Wells-Gardner Vector Monitor 6100 Faq And Guide Version

							Wells-Garnder Color Vector Monitor Guide Page 41 of 75  
Symptom: Waveform At IC901 Outputs; If Missing, Check: 
 
· R914 and/or R927 (wrong value)  
· R916 (broken wire) 
  
Symptom: Waveform At Q906; If Missing, Check: 
 
· R926 (open)  
· Q906 (white wire open)  
· Q905 (emitter open) 
  
Symptom: Waveform At Q905; If Collector Wrong, Check: 
 
· Q906 (broken black lead or broken wire at emitter) 
  
Symptom: Waveform At R921; If Wrong, Check: 
 
· Q906 (white and black leads interchanged at socket) 
  
Symptom: IC901; If No Input Voltages, Check: 
 
· Q900 (red and black leads reversed)  
· ZD901 (check voltage drop)  
· ZD900 (shorted) 
  
Symptom: IC901; If Input Voltages Present, Check: 
 
· R914 (may be open; will cause waveform at C911 to not be x1K range)  
· C911 (open)  
· C915 (open)  
· C916 (open)  
· R901 (open)  
· R904 (open)  
· R905 (open)  
· R913 (open)  
· R923 (open)  
· R924 (open)  
· Q900 (shorted; +25 line is grounded by this)  
· Q904 (reversed, open, or missing)   
						

							Wells-Garnder Color Vector Monitor Guide Page 42 of 75 · Q905 (reversed or collector wire broken)  
· IC901 (defective, reversed, or unseated pins)  
· T901 (pins unseated or primary winding shorted)  
· Broken wire at R913  
· Broken wire at R919  
· Broken wire at base or collector of Q905  
· Broken wires or pins at P900  
· White wire disconnected at Q900  
· Red wire disconnected at Q906 
  
Symptom: If You Are Also Blowing Any Fuses, Check: 
 
· C910 (reversed)  
· R907 (open)  
· R913 (shorted)  
· D902 (wrong value)  
· Red and white wires interchanged at Q906 
  
Symptom: F600 Blows Immediately On Powerup 
 
· Replace R612 if open. 
  
Symptom: Blooming/Weak Brightness/Low HV 
 
Since most of you do not have a HV probe, the most common symptom of low HV is that the 
screen looks as though you are looking at the center through a magnifying glass. This visual 
symptom is known as blooming. I have seen several HV boards where ZD902 (150 volt Zener 
diode) goes bad and the HV drops from 19.5 kilovolts to around 10 kV. It is kind of like the 
electron beam moves slower with less HV giving the deflection magnets on the yoke more time 
to deflect the beam (but what is really happening is that there is not enough HV to strip all of the 
electrons off of the phosphor coating which causes the screen to develop a negative charge which 
then deflects new electrons which are expected to be hitting a screen with no charge on it). A 
new ZD902 and everything is better. NTE5100A is a common modern day replacement for this 
part. If ZD902 is OK, check the following: 
 
· R915 (open) 
· R922 (open or wrong value) 
· Q900 (emitter pin open) 
· Q902 (bad) 
· Q906; white and black leads reversed (scope pattern is wrong) 
· ZD901 (shorted) 
· IC901; if scope output is a little high, replace IC901 
· P900 (ribbon pin #7 broken)  
						

							Wells-Garnder Color Vector Monitor Guide Page 43 of 75  
Symptom: HV Range Wrong, What Causes It? 
 
Normal HV range is between 16-24 kV 
 
HV Voltage Range Look at ??.?-12.0 kV Q902 (reversed) 7.0-10.0 kV ZD902 (bad) 7.0-17.0 kV ZD902 (bad) 7.0-22.0 kV Q903 (bad) 9.0-18.0 kV ZD902 (bad) 11.0-22.0 kV ZD902 (bad) 15.0-18.0 kV ZD901 (wrong value) 16.0-19.0 kV ZD902 (bad) 18.0-27.0 kV ZD902 (bad) 19.0-27.0 kV R912 (wrong value) 21.7-30.5 kV C916 (open) 28.0-20.0 kV C916 (bad)   
						

							Wells-Garnder Color Vector Monitor Guide Page 44 of 75 FINE-TUNING THE PICTURE  
 
Now that you have a working monitor (and game board), it is time to fine-tune your picture. 
Before making any adjustments, turn your game on and let it warm up for at least 10 minutes. 
R918 is the HV adjust and unless you have an HV probe, you probably should not mess with it. 
If you have an HV probe, set the HV for 19.5 kV with zero beam current (i.e., with the game 
boards disconnected from the machine so that no input signals are being supplied). 
 
Here is a trick for adjusting R918 without an HV probe. Hook up power to the monitor (but 
without any input signals from the game board) and let it warm up for about 10 minutes. Now 
measure the Video B+ voltage either at pin 5 of P900 on the HV board, or at J501 on the neck 
board (refer to your schematics). Adjust the HV so the B+ is 181v DC. Since the Video B+ and 
the 19.5 kV outputs are linked together, you will get the HV pretty close to perfect. 
  
HV Over-Voltage Protection Circuit 
 
The later revision HV supplies (P329) have a circuit called the HV over-voltage protection 
circuit. It monitors the voltage of the focus assembly in the secondary circuit of T900. If the 
high-voltage at the anode of the picture tube increases beyond the threshold set by H.V. TRIP 
adjustment R930, this circuit shuts off the timer of IC901 and LED D903 turns on to indicate the 
over-voltage condition. Presumably, this was added to help discourage Tempest from eating HV 
transformers, as it is prone to do since they are by far the most expensive component in the 
game. If you know your HV is good, adjust R930 so that it is just beyond the point where LED 
D903 lights (so that the LED is off). 
 
NOTE: The following adjustments are a 2-person job (unless you are very handy with mirrors) 
because it is nearly impossible to view the screen and turn the pots at the same time. When 
adjusting your monitor, all adjustments should be made exactly in the order as presented below 
as many of the adjustments have effects on other qualities and will cause you to have to go back 
and redo them if you change the order. 
 
On the outside of the HV assembly are the focus and brightness adjustments. Adjust the focus 
until the picture is sharp then adjust the brightness just under the point where the dot in the center 
starts to show or just under the point where you can see the connecting lines between objects. Be 
careful not to get carried away with the brightness as you can do permanent damage to the 
phosphors in the tube. 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 45 of 75  
Size and Position 
 
The manuals do not talk much about adjusting the size and positioning of your screen but that is 
easy to do. There are small potentiometers on the game board that are clearly labeled which 
control X and Y centering as well as X and Y size. There are no positioning or size adjustments 
on the monitor itself. 
 
The following adjustments refer to the eight tiny blue and/or black potentiometers found on the 
game board. If your lines on the screen are not meeting at the joints properly or your text and 
numbers are not lined up properly on the statistics screen then you need to make these 
adjustments. This information is directly from the Tempest schematic diagram supplements 
(sheet 2, side B, 3rd printing) so locations/numbering/labeling of the pots may be different for 
other vector games but the instructions should be relatively portable... 
 
All of the following controls exist in the Vector Generator section of the game PCB; 
THEY ARE NOT IN THE MONITOR! 
 
          +------+        +------+        +------+ 
          |/\/\/\|        |  |   |        |  |   | 
          |\/\/\/|        |  |   |        |  |   | 
          |/\/\/\|        |  |   |        |  |   | 
          |\/\/\/|        |---   |        |--+---| 
          |/\/\/\|        | -----|        |  |   | 
          |01..YZ|        |   |  |        |  |   | 
          |\/\/\/|        |   |  |        |  |   | 
          +------+        +------+        +------+ 
          screen I        screen J        screen K 
 
· Enter self-test and advance screens to the diagonal crosshatch pattern [the one with the 
line of numbers and letters at the bottom; screen I].  
· Adjust CENTER pots: Adjust X-CENTER (R147) and Y-CENTER (R167) so that the 
pattern is located at the middle of the screen.  
· Adjust SIZE pots: Adjust X-SIZE (R150) and Y-SIZE (R168) so that the pattern 
exactly covers the whole visible screen.  
· Adjust the BIP pots [BIP stands for Bipolar. The BIP pots provide the offset 
current to convert the Unipolar DAC to one that provides a Bipolar output]: Adjust the X-
BIP (R118) and Y-BIP (R117) so that the corners of the diagonal lines rest exactly on the 
sides of the outer rectangle. [NOTE: It may be easier to advance to the screen with the 
single large cross-hair on it to make the BIP adjustments; just make sure the lines meet at 
exactly the center. Using the cross-hair screen, you should try to make screen J look like 
screen K. Be careful when joining the lines in the middle that you do not overlap; it is 
VERY hard to notice this. You might want to make a big gap (go the wrong way) and 
then converge until the two segments just touch. Screens J, and K were added and are not 
shown in the original document.]  
						

							Wells-Garnder Color Vector Monitor Guide Page 46 of 75 · Adjust the LIN pots: Adjust the X-LINEAR (R169) and Y-LINEAR (R165) so that the 
diagonal lines are straight. Since the LIN pots change the size of the displayed picture 
on the screen, you may have to readjust the SIZE pots in order to get the correct 
adjustment. 
 
  
White Balance Adjustment 
(From sections of TM-183) 
 
Here is a summary of the white balance adjustment sections of TM-183. This is paraphrased and 
abridged since the information was spread out over many pages. You should make these 
adjustments before you adjust the purity and convergence. Do not adjust the white balance in 
reverse order because color changes do slightly impact those other adjustments. 
 
1. Flip the test switch inside the coin door on the top near the hinge (some games may have 
the self-test switch mounted in a different area such as on a plate near the top of the coin 
box). Tempest requires you to rotate the spinner until the prompt reads Press Fire and 
Zap for Self-Test. (Other games may have similar requirements to get to the self-test 
screens or they may take you directly to them automatically. Do whatever is required to 
enter the self-test screens.) 
 
2. Advance the screens with the slam (a.k.a. tilt) leaf switch (this is typically inside the 
coin door below the lock) until you get to the diagonal crosshatch pattern screen (see 
screen I in the previous section). For Tempest, this should be the 1st screen. 
 
3. Turn the focus control (one of the two white knobs on the HV unit) until you get the 
optimum screen sharpness possible. Your goal is the best character appearance without 
appreciable fuzziness. 
 
4. Advance the screens until you get to one showing seven groups of colored bars of various 
intensities. For Tempest this should be the 5th screen. 
 
5. Turn all the potentiometers on the neck PCB to the full clockwise position. Turn the 
brightness control (the other white knob on the HV unit) so that only five lines are visible 
and sixth line is completely invisible. Adjust the red, green, and blue bias potentiometers 
(the black ones) until the 5th line from the right is pure white without any hint of color in 
it (the 5th line is the dimmest one and color bias abnormalities are most visible at lower 
brightness levels; the goal is to get all five lines to be completely white). Adjust the red, 
green, and blue drive potentiometers (the white ones) until the first line on the right is 
pure white. Repeat the bias adjustment if the fifth line from the right is no longer pure 
white.  
  
						

							Wells-Garnder Color Vector Monitor Guide Page 47 of 75  
COLOR PURITY 
(Figure 6; from sections of the Wells-Gardner Service Manual) 
 
 
As far as adjusting purity (red gun hits red phosphors only, green gun hits green, etc.) and 
convergence (red, green, and blue guns hit adjacent dots to make white instead of separate 
colors), the manual does a decent job of walking you through the procedure. 
 
For best results, it is recommended that a purity adjustment be made with the monitor facing 
west or east. The monitor must have been operating 15 minutes or more prior to this procedure. 
 
1. With the yoke on the CRT neck, place the convergence assembly on CRT neck with the 
center line (of Purity Adjustment Magnet) over gap between grids No. 3 and No. 4. The 
convergence assembly consists of three sets of ring magnets with tabs (Figure 6).  
 
FIGURE 6:  
 
 
2. Tabs of the three magnetic ring-pairs are to be in a vertical position, which will produce a 
zero-correction state and facilitate adjustments. (see Figure 6 above). 
 
3. Connect a pattern generator or game board (in self-test mode), which can generate a 
crosshatch pattern of red, green and blue independently and in combination of colors. 
Refer to INTERFACE BOARD ADJUSTMENTS for input signal level and pattern 
size. 
 
4. With a green crosshatch pattern, pull the deflection yoke backward as far as it will go. 
The center vertical portion will be green. If green is not horizontally centered between  
						

							Wells-Garnder Color Vector Monitor Guide Page 48 of 75 other colors, move the 2 purity magnets with respect to each other in order to center 
green crosshatch on the screen. 
 
5. Push deflection yoke forward gradually, until crosshatch is a uniform green (pure in 
color) across the entire pattern. The deflection yoke should now be secured in place. 
 
6. Both red and blue colors are to be checked for uniformity and true color. Reposition the 
deflection yoke, if necessary, to obtain optimum purity of all colors. Tighten clamp to 
secure deflection yoke.  
STATIC CONVERGENCE ADJUSTMENT 
(From sections of the Wells-Gardner service manual) 
 
4-Pole Magnets and 6-Pole Magnets are for static convergence. 
 
1. A crosshatch signal should be connected to the monitor [using either a pattern generator 
or a working vector game board in self-test mode]. 
2. A pair of 4-Pole Convergence Magnets is provided and adjusted to converge the blue and 
read beams (Figure 6). When the Pole opens to the left and right 45 degrees 
symmetrically, the magnetic field maximizes. Red and blue beams move to the left and 
right. Variation of the angle between the tabs adjusts the convergence of red and blue 
vertical lines.  
3. When both 4-Pole Convergence Magnet Tabs are rotated as a pair, the convergence of the 
red and blue horizontal lines is adjusted.  
4. A pair of 6-Pole Convergence Magnets is also provided and adjusted to converge the 
magenta (red + blue) to green beams (Figure 6). When the Pole opens to the left and the 
right 30 degrees symmetrically, the magnetic field is maximized. Red and blue beams 
both move to the left and right. Variation of the opening angle adjusts the convergence of 
magenta to green vertical lines.  
5. When both 6-Pole Convergence Magnet Tabs are rotated as a pair, the convergence of 
magenta to green horizontal lines is adjusted. 
  
ADJUSTMENT OF DYNAMIC CONVERGENCE 
(Figures 7, 8 and 9; from sections of the Wells-Gardner service manual) 
 
 
1. Feed crosshatch signal to the monitor [using either a pattern generator or a working 
vector game board in self-test mode]. 
2. Insert a wedge temporarily and fix the Deflection Yoke so as to obtain the best 
circumference (Figures 8a through 9b). NOTE: The wedges may need to be moved 
during adjustments.  
3. Insert three rubber wedges to the position as shown in figure 7 to obtain the best 
circumference convergence. 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 49 of 75  
ADJUSTMENT OF DYNAMIC CONVERGENCE (continued) 
 
NOTE: 
1. Tilting the angle of the yoke up and down adjusts the crossover of both vertical and 
horizontal red and blue lines (Figures 8a and 8b).  
2. Tilting the angle of the yoke sideways adjusts the parallel convergence of both horizontal 
and vertical lines at the edges of the screen (Figures 9a and 9b).  
3. Use three rubber wedges (tapered rubber wedges are used for this purpose.)  
4. The position of each rubber wedge is shown in Figure 7.  
5. Do NOT force the permanent wedges in. They are to be inserted until they just make 
contact with the yoke - after the yoke has been positioned.  
6. Fix the three permanent rubber wedges with chloroprene rubber adhesive.  
7. After the adhesive has dried enough to hold the wedges in place, carefully remove the 
temporarily installed wedge(s).  
  
FIGURE 7 (Rear View) 
                      _ 
                     | | 
						

							Wells-Garnder Color Vector Monitor Guide Page 50 of 75  
ADJUSTMENT OF DYNAMIC CONVERGENCE (continued) 
 
 
FIGURE 8B 
                   +---------------------------+         \ 
                   |        R    G    B        |          \  
                   |         \   |   /         |     ------\------+ 
                   |          \  |  /          |     \      \-----+ 
                   |  B___     \ | /     ___R  | S V  \ DY  /\ 
                   |      ---___\|/___---      | I I   \   /  \ 
                   |  G----------*----------G  | D E    \ /    \ 
                   |      ___---/|\---___      | E W  ^ 
                   |  R---     / | \     ---B  |      | 
                   |          /  |  \          |  Insert rubber wedge 
                   |         /   |   \         |  from lower side 
                   |        B    G    R        | 
                   +---------------------------+ 
 
 
FIGURE 9A 
                   +---------------------------+     TOP VIEW 
                   |+-------------------------+|        /\ 
                   ||+-----------------------+||       /  \  / 
                   |||                       |||      / DX \/ 
                   |||                       ||| +-> /     /| 
                   |||                       |G| |   -----/|| 
                   |||                       B|R |       / || 
                   |||                       ||| |         ++ 
                   |||                       ||| | 
                   |||                       |||  Insert rubber wedge 
                   ||+-----------------------+||  from left side 
                   |+-------------------------+| 
                   +---------------------------+ 
 
 
FIGURE 9B 
                   +---------------------------+     TOP VIEW 
                   |+-------------------------+|        /\ 
                   ||+-----------------------+||    \  /  \ 
                   |||                       |||     \/ DX \ 
                   |||                       |||     |\     \