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  • problem with a RL01 drive

    From Mikesch@mikeschpdp@gmail.com to alt.sys.pdp11 on Wed May 25 11:46:34 2022
    From Newsgroup: alt.sys.pdp11

    Hello,
    I've a RL01 drive with the following errors:

    Pressing LOAD SpinUp starts and after approx. 20 sec FAULT light went on - heads don't go in!

    Posit.systems works (without cardtridge) retracks to track 0 strong on manual leaving track zero and emergency retracktion works.

    Here is the another problem:

    Also at standstill the Posit.system is getting very hot (takes 15 min) and you can smell a little bit electric.

    DC servo power voltages 5V +/- 8V are ok but +V and -V are only 13,87 V - that's to low should be greater 14 Volts.

    Changed the DLM from another drive - same result with FAULT after spinUp. The DLM works fine in my other drive.

    I'm looking for a spare DC servo board in my storage tomorrow.

    Any idea's what's the reason for this error?

    regards

    Michael
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  • From Mikesch@mikeschpdp@gmail.com to alt.sys.pdp11 on Thu May 26 04:03:26 2022
    From Newsgroup: alt.sys.pdp11

    Mikesch schrieb am Mittwoch, 25. Mai 2022 um 20:46:35 UTC+2:
    Hello,
    I've a RL01 drive with the following errors:

    Pressing LOAD SpinUp starts and after approx. 20 sec FAULT light went on - heads don't go in!

    Posit.systems works (without cardtridge) retracks to track 0 strong on manual leaving track zero and emergency retracktion works.

    Here is the another problem:

    Also at standstill the Posit.system is getting very hot (takes 15 min) and you can smell a little bit electric.

    DC servo power voltages 5V +/- 8V are ok but +V and -V are only 13,87 V - that's to low should be greater 14 Volts.

    Changed the DLM from another drive - same result with FAULT after spinUp. The DLM works fine in my other drive.

    I'm looking for a spare DC servo board in my storage tomorrow.

    Any idea's what's the reason for this error?

    regards

    Michael

    Done!

    Got the RL01 up and running.

    Causes:

    Home sensor with contact problems and poorly adjusted.
    - Follow constant "pulling" of the posit. towards the home position.
    - Follow high current of Pos. damage DC Servo Board
    - Consequence of heat generation
    - Defective power transistor on the DC servo board
    and depending on the vibration, the home switch worked or not. - Stupid hardware error!

    But the fact that I had a spare DC servo board and a spare home microswitch here solved the problem.
    (I have good spare parts here from 4 RL drives with broken motor or rust and similar damage)

    Spare parts storage is important with now 3 x RL01 and 6 x RL02 - but they all work at the moment and I still have 9 air filters original packed and sealed from DEC.

    regards

    Mikesch
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