HP DDS-1 C1534-00100, HP35470a drive repair attempt

[mita]

[ Specified attachment is not available ]Hi,

I am trying to repair a HP35470a scsi tape drive. I got the drive in the following condition:

- adaptec controller recognized correctly the drive
- was able to feed with cleaning cartridge and eject using Tapemate backup sw

I feed with a normal tape and tried to initialize the tape but the drive mount was unsuccessfull. Tried to eject the tape but it was unsuccessfull. Than the journey began.

I disassembled the drive cover. The tape was stuck in the drive, the head motor was blocked by the tape. It seemed he tape tension arms were not woking right left the tape loose and the revolving head got stuck by the tape. Luckily it was not too difficult to free the head and remove the tape cartridge.

I found one 2.5mm of length 0.8mm of diameter plastic piece falling from the drive. Some plastic part broke in the drive. I got a deep breath and started to disassemble the drive to find the part which has this broken piece.

I completely dissassembled the drive. Checked every plastic component, their surfaces but was unable to find where this tiny piece was breaked from. I started to assemble the drive. As usual it was much harder to assemble but finally I managed it.

Switching on the drive the green led started to blinking fast and after 11 blink the amber led light steadily, signaling error condition. Long pressing the eject button the drive started to initialize itself but the result was the same, steady amber light. I spent considerable time to figure out what went wrong with the assembly process.

Immediately after the switch on I tried to feed a cleaning tape into the drive. It taken the cartridge but the internal test failed and amber led lit. I tried to eject the cartridge but the drive was not able to eject it. It tried but failed. I suspected a mechanical error.

I removed one of the gear and I was able to move the remaining gear by hand. In this way I was able to "simulate" the motor. Interestingly I was able to move the gears and the cartridge ejected with a loose tape because the cartridge driving motors did not worked in switched off state. It proved that there is no mechanical blockage in the mechanic.

I payed attention what the cartridge mover motor does. When the cartridge is fully loaded and the eject button is pressed the motor starts to spin to eject the cartridge. But after one second the motor stops and rev back to the original position. At the reversal point there is no mechanical barrier, the cartridge mechanic did not move at all. At this point I do not know how to proceed further. What makes the motor revving back? I got a feeling the drive should be calibrated from a diagnostic software again.

I am looking for somebody who has experience with the repair of the DDS-1 drives from mechanical and software diagnostic point of view. I know HP Library and Tape Tools has a diagnostic function. Does somebody used this tool? I do not know wether this drive is supported or not by a given version of this sw.

In the attacjed picture in the lower right corner next to a small screw is the broken white plastic piece. (zoom required)

Any help, suggestions are appreciated in advance!


 

[m k]

Quite a small piece.
I'd say it's a too small for turning or pushing a button.
Maybe it is for blocking a light sensor.

When motor is pulling back it usually means that the operation is not completed.
Completion usually means that somewhere is an electrical feedback something.

I would concentrate to area around the jam, also vertically.

[mita]

Thank you your reply!

Next week I will get a dds2 drive. I do not know the condition of that drive but if it is mechanically working - ie. accept cartridge and eject it - than I will disassemble it extra carefully, fully documenting every steps. I think there is not too much difference mechanically between the dds1 and dds2 drives. Let see what can I found.