New DIY RF Box Build for 4-Port

[mikey.shake]

Hi everyone,

 

I've been battling a batty RF switchbox for my 4-port (which I'm going to try to troubleshoot in another thread).

 

I decided to try and go out and build my own before I bother doing a full mod to the console itself. I used the instructions from this site, and followed them as closely as I was able. I thought I was able to follow them to a T. I'm a bit of an amateur, but can solder-by-numbers in the right situation.

 

I put everything together full of hope, and when I fired it up, just got a damp squib, but with tiny progress. At least i can see SOMETHING:

 

 

 

But I can't figure out what's gone wrong. It seems like these instructions have been getting the "thumbs up" online for years, so I'm assuming it's not those. I also used this video as a reference for the work:

 

Here's a gut shot of the newly-built box:

 

 

- I used a 7/16-inch bolt for the choke, 22-gauge wire, wrapped it 12-14 times, taped that off to keep it secure and wound.

 

- Choke gets connected from RF port to power input.

 

- Connected the RF port to the coax-F TV output with a .01uF, 500V capacitor.

 

- Nothing seems shorted, and the metal case should be grounding everything via the jacks.

 

- It's connected to the TV via a brand-new 3ft coax cable.

 

The original switchbox that's been giving me trouble has an issue switching between inputs, but when a 5200 game shows up onscreen, it's clear as can be. I even retested the system using the old switchbox, and here's how it looks (taken 3 minutes after the above photos):

 

 

 

Again, those are AFTER hooking it up to the older, "funky" switcher, so I know the console's still good. I'd LOVE to just build a basic box that would allow me to output the 5200, but I'm going batty. What's in my hand is exactly what I want, only it doesn't work.

 

So can anyone help me figure out where I went wrong?

 

 

[And yeah, if I absolutely, ultimately, and completely strike out on building a replacement box or fixing the old one I have, I will probably mod the console. But that's a last resort, and I'd like to focus on figuring out how to build a better RF box first, since I literally have the materials sitting in front of me.]

[0078265317]

So the old box works. So what exactly is wrong with it?

[deltronik]

Maybe the box isnt grounding as well as you think or is actually picking up interference?

 

I would try soldering direct grounds between ports and if that doesnt help get a plastic project box and try that, assuming you followed the directions exactly.

[mikey.shake]

So the old box works. So what exactly is wrong with it?

 

 

It won't switch back to whatever input was going through the "antenna" input once it's shut off. For example: the antenna feed will be on, I turn on the 5200, it kicks over fine, like it's supposed to. But then I turn off the 5200, and it doesn't go back to the antenna input, it goes to snow. It also clicks a few times when I plug the power into it, rather than once, like something's not catching. Other times it won't click at all.

 

I replaced the chip in it when it got it, and for a while, it worked perfectly. But since it's now intermittent, there's something in there that's not right. I don't wanna keep using it and potentially further mess up some component since I don't know what's going on.

 

If the original is easily fixable/diagnosable, I'd fix that up and use it. But I want to be able to play my 5200 until I can diagnose it. Since the DIY build should be a simple, clean alternative, it would be optimal. Otherwise, I'll have to go grab a couple of caps and a diode and give a whirl to CPUWIZ' power mod.

 

But again, i've got the box, I seem to have the right parts, and I have SOME idea of what I'm supposed to be doing. I just want to make this DIY build work if I can.

[mikey.shake]

I would try soldering direct grounds between ports

 

At the risk of being dense, could you elaborate on this? Do you mean within the RF box build? I'm intrigued, as it may be a solution, and I'm willing to try it!

 

EDIT: I also noticed that the power input I grabbed was a 2.1mm pin / 5.5mm ID. The instrux for the CPUWIZ version of the mod indicates a 2.5/5.5 power input. I thought I'd grabbed the right one. Could that be a factor?

Edited July 9, 2016 by mikey.shake

[deltronik]

I haven't watched the video and I am unsure the schematics on the rf box, but the best ground is the shortest path between points. So, solder the shortest wires possible between the ground pads on the jacks and dont rely on the metal box to ground. You can daisy chain the ground from one to the next to the next.

 

And I may be crazy, but I get more video noise with the shield installed on my av modded 5200 and I get more pronounced "jailbars" like you are seeing on the left of the screen.

 

Just shooting ideas since you're the only one that can tell if you've got the rest wired up right and used the right parts.

Edited July 9, 2016 by deltronik

[mikey.shake]

I tried a plastic enclosure, then hooking up some grounding wire in the new DIY box... unfortunately, no luck. Rebuilt the thing from scratch with the backup parts I bought, and no luck.

 

I had a couple beers and decided to consider CPUWIZ' version of the power supply mod. I prepped materials in case I wanted to pursue it, and then opened up the case. I saw an almost-literal red flag. A red wire connected to one of the components I needed to remove. Leading under the shielding to the cart slot.

 

 

 

So I dig a little deeper and take off the shielding and immediately see something terrifying to an amateur like me. Someone else's work.

 

 

Here's a closeup of the mod/fix/hack, with an attempt to make it more visible:

 

 

 

I love this console. But I'm in way over my head. I'm exhausted, confused, and completely frustrated. At this point, the 5200 is just making me angry, and that's making me sad. I can't get a switchbox set up to work, and I'm willing to bet with that red wire leading where it is that it's going to screw up my ability to do the power supply mod on my own. I know this system isn't without its quirks, but I can deal with controllers and calibrations. This is just too much, and I can't afford to throw much more money at it. Nor can I afford to buy another one right now. And OEM switch boxes aren't turning up anywhere I can find them.

 

Might this mod (clearly connected to components involved in the power mod) be the reason I can't get things to work right with the switchbox? Or is this something unrelated?

 

What the hell is going on? Can anyone tell me what I'm looking at?

 

Is this the "2600 adapter" mod? If so, where do I go from here?

[deltronik]

Yeah, looks like the vcs mod alright. I'm not sure that would affect your diy rf box though, especially if your real switch box doesn't have that static. Gotta be the DIY box, maybe someone else that has made one can chime in with some advice.

 

I chose the av/power mod route on mine, the real switch box and rf cable gave me horrible static. The AV mod gave me much better results... if only we could get RGB.

Edited July 10, 2016 by deltronik

[mikey.shake]

Yeah, looks like the vcs mod alright. I'm not sure that would affect your diy rf box though, especially if your real switch box doesn't have that static. Gotta be the DIY box, maybe someone else that has made one can chime in with some advice.

 

I chose the av/power mod route on mine, the real switch box and rf cable gave me horrible static. The AV mod gave me much better results... if only we could get RGB.

 

 

Deltronik, you have made my night. I was ready to give up, I really was.

 

Your affirmation that the mod I spotted was, in fact, the VCS mod, encouraged me to press on right when I was about to throw in the towel. (Hence the exasperated tone of my last post.) I couldn't get my Build Box to work, and had no idea how to get around that VCS mod if I wanted to power-mod it. Realizing that you were right -- if the original box worked, this one probably should, too, as long as the recipe was correct.

 

Being reasonably new to all this, I'm cautious. With a limited understanding of this stuff and a strange contraption like the 5200/switchbox, I was worried I'd do something stupid and send too much juice to the wrong place and fry whatever good parts were left. I was also concerned that the VCS mod would preclude my being able to power mod it (and having a hard time digging up compatibility info), and since I clearly can't build a DIY RF box, I felt I was doomed to a life of buying crappy probably-broken switchboxes from shady resellers and keeping a stock of IC chips on hand for periodic swapping.

 

As one last effort, I completely pulled apart the DIY box one connection at a time and rebuilt it into exactly the same shape, using the last of my spare fresh parts (and one solder-sucked and re-used power jack from earlier). I once again led some grounding wire from the tab on the phono jack to the tab on the power jack (as short a length as space would allow), and made sure that every joint was well-flowed and every mount nice and secure.

 

Much to my surprise, it worked this time. Like, for real. It really works!

 

So, now I have a replacement box that's not likely to fail anytime soon, and I know I theoretically have the ability to build a working one (thanks to the great instructions out there, available on the AtariAge 5200 FAQ). Now I can get back to what matters to me -- playing, not tinkering.

 

For what it's worth, even despite the trouble, I still think the "single cable" design is a pretty cool flawed idea, provided all the components in your setup are working as they should. I DEFINITELY get why people don't want to have to deal with it, though, and mod for power and A/V.

 

Thanks, Deltronik. I'm gonna name this lil' rascal "Del" in your honor!

 

 

 

[I'm also going to go pick up that VCS adapter sitting at the local retro shop. Now that I know I might be able to use it. What do you think -- is the mod work in the pictures above an early-'80s factory job, or something more... "after the fact(ory)"?]

[walter_J64bit]

WOW that's a super clear picture!

[deltronik]

Great work Mikey! That really is a clear picture! I could never get my rf to look like that, so I quickly just ditched it.

 

Maybe you should name it Mikey Jr. instead, I'm not sure I deserve the homage. You put in the work! lol

 

Grab a VCS adapter and enjoy!

Edited July 10, 2016 by deltronik

[ave1]

I admire your work- that's really great! When I ran into some display problems recently, I contacted Atariage member, atari-dna, about it. He does 5-port switchbox rebuilds and did a fine job putting some new parts into mine for a very reasonable price. I've had a very sharp picture on my Panasonic LCD tv ever since.

[mikey.shake]

WOW that's a super clear picture!

 

 

That really is a clear picture! I could never get my rf to look like that, so I quickly just ditched it.

 

Thanks, everyone! I agree -- I'm really lucky that, when it works as it should, I do get a really clear picture with my setup. No static on the black really at all. Lol, however the old downtown apartment I live in has, uhhh, "creative" wiring. So when I turn on the TV in the other room, I get a little interference, and when I turn on the PA system in my office, it goes REALLY static-y. But under "primo" conditions, it's as clear as I could expect RF output to be!

 

Now that I have it up and running thanks to your wisdom, I cannot recommend the DIY route enough, if "a new RF box" is your primary goal. (If the power input mod isn't your bag, or if you're unable to do that, like I was.) A basic step bit for my 30-year old hand drill, a seven dollar enclosure, and ten bucks worth of components, and I have a tank-proof replacement option. And I PROMISE, I'm all thumbs when it comes to soldering. This new device is half the size, sticks to my wall, and can have more than five inches of coaxial cable running to the TV. Now that I know even a goon like me can do it, it's preferable to buying another potentially rickety CX522 of questionable heritage online. So, if anyone else wants to do it down the road, hopefully these resources can help:

 

Text Instructions:

https://www.eskimo.com/%7Etmcintos/atari/5200.switchbox.html

(also on AA 5200 FAQ under section 4.14:)

https://atariage.com/5200/faq.html?SystemID=5200

 

 

Video Tutorial:

https://www.youtube.com/watch?v=icfVkWHScW0

 

 

Parts List:

(w/Radio Shack part #'s)

- Coaxial DC power jack (#2741563)

- Cable TV type F jack (#2780212)

- RCA type phono jack (#2740346)

- 0.01 uF Ceramic Disc capacitor (#2720131)

 

- 7/16 inch bolt ($.14 @ hardware store)

- 22 gauge solid insulated wire

- Step Bit for drill (to drill enclosure holes)

- Electrical Tape (to wrap the bolt/choke)

 

 

 

Now that I can, y'know, PLAY my 5200, getting the original box fixed (just 'cause) is something I can turn into a slow-paced project, rather than muck something up in my haste and eagerness to get back to Mario Bros. and Berzerk. Since it seems to be a problem with the switching process and not the output (when it plays, it plays fine, as you can see in my original post), but won't click back to the antenna input when I power off the 5200. Maybe that isolates where I should start sniffing first. But that will give me a good reason to get to know how to use my new multimeter, and maybe ask some more questions this summer.