How to make grub2 boot another drive MBR?

My laptop (DELL Vostro 3350) has two hard drives:
Main one (/dev/sda), is a ssd mounted on SATA-HDD slot with Ubuntu14.04 (grub2 installed to this MBR). Installed on normaly hd bay
Second on (/dev/sdb), stock hd (with recovery partition etc etc) moved to SATA-ODD slot in place of dvd drive with an adapter

I can not figure out how to boot Windows from grub2. In the past I remember that (maybe with grub1) I could point to second disk mbr and then Windows booted normally.

So my config is:

Disk /dev/sda: 128.0 GB, 128035676160 bytes
255 testine, 63 settori/tracce, 15566 cilindri, totale 250069680 settori
Unità = settori di 1 * 512 = 512 byte
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Identificativo disco: 0x0007d87d
Dispositivo Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048   175781887    87889920   83  Linux
/dev/sda2       175783934   250068991    37142529    5  Esteso
/dev/sda5       175783936   246163455    35189760   83  Linux
/dev/sda6       246165504   250068991     1951744   82  Linux swap / Solaris
Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 testine, 63 settori/tracce, 60801 cilindri, totale 976773168 settori
Unità = settori di 1 * 512 = 512 byte
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Identificativo disco: 0xb3e7a9bf
Dispositivo Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048      206847      102400   de  Dell Utility
/dev/sdb2          206848    30926847    15360000    7  HPFS/NTFS/exFAT
/dev/sdb3   *    30926848   167600175    68336664    7  HPFS/NTFS/exFAT
/dev/sdb4       167604160   976768064   404581952+   f  W95 Esteso (LBA)
/dev/sdb5       167606208   976768064   404580928+   7  HPFS/NTFS/exFAT

Here is my /boot/grub/grub.cfg section of os-prober

menuentry 'Windows 7 (loader) (su /dev/sdb2)' --class windows --class os $menuentry_id_option 'osprober-chain-CC70378A703779F2' {
insmod part_msdos
insmod ntfs
set root='hd1,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd1,msdos2 --hint-efi=hd1,msdos2 --hint-baremetal=ahci1,msdos2  CC70378A703779F2
else
  search --no-floppy --fs-uuid --set=root CC70378A703779F2
fi
parttool ${root} hidden-
chainloader +1
}
menuentry 'Windows 7 (loader) (su /dev/sdb3)' --class windows --class os $menuentry_id_option 'osprober-chain-AC7C4EC27C4E86D4' {
insmod part_msdos
insmod ntfs
set root='hd1,msdos3'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd1,msdos3 --hint-efi=hd1,msdos3 --hint-baremetal=ahci1,msdos3  AC7C4EC27C4E86D4
else
  search --no-floppy --fs-uuid --set=root AC7C4EC27C4E86D4
fi
parttool ${root} hidden-
chainloader +1
}

Both give me this message if i selected them on boot menu:

error: no such device: CC70378A703779F2 (or AC7C4EC27C4E86D4)
error: hd1 cannot get C/H/S values

http://i.stack.imgur.com/hvE3k.jpg

Last, but not the least, from my BIOS i cannot change hard drive boot priority, so there's no way to boot /dev/sdb first.

Edit:

this is my blkid

/dev/sda1: UUID="1597fe18-faf5-48a5-b80f-4cbb7f8b896e" TYPE="ext4"
/dev/sda5: UUID="ea6548f1-3004-49ff-8d1d-4c84dfed3a6a" TYPE="ext4"
/dev/sda6: UUID="e24dbc3b-d2da-4a63-97ce-7430cfce9fce" TYPE="swap"
/dev/sdb1: SEC_TYPE="msdos" LABEL="DELLUTILITY" UUID="3030-3030" TYPE="vfat"
/dev/sdb2: LABEL="Recovery" UUID="CC70378A703779F2" TYPE="ntfs"
/dev/sdb3: LABEL="OS" UUID="AC7C4EC27C4E86D4" TYPE="ntfs"
/dev/sdb5: LABEL="VostroHD" UUID="01CCBB70E50A71E0" TYPE="ntfs"

EDIT:
I ran bootinfo script. HERE the result

EDIT2:
PC configuration at top