Atari Vector Monitor Repair/Upgrade


    9.1.3) Capacitor Failure

STAR WARS Color X-Y Display [Amplifone ONLY; not Wells-Gardner models!]

PROBLEM: Capacitors C3 and C4 on the High-Voltage PCB may be defective. These are rated at 100uF, 35V.

SOLUTION: Change C3 and C4 to 220uF, 35V with a low E.S.R. (Effective Series Resistance) rating. The Atari part no. is 123009-227. The following manufacturers' capacitors will also work:

Illinois Capacitor, part no. 227 RMR 050M (50V)
Nichicon, part no. UPA1V221M (35V)

[NOTE: Digi-Key also sells "HFS SERIES Low Impedance" capacitors which will work. Dial 800.DIGIKEY and order part number P1339; my last catalog (April 1994) lists them for $1.68 each. The Nichicon capacitors should be obtainable from TTI. TTI is the nations largest distributor of passive components such as resistors and capacitors. Dial 800.CALL.TTI to place an order.]

\\\ A Warner Communications Company
                              (800) 943-1120


The following information is excerpted from a photocopy of a photocopy (of a...) which has no visible attribution or copyright. It appears to be from the Star*Tech Journal but I don't know for sure and the guy who sent it to me doesn't know where it came from.

  9.2) STAR WARS Display Problems


PROBLEM: No filament voltage from the high voltage (HV) PCB.

SOLUTION: Check for a loose connection on the lugs that hold the HV transformer to the PCB.

PROBLEM: Can any other power transistors be used on the Deflection board?

SOLUTION: Yes, MJ 15003 NPN replaces 2N3716, and MJ15004 PNP replaces 2N3792 [NOTE: these substitutions are valid for the Wells-Gardner model, too].

PROBLEM: What should the output of the 555 IC on the HV PCB be?

SOLUTION: The output at pin 3 of the IC should be a 20-kHz square wave. This is adjusted with potentiometer R7.

PROBLEM: There is no high voltage. The positive and negative 24 volts are present.

SOLUTION: Check transistor Q3. The problem may be that the transistor tab (collector) may not be making good contact with the heat sink.

PROBLEM: The schematics for the HV cutoff circuit do not match the board assembly.

SOLUTION: There are three board revisions. You can tell which one you have from the table here. The schematics for all three boards are shown.


PCB Revision   R16        R18
Original       470 Ohms   27K Ohms
First rev.     Zener      Missing or 27K Ohms
Second rev.    470 Ohms   33K Ohms


                     o 24V
 |                   |
 |      R15    CR2   |
 |                   |
\ / Q4             c \ Q5                 HV PIN 4
--- MCR100-3          =|------+-------+--------+----->
 |                 e / 2N3904 |       |        |
 +                   |        \       |  C10   \
 |\                  |        / R18  === 0.1uF / R19
 | \        R16      \        \ 27K   |  50V   \ 68K
 |  +-------/\/\---->/ R17    /       |        /
 |  |       470      \ 1K     |       |        |
 |  |                /       ===     ===      ===
 | ===  C9           |        =       =        =
 |  | .01uF          |
 +--+                |
    |                |              DAG GROUND
   ===               +------------------------------->

  9.4) First Revision

                     o 24V
 |                   |
 |      R15    CR2   |
 |                   |
\ / Q4             c \ Q5                 HV PIN 4
--- MCR100-3          =|------+-------+--------+----->
 |                 e / 2N3904 |       |        |
 +                   |        o       |  C10   \
 |\                  |               === 0.1uF / R19
 | \     1N754 /     \       R18      |  50V   \ 68K
 |  +-------+->|---->/ R17            |        /
 |  |       |  /     \ 1K     o       |        |
 |  |       \        /        |      ===      ===
 | ===  C9  /        |        |       =        =
 |  | .01uF \ 1K     |        |
 +--+       /        |        |
    |       |        |        |     DAG GROUND
   ===     ===       +--------+---------------------->
    =       =

  9.5) Second Revision

                     o 24V
 |                   |
 |      R15    CR2   |
 |                   |
\ / Q4             c \ Q5                 HV PIN 4
--- MCR100-3          =|------+-------+-------------->
 |                 e / 2N3904 |       |
 +                   |        \       |  C10
 |\                  |        / R18  === 0.1uF
 | \     R16       \---\      \ 33K   |  50V
 |  +----/\/\---+   / \       /       |
 |  |    470    |    | 1N754  |       |
 |  |           |    |        \      ===
 | ===  C9      |    |        / R17   =
 |  | .01uF     +----+     +->\ 20K
 +--+                |     |  /
    |                \     |  |      DAG GROUND
   ===               / R19 +--+---------------------->
    =                \ 1K

PROBLEM: The schematic for the deflection board shows CR5 as a 1N714 diode.

SOLUTION: The schematic number is wrong. It should be labeled a 1N751A zener diode. The rating of 5.1 volts is correct, however.

PROBLEM: On the HV PCB, the output voltage of the regulator is good when the pin is lifted, but there is no voltage when the pin is connected back to the board.

SOLUTION: Check for bad 0.1uF glass capacitor across the voltage regulator. The decoupling capacitor may be shorted.

PROBLEM: The 24-volt regulator has failed.

SOLUTION: Check for cracking around the regulator leads on the PCB. Also check for cracking around the leads of C3 and C4.

PROBLEM: The voltage is low on the supply lines on either the Deflection PCB or the HV PCB.

SOLUTION: There are jumpers on the supply lines of both boards. The jumpers are marked with a "W" on the schematic. They look like resistors on the board and have a single black band on them. The jumpers should have no resistance. However, the brown jumpers may have created some resistance to them. They should be replaced with a piece of wire. The white and tan jumper should have no problems.

PROBLEM: The picture shrinks in from the negative X and Y sides of the screen.

SOLUTION: On some deflection boards, R35 and R12 may have a 15 Ohm resistor and a 30 Ohm resistor in parallel to get 10 Ohms. If these come loose, then some picture shrinkage may occur.


Unfortunately that's all I have for the Amplifone. It is worth noting that I recently acquired a copy of the Empire Strikes Back manual which includes the previous tech tip (2 sections above) in a condensed form that is mostly the same (it advocates replacing C3 and C4 as a matter of course, rather than waiting for them to cause a problem). Now I'll talk about specifics and what devices I often find bad in the Wells-Gardner color vector monitor. If you don't have a manual for this monitor, get a copy, as it does a good job of explaining how each section works and also how to adjust it.

For you people who don't like reading manuals, or who don't feel like locating local sources for specific parts or who don't want to hunt through a huge catalog to put together part numbers for an order, you can order everything you (probably) need (except for the upgrade parts and the extra capacitor for P329 versions of the HV unit) bundled together in one package from ZANEN ELECTRONICS. I suggest you order a couple of these to keep as spares since you never know when you might need to do a rush repair job and the price simply cannot be beat.

Call them at 806.793.6337 and ask for "get well kit #206" which at last count had 30 pieces including all the capacitors that go bad, 6 replacement chassis transistors, several of the smaller transistors (and their corresponding resistors), several diodes (including ZD902), and also (rather sparse) documentation on how to replace the parts. Please be careful if you decide to replace R918 (25K potentiometer) in the HV unit; it needs to start out adjusted to an in-circuit resistance of 5.5K when testing the upper 2 contacts of the 3. (this is the average of what I find to be the normal adjustment range which is always between 5K and 6K. If you have it maxed out you will probably damage your unit when you turn it on. I'm not sure why the kit includes this part as I've never come across a bad one yet.

Ordering a kit from them also entitles you to FREE technical assistance and they seem to be very experienced and knowledgeable. They take credit cards and do not charge anything for UPS shipping (< 7 days). You can tell them Gregg sent you if you want. As of December 1994, the price for this kit was $14.95 which is probably cheaper than any deal you could put together yourself, anyway. I should also mention that they sell a kit for the black and white vector monitors, too, specifically for the Electrohome G802/805 series which is "get well kit #104". They sell kits for most of the monitors that are/were commonly used in the industry; I cannot recommend Zanen and their kits highly enough.

This is a good way to go if you don't feel like doing any testing to find out what exactly is bad. If you replace all the parts included in this kit, you may be throwing out a lot of parts that still work OK (but which may be on their last legs, anyway), but you will be virtually assured of having a working monitor when you are done. If you get them all in and it still doesn't work, then go through the flowchart shown later in this document. It is quite likely that you have a bad HV transformer and you will have a heck of a time locating a replacement (I have a few but they won't last long) :<

Be aware that some of the parts that Zanen will send you are from the original spec and should not be used as this spec is known to be deficient. Consult the section below about how to upgrade the deflection boards and switch out the indicated parts for the upgraded replacements.

Here are some good parts places to get the big transistors (and other things) that I've used before:

Allied Electronics; 800.433.5700
Digi-Key; 800.344.4539
Mouser Electronics; 800.346.6873
Newark Electronics Chicago; 708.495.7740

Mouser also has the coin door "type 47" bulbs. Here are a few surplus type places that I've ordered from that have great prices on things like electrolytic capacitors that will be happy to send you a catalog:

All Electronics; 818.904.0524
Marlin P. Jones; 407.848.8236

Before we get started let me clear up something that causes a LOT of confusion when working on monitors of all types. All the documentation and boards for these monitors refer to "X" as the longer axis and "Y" as the shorter axis, independent of how the monitor is oriented in your game. Confusion arises because the game PCB will refer to "X" as the axis parallel to the floor and "Y" as the axis perpendicular to the floor and this is dependent on how your monitor is oriented. Why is this important to distinguish? Well if you notice that there is a horizontal line on your Tempest screen and you go to figure out why you aren't getting any "Y" deflection, you must check the "Y" portions of the vector generator circuitry on your game PCB but you need to check the "X" portions of your monitor (deflection board)!

Some words of caution about the manuals. I've got 3 versions of TM-183 (originals of the 1st and 2nd printings both from 1981 and a photocopy of the 3rd printing from 1982; let me know if you have an original of the 3rd printing that you'd be willing to sell). Also, if you are lucky enough to have a copy of the Wells-Gardner service manual for this monitor, the parts list on page 31 has an error; it lists C916 as .35uF when it is really .035uF. It is labeled properly in the schematic on page 28. None of the manuals show all the different versions of this monitor.

Since the 3rd printing is uncommon, I will describe the significant differences from the 2nd printing (not noting the layout changes such as replacing the crummy photographs with clear, sketched, exploded-view diagrams and minor rephrasings that are sprinkled throughout). All figures show later versions of all boards with the exception of Figure 13 which still shows the old deflection board (even though the parts list and everything else refer to the newer versions; obviously a mistake). Section 3 (Adjustable Controls) describes a later version of the neck board (P328). Section 5 (Purity, Convergence, and Tracking Adjustments) is completely rewritten and is MUCH less vague and more complete (2 pages longer). Section 6 (Details of Operation) has a section which discusses the Input Protection Circuit and has a schematic (Figure 8), too. There is also a new section G (Over-Voltage Protection) which describes the new circuit in the later version of the HV unit (P324).

The 3rd printing fixes some typos in the deflection PCB parts list:

Unfortunately, it also introduces one:

(see next section...)

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