Sega Light Phaser to 7800 - Adventures in Fixing Old Crap (PIC HEAVY)

[+DrVenkman]

So a week or so ago I bought a used Sega Light Phaser from eBay with the intention of modding it to use with my 7800, per the simple schematic here:

 

https://133fsb.wordpress.com/2010/05/08/sega-light-phaser-to-atari-xg-1-adapter/

 

I didn't have any female 9-pin connectors for the 7800 end of the adapter, so I used a male, then bought some cheap 9-pin gender changers. Sadly, I seem to have done something wrong and it didn't work. I even went so far today as to start from scratch and built an entire second example. I think one problem is I keep getting thrown off my pin numbering on the front/back sides and male/female ends of connectors. Since the Atari end needs to be a female connector and the Sega end needs to be a male, I am working with two different pin numbering schemes, plus the little gender changer I ordered flips the connector orientation top-to-bottom, making things even more confusing. Aaargh! So this afternoon I ordered a pair of male and female 9-pin connectors with breakout terminals - I'll trial-and-error my way past my pin numbering confusion eventually! 

But along the way, I started to wonder if something else might be going on, so while I wait for the new connectors, I decided to take the Light Phaser apart. Underneath the soldered-on metal light shield on the barrel end, the PCB was kind of cruddy, but that white stuff is only dried, powered flux residue. Cleaned right off with isopropyl. But aside from the ligh shield and magnifier lens, the thing is only a photo diode, a bunch of transistors, a bunch ceramic caps and a couple of nice-quality Tracon electrolytic caps. The trigger switch is a Matsushita that is nice and clicky after all these years, and based on my continuity testing works great. Everything generally looks fine but unless I desolder all those transistors there's no way to be 100% sure. 

So I did the next best thing: since there are only four wires from the connector to the board, plus two wires for the trigger, I tested continuity on those. The switch works and had continuity to the PCB, and Vcc, GND and a signal called TH all have continuity from the plug to the PCB solder points. But a fourth signal, TL, does NOT have continuity to the plug. I even completely desoldered the wire and checked it directly, in case old oxidized solder was a problem. Nope. So I've apparently got a broken wire SOMEWHERE between the PCB and the connector plug. Unfortunately, there's no good way to tell where that might be. Could be at the plug end, could be at the pass-through grommet, where the cord makes a couple tight bends and twists. So tomorrow I will probably cut the pass-through grommet out of the cable and check from each end. I worse comes to worse, I have a brand new spare 9-pin extension cable I can cut one end off of and make a brand new cable. This person had a similar issue at the grommet, so that's where I'll start too.

I will lick this bullshit one way or another. 

 

(I will also add to this thread when my breakout connectors arrive and I'm 100% certain I've got the adapter wired up correctly!)

 

[Jinks]

I bought a sega then looked at my switch and was not an easy fix to get it to work so i bought a xe gun and just aim off to hit the mark as all are inaccurate as hell..

Sega gun gathers dust..

saves lots of headaches. 

[+DrVenkman]

29 minutes ago, Jinks said:

so i bought a xe gun

Have you priced those lately?

[Dopy25]

I have 2 questions because I don't have a light phaser or any 7800 games that support it so this is speculation, but,

 

Have you checked continuity on the cable itself? That could tell you if it's a break in the cable as opposed to a trace, no?

 

Would it be easier to cut the extension cable and add the resistor than to mess around with female/male adapters?

Edited April 18, 2021 by Dopy25

[Jinks]

10 hours ago, DrVenkman said:

Have you priced those lately?

One for 50 bucks on ebay with a xe joystick. That is cheap compared to ones time for screwing with wiring. 

 

 

[+DrVenkman]

8 hours ago, Dopy25 said:

I have 2 questions because I don't have a light phaser or any 7800 games that support it so this is speculation, but,

 

Have you checked continuity on the cable itself? That could tell you if it's a break in the cable as opposed to a trace, no?

 

Would it be easier to cut the extension cable and add the resistor than to mess around with female/male adapters?

Yeah, the cable has continuity on three of the four signals. I noted above that TL - which is the trigger signal - does NOT have continuity from the plug to the PCB inside the gun. So I will have to cut out the damaged section if it’s at the grommet, or replace the cable if I can’t find the break. 

 

As for the adapter, it’s a resistor and transistor that operate as an inverter on the trigger signal. I’d rather get an adapter working so I can keep the Light Phaser itself intact to use with a Sega Master System if/when I ever get one. 

[+DrVenkman]

4 minutes ago, Jinks said:

One for 50 bucks on ebay with a xe joystick. That is cheap compared to ones time for screwing with wiring. 

 

 

Really? I have been checking and haven’t seen one for $50. Got a listing? Because the only listing like that I see is $79.

 

https://www.ebay.com/itm/Vintage-Atari-XE-System-Gun-Controller-Joystick-Controller-both-in-good-shape/402794692993?hash=item5dc86f4181:g:1qsAAOSwSgNgeIqN

 

And maybe you don’t like “screwing with wiring,” but I do. I’ve been taking stuff apart since I was 5 and I’m not going to stop now  

[Bratwurst]

Sega Phaser's supposed to be more accurate than the Atari gun besides, isn't it? I'll be committing to this mod sometime soon hopefully myself, so this thread is of particular interest to me.

1 hour ago, DrVenkman said:

And maybe you don’t like “screwing with wiring,” but I do. I’ve been taking stuff apart since I was 5 and I’m not going to stop now  

A toast, to the spirit of screwing around with wiring!

[gilsaluki]

I have all three variants of light guns for the Atari.  The XG-1 Atari, Sega Phaser, and Best's Light Gun.  All three are inaccurate to the same level.  All the hype about Sega's and Best's light gun accuracy are bunk.  I use which ever one is handy.  For the Sega, I didn't mod the Phaser Gun at all, I just built a simple adapter that reverses the Normally Open/Normal Closed Switch Orientation.  Much simpler to do.  

[+DrVenkman]

4 minutes ago, gilsaluki said:

For the Sega, I didn't mod the Phaser Gun at all, I just built a simple adapter that reverses the Normally Open/Normal Closed Switch Orientation.  Much simpler to do. 

Yeah that’s what I set out to do. But along the way I’ve discovered a broken wire somewhere in the cable on the trigger signal. So I will be fixing that either today or in the next week or so, depending on time and other commitments. 

[+Mitch]

1 hour ago, gilsaluki said:

I have all three variants of light guns for the Atari.  The XG-1 Atari, Sega Phaser, and Best's Light Gun.  All three are inaccurate to the same level.  All the hype about Sega's and Best's light gun accuracy are bunk.  I use which ever one is handy.  For the Sega, I didn't mod the Phaser Gun at all, I just built a simple adapter that reverses the Normally Open/Normal Closed Switch Orientation.  Much simpler to do.  

From what I remember, the Best and Sega guns are consistently inaccurate. As in, the will always hit the same spot, it just may not be quite where you are pointing it. But if you are aware of it, it is not hard to compensate for it. The Atari gun is just all over the place and not consistent at all.

 

Mitch

[Jinks]

3 hours ago, DrVenkman said:

Really? I have been checking and haven’t seen one for $50. Got a listing? Because the only listing like that I see is $79.

 

https://www.ebay.com/itm/Vintage-Atari-XE-System-Gun-Controller-Joystick-Controller-both-in-good-shape/402794692993?hash=item5dc86f4181:g:1qsAAOSwSgNgeIqN

 

And maybe you don’t like “screwing with wiring,” but I do. I’ve been taking stuff apart since I was 5 and I’m not going to stop now  

Oh yeah. I thought that was cad... I have been fixing things forever too. But with this vintage gaming stuff I don't like wasting my time.been there with a coleco(junk)vision also have too many other fixing hobbies. 

 

[+DrVenkman]

14 minutes ago, Jinks said:

Oh yeah. I thought that was cad... I have been fixing things forever too. But with this vintage gaming stuff I don't like wasting my time.been there with a coleco(junk)vision also have too many other fixing hobbies. 

 

To each his own. I started this particular thread to document my efforts in fixing this Light Phaser and building an adapter. You are certainly not required to do anything like it yourself. 

[Jinks]

Best of luck and hope you get it working.

 

[+slx]

On 4/18/2021 at 2:39 PM, DrVenkman said:

Really? I have been checking and haven’t seen one for $50. Got a listing? Because the only listing like that I see is $79.

Darn, I sold a whole boxed XEGS (without manual and joystick) for about the same not too long ago....

[+DrVenkman]

So following up on this -

 

I ended up snipping out the grommet and a half-inch or so of cable on each side of it. After I did that, I checked continuity on the four wires from the internal end up to the PCB and had good signals all the way to the board. Then I did the same from the external side of the cable all the way to the joystick connector. Excellent! The failure was indeed inside the grommet somewhere. So I spliced the conductors together, heat-shrunk them each, then heat-shrunk the entire cable splice. I then gave the little plastic magnifier lens a cleaning, then did the same for the PCB and wiped down the plastic internals. They were all clean but there was a little bit of what might have been some nicotine staining. Isopropyl cleaned it all up easily.

 

I reassembled the Light Phaser, carefully routing the cable around the cable-stays inside the handle and putting a Zip tie around the now-spliced cable since there's no longer a grommet there. After it was all put together, I decided to give things a try with my 7800 - nada. Still didn't work. Frustrated, I put the whole thing away until today. This afternoon, I realized/remembered that the Sega Genesis/Megadrive + my MegaEverdrive multi-cart can also load SMS games. And I just happen to have a pretty good library of SMS stuff on the SD card. So I fired up SMS Shooting Gallery and whaddaya know, the Light Phaser works great after I've fixed the cable.  At least now I'm 100% sure the Light Phaser's internals are all good - the photodiode, all those little ceramic caps, the electrolytics, and transistors are all fine. That's good, as it saves me a crap-ton of trial-and-error work replacing transistors and caps on that little PCB. 

 

That means I've fubared up the little adapter(s) I made before. So tomorrow you know what I'm gonna do, right? Try to wire up another adapter and then finally at long last play Alien Brigade and Crossbow with a light gun as they are supposed to be played. 

[Dopy25]

Sounds like a fun time for sure! Glad you got it worked out. I picked up a light phaser as well and have been working on an adapter. It seems the information you may have found was a tad incoherent. I thought the adapter I made was bunk as well and was driving me nuts, arg.

 

I too had an issue with the cable and a couple of the ceramic caps seem toast. They just look out of sorts. I ordered some replacements based on the schematic on smspower. 3 of them have a white powder on them and look like they've failed. The gun itself did work but super intermittent. I figured out the wiring in my cable was junk but I'm going to replace those caps when they come in the mail. I was able to remove the grommet and replace it further on down the cable. I like the original look of it so I wanted to keep it on there.

 

Enjoy!

[+-^CrossBow^-]

19 hours ago, DrVenkman said:

Try to wire up another adapter and then finally at long last play Alien Brigade and Crossbow with a light gun as they are supposed to be played. 

Alien Brigade really plays best with a light gun and that was how I was able to finally beat the game after I got my XE light gun from Best years ago. Crossbow on the other hand, I actually do better with a controller. Specifically an actual joystick and not a NES gamepad type. This is why I have different controller types on hand. Some games work best with a gamepad controller and others need an actual joystick. CB, I found I could be far more accurate with vs a light gun. Makes it easier to setup the crosshair on a spot and just move left and right to take out stuff that fall along the same line across the screen. Icicles, the monkeys in the jungle, dudes in the windows of the town level...etc. 

[+DrVenkman]

It’s janky as hell but success!  
 

CROSSBOW is a lot of fun, but ALIEN BRIGADE is great with a light gun! I guess I should RTFM and not just shoot everything in sight. ? 

 

I think this summer I’ll finally sit down and learn Kicad or something and make up a PCB for this. It’s a dead simple circuit. It’s only a PITA because of the point to point soldering and keeping the controller jack and transistor pins straight. 
 

 

[+sramirez2008]

4 hours ago, DrVenkman said:

It’s janky as hell but success!  
 

CROSSBOW is a lot of fun, but ALIEN BRIGADE is great with a light gun! I guess I should RTFM and not just shoot everything in sight. ? 

 

I think this summer I’ll finally sit down and learn Kicad or something and make up a PCB for this. It’s a dead simple circuit. It’s only a PITA because of the point to point soldering and keeping the controller jack and transistor pins straight. 
 

 

Congratulations on the conversion.  I love playing Alien Brigade with my XG-1 or Best Electronics light gun.

[+DrVenkman]

You know, this stupid little converter shouldn't be as annoying to wire up as it is. Hopefully it won't be for people in the future.

 

 

I'll have connectors in a few days and sample boards in 2 weeks. If they work without any tweaking, I'll post the Gerbers and let people build them themselves if they life. 

[john_q_atari]

You learned Kicad in 8 hours?!?! Can I pay you to teach me?

[+DrVenkman]

1 minute ago, john_q_atari said:

You learned Kicad in 8 hours?!?! Can I pay you to teach me?

I ended up using EasyEDA. Not sure it’s any easier but it works pretty well.  Hopefully the connector footprints are accurate! I’ll know in about two weeks. 

[john_q_atari]

5 minutes ago, john_q_atari said:

You learned Kicad in 8 hours?!?! Can I pay you to teach me?

Actually a quick websearch turned up lots of stuff. Thanks for the heads up on EasyEDA.

Edited May 17, 2021 by john_q_atari
I just read your response. Thanks!

[+DrVenkman]

It’ll still be ~two weeks to get my sample boards but I’m excited. I don’t care how simple it is, I’ve never designed a custom PCB before.