FIELD SERVICE TECH MANUAL

(1)

(

· i ..

~!'ll:". 'I£-.._:..,...~'111~ .• ~.---.: ~111'::.~~~ ItLS2 "-'--~tn...--~·~~~~~= ____ ~"'~IlI!IIr;"""",,,_oe.~

p[flr~~S/

^FAMILY ^DECTAPE

FIELD SERVICE TECH MANUAL

ADJUSTMENTS FOR DECTAPE ^~YSTEMS(Continued) TO USE: (1 )

(2)

Plug in skew tester AFTER selecting source of V plus, see NOTES on S3 and TO USE: (5), 53.

Calibrate. See NOTES on 51 and TO USE: (5),53.

(~) Select correct split winding, see NOTES on S2 and TO USE:

(5), S2.

(4) Skew Test

A. Zero Skew Tape Available: (Certified DECtapes are not zero skew. They may· have a ^l~sec skew.) Run tape across head in normal manner. Gain of tester is enough to give clipped sine wave out. About 10V PIP. Go to step 4C. This skew is real.

B. No Zero Skew Tape Available. Clean tape head and guides.

(4~E) Format Tape. Reverse tape so oxide side is up.

(4-F) Now thread this tape from take-up reel across head with oxide up onto original supply reel. Move tape in local mode. Go to step 4C. The skew indicated is twice real skew.

C. Skew is measured by measuring the time difference between the two signals crossing a given reference line. Figure 1. To test skew; with tape in motion, depress lightly on the back edge of the tape on the right or left sides of the head. Record whirih side causes the skew to increase when pressure is applied to 'one side or the other. If

D.

the real skew is greater than 2/-4... sec, the head should be deskewed. This tolerance will apply to both TU5S and Tu56 transports to gain an added factor of interchangeability of tapes. I f the head is to be deskewed, i t should be taken as close to zero as possible. If a non-zero skew is used,' i t must be formatted after each attempt to deskew.

To deskew:

1. Remove head and thoroughly clean back of head and mounting surface of ail dirt, glue, skew shims, etc~·

Remount head and redo 4A or 4B as applicable.

2. I f shimming is necessary, magtape reflective marker (DEC #29-15191) is acceptable. Place the marker on

~.

the back of the head on the edge of the side which caused the skew to increase in step 4C. (For TU56.

heads, the reflective tape must be placed only below the mounting screw.) Remount head being careful not to curl the ship tape edge and redo step 4A or 4B.

(2)

~ .... ,"r,,~~-_::'"""l2J_~,-..:;,r=-a~~~_"Z!mI_osm:laIIe-:l" _ _ zmm_~ ... __ -nt='r-

. I ' I

I PDP..",S/S

^DECTAPE

( FIELD SERVICE TECH MANUAL.

ADJUSTMENTS FOR DECTAPE SYSTEMS (Continued) TO USE: ⁽⁴⁾ Skew Test (Continued)

E. To Clean:

1. Heads and Guides: Use DECtape cleaning solution generously on the head, wiping dirt wi tho clean, lint free towel (Kimwipe).

2. Guides: Disassemble guide from plate and thor- oughly clean with solution all parts including wear plates, studs, springs, spring holes and guides themselves.

3. Tape: Place doubled clean, lint free towel over head; thread tape over tow~l; place free end of

towel over tape.

Run tape from end-tp-end at least once in each direction.

F. Reversing Tape: (Oxide side up) Figure 4-F-1

Mount normally full reel of tape on right hub and empty reel on left. Thread tape from bottom of full spool onto top of empty reel. In local move all tape to left reel.

This places oxide side up for skew test.

CAUTION: Maintain manual pressure on the supplying reel to prevent tape runaway.

(5) Switches: NC

=

DOWN NO = UP

Sl (Middle Switch) Calibrate - NO/Normal - NC

NO Select signal to lower amp to compensate for internal drift and phase shift of op amps. To calibrate, put switch in NO position, scope in Add, tape oxide side

up and move tape in local. The two signals are 180⁰ phase and should cancel. ADJ 10KPOT for smallest resultant signal. Return switch to NC position.

NC Signal from other half split winding is applied to lower amp for skew test. Do not adjust pot for any difference in amplitude. This difference is a result of low signal from one half of split winding due to sket-l.

~

⁹ ^OF

16f1 ~AGE

^REVISION ⁰ [[pUBLICATION

DI~TE

February: 15, 197: ) DIGITAL EQU~PMENT CORPORATION 0 MAYNARD. MASSACHUSETTS

(3)

ADJUSTMENTS FOR DECTAPE SYSTEMS (Continued) TO USE:

TU55/56

(5) Switches (continued)

S2 Top Switch: Select split wi~ding, due to different vendors assigning different pins for head connection.

I f switch is in wrong position, SlG2 will be twice amplitude of SlG1 in normal position of Sl, when oxide side up. I f oxide sid~ is down, a phase shift plus skew will result.

S3 Bottom Switch: For compatibility to R series transports NC-- +5V i f applied to V plus.

NO-- +10V is divided to +5 for V plus.

CAUTION: This selection is to be made before voltages are applied.

Skew Tester may be placed in any empty slot which has +5 (or +10), -15, and ground in pins A2, B2 and C2 respectively.

Attach female data cable from head to male of tester.

PARTS LIST:

NOTES:

MC1709CG

220 011M 1/4W 5%

4.7K 1/4W 5%

1.5K 1/4rl 5%

22K 1/4W 5%

10K POT

470K 1/4W 5%

·330 OHM 1/2W 5%

1N753A

22pf 100V 5%

10pf 100V 5%

.01mf 100V 5%

6.8 mf 35V 20%

1 PST 6 AT1-T2 Ampheno1

19-9344 - E1 through E4 13-0271

13-0447 13-0391 13-1808 13-9143-10 13-2398 13-0296 11-2421 10-0021 10-0006 10-1610 10-0067 12-1168

133-022-03 12-2909

680 OHM 1/2W 5% 13-0347 1. Ampheno1 Pin Assignments

-pin A Skew Tap.

-Pin D Center Tap.

-pin B solid winding on Western Magnetic head.

Split winding on Brush head.

-pin C Split winding on Western Magnetic or General Instrument.

Solid winding on Brush.

Split winding for skew measurement.

~100~~

PAGE HEVISION .

~ lJ

PU3L1C/\TION DATE February 15,

~9i}

DIGITAL EC.Jt.JH.;orv1EN1~ CC)r-1PC)F~Al-tO'" 0 MAYNt'l,.f~[) ^t MASSAC~~USE·rTS

(4)

( ,

DECTAPES

FIELD SERVICE TECH MANUAL

tliC!025i.UCW ili&C za ESi!Sl!d(,'M"

ADJUSTMENTS FOR DECTAPE SYSTEMS (Continued) Notes: (continued)

2. M series use NC position of 83 (+5 applied to A2).

R series use NO position of S3 (+10 V applied to A).

j. i El-E4 MCl709 CG. Pin 4 = V minus 'Pin 7

=

^{V plus.}

unless otherwise noted resistors are in OHM, l/4W. 5%

4. MC1709 CG.

Pin side.

1 E-

5. Sl = calibrate/normal S2 = select split wina~ng

S3 = select V plus source

(5)

i5 o

rjg

~

G>

mfTl

~~

!-.o

"'~

"

]l~

~;-.

Z in

-.~i _I]>tJ

Q

0

¹¹¹

0"

_r.:~_tTl

_tJ

<

'TIiU>

0,'0

~ ^YI

^z

4 f

-tiC)

o ZI"U

a c:

~.~ 91

,,>

v~

-(0 ZjZ

P

^I^O

:ol~

nrri

~I

_'"ll

~I~ »Ici

ff)IPJ

~F.

₀_:"""'

-f'"

.L r-

Lr-a

Ull\tl

m

-i

~ (f)

"--"

f

---

^_

...

1"--"""

; ,

~~ANNeL

'

1 ' -...

C~-ANNE~ ...

"Z. ~

"

FIGURE 1

Input Coupllng: AC; Sync: AC HF REJ; ADJ,both

eH

to , level Sync on channell. Put start of sweep at left ~nd of X axis.

Position seep 2 to start at same point. The difference in time where the two sweep across the X axis is the skew.

NOTE: Signals shown are for reference only to show skew measurement.

They may be square wave (step 4A) or negative portion of this signal depending on tape direction (step 4B).

r- --"

"

- _m

r o en m

~ fjlJl

mD

_~

I::nl

-I

^~

"m, , .~

O[Q@

I

» ~

z c

» _r

...

'"ll

~

~ I--t

~

t:J ~

~ ~

~

t:J

,

!

I

e:-_-=-.-.J

(6)

J

-:l .!~

~

>1""0

->

~l~ l:!f-...

'.I I....J

-10 --!-,

,

":,>l"~,,,' r-:.^l^,-

1.'1

~p,~O)

111

~'~

{!" J~

"I

rn,'1

1,'::;

') (l,)

jl§ll

] I

;10 p

:Q ~G

.I~I

_1(>

I.>

Il~

'j(5

;Iz

:p~

'!-f

;!!"i1!

~ I

.~ -r,

^:'Ij

~~

-..

~

) 1...: _C'i',. "'n

"to "'J '\ ..

)b ~

^C}

»

1

!N

^{~ ~}

,. \ I'

~~I~ ~

,§J

-I

Q

I i \

r--.

i

L

O'l.loe 5 IDt: v( P

~ ~ ⁰⁰ ⁰ ^{U T} ^P^fA^TAg⁰^I.(

r

~" ^{p /}?

/~-...

(

~-

^SKt5^W

I b~/Dt£ $I/)~

^j}oWI'I

. l?

~

() () ^C^{tl "(}f? tI 7 ,4 8 ^(HIT 10 V f / P.

These pictures are for reference only; however can be used to illuatrate a point.

Given: Tape: Moving Forward

Channel 2 leads channell as shown.

If tape is reversed, channel 2 should lag channell, as shown with dotted lines, the same amount as i t leads going forward. If this condition is ~ot met, either amount is different or does not swap

from lead to lag~ It indicates faulty guides ~hich must be cleaned or replaced.

.----'\

" ^- _m l

r o

m m

O ~ ^-~ m D ^_','U

^~s

^~ ^~

rri 11 ~

O ^m

",~"f;i" J-:.'1.

.:'-:.'~

T "-

...c.... ~

l> ~ Z C l>

r

~

~ ~

/:'i

~

t::1

ttj (')

~3

~I

'\J ttl

i

~ ~

(7)

·0

(j)

»1"'0

-i

rl>

G>

mlrn

~' ,,'[I~

- i ' l

1]1---0

7~ ~

m ; Z -11;g

G)

Olm Q::r.J

IJ<

(T1 - M -

tJ ~

Dig "'0 .:;.

,/--

1>

-; ', \0

o Z~

^NORMAL

o ~ . E Nt PT'I

~ ~ REf:l

l>~

-< -I

Z,~

)> ~~

JJ

-l -"

O·fTl I

D'-

~~ i

»~ m

m~

I

^.t:.

m . E ..

VJ~ 'l1

»1 ~F cL

(J)~

~tJ

_-i

en

Link Tape:

Q

TAPE

FLOW

TU55/56

Reverse Tape

NORMAL FtALL

RE"EL

Put normal full reel on left hub, empty on right hub. Thread from bottom of left to top of right.

In local wind all tape onto right reel.

r

. . -... "\

" ^- m

r o

m m

1 ~ ,..,

^~ ^,^,,-

m ^~ _~~ ^-,' ^,:' ⁱ

~' .', ~

-1 ~~ "

m .~

" ^{~ ~}

l J ~. "

I

» ~

z c

» _r

"

^~_~

::::

\-.f f:-i

~

I

~

c

I

'

• tl I?

~ '

() .

~

.

~ ~

' ~ i

... "

(8)

~ I~-'.:lir.ok _ _ _ """"""a.::r'_""

.'£"'<'"!"---

_~~~'~.c,3lI!III!:':iI _ _ ~~"""""'~--""""-~=...,.C&Zt~!b"

( I

C

-::r

t ("'(

\I') \.E

(\...

...t

<to _\(\

':;j \on

<-

^:S'

ct. 1-

£

(..\.

\u c:a::.

\ ,_

^..^/

~[O~~~

^/FAMILY

FIELD SERVICE TECH MANUAL

~

\U ~

V\

\U

\-

o

~

~\lJ

w~ \I)

Q

<t

::r:

\lJ

r-

\

\1\

\!)"

(L

- t

\J'\

:s I-

DECTAPE

?! 0.1-;J iJ /'./ A' 0 ;;J

.;:?7t:/W;J.:l oV:9H WO~.:J

(9)

o

G1

-i

PI

^'"0

r~

~~O\

ml~

---n VI-

/ 0 \

m

~

^I

LI-o

--1Ii>

Q

Om 1J<

O~

0

lJ~ ⁰

~Zl

• t f -1. c

o Z

^IJ f;\

a C w v,.

7' C

0 ~ ~i

^<)

v ·

~~

ZG;.

p~ JJ~

Om

'"ll CD

~ ~ l>

~ ill ~ (DtC

» _n

^{l -}

~"l

~ ...

I CI-

(J)~

m

^r-v

-I -i

en

V\

"

^m_~_'

-\ tn C/\

-l rn

;Q ,,"'.'.

~ ~ 1"\

~ <:)

~ \

-:t:~

g. <:)

. - ' ~t'l"')

<~

~o

No

N~

,~ r-l~

I~o-l " ^J,.

^C.

!~r>. ~

U ^v-I-L

_{_} _fOP^NO:uP^$1..

~~ er(. (-oJ

q

I

51

f!No:t..tP M\DOLC swlTC. H

, 1

1..'20

'Z.Zo

1..2D

, 2 0

~,

22K

vpt..^rJS

V f{\INU, S

"lZK

" PLU"

2.U>Q'!>

^f'+ ^K

~Ul ^f----::

f lJ. ~ ^I

^.Of/,,-t

10 rf

:l

V MINUS

PJrI~2.

-L

3~"O "til/NUS

?ltll:l2

"v I I ~7

^IN7S3A ^PIIJA2

LJ7

^0K

V Pz..u..,5

I

V MINUS

Ll1°1{

V PJ. u.s

_-~-CIZ

t./.7K

I

1 t-1"5

^l/

" MINc/'~

5)~ <.

61..\.(£

Sl6 J RfO

V PLIAS

we. ~

c. S "3

" tV 0 :: ./.L P

-'sv ~1Fft· ^II'

+5"

o R - flo

v

I

• 0

~-r

I

^j) ^"80

"""0

^M

I

r 5wtT£.tI

• 0 p~

----.,

----' 1

" ^- m

r o

,

i

_~

I

~ I

ffi i

~ !

fj ~ i

g

m , (J~' " .'".}:!" ^I

-'~ -. ~

m~. I

(1

^~¥'!^~,i^,',^"~^:;)^~, ^ill^,

11

I

,

~

~ ~S

c »

r

o :

m

i"tl

't;lj i/. ~

., _1

FIELD SERVICE TECH MANUAL

· i ..

p[flr~~S/