Tandy 6000 HD, Service Manual

Page: 398 / 416

FRONT PANEL
REPLACEMENT
REMOVAL
T o rem ove th e fr o n t panel:
1. W edge a ta p e r sh im 0.030 in c h u n d e r the
edge o f th e fr o n t panel.
2. R em ove th e fr o n t panel fro m th e d riv e
fra m e .
3. Clean the fr o n t p a n e l th o ro u g h ly w ith
solvent.
REPLACEMENT
T o replace th e fr o n t panel, a p p ly new dou b le back
tape, and f i t th e panel over th e d riv e fra m e .
SPINDLE CONTROL CIRCUIT
BOARD ASSEMBLY
REMOVAL
T o rem ove the S pindle C o n tro l C irc u it B o a rd
A ssem bly:
1. R em ove the C o n tro l a nd D a ta C irc u it
B o a rd A ssem bly.
2. R em ove C on n e cto rs J10 and J l 1 fr o m the
S pindle C o n tro l c irc u it b o a rd .
3. Rem ove th e three screws th a t a tta ch the
b o a rd to th e chassis.
4. L i f t the b o a rd s tra ig h t u p and o u t.
T o replace the b o a rd , reverse Steps 2 th ro u g h 4.
W hen re p la cin g connectors, ensure th e p ro p e r p in
o rie n ta tio n .
ADJUSTMENT
T o a d ju s t the S pindle C o n tro l c irc u it b o a rd :
1. Set p o te n tio m e te r R23 (closest to in te rfa c e
connecto rs, single tu rn ) to its a p p ro x im a te
center p o s itio n .
2. U sin g a d u a l channel oscilloscope, connect
one channel to R 26 (resistor lead closest to
the p o w e r tra n s is to r leads o n S pindle C o n ­
tr o l C irc u it B o a rd ), and set scope to 100
m illiv o lts per d iv is io n . C onnect the o th e r
channel o f the scope to test p o in t three on
th e lo g ic b o a rd (in d e x), and set th e vo lta g e
scale a t one v o lt per d iv is io n and the tim e
base a t tw o m illiseconds per d iv is io n .
3. A p p ly p o w e r to th e d riv e and w a it 15
seconds fo r the spindle m o to r to com e up
to speed.
4. W h ile the scope is trig g e re d o n in d e x , ad­
ju s t the speed c o n tro l p o te n tio m e te r R5 on
the spindle c o n tro l b o a rd (10 tu r n p o t
closest to th e fr o n t o f th e d riv e ), so the
tim e between in d e x pulses is between 16
and 17 m illiseconds.
5. T rig g e r the scope to the lin e fre q u e n cy (60
H e rtz ). A d ju s t R5 so in d e x pulses are sta­
tio n a ry o n the scope screen.
6. A d ju s t R23 so voltage spikes, b o th po sitive
and negative go in g , across R26 are
m in im a l (see F igure 4-5).
7. Repeat Steps 5 and 6 u n til n o fu rth e r im ­
p ro ve m e n t can be made.
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