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Old 19 August 2015, 10:58   #1
Cubemon
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Question More power to A1200's joystick port

I have an X-Arcade Tankstick. I bought the 5-in-1 (Playstation, Gamecube and Dreamcast) adapter for it, as well as two PSX to Amiga adapters from Kipper2k.

I went through my retro collection and tested the Tankstick with different devices. Playstation 1 worked beautifully. C64 worked without a hitch. However, when I plugged the Tankstick into my A1200, it didn't work at all or really erratically.

The culprit seems to be the low current supplied by the A1200's joystick ports. Apparently the C64 gives out 100 mA on the joystick ports' +5 V line, while the A1200 only gives out 50 mA.

Here's the question:

What's the easiest way to ramp up the juice on the A1200's joystick port?

I'm not exactly sure about the exact power requirements, since in addition to the joysticks there's also a Jerry+ mouse adapter/joystick switcher and the Tankstick trackball (connected via USB to the Jerry+) to power up.

I figured there's a few ways I could go about this. Make an internal mod to the A1200, make an external dongle (there's a stronger +5 V on the external disk drive port) or mod the tankstick to get its power from an external power source.

However, since the Amiga is the only device that has a problem, it would make sense to mod the Amiga and not the Tankstick. The Tankstick is also used with a regular Windows PC with the USB cable, so we can't mess with that side of things.

I have no problem soldering things, but I haven't got much of an idea when it comes to connecting different power sources.

Can I just connect the floppy connector's +5 V to the +5 V pin on the joystick port? Can I connect it to both joystick ports, since I'm not sure how the powering works on the Tankstick (and there's really not much discussion or specs floating around the Internet)? If I make a dongle, can I just pull the +5 V from the floppy connector, while the Tankstick's ground connection goes to the joystick port?

The thing is: all of this hardware is sort of expensive. Not anything that'll ruin me, but if I break something, I might not be able to replace it in the near future. So the safer and simpler the solution is, the better.

Any ideas, suggestions, actual knowledge and humorous remarks are appreciated.
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Old 31 August 2015, 16:45   #2
Megol
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The easiest way should be bypassing the resistor from VCC to pin 7. While it is used for protection in practice (for normal joysticks) it should cause no problem to bypass it.
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Old 07 November 2015, 03:47   #3
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Holy crap. It works!

I was up to my neck in doubt because of my soldering skills, but I finally got around to opening my A1200.

I checked the schematics and found out the resistors in question were R352 and R362. After searching for a while I found them on the top side of the motherboard: close to the joystick ports, under the disk drive. Here's a picture with the jump wires soldered:



I started by doing the mouse port resistor first, since it has to support the Jerry+, the trackball and a joystick. It did sort of help, but the controls were still intermittent.

After doing port 2, things started working. Ship moving smoothly from side to side in Deluxe Galaga, and I even got to brown belt on the first try in IK+! I even got through two of the bomb kicking stages, a feat I usually can't do with a Tac-2.

The only worrying part was when I tried to measure the amperage from the joystick port; I'm not quite sure I did it right, but when there were no jump wires, I got a reading on the multimeter and that was it. But when the jump wires were in place, connecting the multimeter to the +5V and ground pins reset the Amiga, and it sounded like there was some sparking.

However, if connected properly with THE POWER OFF, all the joysticks, mice, adapters and trackballs seem to work perfectly fine!
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Old 07 November 2015, 05:34   #4
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An ammeter is essentially a short so you should never use it directly on a power source otherwise you are shorting it, which is why you got sparks!
Amperage is always measured with a load, never empty.

Use it like so:
Code:
  +5V |---(Ampere-meter)---+
                           |
                      (Joystick)
                           |
  GND |--------------------+
Regarding the resistors, I wouldn't short them entirely because they protect the Amiga from short-circuits in the first place. As it is, the current is not limited anymore by the resistors. Frankly it's not a good idea.

Using 2k resistors for each should restore this protection while giving enough juice for more than 100mA to flow through, that is more than you need.
If you do not have them you could simply use wires to connect their both ends together which will divide the resistance by two (cf below for caveat).

Code:
VCC (5V)                             VCC (5V)
+++ +++   Current wire               +++ +++
 |   |    +--------+                  |   |
 |   |    |        |                  |   |
 |   |    | +----+ |                  |   |      +----+
 |   +----+-+R352+-+--> Joy0          |   +------+R352+-+--> Joy0
 |          +----+                    |          +----+ |
 |                                    |                 | New wire
 |          +----+                    |          +----+ |
 +--------+-+R362+-+--> Joy1          +----------+R362+-+--> Joy1
          | +----+ |                             +----+
          |        |
          +--------+
          Current wire

 Protection = zero Ohms (none).       Protection = 2.35kOhms
                                     (100mA max for one, or 50mA max for two).
This should definitely be safer than your current setup and good enough for powering a single joystick. If you want to plug two devices which need 100mA then you will not get enough current and should replace the resistors by 2k Ohms ones intead (and remove the wire obviously ).

Also, never plug any connectors while the power is on. Your Amiga is old, and you should take great care of its electronics.
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Old 07 November 2015, 15:10   #5
Cubemon
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Quote:
Originally Posted by ReadOnlyCat View Post
An ammeter is essentially a short so you should never use it directly on a power source otherwise you are shorting it, which is why you got sparks!
Amperage is always measured with a load, never empty.
Right, I usually just measure voltages and figured that joysticks are just simple switches anyway, but didn't realise they don't connect +5V and ground, but the respective joystick signals instead... That information will come in handy, so thanks!

Quote:
Originally Posted by ReadOnlyCat View Post
I wouldn't short them entirely because they protect the Amiga from short-circuits in the first place. As it is, the current is not limited anymore by the resistors. Frankly it's not a good idea.
I waited pretty long for someone to disagree with Megol, but once again I had to do something before things started moving along.

There probably is a reason for the resistors to be there, so it would make sense to have something there instead of bypassing them completely.

Any other points of view on the subject are welcome, if someone else is reading this thread!

Quote:
Originally Posted by ReadOnlyCat View Post
Using 2k resistors for each should restore this protection while giving enough juice for more than 100mA to flow through, that is more than you need.
I hope it's enough, I wouldn't want to ruin the original connections on the motherboard because of too much messing around. The problem is that there's so much stuff to power. So far I know the Tankstick works with a C64, but then again I don't use the Jerry+ and trackball with it. I suppose the next step is to try that and see if it works -- that way I would know 100 mA is enough.

And after that I'll have to come up with a nice and clean way to solder an axial-lead resistor to the motherboard...

Thanks for the good advice and thoughts, excellent!
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Old 07 November 2015, 19:09   #6
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Quote:
Originally Posted by Cubemon View Post
[regarding the 2k resistors]

I hope it's enough, I wouldn't want to ruin the original connections on the motherboard because of too much messing around. The problem is that there's so much stuff to power. So far I know the Tankstick works with a C64, but then again I don't use the Jerry+ and trackball with it. I suppose the next step is to try that and see if it works -- that way I would know 100 mA is enough.
You don't have to remove the existing resistors actually.
Simply soldering another 4.7k resistor on top of the existing one is sufficient to divide the resistance by 2. You could probably go with a 4k and the resulting resistance would be equivalent to a 4*4.7/(4 + 4.7)=2.16 k Ohms resistor.

This way, you do not have to remove anything and it will still be easy to restore the Amiga to its original condition if needed.

Quote:
Originally Posted by Cubemon View Post
And after that I'll have to come up with a nice and clean way to solder an axial-lead resistor to the motherboard...
Do it just like you did for the wires. Seems like a clean enough job to me.
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Old 08 November 2015, 00:46   #7
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After some testing, it seems there's something fishy after all.

I never tested the tankstick with the C64 in detail, just enough to see that it seemed to work. It does work alright, but not perfectly. There are random interruptions in the joystick signals. For example, if you push left while playing a game, the character will go left, but at some point it's like the joystick is centered and then pushed left again. In other words, the character stops for a fraction of a second.

Kipper2k's adapters work perfectly with Playstation controllers. The Tankstick works perfectly with the Playstation. It's the combination of Tankstick's Playstation adapter and Kipper2k's PSX to Amiga adapter that has problems.

It might be there's an obscure incompatibility with the two. Even if the Tankstick plays nice with the Playstation, it could very well do something non-standard that messes up other devices.

I figured it was a power problem since the Tankstick seemed to work with the C64 giving out 100 mA in the joystick ports, and didn't work with the Amiga's 50 mA ports. It could very well be some other problem.

The Playstation apparently supplies a lot more power to the controller ports. From what I understand there is/can be a 3.3V line with 300 mA or a 5V line with 500 mA. The 5V line would make sense, since the Tankstick also works with an USB connector, and they are spec'd for 5V with a minimum of 500 mA.

I'd hate to go the external power supply route for a joystick (and don't really know how it could be done), but it would seem both the Amiga and the C64 might a bit underpowered for a Tankstick.

It's always a possibility to dedicate the Tankstick to use with a PC and emulators, but damn it I still want play Deluxe Galaga with a Tankstick on real hardware.
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Old 08 November 2015, 04:33   #8
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My, 500mA is a lot of current for a very passive device overall indeed.

You don't have to go the external power supply route though: you could simply power your tankstick via an internal battery (3x1.5V serial mounted) coupled with one or two charge pumps (such as a MAX682) to guarantee 5V output.

I would not be surprised if that kind of circuit was already available pre-made for hobbyists.
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Old 08 November 2015, 10:41   #9
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Quote:
Originally Posted by ReadOnlyCat View Post
My, 500mA is a lot of current for a very passive device overall indeed.
The Tankstick is a complicated beast, I'm afraid.

In its core it's a ps/2 keyboard packaged as a dual joystick. It's also programmable, you can attach a ps/2 keyboard and assign any key to any of the joystick directions or buttons. There are three user programmable slots and a default setting, that corresponds to MAME's default keymapping.

The joysticks and buttons on the other hand are pretty much standard arcade style parts with passive microswitches.

Some people have suggested wiring D9 connectors directly to the microswitches, effectively making them regular Atari-compatible passive joysticks. It would be sort of hacky, since I want to keep the normal USB and Playstation connectivity intact. And going that route, I wouldn't have the 7-button CD32 pad emulation Kipper2k's adapters offer.

Too bad there isn't much help in the way of official support. X-Arcade does refer to this old discussion on Amiga.org in one of their FAQs, but there's really nothing substantial, just speculation and this one guy who took out all the original PCBs and rewired his controller.

Last edited by Cubemon; 08 November 2015 at 11:50.
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Old 08 November 2015, 12:51   #10
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To see if it's a power issue, I'd like to try adding an external power source.

I've been reading this tutorial about connecting an external power source to a passive USB hub. In short, it's just disconnecting the +5V from the USB connector, and connecting a 5V wall wart to the +5V and ground.

There's just one kink: there's no official pinout of the Tankstick connector. There's one pin that measures +5V when connected to USB, but who knows how the PSX adapter is relaying power.

I was trying to measure the amperage to figure out how much current the Tankstick actually draws, but to my surprise the Tankstick's power led lit up even when the +5 lead was disconnected.

I might have to contact X-Gaming and ask for more detailed specs.

Last edited by Cubemon; 08 November 2015 at 14:48.
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Old 09 November 2015, 13:07   #11
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I think everyone is missing they were 4R7 resistors to begin with (4.7 Ohms).
A 2K resistor in it’s place (2000 Ohms) will limit current much more severely than it was initially.
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Old 10 November 2015, 01:16   #12
Cubemon
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X-Arcade Tankstick with Amiga

Quote:
Originally Posted by xArtx View Post
I think everyone is missing they were 4R7 resistors to begin with (4.7 Ohms).
Whoa, nice catch. I think there was a 4.7K somewhere in the schematics and then a 4.7 in the joystick port part, so I didn't even notice. I'm glad I didn't start soldering those resistors...

---

Anyway, in other news: I think I cracked it!

There's still a chance something will come back and bite me in the arse, but this is what I did:

I measured the different connection cables I had and came to the conclusion the Tankstick is powered by Pin 9 of the D9 connector behind the Tankstick. With the console cable there's +3.5V (probably +3.3V with some extra), and with the USB cable +5V on pin 9.

After figuring that out, I started measuring things. I found out that with the perfectly working Playstation, the connection measured just under +5V. With the Amiga it was measuring just about under a pathetic +1V!

The Tankstick is apparently designed to work with different voltages, so it bravely tried to manage with the barely +1V connection, but didn't quite get there, even though it sort of worked.

I simply took a D9 extension cable and desoldered pin 9. After that, I took a smart phone charger (there's plenty of +5V going around in USB connectors!). I had a previously cut USB cable from a previous project, so I only needed to solder the +5V to pin 9 of the connector and ground to the shield.

Now it seems to work. No more erratic movements, both joysticks seem to work fine. The only drawback is now I have to get +5V from somewhere else when using the Tankstick with my A1200 or C64, but I think I'll manage. There's already going to be a crapload of cables going everywhere, so no matter!

The good news is, this way enables using the Tankstick (or probably the X-Arcade Dual) on anything you can connect it to, no matter how little power it puts out.

Last edited by Cubemon; 10 November 2015 at 01:34.
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Old 10 November 2015, 02:20   #13
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Quote:
Originally Posted by xArtx View Post
I think everyone is missing they were 4R7 resistors to begin with (4.7 Ohms).
A 2K resistor in it’s place (2000 Ohms) will limit current much more severely than it was initially.
Oops!
Indeed. With a 4.7k resistor the maximum current would be around 1mA.
Shame on me for missing that point.

Quote:
Originally Posted by Cubemon View Post

[/B]There's still a chance something will come back and bite me in the arse, but this is what I did:

I measured the different connection cables I had and came to the conclusion the Tankstick is powered by Pin 9 of the D9 connector behind the Tankstick. With the console cable there's +3.5V (probably +3.3V with some extra), and with the USB cable +5V on pin 9.
[..]
Now it seems to work. No more erratic movements, both joysticks seem to work fine. The only drawback is now I have to get +5V from somewhere else when using the Tankstick with my A1200 or C64, but I think I'll manage. There's already going to be a crapload of cables going everywhere, so no matter!

The good news is, this way enables using the Tankstick (or probably the X-Arcade Dual) on anything you can connect it to, no matter how little power it puts out.
Ooooooohhh, now this makes sense. The tankstick attempts to draw current from a logical pin which is pulled up through a 4.7k resistor so there is no way it will ever get more than 1mA (cf above).

There is an ever better news for you: you can very likely power the tankstick by using an adapter which swaps pin 7 and pin9: cf this message on another EAB thread about joystick pinouts. The Amiga +5V output is done via pin7 and should be sufficient to power the tankstick.

I should have thought of that, sorry for overlooking this point. Double fail for me on this topic.

Before doing so you should also remove the wires you soldered so as to restore the protection provided by the resistors.
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Old 10 November 2015, 11:11   #14
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Quote:
Originally Posted by ReadOnlyCat View Post
Ooooooohhh, now this makes sense. The tankstick attempts to draw current from a logical pin
I would guess the power is drawn from the correct +5V pin. The signal path is as follows:

A1200 joystick port-> Amiga-to-PSX adapter -> X-Arcade 5-in-1 adapter's PSX connectors -> X-Arcade 5-in-1 proprietary D9 connector -> Tankstick proprietary D9 connector.

(Links included for those wanting detailed information)

There's a lot of converting and adapting going on, but that's the only "official" way of doing it. The Amiga-to-PSX adapter converts the +5V to whatever pin it is on the Playstation connector and so on.

The point of using all these adapters is that there are several different modes the adapters can be used in: Kipper2k's PSX adapter offers 1 button, 2 button, and 7 button (CD32 controller) modes (and many more, including different mice modes and programmability), and X-Arcade's adapter provides different ways of emulating the Playstations analog sticks and such.
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Old 11 November 2015, 16:57   #15
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Didn't know that Tankstick would have issues on Amiga 1200. But happy to see you have found solution
I have used X-Arcade Tankstick with CD32 and Turbo Chameleon 64 (standalone/docking station) and there haven't been any issues so far. I have 5-in-1-adapter and two Paul Willingham's CD32-PSX-adapters. On CD32 I haven't tried trackball, only joysticks.
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Old 13 November 2015, 15:42   #16
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Oh hey, I've never seen or heard anyone else having an X-Arcdade stick in Finland. Woo!

After doing some testing, the controls feel a bit laggy. There are two adapters after all, and I'm using an LCD TV/monitor as a display, so there's bound to be some lag in both the input and display (even though X-Arcade claims their sticks and adapters are "lag-free").

I'll have to do some testing and compare Kipper2k's adapters with just regular PSX controllers vs. with the Tankstick.

Are you noticing any lag with your adapters on the CD32?
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Old 13 November 2015, 21:32   #17
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Yeah, then there's at least two X-Arcade-sticks in Finland Bought mine from wolfsoft.de about one year ago.
I'm such an average gamer, but anyway, if there would have been considerable lag, even I would have noticed. So on my eyes no problems with CD32 so far. I haven't played too much on CD32, but just tried Disposable Hero, Project-X, Super Stardust and SWOS. Project-X had problems with firing, but others were fine, and I didn't recognize lagging.
CD32 has joystick-extension-cable and it's connected to CD32-PSX-adapter then to 5-in-1-adapter and then Tankstick. And my tv-setup is Sharp LCD.
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