Flashback2 Harmony Mod

[+batari]

My FB2+ mod is complete:

And I only lost one screw...

 

Nice work - it looks like you attached the Harmony PCB to the bottom of the case (instead of the top as I did). I'd be interested to see a photo of the inside of the modded unit?

Yes, it is on the bottom of the unit. If I feel like opening it up again, I'll post something.

EDIT: One thing I noticed recently with my mod is that the FB2 remains powered-on when the USB cable is connected (and the wall adaptor is switched off). This could be because I used the prototype Harmony, but I thought there was a diode to prevent this?

That should not happen, and does not happen with mine. I would guess the diode on your main board is allowing current to flow in both directions, and this wouldn't surprise me on a prototype board where we may have done experiments that exceeded its ratings.

 

If you want to replace the diode, I will send you one or point you toward the correct part.

[Zoyx]

I do like the idea of this being USB powered.

 

Edit: Measured my unmodded FB2 through a Kil-o-watt... only pulls one watt. Probably not much more for a Harmony modded FB2. How much current goes through USB?

 

Any tips to mod your FB2 to run through USB?

Edited February 28, 2010 by Zoyx

[Emehr]

I may just have to get a Harmony cart (even though I have a CC2). That looks like a fun project.

[+batari]

I do like the idea of this being USB powered.

It's not as good as it sounds. Besides being unintentional, Chris's unit should power up even with the power switch off, so to select a new game, one would need to disconnect and reconnect USB.

 

However, one could wire something up using the power pins on the header that connects the two Harmony boards together if USB power is desired and one wishes to keep the power switch. Some modifications to the FB2 would also be needed.

Edit: Measured my unmodded FB2 through a Kil-o-watt... only pulls one watt. Probably not much more for a Harmony modded FB2. How much current goes through USB?

 

Any tips to mod your FB2 to run through USB?

USB can supply up to 500ma, so you could probably power a real 2600 if you really wanted to.

 

Anyway, to power an FB2, you could apply 5v on the output side of the 7805 on its board, and rewire its power switch as needed. Shouldn't be too hard.

 

If one wanted to tap into a Harmony, there is 4.3v and GND available on the header pins (due to the drop from a series diode.) There may be 5v available on a via somewhere if you need it, but the FB2 also can use 4.3v as it also has a series diode. You could probably apply this power to the other side of the FB2's series diode (which I believe is on pad 23?)

 

EDIT: Just remembered, when powering down, the Harmony also needs to reboot so I guess it's not all this simple. Either you'd have to hack up the Harmony board by cutting the power pin between the two boards or tap into the RESET line for the board and pull it low when you power down.

 

Disclaimer: Hacking your Harmony will void its warranty

Edited February 28, 2010 by batari

[Zoyx]

I realize what cd-w did wasn't intentional... or ideal... or safe. But powering through USB would open possibilities. Power it directly from your PC, power from the wall via this adapter, power in your car through this adapter. Since this thing sips electricity, wiring in a 9-volt battery would be a good idea as well.

[atarinewbie]

I mounted the Harmony cartridge to the bottom of the case, as well. I just cut the relevant part out of the cartridge housing, roughed it and the inside of the FB2 up with sandpaper and epoxied it in place. There's plenty of clearance for the connector at the back. I also bonded in the an additional support stud through the hole in the PCB, but this was probably not necessary. The SD card slot and the USB plug end up upside down.

 

 

Unfortunately that's where my success seems to end. I wired it all up, closed it up, and it looks really nice but doesn't work. All I get on the screen is garbage. I opened it up and tried with the several game cartridges with the same result, and also get garbage on the screen if it's turned on without a cartridge in at all. I checked and rechecked over my wiring, did continuity and short checks, checked for power at the cartridge (4v not 5v, right?), and even shortened the ribbon cable and resoldered everything, all to no avail. I reopened J3 and closed J9, and the on-board games seem to work, though always in b/w (I was too excited to pull it apart to check if it worked right out of the box, so I'm not sure if this is a related problem ). Any suggestions on what else I should check or what I might have damaged? Also, please verify that the pins labeled 13-24 on the Harmony cart correspond to pin numbers 1-12 on the FB2 (though I tried it in both orientations, with the same results, which hopefully didn't damage anything)

 

Thanks again for the help!

[+batari]

I mounted the Harmony cartridge to the bottom of the case, as well. I just cut the relevant part out of the cartridge housing, roughed it and the inside of the FB2 up with sandpaper and epoxied it in place. There's plenty of clearance for the connector at the back. I also bonded in the an additional support stud through the hole in the PCB, but this was probably not necessary. The SD card slot and the USB plug end up upside down.

 

 

Unfortunately that's where my success seems to end. I wired it all up, closed it up, and it looks really nice but doesn't work. All I get on the screen is garbage. I opened it up and tried with the several game cartridges with the same result, and also get garbage on the screen if it's turned on without a cartridge in at all. I checked and rechecked over my wiring, did continuity and short checks, checked for power at the cartridge (4v not 5v, right?), and even shortened the ribbon cable and resoldered everything, all to no avail. I reopened J3 and closed J9, and the on-board games seem to work, though always in b/w (I was too excited to pull it apart to check if it worked right out of the box, so I'm not sure if this is a related problem ). Any suggestions on what else I should check or what I might have damaged? Also, please verify that the pins labeled 13-24 on the Harmony cart correspond to pin numbers 1-12 on the FB2 (though I tried it in both orientations, with the same results, which hopefully didn't damage anything)

 

Thanks again for the help!

EDITED because my original response was wrong...

 

Anyway, 13-24 on Harmony indeed corresponds to 1-12 on the FB2.

 

Also, 1-12 on the Harmony correspond to 13-24 on the FB2.

 

Do you have an FB2 or FB2+? My FB2+ had a bad trace.

Edited March 4, 2010 by batari

[cd-w]

Unfortunately that's where my success seems to end. I wired it all up, closed it up, and it looks really nice but doesn't work. All I get on the screen is garbage. I opened it up and tried with the several game cartridges with the same result, and also get garbage on the screen if it's turned on without a cartridge in at all. I checked and rechecked over my wiring, did continuity and short checks, checked for power at the cartridge (4v not 5v, right?), and even shortened the ribbon cable and resoldered everything, all to no avail. I reopened J3 and closed J9, and the on-board games seem to work, though always in b/w (I was too excited to pull it apart to check if it worked right out of the box, so I'm not sure if this is a related problem ). Any suggestions on what else I should check or what I might have damaged? Also, please verify that the pins labeled 13-24 on the Harmony cart correspond to pin numbers 1-12 on the FB2 (though I tried it in both orientations, with the same results, which hopefully didn't damage anything)

Thanks again for the help!

 

Did you get it to work? The most likely cause is that the pins are wired-up incorrectly. Here is the wiring diagram looking down onto the end of the Harmony cart (i.e. the same as looking down onto the Atari 2600 cart socket). The numbers correspond to the ones on the FB2 PCB:

 

     24 23 22 21 20 19 18 17 16 15 14 13 
    ,------------------------------------,
    |                                    |
    |   [sD CARD SLOT]   [uSB]           |
    |                                    |
    `------------------------------------'
     01 02 03 04 05 06 07 08 09 10 11 12

 

Chris

[atarinewbie]

Thanks everyone for your help! I finally got back to tinkering with this today. The problem was a messed up pad on the board (possibly my doing) and the on-board games were showing up in black and white because of a bad connector on the CRT in the shop.

 

Here is the final result. I'm quite happy with how it turned out - the USB and SD card slots are flush with the case, the Harmony PCB simply snaps in and out after the one screw is removed, and everything fits inside nicely.

 

 

Cheers!

[jamesk]

Here is the final result. I'm quite happy with how it turned out - the USB and SD card slots are flush with the case, the Harmony PCB simply snaps in and out after the one screw is removed, and everything fits inside nicely.

 

 

How did you cut out the SD and USB slots? They are very nice looking. I'm not very good at cosmetics and could use the tips before I start hacking my FB2+.

[atarinewbie]

Here is the final result. I'm quite happy with how it turned out - the USB and SD card slots are flush with the case, the Harmony PCB simply snaps in and out after the one screw is removed, and everything fits inside nicely.

 

 

How did you cut out the SD and USB slots? They are very nice looking. I'm not very good at cosmetics and could use the tips before I start hacking my FB2+.

 

I marked where I wanted the connectors on the inside of the case, and then cut holes from the inside of the case using a Dremel. I used a cut-off wheel to make the slot, and a tiny ball-end cutter to make the hole for the USB plug. I kept the Dremeled holes undersized, but thinned out the plastic around the perimeter of the holes at the same time. Then, using an Exacto knife and a small file, I enlarged the holes to the right size from the front, regularly checking the fit of the connectors. Doing the Dremel work from the back means you don't mark up the outside of the case when it slips, and thinning out the plastic a bit makes shaping the final holes from the front really easy.

[patbb]

Thanks everyone for your help! I finally got back to tinkering with this today. The problem was a messed up pad on the board (possibly my doing) and the on-board games were showing up in black and white because of a bad connector on the CRT in the shop.

 

Here is the final result. I'm quite happy with how it turned out - the USB and SD card slots are flush with the case, the Harmony PCB simply snaps in and out after the one screw is removed, and everything fits inside nicely.

 

 

Cheers!

 

Very clean job, congratulation.

 

I hope they are still some flashback available at my local costco (Canada).

[keilbaca]

This mod is amazing, I REALLY want to do this.

 

Looks like I'll be buying another harmony cart soon.

Edited April 27, 2011 by keilbaca

[ComputerSpaceFan]

Thanks everyone for your help! I finally got back to tinkering with this today. The problem was a messed up pad on the board (possibly my doing) and the on-board games were showing up in black and white because of a bad connector on the CRT in the shop.

 

Here is the final result. I'm quite happy with how it turned out - the USB and SD card slots are flush with the case, the Harmony PCB simply snaps in and out after the one screw is removed, and everything fits inside nicely.

 

 

Cheers!

 

I have a bit of an odd question here, what game is playing on your TV in that second picture? It almost looks like Night Driver but a much closer version of the coin op than Rob Fullop's original cartridge. Whatever it is, I'm interested to try it. As I posted once before, I would like to know if the 2600 can more closely emulate the coin op version of Night Driver.

[+rbairos]

Quick question. Does anyone know if the modded Flashback 2 outputs 5V ?  When I run a real cartridge (like Combat) I only see 4.2 volts at the cartridge connector.
Is this normal, or have I monkeyed with something eg adding power on LED ?

Thanks

 

[sdave]

On 1/9/2022 at 12:27 PM, rbairos said:

Quick question. Does anyone know if the modded Flashback 2 outputs 5V ?  When I run a real cartridge (like Combat) I only see 4.2 volts at the cartridge connector.
Is this normal, or have I monkeyed with something eg adding power on LED ?

Thanks

 

That's normal. The main system chip in the Flashback 2 runs off 3.3V instead of 5V. There is a diode in series with the 5V to the cartridge pad so that it runs at a lower voltage to keep the voltage levels on the system chip lower. It's kind of a hack way to do it. This is probably also why some of the carts don't work with the Flashback 2. The correct way to handle this would have been to use level shifting buffers between the 5V cart signals and the 3V system chip. I've kicked around the idea of designing a proper interface board with level shifters and see if that would make more carts compatible with the FB 2. I just haven't had the free time to try it out yet.

[+rbairos]

17 hours ago, sdave said:

That's normal. The main system chip in the Flashback 2 runs off 3.3V instead of 5V. There is a diode in series with the 5V to the cartridge pad so that it runs at a lower voltage to keep the voltage levels on the system chip lower. It's kind of a hack way to do it. This is probably also why some of the carts don't work with the Flashback 2. The correct way to handle this would have been to use level shifting buffers between the 5V cart signals and the 3V system chip. I've kicked around the idea of designing a proper interface board with level shifters and see if that would make more carts compatible with the FB 2. I just haven't had the free time to try it out yet.

Yah thanks for the detailed info.

It really threw me for a loop for the longest time.
I had some 5V custom hardware running fine on it, then when I built something using a different 5V part, it failed.
Turns out the former chip I used was actually 1.8V-5.5V but the new chip was only 4.5V-5.5V.
In my case going to switch to 3.3V chips with some 5V tolerant inputs.

Edit.
I really like your idea of making a level shifting interface board.

 

Edited January 22, 2022 by rbairos

[+rbairos]

With that level shifter board, it would *almost* be a perfect Atari clone.
The one thing remaining would be the frozen A12 line unfortunately.
Too bad, so close.

[+rbairos]

On 1/22/2022 at 6:00 PM, rbairos said:

With that level shifter board, it would *almost* be a perfect Atari clone.
The one thing remaining would be the frozen A12 line unfortunately.
Too bad, so close.

Compelled to update this in case anyone lands here.
Besides the A12 line, the Flashback 2 *does NOT* populate the data bus with TIA or RIOT data:

It also starts reading from the bus about 1.5 msec after powerup, instead of 20+ msec like a real Atari.
Not as similar as I had first thought.