Fisher Projection Television TW 7700 User Manual

TW-7700  
Digita l Lin e Tr a cer  
Op e ra ting Ma nua l  
F I S H E R R E S E A R C H L A B O R A T O R Y  
 
DESCRIPTION  
The TW-7700 Dig ita l Line Tra c e r c o nsists o f a tra nsm itte r, re c e ive r,  
g ro und -p la te / g ro und -ro d a sse m b ly, c a rrying c a se (ha rd o r so ft),  
a nd a n op e ra tors ma nua l. The TW-7700 is a sing le fre q ue nc y line tra c e r.  
The TW-7700 is an active locating line tracer. There  
are three methods of active locating that an operator  
can use to trace a utility. The con d u ctive method is  
the most preferred method, since a strong transmitter  
signal is transmitted through the intended target. The  
in d u ctive method is the easiest method to use, but  
may not yield the best results. When a direct connec-  
tion is not available, but the operator has good knowl-  
edge of where one point of the utility may be, the op-  
erator can place the Transmitter over the utility mak-  
ing sure that the arrow on top of the transmitter is  
parallel to the path of the utility. The third method of  
active locating involves using the cou p lin g cla m p ac-  
cessory. The coupling clamp is used when the utility is  
exposed, but a direct connection is not available. The  
clamp jaws are opened and placed around the utility.  
The clamp never makes a direct connection with the  
utility, that is, the utility can move freely with the  
clamp around it.  
The features of the TW-7700 make it a very easy and  
practical instrument in todays world of underground  
locating.  
1
3
 
TW-7700 TRANSMITTER  
Tra nsm itte r  
Located on the transmitter are the power mode and  
the accessory output. The power mode enables the  
operator to turn the transmitter on or off, and to  
check the condition of the batteries. When checking  
the batteries, a reading if 50 or greater on the display  
meter indicates that batteries are usable.  
The accessory output is for the ground plate/ground  
rod assembly, and for the coupling clamp. There is a  
Red LED light that blinks when the transmitter is  
on. The batteries are located underneath a lid on top  
of the transmitter housing.  
WARNING: Do no t ha nd le o utp ut le a d s unle ss p o we r is o ff.  
ELECTRIC SHOCK HAZARD: Se rvic ing to b e p e rfo rm e d b y  
q ua lifie d p e rso nne l o nly.  
The TW-7700 Tra nsm itte r.  
4
 
TW-7700 RECEIVER  
Re c e ive r  
The TW-7700 Re c e ive r.  
Controls  
Mod e  
This button does not have a function on the TW-7700.  
(It allows users of the TW-8800 Multi-Frequency Line  
Tracer to change frequencies.)  
Powe r On/ Off  
Turns the receiver on or off.  
Light  
Lights up the display for usage in dark areas. When the  
display is backlit, LIGHT is shown on the bottom left hand  
side of the display screen.  
Ba t  
Press and hold this pad to check the battery level of the  
receiver. A bar graph on the right side of the display will  
give status of the batteries. When the graph shows 1 bar,  
it is time to replace the batteries. Additionally, as the  
operator uses the Receiver, if the batteries get low, RE-  
PLACE BATTERIES will appear in the lower area of the  
Display screen.  
Vol(up )/ Vol(d own)  
Increases or decreases the volume of the speaker.  
De p th  
After determining the centerline of the utility, set the  
blade of the receiver on the ground, press and hold this  
pad to get the depth to the center of the target.  
5
 
TW-7700 RECEIVER  
Displa y  
Fre q ue nc y Mod e s  
The frequency at which the receiver is operating.  
<< Le ft/ Ove r Ta rg e t>/ Rig ht>>  
Indicates where the receiver is in relation to utility.  
Num e ric Disp la y  
Serves a dual function:  
• Relative signal strength of the transmitted signal (%  
shown). Responds in conjunction with the bar graph.  
• Depth to the center of the target (when DEPTH pad is  
pressed - IN or CM shown)  
Light  
Indicates the display is lit (activated by pressing LIGHT pad).  
Ba r Gra p h  
Serves three purposes:  
• Responds in conjunction with signal strength.  
• Visual indicator for battery test (when BAT pad is pressed).  
• Volume loudness indicator (when VOL(up)/VOL(down)  
is pressed.  
Re p la c e Ba tte rie s  
When the receiver batteries fall below a nominal level,  
REPLACE BATTERIES will be displayed.  
No Sig na l  
When no signal is received by the receiver, NO SIGNAL  
will display. This response may be due to the transmitter  
not being turned on, or the transmitter and receiver not  
be set at the same frequency.  
6
 
ACCESSORIES  
Coup ling Cla m p  
The coupling clamp is useful when the utility is exposed,  
and a direct connection is not possible. It is plugged into  
the same plug-in socket as the ground-plate/ground-rod  
assembly. The coupling clamp only operates at the 82  
kHz frequency. The coupling clamp will fit around utili-  
ties that are 3-¼ inches in diameter or smaller. The length  
of the cable is approximately 10 feet.  
Coup ling Cla m p Ap p lic a tions Dia g ra m  
D. Tra c e sig n a l w ill re tu rn to  
A. The c o up ling c la m p is fo r a ll  
tra c ing a p p lic a tio ns with c o n-  
d uc to rs e xp o se d ; e xc e p tio n, a n  
op e n c irc uit a t line s te rmina tion.  
B. A g ro und m ust b e p ro vid e d fo r  
the p ro p e r c urre nt flo w whe n the  
c o up ling c la m p is use d a t a te r-  
m ina tio n.  
C . The c o up ling c la m p m ust b e  
u se d b e tw e e n th e g ro u n d in g  
a nd whe re the line g o e s und e r-  
g ro und .  
g ro u n d  
w h e n  
in c o rre c tly  
c o up le d .  
E. Sig na l will b e tra nsm itte d in  
b o th d ire c tio ns whe n c o nne c t-  
ing is mid wa y in a long c ond uc tor.  
F. Dro p line s o r la te ra ls d ivid e the  
sig na l stre ng th in ha lf a t e a c h  
junc tio n.  
This re p re se nts a jum p e r  
He a d se ts  
Fisher Research Laboratory has a variety of headsets avail-  
able.  
Ultra-quiet deluxe Fisher Phones. High quality sound  
while reducing the outside noise.  
• Standard Stereo Headphones  
• Single Earpiece Headset. Enables the operator to effec-  
tively listen to the TW-7700 and remain aware of noise in  
close proximity.  
7
 
OPERATING INSTRUCTIONS  
The fo llo wing instruc tio ns a re d e sig ne d fo r a sa fe a nd e ffe c tive  
m e tho d o f line tra c ing a nd utility a vo id a nc e . So m e o f the ste p s  
m a y no t b e a p p lic a b le in a ll situa tio ns. The und e rlying g uid e line is  
tha t o p e ra to r sa fe ty m ust b e m a inta ine d a t a ll tim e s. Use o f  
sa fe ty e q uip m e nt, e xtra p e rso nne l, a nd up to d a te a s-b uilt p la ns  
sho uld b e c o nsid e re d whe n ne c e ssa ry.  
INITIAL SCAN  
Set-up Transmitter either Inductively or Conductively  
Ind uc tive  
Be aware of air coupling, the transmitted signal travelling  
to the Receiver via the air, not the utility.  
Cond uc tive  
Connect the ground plate/ground rod assembly to the trans-  
mitter. Connect the red lead to the non energized utility. Con-  
nect the black lead to the ground plate/ground rod. Place the  
plate/rod at a 90 degree angle in reference to the utility. Be  
sure not to place the wires over any other utility.  
After transmitter set-up, move away from the point of con-  
nection (or Induction) about 25 feet (8 meters). Sweep a  
circle around the point of connection. Initially, disregard  
the LEFT/RIGHT indicator and rely on the signal strength  
readout. Make note of the high readings. These are areas  
that need to be traced/examined in more detail.  
Tra c ing  
After locating the point(s) where the signal strength was  
the highest, return to that/those points and start tracing  
your utility. This is where the LEFT/RIGHT indicator is  
very helpful. Swing the receiver from left to right and lis-  
ten for the change of tone. When the target is to the RIGHT  
of the receiver, the tone is pulsed tone. As the receiver  
gets closer to the target, the pitch gets higher. When the  
target is to the LEFT of the receiver, the tone is a continu-  
ous tone. As the receiver gets close to the target, the pitch  
also becomes higher. When the receiver is over the target,  
OVER TARGET is displayed on the display screen, and the  
tone is at its highest peak sound.  
De p th Me a suring  
When an OVER TARGET response is displayed, position  
the blade of the receiver directly over the utility and  
place the tip on the ground. Hold the receiver steady,  
press and hold the DEPTH pad. Depth will be measured  
to the center of the utility.  
8
 
DEPTH ACCURACY  
De p th m e a sure m e nt is a fe a ture o f the TW-7700. Ac c ura c y is  
d e fine d o n a n id e a l ta rg e t, tha t is, o ne tha t is c o ntinuo us, a  
g o o d c o nd uc to r, a nd no t surro und ing b y o the r utilitie s. The re a re  
fa c to rs tha t c a n c a use the o p e ra to r to q ue stio n the a c c ura c y  
o f the utility b e ing tra c e d .  
Ind uc tive Tra nsm itte r Se tup  
Inductively, only a small portion of the signal attaches  
itself to the utility. With a weakened signal, trace should  
be accurate, but depth may not. The conductive method  
will yield better results.  
Low Re c e ive r Sig na l Stre ng th  
When the signal strength falls below 20 – 25%, depth  
readout may not be accurate. It would be beneficial to  
move the transmitter to a closer point of contact.  
Ne a rb y Utilitie s  
Close, nearby utilities may have some influence on the  
accuracy of the Depth readout. This is more prone to  
happen in the higher frequencies where signals can jump  
to nearby utilities. Switching to a lower frequency can  
give better results.  
Moisture  
Ground that is too dry or overly saturated may skew the  
depth readout.  
Ts”, e lb ows, or sp lits in the utility c a n d istort the  
tra nsm itte d sig na l in tha t g e ne ra l a re a .  
WARNING: Do no t c o nne c t o utp ut le a d s to a live  
(e ne rg ize d ) utility. Ple a se p re ve nt sho c k ha za rd a nd  
e q uip m e nt d a m a g e .  
9
 
SPECIFICATIONS  
Sub je c t to im p ro ve m e nt o r m o d ific a tio n witho ut no tic e .  
RECEIVER  
Depth Accuracy ...................... +1 inch per foot in nominal condi-  
tions  
Readout Units ........................ Inches or cm (factory preset)  
Left/Right Guidance ............... Audio: continuous tone=Left,  
pulsed tone=Right. VCO (varying pitch) output for easy over  
........................................... target location. Visual: Left/Right/  
........................................... Over Target messages  
Signal Strength ...................... Digital Numeric Readout (0-99%)  
& Bar Graph  
Sensitivity Adjust ................... Automatic  
LCD Backlight ........................ Included  
Battery Test ........................... Automatic Low Battery alert  
Push button readout  
Battery Type ........................... Six C” cells  
Battery Life ............................ 80 Hours  
Weight ..................................... 5.4 lbs.  
Operating Temp ..................... -4 0 to +1400F (-200 to +600C)  
TRANSMITTER  
Output Frequency .................. 82kHz,  
Output Power (nominal) ........ .5Watts,  
Battery Test ........................... Yes  
Battery Type ........................... Two 6 Volt lantern batteries  
Battery Life ............................ 80 Hours  
Weight ..................................... 5.0 lbs.  
F ish er Resea r ch La bor a tor y d oes n ot w a r r a n t su ita bility to sp ecific u se. F ish er  
Resea r ch La bor a tor y sh a ll in n o even t be lia ble for a n y d ir ect, in cid en ta l, con se-  
qu en tia l or in d ir ect d a m a ges.  
10  
 
NOTES  
 
QUALITY  
Fishe r d e te c to rs a re re no wne d fo r the ir q ua lity.  
Ea c h d e te c to r is ha nd c ra fte d in the USA with p rid e  
PERFORMANCE  
Our d e te c to rs a nd lo c a to rs a re d ura b le , d e p e nd a b le , a nd  
se a rc h d e e p e r.  
REPUTATION  
Fishe r p ro d uc e d the first p a te nte d m e ta l d e te c to r in 1931. Fo r  
o ve r 70 ye a rs, the Fishe r lo g o ha s b e e n a m a rk o f e xc e lle nc e .  
2 YEAR WARRANTY  
Fishe r b e lie ve s in the p ro d uc ts we p ro d uc e a nd b a c ks this b e lie f  
with a 2 ye a r lim ite d wa rra nty. Wa rra nty m a y va ry o utsid e the  
Unite d Sta te s. Se e yo ur d e a le r fo r d e ta ils  
SERVICE  
Fishe r is c o m m itte d to p ro vid ing yo u, o ur va lue d c usto m e r, with  
sup e rio r se rvic e . Ea c h a nd e ve ry instrum e nt is rig id ly te ste d a nd  
c a re fully insp e c te d d uring a sse m b ly a nd b e fo re ship m e nt. Sho uld  
yo u ha ve a ny q ue stio ns o r p ro b le m s, c o nta c t:  
FISHER RESEARC H LABO RATO RY  
200 W. Willm o tt Rd .,  
Lo s Ba no s, CA 93635  
Te l 209.826.3292 Fa x 209.826.0416  
www.fishe rla b .c om e ma il:info@fishe rla b .c om  
EXPORT DEPARTMENT  
P.O. Bo x 1896  
Ne w Ha ve n, CT 06508 USA  
Te l 203.288.1638 Fa x 203.287.8099  
e m a il:m b @e xp ortd e p t.c om  
 
FRL 8708002-A  

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