What's new
By:
Filters

Sentinel Supergun - Prototype

Frank_fjs

Frank_fjs

Multi Boyz 4 Lyfe
Legendary
Multi Boyz
Joined
Mar 3, 2018
Messages
3,410
Reaction score
5,839
Location
Australia - Adelaide
Hi all,

Just thought I'd showcase the current progress of my supergun. My intent is to offer a middle range product at a bottom range price. My opinion is that my supergun is beyond that of similar units such as the Vogatek, Mak-Strike, Retroelectronik but beneath that of the HAS. Basically somewhere in the middle.

Specs:

Powered by a 20/24 pin ATX PSU. Pico ATX works fine too. Can also be powered via a traditional arcade PSU via an additional harness. Switch to power on/off.

Onboard negative 5V generation. Toggled via a switch to enable/disable.

Voltmeter with switch to toggle 5V/12V readings.

3 x LED's to indicate voltage presence and serve as a power indicator. Red LED for 5V, yellow for 12V and white for -5V.

RGB scart video/audio output via Sega Mega Drive 2 cable. Composite video and audio output via RCA. S-video output.

Mono/stereo switch. Audio attenuation with a switch to enable/disable. Bridged mono or stereo audio can be output via either scart or the onboard RCA's.

Individual RGB knobbed trimpots.

Switch to toggle attenuated sync or TTL.

RGB buffered via THS7314.
Sync buffered via LM1881.

Coin/test/service tactile switches.

Kick harness connector.

Onboard Neo-Geo controller connectors x 2.

Optional Snes to Neo-Geo controller adapter.
Mega Drive to Neo-Geo controller adapter currently in development.

Performance wise I'm very happy. RGB is as stunning as you would expect. S-video is fabulous, in fact if I didn't have RGB capable monitors I'd be more than happy sticking with s-video. Composite video is good with room for improvement however perfectly fine as is. I've tested on a wide range of CRT and modern LCD displays without issue. Also tested with a Hydra scart switcher, RGB to YUV and RGB to HDMI encoder without issue.

Audio is clear and I've not encountered any issues.

Have ran a variety of boards through it without issue. E.g. Neo-Geo, CPS1, CPS2, Atomiswave, PGM, STV, F3, System 16, 60-in-1 and a variety of other boards such as Robocop, Shadow Warriors, Double Dragon etc.

Excuse the crappy soldering, threw this one together very quickly as I was on my way out.

Anyhow I think that covers most of it. Let me know what you think. Not ready for production or sale as of yet but hopefully soon.
 

Attachments

  • Sentinel-Proto.jpg
    Sentinel-Proto.jpg
    920.4 KB · Views: 6,629
Also would the svideo/composite board be detachable?

Would like to try one out with the snes adapter and 8bitdo controllers :)
 
Sounds nice! A few things that might not matter:

1. Could you use a jumper instead of a switch to disable attenuated audio, to make it a little harder to disable? This prevents people breaking their gscartsw by flipping the switch.
2. 7314 is an excellent choice, but maybe consider upgrading that to 7374 (with the low-pass filter disabled) or 7316? Those would give sharper/cleaner RGB.
 
Last edited:
Please remember that properly built Genesis 2 cables have 75 Ohm resistors on the RGB lines. This has caused many issues over different products. I recommend switching to a different MiniDIN, such as the one the Framemeister uses.
 
Yeah, it seems like mini DIN-8 is the new standard. That allows people to use any componentless cable like this one and it avoids confusion with all of those cables that have various resistor schemes inside.
 
Yep the video hat is detachable.

Originally I used a Neo cable as it doesn't contain any components inside the cable. Only thing I disliked is that by default they don't cater to stereo sound and the PCB connector is rather large.

I switched to MD2 as the connector is compact (important as the video board sits above it), it caters to stereo sound, is readily available and I need those 75R's anyhow.

I love the idea of a mini 8 DIN but they don't seem to be as readily available and I can't be bothered having to make cables.

There's 3 x SMD 75R on the sgun but they don't connect to the MD2 DIN, they're for the composite video board.

Good idea re the audio attenuation switch. I will definitely change this over to a jumper. I've not encountered an issue with attenuation enabled however have heard that some boards nay not work with it so figured an option to disable it is needed.

Originally I was using the 7374 but it seemed like overkill. 7316 would be easy to change to. I do like the 7314 as they cost less and the image still looks great. I shall experiment.
 
Re pricing, this hasn't been finalised but this is what I'm aiming for.

$70 Base unit.

Just the supergun board without negatron, video hat or any cables.

$130 Deluxe package.

Supergun board with:
4 x PCB feet
Negatron
Video Hat
Arcade PSU adapter
CPS1 harness
CPS2 harness
Snes adapter x 2

I'm contemplating using a mini 8 DIN for the RGB scart output. Guessing I'm best using the attached pinout?
 

Attachments

  • images-9.png
    images-9.png
    15.3 KB · Views: 2,233
As I mentioned over on AussieArcade, I'm pumped for these because I want some good but more budget superguns for my 4p Gundam setup :)

Some notes:
- If someone knows a good place to get mini 8 DINs let Frank_fjs know!
- Please listen to RetroRGB and SmokeMonster, I think you are so close to making something amazing, don't screw up the last mile!
- I am interested in some things in the "deluxe" package, but not others. For example, I don't care about SNES adapters or the Arcade PSU adapter but I want the other things. Maybe be more modular?
- I'm sure you have already, but make sure your pinout is the undamned db15 one! Also some superguns fried undamned's adapter, so whatever caused that make sure it's not an issue on your board!
 
Getting the mini 8 DIN PCB connectors isn't a problem. My main concern is the cable as they're not as readily available to purchase. The OSSC has scart input now and doesn't even utilise a mini 8 DIN. It's the future of upscaling and I'm not really interested in supporting legacy devices such as the XRGB etc. So I'm left wondering if the mini 8 is the best choice? I really don't want to have to assemble my own video cables. At least with the MD2 scart cable they can be purchased anywhere and RetroGamingCables have an awesome high quality packapunch version. Thoughts people?

Will definitely listen to all advice offered! I will change the 7314 to a 7374 and incorporate a switch to enable/disable the low pass filter. Maybe it's just best left disabled possibly no need for a switch? Thoughts?

Re pricing, the deluxe package just represents all available accessories at a bulk discount price. Naturally I will list individual pricing and allow people to mix and match.

Re DB15 pinout, yep mine is identical to Unfamned. It's the most logical choice if you examine the existing Neo standard. This means you can use any Neo controller or with my Snes adapter, any Snes/8Bitdo/PS/Xbox/Wii wireless controller. Add an Undamned adapter for even more controller options. Doesn't get much for versatile than that! Oh and don't forget I'll have adapters for 6 button Mega Drive controllers soon.

P.s. my board won't fry the Unmanned encoders. I believe the earlier Mak-Strike boards were responsible for this due to an incorrectly wired power switch.

Part of the reason I decided to make my own sgun. Having owned several others and never being happy with their performance.
 
It's great that you're taking feedback, thanks for keeping an open mind. That's a killer price too, for both packages :D

A switch for the 7374 low-pass filter could be a cool option if it's cheap on your side to include. Most of us would leave it disabled, but there may be people who would want that smoother look it gives. I guess this subject is pretty complex though, so hopefully I'm not giving bad advice!

Genesis RGB cables are readily available, but you'd have to figure out how to handle the fact that they usually have 75ohm resistors in them. So you'd have to make the Sentinel's RGB output out of spec to accommodate the cable probably, which would be kind of a bummer.

Here's a £5.99 passive DIN-8-to-SCART break-out cable that would do the trick, and those retroaccess cables I linked are what a lot of use with our HAS.

Keep up the great work!
 
Last edited:
Awesome work as always @Frank_fjs, definitely down for one when they are ready.

I think keeping the MD2 cable for accessibility and affordability is a good idea.

Yeah, they had issues with the PC Engine Super SD System 3 and Mega Drive 2 cable, but those issues were ironed out I believe, and with proper Beta testing / or a shortlist of recommended cables, it's not going to be an issue.

I have the MD2 Packapunch cable, and I'm sure many others would have the same.

Thumbs up mate!
 
Interesting and I’m following. Can you list out what makes this under the HAS?
 
Hey @SmokeMonster

Can you elaborate on the 75R issue? Maybe I'm missing something but the resistors are required either way, so what does it matter if they're on the PCB or inside the cable? I.e. the THS amps expect a 75 Ohm resistor on the output lines for correct impedance. Ultimately I suppose it's technically better to have them on the PCB closer to the IC however I've not heard of any issues with them being at the other end inside the scart connector of the video cable. Long story short, why do you oppose the MD2 cable?
 
Oh, it's completely up to you. I don't oppose the cable, and in the end you need to do what's most practical.
 
Haha sorry, just trying to establish if there was an issue with the MD2 cable that I was overlooking.
 
I'm just confused and hoping I'm not missing something is all, re the MD2 cable and its internal 75 Ohm resistors. Just to clarify, the resistors are definitely required so it's just a question as to whether they're routed from the THS amp output pins to resistors on the sgun PCB or if the sgun pcb omits the resistors and relies on them being incorporated into the scart cable. Either way the end result is the same so it won't be out of spec.

Actually the resistors will be populated on the sgun pcb either way as I need them for the RGB to composite video conversion. Just a matter of whether I bypass them with the RGB MD2 DIN output, which is what I'm doing now.

Perhaps I'm reading too much into it and maybe people mentioned it just as a heads up. Would rather be safe than sorry though.
 
xtrasmiley said:
Interesting and I’m following. Can you list out what makes this under the HAS?
Click to expand...
I can't outperform @RGB design and knowledge. His supergun is extremely well executed and he's thought of everything. His button mapping feature is insanely great. HAS also has a single pot for brightness where I'm using 3 separate pots. Other than that I would speculate that he's handling video and sync more thoroughly. Just good design choices all around matched with high quality components and upper end PCB manufacturing options.

He's definitely inspired me to raise the quality of my supergun to another level. Nothing but respect for the best.
 
You must log in or register to reply here.
Back
Top