Replace Woocommerce default image placeholder

functions.php

<?php
/**
 * Change the placeholder image
 */
add_filter('woocommerce_placeholder_img_src', 'custom_woocommerce_placeholder_img_src');

function custom_woocommerce_placeholder_img_src( $src ) {
	$upload_dir = wp_upload_dir();
	$uploads = untrailingslashit( $upload_dir['baseurl'] );
	// replace with path to your image
	$src = $uploads . '/2012/07/thumb1.jpg';
	 
	return $src;
}