren't glued in, the connector is just epoxied to the case for reinforcement, and the screws actually thread into the holes.

Sigh.. That's a fine install. The epoxy is a nice touch, as long as you never intend on removing the Multi-Out. It will keep the flexing down.

Well done!

Thanks! And yeah, it's solidly connected. There's no way it's coming undone or even flexing now.

I ended up cutting the trace to pin 54 on my Everdrive and wiring it up to a switch. Now I can turn off expansion audio from the Everdrive cartridge itself, and avoid the audio noise of it unless I'm actually playing an expansion audio game.

[TheRetromancer]

I am jealous. I'm still waiting for more boards to be available so I can get in on this...

...And hopefully not wreck the circuit traces on my AV Famicom when I remove the PPU...

(I guess I could play it safe and cut out the PPU from the Famicom, and desolder the one from my NES to replace it... But I dunno, I just think I'm better than that.)

*Winces*

Please don't hack up your PPU. Get a proper desoldering iron like the Hakko 808 - when I threw this mod into my AV Famicom, it took about five minutes (maybe less) to pull the PPU out, and there was absolutely no damage whatsoever.

Remember, always use the proper tools.

[darcagn]

I am jealous. I'm still waiting for more boards to be available so I can get in on this...

...And hopefully not wreck the circuit traces on my AV Famicom when I remove the PPU...

(I guess I could play it safe and cut out the PPU from the Famicom, and desolder the one from my NES to replace it... But I dunno, I just think I'm better than that.)

*Winces*

Please don't hack up your PPU. Get a proper desoldering iron like the Hakko 808 - when I threw this mod into my AV Famicom, it took about five minutes (maybe less) to pull the PPU out, and there was absolutely no damage whatsoever.

Remember, always use the proper tools.

Indeed. And if you don't think you're up for the task, please don't destroy any hardware to cut corners--it shouldn't be too hard to find someone who would be willing to do it for you, the right way, without destroying a finite resource like classic game consoles.

[ms06fz]

If you cut a DIP IC's pins, the chip isn't destroyed. New pins can be attached. Ugly perhaps, but perfectly functional.

That said, I have no intention of going that route anyway. If I can't hack it with the tools I've got, I'll visit my local hackerspace and use their tools.

The "cut the pins" thing was a recommendation I saw a few years back when I first got interested in doing a Playchoice PPU mod. It was said that there was a particular danger of wrecking the motherboard of the AV Famicom when extracting the PPU. If it really were one or the other, it'd be better to cut the PPU pins rather than wreck the main board. Though this was also for a mod that completely replaced the PPU anyway...

[lettuce]

Does anyone know where i can source a row of the pin sockets that you solder onto the NES PCB please (the sockets that you plug the NESRGB into)?

[ms06fz]

Does anyone know where i can source a row of the pin sockets that you solder onto the NES PCB please (the sockets that you plug the NESRGB into)?

Sparkfun has machine-pin sockets and headers. You can also get 'em at Mouser or Digi-key, I'm sure.

[Pasky]

Pretty ridiculous price for 3.95 for 1.

http://www.ebay.com/itm/10PCS-Strip-Tin ... 2ec80e7e14

10x 40 pin rows for $6.

They come in different quantities for much cheaper on ebay. Just depends if you dont mind waiting a week and a half for them.

[ms06fz]

Yeah Sparkfun's for convenience, not for price.

[lettuce]

Thanks, dont mind waiting a week or so

[TheRetromancer]

Yeah Sparkfun's for convenience, not for price.

Yeah? Well, I'm finding the prices totally INconvenient. Pass like a tiny kidney stone.

EDIT: Wow, now that I look at this, I sound totally douchey. Not my intention.

[ms06fz]

Yeah Sparkfun's for convenience, not for price.

Yeah? Well, I'm finding the prices totally INconvenient. Pass like a tiny kidney stone.

Admittedly it wasn't the best suggestion... *shrug*

[CkRtech]

Get a proper desoldering iron like the Hakko 808

That is kinda like telling someone that needs a car instead of a bike that they should go buy a Ferrari. Unless anyone here that is considering purchasing a Hakko plans on having many more projects in the future, it would be easier to just pay someone else to do the mod work for them or purchase other, cheaper tools out there that will do the same job as the Hakko and simply take a bit longer.

[TheRetromancer]

Get a proper desoldering iron like the Hakko 808

That is kinda like telling someone that needs a car instead of a bike that they should go buy a Ferrari. Unless anyone here that is considering purchasing a Hakko plans on having many more projects in the future, it would be easier to just pay someone else to do the mod work for them or purchase other, cheaper tools out there that will do the same job as the Hakko and simply take a bit longer.

Eh, not quite an accurate metaphor. Expanding on your example, I would say it's more akin to telling someone that needs a car instead of a bike to buy a new 2015 All-Electric model instead of a 1980s-era used model.

In my opinion, the differences between our respective statements is that I view the Hakko as a high-quality product that is purpose-built to be useful in all of its applications. Where your example breaks down is that a Ferrari, despite being high quality vehicle, is a luxury vehicle, with most of its pricing being dependent upon only its aesthetic appeal, not being derived from its actual usefulness.

Is the Hakko 808 expensive? Sure. Quality is always going to cost you. But think about this - what is it worth to a person to free them from the fiddly annoyance of using desoldering braid, desoldering pumps, or any of the other, cheaper methods of desoldering through-hole components? Is it worth a one-time payment of about $200 to cut down desoldering time by 80% or more for the lifespan of the device? I've had my 808 for about a year, and unless this thing shoots my dog, sleeps with my wife, and punches me in the face, I'm never going to get rid of it.

Naturally, the end decision is up to the individual user. It's worth it to me. WELL worth it, in fact. I will always encourage others to take the path I've gone, because I truly believe the investment is worth it, and as a somewhat nice guy, I want to give others the benefit of my experiences.

Here endeth the lesson.

[Ed Oscuro]

People considering getting a Hakko could wait until the new model is properly released in hopes that prices on the 808 will fall. It won't help me any, but on the other hand I can't say I regret my purchase either (it's too bad the new model will heat up so much more quickly, but the old model is fine - and lighter).

[Pasky]

I don't think the price on 808's is going to drop at all if any (maybe used ones). The Fr-300 will be priced much higher new (I think it's $250+) opposed to the 808 at $170~. THe fr-300 has already been released in Europe iirc.