DonNews #20 26 февраля 2004

Железо

Repair - Continuation of cycle repair the Pentagon. "

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         REPAIR



Drive is spinning, but does not stop.


(C) Wild_oHg_XXL
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 One reason may be wrong
Wiring output connector drive
open line or a loose fit
connector. Check the supply voltage
supply. The reason may be defective
Products 1818VG93 (it is advisable to check on another 
computer). When it Installation on board check

+12 V. Check for shorts between 28 and 32 feet on 1818VG93
board.
 The reason may be lack of signal
select the drive, which is responsible for
Chip D98. On admission to the findings
D88/15, 12 Address the drive and decrypt
his chip D98, the signal is fed to
output sample of one of the 4 drives. When
no chips on 1818VG93 D98/15
low capacity, and therefore the scheme include motor control 
and without the motor will rotate without stopping. It usually

happens when a faulty chip 1818VG93
When you receive the item with the VG93 D98/15
+5 V drive must stop. To select a drive from the element
D98 served very rare pulses (Q10
- Q13). Check their availability and correct
jumpers on the drive.
 Check the transmission of signals through
buffer chip D94 (without IC
1818VG93 submit its findings to some
pulse signal). Check transmission
signals through the buffer chip D95
(155LP9-buffer contains six elements
without inversion of the open-collector).
 The trouble may be the lack of treatment or failure of chips 
D91 (155LP11, contains six buffer elements of the tri-state 
output). When a high-level input D91/15

Released D91/11, 13 should open. When
lower potential at the input element D91/15
is the transmission of signals to the output without
inversion. Check out the passage of these
signals. To check the reference to D91
Connect to ground a conclusion D13/20
(Non-Z80) and transferred to the zero state
flip-flop D76. As a result, the chip
D89/15 will be a low potential for resolution of appeals to 
her, and at high potential at the inputs D89 / 3, and D89/13 in

D89/12 output should appear low
potential. This condition treatment to the chip D91. Trouble may
be defective chip decoder
D89. This decoder allows you to access
either the floppy drive controller, or to register
D88. The choice of the controller or register determined by the 
combination of levels on the inputs element D89 / 3,13,15. The 
outputs of this chip - are mutually exclusive, active levels - 
Low. Active level for D89/15 - Low.



   Input Output D89 D89

  15 3 13 9 10 11 12


   1 X X 1 1 1 1

   0 0 0 0 1 1 1

   0 1 0 1 0 1 1

   0 0 1 1 1 0 1

   0 1 1 1 1 1 0

 To check the circulation to the element D88
connect to ground (not Z80) on
processor board D1320 conclusions and D13/22
(IORQ and WR), and D1337 (A7) to +5 V.
As a result, the output circuits D89/11
you should see a low potential - is
the condition of the sample chips D88.
 To check the circulation to the element D90
Connect to ground conclusions D13/20
(IORQ), D13/22 (WR), D13/37 (A7).
As a result, the derivation of the element D89 / 9 will lower 
potential for D82 / 8, too low capacity, a condition the sample 
D90.  Install the Z80, ROM, and press

ENTER. With each keystroke, the magnetic head must move from 
the track 00 to the center by one step. This shows the

serviceability chips D88 and D89.