HP Data StorageWorks Ultrium 960 tape drive power issue

Few months ago we have to give away are HP Data StorageWorks Ultrium 960 tape drive. That device worked perfectly. And now it was gone. For good. And we need another device but it has to be HP tape device and we needed fast.
Instead of that perfect device we receive same (HP Ultrium 960) device but not so perfect. I will call this device D1. Device was showing that it has power/fan issue. Back LED was steady amber colour. I opened device thinking that if is a fan issue it can be easy replaced with different fan. When I attached fan wire, to battery fan was working perfectly. So it was power issue. As I have no spare power supply, this was dead end fow device D1. :(
After a while we realize that we two more HP  data drive (Data StorageWorks Ultrium 960). One was on server that don't have need for tape device any more. We will call this device D2. Second tape drive was on server that periodicly need tape drive. We will call this device D3.

I detached D2 device from server OS(RHEL 5.5 x64) using

echo 0 > /sys/class/scsi_tape/device/delete 

and than physicaly detach device. At that time back LED was green and front LED that is on power button was green to. Device was attached to this server more that 5 year with no power off.
 When I attached that perfectly D2 device to first server I was showing errors! Power supply/fan error! Again! On totally different tape device that 20 minutes ago was working perfectly. My first tought was that it got something to do with voltage because those devices were on different location and probably different voltage level burn something in power supply or fan. So I opened D2 device and attach fun to battery, it was working perfectly. So power supply issue again. Dead end again. :(

Same thing happened with device D3. :(
So I have 3 tape device that was working for quite some time(5 years and more) and now all of them have same issue-bad power supply.
I even try to switch power supply from one device to another hoping that somehow it will start to work. But no luck.
After few days I was thinking why I would not attach PC power supply to tape drive? It has same jacks,same 12V voltage. I found old PC that was lying around in a server room. I connected power to PC and connect it to dismantled tape drive and turn PC on. After a few seconds tape drive was in READY state, back LED for power/fan issue was blinking amber. I attached tape drive to server and after rescaning scsi_host I could see tape drive! Finally succsess!!! I found two more power supplies from PC and now ALL tape device are in READY state and working! All device are fully operational even if they are have yellow blinking LED from power/fan issue and have external power supply! :)
Working of devices was tested using tar for backup and restore and using HP Data Protector for restoring data from LTO3 tapes! :)

I hope this will help someone and save some critical time!