ZX-News #21 21 февраля 1997

Железо

Iron - Repair Scorpio with his hands part 3: The drive does not read or formats.

 IRON



                          (C) Sergey Zerov


     Repair Scorpion with his own hands.

                Part III.



               Hi everyone!


  Today I will tell you the tale of repair diskovodnoy part of 
the "Scorpion." It is well very similar to the repair manual. 
The numbering of the elements shown on the old scheme (no 
turbo). 



   1. Drive can not read or format.


   1.1. LED on the drive (drive) lights

        constantly. Floppies go bad.


       ** Check VG93.

       ** Check for a protection scheme for a 12. (KT361,

            KT315, KS139). Fault protection scheme

            may be responsible for the regular exit

            VG93 system.

       ** Check all voltages on the VG93.

       ** Check the power supply of +12 V (to

            absent surges in moments

            On / Off).


   1.2. VG93 is healthy, tension is normal.


       ** Check the drive.

       ** Check the cable between the motherboard, power supply

            and drive.

       ** Check the supply voltage

            (4.4 - 4.8V) at 14 leg IC PLL D63 (155RT11)

            when accessing the drive. If the voltage

            none or it is less than 3.5V - replace KT361.

       ** Check the control signals to the

            VG93 (D54, D65), followed by the scheme.

       ** Check schema reading (D68.3 - D67) and PLL

            (D62 - D63).

       ** Sometimes crashes multiplexer D63 1533KP11

            by signals DRQ or INTRQ. This test
            The summation in the shadow of the monitor is

            rapid delivery of error (the healthy sectors do not 
have). 


   1.3. VG93 defective. In the process of formatting or

        check disk shadow monitor arise

        systematic errors (one or more

        the same sectors on each track).


       ** Defective drive (speed drive

            disc is significantly different from 300 rev / min.)

       ** Check schema formation of clock frequencies

            VG93, TM9 (D63), IR16 (D61). She collected by IMS

            1533LN1, 1533IE10 and 1533LP5 (D1, D56 and D11

            respectively).


   1.4. VG93 defective. Does not reformat at all.


       ** Check the diagram of the signal on:

            D10, D61, D63, check the clock

            pulses for 9 foot D61.

       ** If the board ceases to format post

            warm or at reduced power (especially

            it concerns the fees turbo), I recommend the mouth
            novit capacitor at 6 foot D61 (signal WD).


                     To be continued ...

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