[TrUnkS]

muchas gracias por la ayuda pude resolverlo:

Código Delphi [-]
procedure TForm1.Button1Click(Sender: TObject);
var Str: String;
    CADENA: String;
begin
 ADOTable.Open;
 ADOTable.First;
 while ADOTable.Eof = False do
  begin
     Str := FloatToStr(ADOTableCAMPO.AsFloat);
     CADENA := Str[1] + ',' + Copy(Str,2, Length(Str));
     ADOTable.Edit;
     ADOTableCH5.AsFloat := StrToFloat(CADENA);
     ADOTable.Post;
     ADOTable.Next;
  end;
end;