Tandy 6000 HD, Service Manual

Page: 213 / 416

Service Manual
TANDY 6000/6000-HD
TAN D Y COMPUTER PRODUCTS ----------------------------------------------------------------------
3. Adjust R2 until the DRUN signal just begins to toggle.
DRUN may be found on U27-15 for rev A boards or on test
point 7 for all other board revisions. This is only a
preliminary adjustment and does not need to be exact at
this time.
4. Replace jumper to position E6-E7 and be sure the primary
drive is connected and powered on.
5. Adjust trim capacitor Cll until a 100 nsec square wave
(10 MHz) signal is seen at TP 6 and the DC level of TP 3
is between 2 and 3 v o l t s .
6. Using a diagnostic, such as HQII or HDREL, format track
1 (diagnostic track).
7. Next, do a continuous track read of the diagnostic
track.
8. Set the scope for 2 msec sweep and trigger one channel
on index (active high) at U19-6. Place the other
channel on DRUN. You should see two index pulses spaced
16.67 msec apart.
9. Adjust R2 until you can define seventeen separate low
pulses on DRUN between the two index marks. By
adjusting R2 in both directions you can find the
location where the pulses on DRUN are distinguished most
clearly. The diagnostic should be incrementing the pass
counter without error.
10. Next recheck the 10 MHz signal at TP 6 and the Vco
reference at TP 3 and readjust Cll, if needed for a
stable setting.
11. If drive has a good format on it, execute random reads
and check for proper operation.
12. If drive does not have a good format (ie. a new drive),
format the entire drive and then execute a random read
test.
6. Register specifications
The important controller ports will now be listed in
greater detail. For more information on controller register
functions and programming, see the WD1010 specification
b o o klet.
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