**DART PROJECT**

**Downstream Terminator Module**

**Assembly and Test Directions**

**Manual**

Tuesday, August 22, 1995

Kevin O. Engram

John T. Anderson

John Chramowicz

Electronic Systems Engineering Department

Computing Division

Fermi National Accelerator Laboratory

Document \# ESE-DART-950822

**INTRODUCTION**

This document is the manual on how to assemble the Downstream Terminator
Network module from start to finish. It provides an outline, a tool
list, and the procedures that I followed to complete the assembly of a
module. There are many parts towards completion of each module; and to
give an estimate, start to finish requires about 8 hours of work. If
there are any questions or problems, consult a technician or an engineer
for assistance. Good Luck!!

**OUTLINE**

I. Board Assembly

1\. Soldering the Connectors

2\. Soldering the Sips (Single Inline Resistor Packages)

3\. Soldering the Remaining Resistors

4\. Soldering the Bypass Capacitors

5\. Soldering the Remaining Capacitors

6\. Soldering the Fuse Sockets and Other Miscellaneous

Components

7\. Inserting the Fuses

II\. Cable Assembly

1\. Cable from the AC Fuse/Socket Assembly to the Power

Supply

2\. Cable from the Power Supply to the DTN Board

III\. Connections to the Bottom Panel

1\. Drilling the Holes for the DTN Board and the Power Supply

2\. Connect the Power Supply

A. Put Kapton tape on bottom panel

B. Screw the Standoffs on the Panel for the Power

Supply

C. Manually fit Power Supply onto the Bottom Panel

D. Put on Washers

E. Put on the Nylon Insert Nuts

F. Put Kapton tape on the Heat Shields of the Power

Supply

3\. Connect the DTN Board

A. Screw Standoffs onto the DTN Board

B. Position DTN Board over drilled holes

IV\. Complete Module Assembly

1\. Assemble Front Panel

A. Attach side panels

B. Insert Status Indicator LED's

C. Connect Status Indicator LED's to DTN Board

D. Connect Front Panel to the Bottom Panel

2\. Back Panel Work

A. Notch Out the Spot Where The Middle DTN

Standoff Goes

B. Insert AC Fuse/Socket Assembly into the Back

Panel

C. Connect The Ground Cable of Cable #1 to

the AC Fuse/Socket Assembly

D. Connect The 3 Pin Center Crimp Terminal

Housing of Cable #1 to the Power Supply

3\. Finishing Touches

A. Connect Cable #2 to both the Power Supply

and the DTN Board

B. Insert One 1/2 Amp 250 Volt Fuse into the

AC Fuse/Socket Assembly

C. Power Up DTN Module

V. The Temperature Cycle Chamber Test

VI\. The Portable Hand Held Battery Powered Terminator Tester Test

VII\. Troubleshooting

Tool List For

The Downstream Terminator Network

Module Assembly

1\. One Soldering Iron

2\. One Spool of Solder

3\. One pair of Crimpers

4\. Two pairs of Wire Strippers/Cutters (that can strip 16 to

30 gauge wire)

5\. One Nibbler (to notch out Panels)

6\. One Phillips Screwdriver

7\. One Flathead Screwdriver

8\. One Razor Blade

9\. One Deburring Tool

10\. One Desoldering Tool

11\. One Roll of Masking Tape

12\. One Roll of Kapton Tape

13\. One Drill (with a drill bit of 0.152 in. in diameter)

14\. Two Center Punches (one for the Power Supply, one

for the DTN Board)

15\. One Nut Driver

16\. Plenty of Medium Sized Cable Ties

**SECTION I: Board Assembly**

[1.1. Soldering the Connectors]{.underline}. The first step toward
completion is to solder the 10 pin, the 34 pin and the 50 pin connectors
to the board. The easiest way to handle this situation is to solder each
connector separately onto the board. Starting off with any of them,
manually fit the connector pins into their respective holes so that the
connector points to the outer boundaries of the board. The leads on
these connectors may be small and awfully short; so secure the connector
onto the board by taping the connector onto the surface with masking
tape. Then, turning the board over, solder each pin to the board, making
sure the connection is with a good solderflow and high quality. After
this is finished, move on to the next connector until all of them are
finished.

[1.2. Soldering the Sips (Single Inline Resistor Packages).]{.underline}
The next step is to solder the Sips onto the board. This part is
somewhat tricky because you must follow a certain rule to successfully
connect these parts. If you look onto the board where the Sips are to be
placed, you will see that there is a string of eight holes that the SIP
will fit into. However, one of the holes (on the end) has a white border
that is square around it (it also has a square pad). This pin hole is
known as pin #1. If you look at the SIP itself, you will see that, on
the label side, the first pin has a square or a line above it. This is
pin #1 and you MUST insert this pin in the hole where pin #1 is supposed
to go. The leads on the Sips may be short as well; so tape the SIP onto
the board with masking tape if necessary. Then, solder the SIP onto the
board. Repeat this procedure until all of the Sips are soldered into the
board.

[1.3. Soldering the Remaining Resistors]{.underline}. The next step is
to solder the discrete resistors onto the board. If you are not sure of
what value of resistor you are putting in, you can check the value by
either using a digital multimeter or referring to the resistor color
code chart. The way that I did this part would be to bend one of the
leads of the resistor so that it would point in the same direction as
the other lead would. Then, from left to right in each row, insert the
resistor into the first two holes of the row and secure the placement.
Repeat this until a row is filled (4 resistors). Then, solder both ends
of the resistor to the board. After doing so, cut the leads so that on
the solder side of the board, the points where the soldering took place
are small in height. Repeat this procedure until all of the resistors
are in place and connected properly. For the resistors on the rest of
the board, simply bend both of the leads, insert, and solder
accordingly.

[1.4. Soldering the Bypass Capacitors]{.underline}. On the DTN board
where the bypass capacitors are to be soldered, there is not specific
legend as to how they are to be placed. Just simply insert the capacitor
into its spot and solder it to the board. However, there are two kinds
of bypass caps used. The first one used is a .1 μF capacitor, which will
have a *104K5* label on top of it. These go in the spots where there is
not a *.001* inside the white border. In the spots where there is a
*.001* inside the white border, it is necessary to solder in a 0.001 μF
capacitor, which will have a *102K5* label on top of it. Solder in each
type of capacitor until all of the spots are filled. The leads are short
enough so that it will not be necessary to shorten the leads on the
solder side of the board when you are finished.

[1.5. Soldering the Remaining Capacitors]{.underline}. For this part,
there is a specific way to connect these parts to the board. If you look
at the board, you will see that where it is necessary to solder the
capacitors onto the board, there is a plus sign (+) on one side and a
negative sign (-) on the other side. This is because the capacitors
being used are polarized. As expected, a certain polarity must be
satisfied; therefore these capacitors cannot be inserted carelessly. If
you look on the capacitor itself, you will see that there is a little
bubble on one side of the capacitor. This is the positive (+) side of
the capacitor. Place this lead in the + hole and correspondingly place
the other lead into the - hole. Solder the part onto the board and clip
the leads. Most of the capacitors look the same; so keep capacitors of
one value separate from the other capacitors. The value of the capacitor
(6.8 μF for example) is located inside each white border for reference.
Repeat this procedure for all capacitors.

[1.6. Soldering the Chips]{.underline}. Now, this step involves
soldering the 74LS123, the 74LS08, and the 96F173 chips onto the board.
The first thing to do is to place the 74LS123 and the 74LS08 chips into
their respective locations and solder the chips onto the board. Then,
place the 96F173 above the sockets where the chip should go. Press down
on the chip with care and precaution; the chip should fit snugly into
the sockets. If necessary, bend the leads of the chip so that they fit
the socket terminals.

[1.7. Soldering the Fuse Sockets and Other Miscellaneous
Components]{.underline}.

For all of the places where there is an f-number, place two of the
sockets into the holes and tape them to the board (on the component
side). Then, solder them onto the board with plenty of solder. Do not
clip anything. Then, insert the LEMOs into its location with the
connector pointing out from the board. Solder the middle pin first, then
solder the remaining four. Please pay careful attention to the
connections on the outer four pins. From my experience, they do not
cooperate very well. After that, place the Molex 4-pin right angle
connector (with the pins facing out from the board) into its location
and solder it in. Next, bend the leads of the LM1086 regulator so that
the leads form a right angle. Insert the regulator into the board,
solder it in, and clip the leads on the solder side of the board.
Lastly, bend the leads on the Transorb (the part that looks like a
silicon diode) so that it can fit into the holes provided. On the board
itself, you will see that on one side on the transorb, the terminal is
marked with a + and a "gnd". This is the side where the lead of the
black end of the transorb is to be placed. After the transorb has been
properly inserted, solder it to the board and clip the leads.

[1.8. Inserting the Fuses]{.underline}. On the board, locate the places
where F1 and F5 are (F1 should be right under the Molex connector and F2
should be under the LM1086 regulator). Using a lot of care, insert one 2
Amp miniature pico fuse into the F1 fuse location (clipping the leads to
a sufficient length first) and press each lead so that it locks into the
socket. Following this same procedure, insert one 1 Amp miniature pico
fuse into the F2 fuse into that respective fuse location. At this stage,
the DTN board is completely assembled from the component side.

**SECTION 2: The Cable Assembly**

[2.1 Cable from the AC Fuse/Socket Assembly to the Power
Supply]{.underline}. Assembling this cable requires making use of three
different 18 or 20 gauge wires (that are in different colors for
discrimination), an AC Fuse Socket, a 3 pin Center Crimp Terminal
Housing, and a female disconnector terminal. Using the colors white,
green, and black, cut about 4 inches of wire and strip both ends. For
all intensive purposes, green will symbolize the ground cable; black
will symbolize the neutral cable, and white will represent the line
cable. With the Ground cable, one end will be soldered to the underside
of the AC Fuse Socket, while the other end goes to the Power Supply. The
end that goes to the Power Supply will be crimped inside a female
disconnector terminal. This side of the green cable will go to the male
ground terminal of the Power Supply (which will be in the bottom right
hand corner if looking from the back panel forward). Concerning the
white and black cables, one end of the cables will be soldered to the AC
Fuse/Socket at the line and the neutral terminals respectively. The
other ends will be crimped to 0.156 inch center crimp terminals. These
terminals will now be inserted into the housing. If you look carefully
on the housing, you will see that there are two ridges on one side of
the housing. These are known as Polarizing Ribs. To properly insert the
cables into the housing, it is necessary to place the black cable on the
right most terminal and the white cable on the left most terminal. The
housing should be sitting right side up and if done correctly, there
should be an open terminal in the center of the housing. Also, to make
sure that the cables are inserted correctly, they should click when they
are pushed all the way into the housing. Then, the other end of the
terminal housing should be inserted into the Power Supply with the
Polarizing Ribs closest to the clip. The male terminals for the terminal
housing are located to the left of the male ground terminal (using the
same frame of reference). When all of this is complete, cable tie the
three wires in two spots for neatness.

[2.2 Cable from the Power Supply to the DTN Board]{.underline}. For this
cable, we need four wires (two sets of two) made from 18 or 20 gauge
wires, a female 4 pin Molex connector, 4 0.156 inch Crimp terminals, 4
0.100 inch Crimp Terminals, and a 6 pin Center Crimp Terminal Housing.
This cable will take the ground and the Vcc (which is +5 volts) from the
Power Supply and supply this to the DTN board. For all intensive
purposes, red will symbolize the Vcc and the gray will symbolize the
ground. For this cable, each wire needs to be about 5 inches in length
with the wires stripped on both ends. On one end of the cables, the four
0.156 inch Crimp terminals need to be applied via a crimper tool. On the
other end, the four 0.100 inch Crimp terminals need to be applied. Once
this is finished, the ends of the cable that have 0.100 inch crimp
terminals need to be inserted into the Molex connector; while the other
ends need to be inserted into the 6 pin Center Crimp Terminal Housing.
Pertaining to the Molex connector, the cables need to be connected to
the connector so that they click when fully inserted. From left to
right, the order of insertion goes gray, red, red, and gray. In case you
forget, look on the component side of the DTN board where the male part
of the Molex connector is located and you can see the order in which the
wires need to be connected in. On the Molex connector, you will see that
there are two ridges on one of the sides. These ridges tell you to
insert the female connector into the male connector (on the DTN board)
right side up. Concerning the 6 pin Center Crimp Terminal Housing, the
other ends of the wires need to be inserted here. Since there are six
terminals and only four wires, skip the outermost terminals when you
insert the wires into the housing. Just like the housing for the
previous cable, there are Polarizing Ribs on one side of the housing.
From left to right, insert the ground wires (gray wires) then the Vcc
wires (red wires). Following the previous cable procedure, to make sure
that the cables are inserted correctly, they should click when they are
pushed all the way into the housing. Then, the housing end of the cable
should be inserted into the Power Supply with the Polarizing Ribs
closest to the clip. The male terminal for this housing should be in the
bottom center of the Power Supply (looking from the front panel). The
female Molex Connector should be connected to the male Molex connector
on the DTN board also. When this is completed, cable tie the wires in
two spots for neatness.

**SECTION 3: Connections To The Bottom Panel**

[3.1 Drilling the Holes for the DTN Board and the Power
Supply]{.underline}. In order to insure that both the DTN Board and the
power supply fit correctly onto the bottom panel, it is necessary to
measure out where the drill holes are to be made. Using the template for
the DTN board, place the template onto the bottom panel, pressing it
against the lip. Be sure to allow room for the side panels. Using one of
the Center Punches, mark the points where the drill holes should be.
Also, take one of the power supplies and place it onto the bottom panel
adjacent to the template (allotting room for the Molex Connection).
Using the other Center Punch, mark the points where the holes should be.
Remove both the Power Supply and the template from the bottom panel.
After this, take the drill and using the 0.152 inch (#24) drill bit,
drill the holes into the bottom panel carefully and precisely.

[3.2. Connect the Power Supply]{.underline}. One of the primary parts to
completing the assembly the DTN module requires the successful
installation of the DC Power Supply. Since the holes for the Power
supply have already been done (section 3.1), the first step is to apply
Kapton tape to the bottom panel where the Power Supply will sit. The
Kapton tape should be applied to the entire area where the Power Supply
sits.

The next step is to screw the 1/8 inch standoffs to the Bottom Panel.
This will allow the Power Supply to occupy the same space, but the power
supply will not sit right on the panel itself. Insert 1/2 inch Binding
screws through the drilled holes and screw the standoffs onto the
screws. The screws should be placed upside down so that the head is on
the outside surface of the panel.

After this, manually fit the power supply onto the bottom panel so that
the ends of the screws fit through the holes of the power supply board.
Now, put the washers on the screws so that the washers are on top of the
power supply board. When that is taken care of, screw on the Nylon
insert nuts onto the screws so that the Power supply is secure. This
will require the use of a screwdriver and the nut driver. Lastly, put
Kapton tape onto the metal heat shields of the Power Supply. The tape
should cover the top edges and overlap slightly on both sides.

[3.3 Connect the DTN Board]{.underline}. The procedure for this is very
similar to the installation of the power supply, but a lot simpler.
Insert the 4-40 1/4 inch Phillips head machine screws into the outermost
holes on the edges of the board. However, there is one screw that should
not be placed in a hole though. This screw is located in the corner
where the 50 pin connector is located. The reason for this is because
the screw (when tightened) will rest directly on top of a trace. This
will cause a short on the board and alter the output of the module.
Leave this hole empty. After all of the other screws are in place, screw
on the 1/2 inch standoffs. Following this, position the DTN board over
the drilled holes so that the standoffs sit right above them. Using the
same screws, screw the DTN Board to the bottom panel so that the Board
is secure and tightly connected to the panel.

**SECTION 4: Complete Module Assembly**

[4.1 Assemble Front Panel]{.underline}. The first thing to do is to
attach the side panels to the front panel. Using the silver screws and
one package of U-shaped handles, thread one screw through the side panel
clearance hole and through the front panel hole into the threaded hole
in the handle. Repeat this for the other three screws. Then, tighten the
screws so that everything is secure. Be sure not to strip the screws or
the threaded holes. Secondly, insert the Status Indicator LED's into the
front panel. On the DTN Board, you will see what light goes to what
label (for example, the red light goes to the +3.3 V power label etc).
After all of the LED's have been inserted into the front panel, trim the
leads to about 4 inches in length and strip the ends. Thirdly, connect
the Status Indicator LED's to the DTN Board by soldering the leads to
the terminals provided. In case of confusion, the red leads get soldered
to the left terminals of each LED; the black leads should be soldered to
the right terminals. After this is complete, cable tie the leads in
three spots for neatness. Lastly, connect the front panel to the bottom
panel. Using the black screws provided, attach the front panel to the
bottom panel by inserting and tightening the screws on the underside of
the bottom panel. These screws should go through the bottom panel in
four spots and through each of the side panels in two spots.

[4.2. Back Panel Work]{.underline}. If you slide a back panel onto the
chassis, you will see that the middle standoff on the DTN board will not
allow the back panel to make a clean fit onto the chassis. Therefore, it
is necessary to notch out the spot on the back panel where the middle
standoff is. This is done with the use of the nibbler tool. After the
notch is made, insert the AC Fuse/Socket assembly into the back panel so
that it clicks into the panel. Connect the ground cable to the male
ground terminal of the power supply. Then, connect the three pin Center
Crimp Terminal Housing to the male connector of the power supply.
Finally, insert and tighten seven black screws on the underside of the
bottom panel and on the back panel. Three screws should go on the
underside of the bottom panel; two should go on either side of the back
panel.

[4.3. Finishing Touches]{.underline}. For the final stages of assembling
the DTN module, three things must be done. One, connect the cable
discussed in section 2.2 to both the Power Supply and the DTN Board at
their respective terminals. Two, insert one 1/2 Amp 250 Volt Fuse into
the AC Fuse/Socket assembly. Three, power up the DTN module by
connecting the power cord to the module and inserting the plug into an
AC outlet. At this point in the game, two lights should come on. These
lights are the +5.0 Volt power LED and the +3.3 Volt power LED. If there
are any problems, please refer to the troubleshooting section of this
manual.

**SECTION 5: The Temperature Cycle Chamber Test**

At this point in the DTN Module Assembly, it is necessary to run each
and every module through a temperature chamber test. This test
determines if the module will maintain successful operation while
undergoing serious (and some extreme) temperature conditions. The
temperature chamber is located in the Northeast corner of the 13th
floor, in the lab. Once all of the previous tasks are accomplished, it
is necessary to place the modules (no more than 13 at a time) into the
temperature chamber. It is possible to power up these modules by feeding
the power cords through one of the chamber ports (on the left hand
side). After this is completed, connect all of the power cords to the
power strips found in the crate next to the temperature chamber. Before
closing the temperature chamber, make sure that all of the modules power
up when power is supplied to the strips. Then and only then can the
temperature chamber be closed and sealed for the test. Thinh Pham and
other authorized members of the group handle the temperature chamber
controls, but it is essential that a cycle is provided for them to base
the settings on. For the purposes of the DTN modules, the temperature
cycle is as follows:

1\. Start at Room Temperature.

2\. Bring the Temperature from 23 °C down to 0 °C. This should be

accomplished in a period of 5 minutes.

3\. Let the modules "soak" at 0 °C for 30 minutes.

4\. Bring the Temperature from 0 °C up to 40 °C. This should be

accomplished in a period of 5 minutes.

5\. Let the modules "soak" at 40 °C for 30 minutes.

6\. Bring the Temperature from 40 °C up to 50 °C. This should be

accomplished in a period of 5 minutes.

7\. Let the modules "soak" at 50 °C for 10 minutes.

8\. Bring the Temperature from 50 °C down to 0 °C. This should be

accomplished in a period of 5 minutes.

9\. Let the modules "soak" at 0 °C for 10 minutes.

10\. Bring the Temperature from 0 °C up to 23 °C. This should be

accomplished in a period of 5 minutes.

11\. Let the modules "soak" at 23 °C for 2 minutes.

12\. Steps 1 through 11 represent one cycle. Perform two cycles.

At this point, the modules have finished the temperature chamber test
and can be removed from the chamber. From previous experiences, removing
the modules (or at least opening the temperature chamber door) as soon
as the test is finished will yield the best results.

**SECTION 6: The Portable Hand Held Battery Powered**

**Terminator Tester Test**

At this stage in the project, it is necessary to use the Portable Hand
Held Battery Powered Terminator Tester Box (P.H.H.B.P.T.T.) to wrap up
the testing and the assembly of the DTN modules. Designed by Jamieson
Olsen and John Anderson, this box will indicate whether or not each
module's status indicators are functioning correctly. Each module is
connected to the P.H.H.B.P.T.T. Box using 10 pin, 34 pin, and 50 pin
ribbon cables. It is important to connect the cables correctly, or else
the readings will be incorrect. To do so, look at the ribbon cable
connectors (on the cable) and find the arrow on each connector. The
arrow points to pin #1 of the connector. On each of the modules, there
are three different connectors (10 pin, 34 pin, and 50 pin) on the back
panel. Locate the arrows on each of these connectors. After this has
been done, line up the connector arrow from the cable to the connector
arrow from the module. Insert the cable into the module. Repeat this
procedure for all of three cables. Then, connect the other ends of these
three cables to the P.H.H.B.P.T.T. Box. The three connectors on the left
hand side of the box are to be used here. After supplying power to the
module and using the legend on the box, properly functioning modules are
determined by studying and analyzing the corresponding light sequence.
For the DTN module, the *strobe* LED and the five LED's marked "DTN
only" should *not* be dimly lit for a properly functioning module.
*Every other* LED on the box should be dimly lit. Now, disconnect both
the 10 pin and the 50 pin connectors from the box and reconnect them to
the right hand side connectors. This test will analyze the Status
Indicator LED's on the front panel of the module. When the switch is
turned on, the bottom LED on the box flashes brightly. Also, the status
indicators on the DTN front panel should be flashing (except for the +5
volt and the +3.3 volt Power LED's). If all of these actions occur, then
the module has passed the P.H.H.B.P.T.T. Box test.

**SECTION 7: Troubleshooting**

+-----------------------------------+-----------------------------------+
| Problem                           | Solution                          |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
+-----------------------------------+-----------------------------------+
| 1\. One or both of the Power      | 1\. There are four possible       |
| LED's (that is the +5.0 V and the | explanations for this problem:    |
| +3.3 V) don't light up.           |                                   |
|                                   | A: There may be a short that is   |
|                                   | caused by the leads touching      |
|                                   | either on top or on the bottom of |
|                                   | the board. Simply trim the leads  |
|                                   | on the bottom. Or, space the      |
|                                   | leads on the top. Make sure that  |
|                                   | the insulation is completely      |
|                                   | covering each wire.               |
|                                   |                                   |
|                                   | B: A bad solder connection could  |
|                                   | be the case here too.             |
|                                   |                                   |
|                                   | C: A fuse may be blown.           |
|                                   |                                   |
|                                   | D: The existing power supply      |
|                                   | could be bad.                     |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
+-----------------------------------+-----------------------------------+
| 2\. Power is not supplied to the  | 2\. There may be a multitude of   |
| DTN Board.                        | avenues to solve this problem.    |
|                                   | Here are a few:                   |
|                                   |                                   |
|                                   | A: Check to see if the fuse on    |
|                                   | the AC Fuse/Socket Assembly       |
|                                   | works. If not, replace it.        |
|                                   |                                   |
|                                   | B: Check the AC voltages on the 3 |
|                                   | pin Center Crimp male Terminal    |
|                                   | (with a multimeter) to see if     |
|                                   | power goes from the AC            |
|                                   | Fuse/Socket Assembly to the Power |
|                                   | Supply. If not, there may be a    |
|                                   | bad cable connection.             |
|                                   |                                   |
|                                   | C: If A and B do not solve the    |
|                                   | problem, check to see if there    |
|                                   | are DC voltage readings on any of |
|                                   | the pins of the power supply's 5  |
|                                   | pin Center Crimp male Terminal.   |
|                                   | If not, the power supply may be   |
|                                   | bad.                              |
|                                   |                                   |
|                                   | D: If A, B, or C do not fix the   |
|                                   | problem, the cable from the power |
|                                   | supply to the DTN Board is bad.   |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
+-----------------------------------+-----------------------------------+
| 3\. The cables don't work         | 3\. This can be a direct result   |
| properly.                         | of bad crimping. Also, the crimp  |
|                                   | terminals may not be completely   |
|                                   | inserted into the housing. Check  |
|                                   | out both scenarios.               |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
+-----------------------------------+-----------------------------------+
| 4\. Other Status Indicator LED's  | 4\. Connect a DTN module with a   |
| (such as the Data Strobe LED and  | UTN module via the 10 pin, 34     |
| the EOR LED) light up.            | pin, and the 50 pin ribbon cable  |
|                                   | connectors. Remember to power up  |
|                                   | both modules separately. The      |
|                                   | problem should go away.           |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
+-----------------------------------+-----------------------------------+
| 5\. The light sequence on the     | 5\. Check the ribbon cable        |
| Portable Hand Held Battery        | connectors to make sure that they |
| Powered Terminator Tester Box     | have not been partially inserted  |
| (P.H.H.B.P.T.T.) was incorrect.   | nor upside down.                  |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
+-----------------------------------+-----------------------------------+
| 6\. An LED on the P.H.H.B.P.T.T.  | 6\. An open circuit exists        |
| box that is marked 'dim' is       | between the 240Ω resistor and     |
| glowing brightly.                 | either of the 120Ω resistors.     |
|                                   | Check the part as well as the     |
|                                   | solder connection.                |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
+-----------------------------------+-----------------------------------+
| 7\. An LED on the P.H.H.B.P.T.T.  | 7\. There is an open circuit      |
| box that is marked 'dim' is not   | between either of the 120Ω        |
| lit.                              | resistors and +3.3V or ground.    |
|                                   | Also, the resistor may be         |
|                                   | inserted incorrectly (backwards   |
|                                   | for example). Check the colder    |
|                                   | connection and make adjustments   |
|                                   | if necessary.                     |
+-----------------------------------+-----------------------------------+

As always, please remember to check the module for bad solder
connections, broken resistors, loose connections, shorts, and bad
crimping to eliminate testing problems during operation.