Example fx file that compiles and runs fine on Windows, iOS & Android.

Effects.fx

float fTimer;
float fPixellateFactor = 1.0f;
sampler ColorMapSampler : register(s0);

float4 NormalShader(float2 Tex:TEXCOORD0) : COLOR
{
  float4 color = tex2D(ColorMapSampler, Tex); 
	return color; 
}

technique Normal
{
	pass P0
	{
		PixelShader = compile ps_2_0 NormalShader();
	}
}

float4 WobbleShader(float2 Tex:TEXCOORD0) : COLOR
{
	Tex.x += sin(fTimer+Tex.x*10)*0.02f;
	Tex.y += sin(fTimer+Tex.y*10)*0.02f;

	float4 color = tex2D(ColorMapSampler, Tex); 
	return color; 
}

technique Wobble
{
	pass P0
	{
		PixelShader = compile ps_2_0 WobbleShader();
	}
}

float4 DiscoShader(float2 Tex:TEXCOORD0) : COLOR
{
	float4 color = tex2D(ColorMapSampler, Tex); 
	
	color.r = color.r - sin (fTimer/3+color.r * Tex.y) * 0.5f;
	color.g = color.g - sin (fTimer/3+color.g * Tex.x) * 0.5f;
	color.b = color.b - cos (fTimer/3+color.b * Tex.y) * 0.5f;

	return color; 
}

technique Disco
{
	pass P0
	{
		PixelShader = compile ps_2_0 DiscoShader();
	}
}

float4 PixellateShader(float2 Tex:TEXCOORD0) : COLOR
{
	float2 brickCounts = { 640, 480 };
	//2.0 is a distortion factor - larger the # the larger the distortion
	float2 brickSize = fPixellateFactor / brickCounts;

	// Offset every other row of bricks
	float2 offsetuv = Tex;
  
	float2 brickNum = floor(offsetuv / brickSize);
	float2 centerOfBrick = brickNum * brickSize + brickSize / 0.5f;
	float4 color = tex2D(ColorMapSampler, centerOfBrick);
	return color;
}

technique Pixellate
{
	pass P0
	{
		PixelShader = compile ps_2_0 PixellateShader();
	}
}