Wells-Gardner Vector Monitor 6100 Faq And Guide Version

							Wells-Garnder Color Vector Monitor Guide Page 31 of 75 CAUTION: When replacing the transistors mounted on the chassis, make sure the pins do not 
short to the chassis. If the chart procedures do not solve your problem, call Atari Field Service. 
 
 
We will finish off with a troubleshooting guide broken down by symptoms. Much of the rest of 
this section is a transcription of repair notes from a Wells-Gardner technician. Just because 
your symptom matches something in here is no guarantee that what he found wrong is the same 
thing that is wrong with your board, but it is a good place to start. Most of the problems he listed 
in his notes were due to manufacturing defects or incompetent repair work. Obviously, if your 
monitor was working OK and then simply stopped, those things are not likely be your problem. 
 
 
GENERAL MONITOR PROBLEMS   
Weirdness between player one and two (Tempest machines only) 
 
Display implodes during intermission screen between player one and player two and 
sometimes on the figure 8 levels (Tempest machines only): I thought I knew what was causing 
this but upon further evaluation, my solution did not make sense (although it did work for me the 
only time I had this problem). Until I get another board to fix that has this problem, I only have 
general advice on how to avoid the problem. Adjust your game board and shrink the Y 
deflection some and this should help. There are 3 sets of ROMs for this game and the compact 
ROM set (revision 3 - only half the ROM sockets are used) is slightly different (the intermission 
screen has some other stuff such as the copyright and credits information at the bottom of the 
screen which balances it out) so the spot killer will not get confused and decide that the bottom 
half of the screen is wiped out. These PCBs do not normally experience this difficulty. 
 
 
 
DEFLECTION PROBLEMS   
Symptom: Fuses F100 [and F101] blow on power up 
 
Fuses F100 and/or F101 on the deflection PCB are blowing as soon as game is powered up. This 
happens to a lot of people after they replace the chassis transistors. Sometimes they forget to put 
the mica (plastic) insulator on the transistor before installing them, which allows the transistors 
case (collector) to short to the chassis (ground). A short can be present even if the insulator was 
installed if the conditions are just right. Check all chassis transistors, particularly Q102, Q103, to 
make sure the cases are not shorted to the chassis. 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 32 of 75  
Symptom: Spot Killer ON and display dead 
 
Check the fuses first. If they are OK, then check the six transistors mounted on the chassis as 
described earlier. If you find at least two of the deflection transistors or one of the power 
transistors bad, then that is definitely tripping the spot killer. A good trick to figure out where the 
problem exists is to turn your brightness up all the way and see what your picture looks like. The 
spot killer does not turn the Z signal all the way off so if you turn the brightness all the way up, 
you should be able to see a very faint picture. Based on what the picture looks like, you can 
decide which half of the circuit is causing the problem (either the X or Y portion). If you know it 
is a problem on your deflection board (i.e., swapping in another board makes the monitor work) 
then check R808 (X) and R809 (Y) to make sure they are not open. These resistors allow current 
to flow to the spot killer circuitry and if they open then the spot killer thinks something has 
happened to the amplifier circuitry so it kicks on. You can tell if this is your problem by turning 
the brightness up all the way; if you see a complete picture, then this may be your problem. If all 
this is OK then you probably have a game board problem, particularly if you are unable to play 
the game (see the credit lights blink after you punch up credits and hear the game sounds after 
you push start). 
  
Symptom: Display dead after a Cap Kit 
 
Cap kit installed but still no picture (spot killer may or may not light). 
 
The problem is most likely Q603. Occasionally you will see Q603 (Q703), or Q604 (Q704) go 
bad. If one of the transistors does die, be sure to check the resistors and diodes around it, 
particularly R611 (R711), R612 (R712), and D602 (D702). A common modern day replacement 
for MPSU57 (Q603/Q703) is NTE189 and the part for MPSU07 (Q604/Q704) is NTE188. These 
should be greased where they touch the heat sink (like the chassis transistors) to improve heat 
dissipation. If you are having trouble with these failing, you might want to beef them up by using 
TO-202 package upgrades to NTE50 (MPSU57) and NTE49 (MPSU07). 
 
  
Symptom: No X (or Y) deflection 
 
I have seen two deflection boards like this. On one, the problem was that R710 (R610 for Y) was 
open. How you fry a 10-Watt resistor and nothing else in the circuit is beyond me; perhaps the 
PCB was dropped and it landed on R710. Anyways, you can test it in circuit and if you do not 
see a virtual short then replace it. On the other deflection board, the problem was a loose 1/2 
watt, 2.2k resistor (R606) in the Y amp. Its intermittent contact was causing the spot killer to 
flicker, and was causing picture to collapse. The solder joint did NOT look cold or bad, and the 
resistor tested fine. These resistors take a good deal of heat, and the traces they are on can heat 
up pretty good. I found that it was loose by pushing on the top of the resistor a bit, and began to 
hear a tick where the resistor lead was touching the solder joint. Probably the traces  
						

							Wells-Garnder Color Vector Monitor Guide Page 33 of 75 temperature (and the resistors heat) caused the resistor lead to separate in the hole on the board, 
while it still looked and tested fine. 
 
NOTE:  
Jeff Young from World Wide Distributors in Grand Rapids, MI reported some words of 
caution about these resistors on Page 3 of the November 1982 issue of the Star*Tech 
Journal: 
 
After fighting a problem in the Atari Tempest for three days and finding a silly 
mistake, I thought I should write to you. Wells-Gardner Monitors #19K6101 use a 1.5-
ohm 10-watt resistor in location R610-R710. If you replace these resistors with standard 
wire-wound units, the monitor will exhibit the shakes or jitters referred to in S*TJ, 
Vol. 4, No. 7 Service Tips, but the symptoms will be misleading in that R601 and R701 
must be NON-INDUCTIVE. Please tell your readers about this problem as Atari and 
Wells do not point out this requirement in the parts listing, and only put down the initials, 
N.I on the schematic. 
  
Symptom: R101 burns on power up 
 
R101 glows red-hot and burns up to an open circuit every time the game is powered up (known 
good deflection board; works in good monitor). 
 
The resistor is burning up because of runaway current from the HV unit. You can confirm this by 
replacing R101 and testing the deflection board in a known good monitor (or by putting a known 
good HV unit in the monitor that is acting up); if R101 does not burn up then you know the HV 
unit is the culprit. Whenever this happened to me, R903 on the HV unit has been the cause. It 
will sometimes short and this causes so much current to flow to the deflection board that the 
puny 15-Ohm resistor burns up. If this goes on for too long, Q101 may fail or occasionally R901 
will burn up to an open circuit. 
 
  
Symptom: Accidentally shifted P101 over 1 pin and power up machine 
 
Although most of the connectors/connections are idiot-proof, P101 is not (due to the poor 
placement of the key pin as the LAST pin). It can be connected shifted over 1 or more pins to the 
right (although it should be obvious if you shift it more than 1 pin). After shifting it 1 pin and 
frying the PCB, when you hook it up correctly, the spot killer LED will glow at 50% brightness 
and you will get no video. The following parts will need to be replaced; Q703, R711, D702, and 
C703 (C703 should be OK but replace it just in case if you can find a new one). Some caps may 
have blown on the HV board, too. 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 34 of 75  
Symptom: Display bad only in lower right quadrant 
 
Distorted image, which exists ONLY in the lower right quadrant of the display. 
 
I have seen this several times and the problem has always been a bad ZD101. Much of the time 
this causes R101/Q101 to fry and spot killer comes on.  
						

							Wells-Garnder Color Vector Monitor Guide Page 35 of 75  
NECK (CRT) BOARD PROBLEMS   
Symptom: Colors Drop In and Out (ZD500 open on neck board) or Display is too bright 
 
On neck board:  
· R515 (broken wire to R531)  
· C503 (reversed; may toast R527) 
  
Symptom: No Red 
 
On neck board:  
· R500 (open)  
· R502 (shorted to nearby component)  
· R510 (open)  
· R511 (open or wrong value)  
· R520 (open; red color can be seen but is very weak)  
· R529 (open or wrong value)  
· broken wire at R517 control 
  
Symptom: Only Red 
 
On deflection board:  
· D802 (reversed) 
  
Symptom: Red Too Bright 
 
On neck board:  
· R501 (wired wrong)  
· R504 (open)  
· Q500 (collector shorted to base) 
  
Symptom: Red does not turn off when dimmed all the way 
 
On neck board:  
· Q500 (reversed or broken wire)  
· R513 (shorted to C500)  
· R519 (open)  
· R529 (open) 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 36 of 75  
Symptom: No Green 
 
On neck board:  
· R503 (open)  
· R513 (wrong value)  
· R520 (wrong value; was 22)  
· R530 (open)  
· Q501 (bad or base shorted to emitter)  
· broken wire at R513  
· jumper from R511 to R513 missing 
 
On deflection board:  
· neck board connector wrong type  
· broken green wire from deflection board to neck board 
  
Symptom: Only Green 
 
On neck board:  
· Q503 (reversed or wired wrong) 
  
Symptom: Green Too Bright 
 
On neck board:  
· Q501 (collector shorted to emitter) 
  
Symptom: No Green + Blue Is Red 
 
On neck board:  
· R500 (shorted to R529 or shorted to R502) 
  
Symptom: Green Is Red 
 
On neck board:  
· R502 (shorted to R500) 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 37 of 75  
Symptom: Green Does Not Turn Off When Dimmed All The Way 
 
On neck board:  
· R512 (shorted to nearby wire or connecting wires wrong)  
· R519 (connecting wires wrong)  
· R520 (open)  
· Q501 (reversed, open, shorted, or broken wire to base) 
  
Symptom: No Blue 
 
On neck board:  
· R504 (wrong value)  
· R515 (open or wrong value or broken wire or swapped with R505) 
 
On deflection board:  
· D803 (bad) or neck board connector wired wrong) 
  
Symptom: Only Blue 
 
On deflection board:  
· red lead in neck board connector broken 
  
Symptom: Blue Does Not Turn Off When Dimmed All The Way 
 
On neck board:  
· R504 (open)  
· R521 (open)  
· R522 (open)  
· R529 (open)  
· Q502 (reversed, emitter open, or shorted to nearby component) 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 38 of 75  
HIGH VOLTAGE BOARD PROBLEMS   
Symptom: Display Unstable 
 
The image is extremely shaky and unstable and lines that should be straight have periodic 
wiggles along their length that make them look like an EKG (the distortion is sort of like when 
you watch TV with a bad antennae and lines walk around on the screen). 
 
Replace C901, C902, and/or C905 in the HV supply. If one of these is bad then the rest of the 
electrolytic capacitors are probably in pretty poor condition too, so I generally replace all of 
them. Make sure the replacements are rated at as least as many working volts DC WVDC and 
have as least as many microfarads. It does not hurt to replace a 22uF @ 50V capacitor with a 
50uf @ 100V if that is all you have around. More Voltage capacity is equal or better but it is best 
to keep the capacitance the same if you can. Also when ordering and replacing these, be aware 
that they are polarized and not idiot-proof; be sure to put them in the circuit so that they are 
oriented properly. The casing will clearly indicate either the negative or the positive terminal 
(but typically not both) and the industry convention is for the positive lead of the capacitor to be 
longer than the negative lead. Be aware that P329 has an extra capacitor (C22) that may not be 
shown in your manual; its value is 10uf @ 63V. 
  
Symptom: Picture Too Bright But All Else OK 
 
The picture is overly bright and all parts check out OK. 
 
Look for a broken circuit board trace between pin 6 of the high voltage transformer and the 
anode of diode D901. This trace is prone to breaking open. It is probably easier to just add a 
jumper and see if it solves the problem or else check the connection (with board removed) with a 
meter to make sure it is a short. 
  
Symptom: R925, R919, and R917 are Smoked 
 
· Q905 (shorted; T901 primary may be shorted, too) 
  
Symptom: R901, R907, R903 are Smoked and Q902 and ZD901 are Shorted 
 
· Q901 (reversed) 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 39 of 75  
Symptom: Top of Q901 Blowing Off 
 
· R902 (open)  
· Q900 (inserted or wired wrong; if emitter shorted to base then Q901, Q902, and ZD901 
get fried)  
· Q901 (shorted)  
· Q902 (shorted)  
· ZD901 (shorted) 
  
Symptom: Top of Q902 Blowing Off 
 
· Q901 (reversed) 
  
Symptom: R901 and R907 are Smoking 
 
· Q902 (shorted)  
· Q906 (red and white leads interchanged) 
  
Symptom: Only R901 Smokes 
 
· Q906 (inserted wrong)  
· Q900 (missing spacer or black lead open) 
  
Symptom: R903 Smokes 
 
· Q900 (shorted; will short ZD901, Q901, and Q902, too) 
  
Symptom: R904 Smokes 
 
· Q902 (shorted) 
  
Symptom: R907 Smokes 
 
· C902 (reversed)  
· broken wire near R902 
  
						

							Wells-Garnder Color Vector Monitor Guide Page 40 of 75  
Symptom: R908 Smokes 
 
· Q900 (white and black leads interchanged) 
  
Symptom: R912 Smokes 
 
· C910 (reversed)  
· D901 (wrong value; perhaps ZD902) 
  
Symptom: R917 Smokes 
 
· Q905 (reversed) 
 
If R920 smokes, check: 
 
· C913 (bad; this can damage T901, too) 
  
Symptom: No HV (Very Dead Sound) 
 
No High Voltage (HV); you do not hear the crackling sound when you first turn the monitor on. 
 
Check the transistors in the HV unit as described earlier. The ones I have seen fail most often are 
Q903, Q902, and Q901 though they are all suspect. These transistors will usually have cracks in 
the casing if they are bad so look closely at them. If all this stuff is OK, look at the electrolytic 
capacitors. 
 
One quick errata: The parts list in Figure 15 of TM-183 lists all capacitors as fixed axial-lead 
when in reality, C905 is a radial-lead cap. These capacitors are designed to burst open (VENT) 
when they fail due to overburdening (but they sometimes do not) so as to be obvious to 
repairpersons. The top (for radial-leads) or the side (for axial-leads) will be open and some of the 
guts will be hanging out. When some capacitors go bad, they sometimes take the final output 
resistors R901 and/or R907 with them (but the resistors will look perfectly OK unless you check 
them with a meter). 
 
Also check to make sure that connector J901 inside the HV unit is intact; one person reported 
that the plastic in his disintegrated on the inside and the wires came loose. If these are OK, check 
the following: