G27 Power supply substitution

Carlos Casas has wrote this useful guide to upgrade the venerable G25/G27. You can find the original spanish version on the TSS site

Introduction

The original power supply of the G25/G27 steering wheel has 24V and 1,75A. This means that it can power up to 42W.

The engines inside the steering wheel sometimes need peaks above these 42W to work properly, so if the original power supply is used, engines stop to work in a optimal way and even can be block.

Trying to solve this little shortcoming we can replace the original power supply by a 24V and 6,5A ~ 8,25A new power supply.

With this features we can get 4 times more power than the original one. From 156W up to almost 200W.

Warning

There is no real danger in the steering wheel with these power supplies. Voltage keeps the same so, there is no linked overheating problems. It is simple, we feed those power peaks in the engines with an extra amperage.

This modification is not related with others power supply modifications like ARC, which tried to double the FFB of the steering wheel adding a 48V, additional boards and fans.

Differences with the original power supply

I will put you an example to try to explain the difference between V and A.

Imagine a water pipe. Pipe width is equivalent to 24V, water pressure would be the amperage, quantity of water liters per second passing through the pipe. More water pressure, more amperage.

If you have a water pump at the end of the pipe, this pump will work better (more efficiently) if the stream is bigger.
Bu if we change the width of the pipe (voltage) the stream will flood the water pump, or in our case, burning the wheel.

So, what are we going to achieve?

• Increase torque of the G27 engines.
• Engines at full capacity.
• Avoid engines saturation locks.

Warning

This is a little and relatively cheap upgrade on your G27. We are not going to reach FFB levels shown in the Thrustmaster Tr300 or Tr500.

Equipment

– New power supply

AC 100/220V DC 24V 6.5A 150W Fuente de Alimentación Conmutada Transformador

or

Fuente de alimentación LED 24V/200W/8.25A, para interiores

– Gembird PC-186A-VDE – Cable de alimentación 15, 1.8m, 10A, color negro
– Cablematic – Conector de alimentación DC 2.5mm 5.5mm
– OUVER CABLE AUDIO HQS OFC TRENZADO 1M 2×1,5mm AL CORTE

Setting up

• Check that new power supply is configured to work with 220V
• Cut one end of the power supply wire and strip the cable
• Connect blue one with the L on the power supply
• Brown to the N
• Yellow/green to the ground connection
• Strip two threads cable and weld on the DC 2,5 connector positive center
• Brown end wire with the long connector terminal (ext negative) the other end goes to the COM (V-) of the power supply
• Blue one end with the short terminal (positive center) and connected to the V+ of the power supply
• Isolate each of the joins with tape
• Search for a safe place to leave the power supply and plug in it to the current
• Connect the jack to the wheel.

FFB intensity

Source

There are two key factors to configure FFB properly; clipping and dead zone.

Clipping means that FFB is working over his maximum allowed performance and all the forces over these maximum are transmitted with equal intensity.

Dead zone otherwise, where our wheel cannot generate enough minimum force due to the internal mechanical resistance forces. We cannot feel them.

We need to find the balance. If we configure the FFB with high values, clipping will be there. We can check this behavior in a test session. With F key we would see FFB among the other parameters. If during this practice, passing over the curbs or turning the wheel bar turns orange or red, then you need to lower FFB forces.