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TT-PACKARD
JULY - AUGUST 1976



The sat ( lmd .re#t IR) inpuFs OyaCIjdo
S
aH a* input cQhrd8&mr: bc;ch ktpm
tyva the paeMitv in&rtor to v h n b is
ve"'
low, the activehDgh outpu?is forced high;
when "R" is low, the active-high output
is forced low. Although normally the
aotive-low output is drs complement of




flipflops: W m n & h w?U sxta mfy
for as long as both "8' and "R" wo brcl
e J-K master/slave low. The flip-flop will return to some
indeterminate state when both " S and
"R" go high.
DUAL DTYPE RIP-FLOP
The duat D-type flip-flop shown in Figura
I of two i m t D-tr.pe
h
flip-flops with inputs on the left and
FIGURE 2 Four-Bit Bistable Latch
.




input.
-flops. Inputs to the
tion is derived as follows: master section on the left side are
- The "DC" input has a AND n controlled by the gate (G) pulse. The gate
relationship with the "C" input w pulse also controls the state of the
shown by the subswipted "C". FOUR-BIT BISTABLE LATCH coupling transistors (not shown) wh
Therefore, Data passas through "Dc" connect the mmw a r d m pd
The fourbit bistable latch shown in
only when " ' active trua
6 is Figure 2 consists of four independent
- Input "C" is sensitive to transition, or D-type flip-flops. FFI and FF2 are
sensitive as shown by controlled by the 61 dock input, and IN THIS ISSUE
h ed%
:
e (dynamic indicator) FF3 and FF4 are controlled by the C2
symbol. clock input. This i s evident by the
subscripted C1 and C2 on the input data
SA FE T Y-R ELA TED
SERVICE TIPS
I
- Absence of the polarity indicator on
lines. Information present a t a data (Dc)
input "C" means that the MORE
input is transferred to the active-high and SERVICE TRAINING
E level is true. Therefore,
active-low outputs when the associated SEMINAR CALENDAR
ive true on a low-to-hi&
clock input is high: the outputs will
tramis#* and when "C" is active true
follow the data as long as the clock CLEANING PC BOARDS
as stated &over data is passed through remains high. When the clock goes low,
the information that was present a t the X-Y RECORDER
and active low outputs are data input when t4e transition occurred is
by the abseme/presence of retained at the outputs until the dock SERVICE TIPS
tarritvindicator{ - P 1. returns high.

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* .-' I
LOGICSYMBOLS
I

sequence of operaion with reference
the gate pulse timing signal shown in
Figure 3 is as follows: t I
a.
a. T1 - Isolate slave from master.
b. T2 - Enter information from "J" and
"K" inputs t o Master. Since the
dynamic indicator symbol i s absent
from input "G", the data is not locked
out of the "J" and "K" inputs
between T2 and T3. In other words,
the inputs will follow the data as long
as the gate is high.
NOTE
In many instances outputs are cross
coupled back t o the "J" and "K"
inputs to latch them up. This
effectively moves T3 closer to T2
so that it appears the inputs are
edge sensitive for a specified
range of clock pulse repetition
frequency. In these instances some
drawinqs may show a
indicator at the "G" in
Figure 4).
d. When "J" and "K" are both high, the DUAL J-K EDGE-TRIGGERED
flip-flop will toggle. That is, the FLIP-FLOP
T3 - Disable "J" and "K" inputs. active-high and active-low outputs will
0
C.
change states for each gate pulse. The dual J-K edge-triggered flip-flop -
&awn in Figure 4 is functionally
identical to the master/slave flip-flop
clsscribd previously. Gate pulse timing
levels present at the "J is indicated by the dynamic and polarity
a t time T2. The four possible when "R" is IQW, active-high output
the indicator symbols. They show that
combinationsare as follows: is forced low. Although normally the the output is determined by the levels
i
a. When "J" and "K" are low, the active-low output is the complement of present a t the "J" and "K" inputs
outputs will not change state. the active-high output, simultaneous low at the instant a negative gate transition
inputs at "S" and "R" will force both (high-to-low)occurs.
b. When "J" i s high and "K" is low, the outputs high on some J/K flip-flops. This
active-high output will go high, unless condition will exist only for as long as The next issue of BENCH BRIEFS will
it is already high. both "R" and "S' are held low. The conclude the articles on Logic Symbology
c. When "J" i s low and "K" is high, the flip-flop will return to some with descriptions of more complex
active-high output will go low, unless indeterminate state when both "R" and circuits such as updown counters, ripple
it is already low. "s"go high. counters, and LED drivers.


CLEANING PC BOARDS Items needed are:
Rex Brush, *sa Clara Divisbn - Conventional dishwasher
Tom Cox, LovdcMd Instrument Division - Detergent (one of the following)
a. Triton CF-54 or CF-76 low foam
industrial liquid detergent; available
Once a pc board has been repaired, it's in 5 gallon (45 Ib.) containers from
with dirt, oil, solder flux, Central Solvents, 31702 Hayman
ts. And naturally, this Street, Hayward, CA. 94544.
can seriously degrade the
performance when the board is used in b. Alco-Zyme Enzyme Detergent.
high input i p d n e instruments. Here
meac This i s a detergent used in hospitals
is a method for cleaning the board using a to clean surgical tools. Available
household-type dishwasher, and then from Scientific Products, 150
recoating the repaired area with a dry Jefferson Drive, Menlo Park, CA.
film conformal coating. 94025.

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c c. Calgonite dishwasher detergent.
(if none of the above are available.)
6. The last r i m cyck shoutd be cam-
eaed d s t i l i e d water
Here is a special note on the above gwd (if none of the above To amomplish this,
detergents. are available.) er supply before the
ns. After the wash
The Triton products are low foaming and Make Fsertain that you perfiqrm the wash, water hrrt been pumped out, turn ioff
nonionic. CF-54 i s more general purpose rinse, a d dry cycles continuous. The
n
the washer (usualty just opening the
whereas CF-76 is recommended only for boards should not be allwed to dry door doss this), open the daor and
dishwashers. Extensive testing has shown between wash and rinse cycles.
paur the pte-heated distilled water
that the superior cleaning efficiency of 1. After the board has been repaired,
the nonionic detergent i s due in part to
i t s ability to solubilize fatty soils.
Alco-Zyme i s a recommended second 6. If an wen i s
choice but be careful, it's a high foaming etc.). Note that most s w i t o h do not
detergent. I f you use too much in the have t o be removed prior to cleaning. houn. Otherwise use,the dry cycle on
dishwasher you could be inundated with However, they do have to be re- the dishwasher twice.
a mountain of suds.
, andwhile the board is
Calgonite i s Sodium Tripolyphosophate 2. the repaired areas with
based and i s to be used only as a last the recommended dry film
resort. The potential problem area is that
if improperly rinsed from the pc board, it
can leave an electrically conductive film,
especially in hard to rinse areas like NOTE
NOTE
switches. Make certain that you wear the
For Triton, 1-1/2 oz. per wash. For
- Distilled water cotton gloves when handling the
Alco-Zyme, use 1/16 tsp. per wash.
boards.
- Cotton gloves For Calgonite, follow directions on
the box.
- Switch lubricant HP Part No.
5060-6086 3. Place the boards on their edges on the 8. I f the board has any switches mounted
top rack. on it, they will have to be relubricated.
- Dry Film coating (one of the
4. Run the dishwasher through the wash Use the conductive grease (HP
f ol Iowi ng) PN 5060-6086) and a toothpick to dab
cycle only. Use the amount of
a. Dry Film 88 (General Electric) detergent recommended in the note in a small amount on the contact/wiper
HP Part No. 6010-0142 step 2. Don't allow the boards to dry area.
b. KENCO #811 Circuit Coat before rinsing in the next step. The board is ready to return to operation.



THERMAL JACKET AIDS 1976 SYMPOSIUM
For a preliminary program and registra-
SOME PC BOARD TESTS NATIONAL CONFERENCE tion information, contact the NCSL
Secretariat, NBS, Gaithersburg, MD.
Here's an easy method to functionally OF STANDARDS 20234.
test circuit boards a t high or low
temperatures where satisfactory results
LABORATORIES
can't be obtained with the conventional
The NCSL is holding i t s annual
hair drier. Build a metal thermal jacket in
symposium October 6-8 a t the National
two halves and fill it with a nonconduc-
tive foam like polyurethane. Select test
Bureau of Standards in Gaithersburg, CRT DISPLAYS IN
leads that will withstand anticipated Maryland. NCSL i s an international MEDICAL SYSTEMS
association of 230 companies and organi-
temperatures and connect them to test
points on the board. Sandwich the board zations, sponsored by NBS, to promote
Application Note 199, "HP Small Screen
between the halves making sure the cooperative efforts in standards and
Displays: Medical Diagnostic
Cali bration.
board's edge connector and t e s t leads Applications," i s now available. It's
extend outside the jacket. Place the practically a textbook on the use of CRT
.assembly inside the thermal chamber, and This year's conference will review the X-Y displays in medical diagnostic sys-
G let it soak for an hour a t the desired
temperature. Then pull it out and plug it
into the interface used for ambient
past 75 years of national measurement
progress a t NBS, provide a program on
Metrication and related Metrology, delve
tems. It addresses theoretical subtleties
affecting diagnostic image quality not
specifically covered anywhere else. A t the
testing. The jacket will maintain the into the practical side of cal lab same time it's a practical "cookbook" of
temperature with less than 7