Sitecore Powershell for Bulk update General Link "External" field

We have a general link field which pointing to different site url , but the domain name of that site changes due to some reason, so it makes us to update our general link field url, we have references in lot of place  , so i tried to use the below scripts to update the domain name

$allItems = Get-ChildItem -Path 'master://sitecore/content/ Tenant/Corporate/Global' -Recurse

  $allItems | ForEach-Object {

    [Sitecore.Data.Fields.LinkField]$field = $_.Fields["Navigation Link"]

    if($field.LinkType -eq "external")

    {

        $Url = $field.Url

        $_.Editing.BeginEdit()                

        $field.LinkType = "external"

        $field.Url =                 $Url.Replace('www.xxxx.com/news/','www.yyyyyy.com/news/')

        $_.Editing.EndEdit() | Out-Null      

        Write-Host $_.FullPath

        Write-Host  $Url.Replace('www.dpworld.com/news/','www.dpworld.com/news/releases/')

    }

}