Logitech G27 Question

[slamminsam]

Greetings

I'm in the process of converting a G27 to a Happ wheel using a servo amp (more info soon), but I've run into a bit of a snag. I'm having the dreaded stutter issue, and before plugging the wheel into the pc the motor constantly turns the wheel back and fourth.

 I believe that part of this is due to me using a 24v input for the wheel and the servo amp being restricted to a 15v input. I've attempted to use a 12 supply, but the wheel does not want to initialize at that voltage. Which brings me to my question(s).

My wheel is in pieces and I am not able to reassemble it. Can someone with a G27 do some testing to see what is the lowest voltage the wheel will operate at?

Also, is there a circuit that will work as a servo de-amp? If I am not able to get the wheel to operate below 15V perhaps I can reduce the voltage coming out of the g27 motor output and then input it into the servo amp.

Thanks in advance
Sam

[BadMouth]

I don't know about the G27, but plenty of us have used 12v with older Logitech wheels.

My guess on the wheel turning back and forth before it's hooked up to the PC is that one of the switches on the servo amp might not be set correctly.
That's assuming it does it indefinitely and it's not just the normal G27 startup procedure where it goes back and forth a few times when first powered up.

Do you have it passing the startup calibration and functioning with the PC?
The big PITA with the G27 is that it must sense the proper amount of movement on startup, or it doesn't function.

[slamminsam]

I was able to get it to pass calibration and recognized by the pc; however, after moving things around it started to do the back and forth rotation when not plugged into the pc. After thinking further, I’m not sure if I had the gain turned up all the way on the servo amp when I tested with 12v, but without a fully functioning wheel I’m pretty much taking stabs in the dark.


I’m using two sprockets connected via a chain to translate the 900 degree rotation to 270 degree rotation. It also uses the donor wheels encoder and helical gear – modified to fit on the steering shaft. I have been able to get the wheel to pass it’s calibration test, so mechanically I believe my designed is sound. It’s just a matter of getting things dialed in now with the servo amp.

The wheel is also switchable between 900 degree rotation and 360 degree rotation via an index plunger on the steering hub. The main steering shaft is a 5/8” piece of DOM tubing that has been machined to the same diameter of the original Happ shaft. A 3/16” DOM tube runs through it for the 360 degree rotation. I plan on doing a more comprehensive write up sometime in the near future but here is a pic I snapped this morning with my cell.

[BadMouth]

Looks like you've got a lot going on there that I've always wanted to try. 
Hollow shaft with the spinny-wire thing....


Another way of handling the voltage concern might be to put a meter on the G27's motor output and see how much it's actually sending to the servo amp.
Then turn down the ffb strength in windows until it doesn't ever output over 15v.

[slamminsam]

Another way of handling the voltage concern might be to put a meter on the G27's motor output and see how much it's actually sending to the servo amp.
Then turn down the ffb strength in windows until it doesn't ever output over 15v.

That might be the way to go if I can figure out what is going on with the motor movement prior to plugging it in. Do you happen to know if any of the settings are saved in the wheel, or are all the settings only saved in Windows?

[BadMouth]

I don't know.  I  wouldn't think they'd be saved on the wheel.

The info about the servo amp settings is spread out among a few different threads.

Check out this post about the servo amp settings:
http://forum.arcadecontrols.com/index.php/topic,115133.msg1290289.html#msg1290289

[slamminsam]

I don't know.  I  wouldn't think they'd be saved on the wheel.

The info about the servo amp settings is spread out among a few different threads.

Check out this post about the servo amp settings:
http://forum.arcadecontrols.com/index.php/topic,115133.msg1290289.html#msg1290289

That's the post that I used when I first set it up. I've spent a little time with it yesterday. I reset all of the pots and started from scratch using ScottoKong's post. The constant back and fourth motion has stopped.

Now all I have to do is reload Windows onto the pc I'm using as my temp rig. The Logitech Profiler software doesn't see the G27. My laptop recognizes the wheel, so I know it's a software issue. I found several posts online that suggested removing and reloading the software and drivers but hasn't been effective.

The wife has other plans for me today (Mall Pack mule) so I'm not sure if I will get anything else done this weekend.

Thanks for your help and insight BadMouth.

[slamminsam]

I decided to order a G27, so that I can do some additional testing with the voltages. Additionally, I'm having trouble getting my arcade pedals to be recognized.  However, I've never owned an original set, so I'm not sure if it is something simple like my cable or the POTs I'm using. Either way this will give me a fully functioning set to test. More to come soon.

[BadMouth]

IIRC, they are 10k pots and don't work unless you have a power supply plugged in.
(the wheel will show up and work without external power, no ffb of course)

I bought a non-working G27 and fixed it just to experiment with.
Sold it last year and have regretted it since.
I have a brand new one, but don't want to hack on it just yet.

[slamminsam]

IIRC, they are 10k pots and don't work unless you have a power supply plugged in.
(the wheel will show up and work without external power, no ffb of course)

I bought a non-working G27 and fixed it just to experiment with.
Sold it last year and have regretted it since.
I have a brand new one, but don't want to hack on it just yet.

10K is what I'm using and I'm sure I had power applied. 
http://www.ebay.com/itm/9738267318?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I don't blame you for not wanting to hack it up. I'm sure that when my test wheel arrives I'll treat it with kid gloves -- at least for a while. 

[slamminsam]

Looks like you've got a lot going on there that I've always wanted to try. 
Hollow shaft with the spinny-wire thing....

BadMouth, I remember seeing a post where you touched on the subject, but I can't seem to find it. Do you happen to know which post it was? TIA

NM I found it: http://forum.arcadecontrols.com/index.php/topic,105003.msg1220482.html#msg1220482

[slamminsam]

After doing some testing, 19V is the lowest voltage that allows the G27 to go through the calibration process. Its not the 15v that I was hoping for, but it will not put as much stress on the servo amp that the 24v will.