Start Button Doesn't Light Up - T2

JODY

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The start button has not lit up on my T2 since I bought it. It is the last thing not working (cross my fingers).

I've been checking on some things and looking at the schematics but so far to no avail. I've spent more time on this than any other issue I've had with it including a board repair and it is driving me nuts.

The bulb is fine. Replaced it anyway. In connecting a meter to one side and to ground (ground wire running under the playfield) it shows just over 2 volts and fluctuates. In doing the same thing to the other side it shows the same thing. Check between the two wires with a meter and it shows nothing.

Checking pin 4 on J6 of the coin door interface board with a meter to ground (ground wire under playfield) yields the same 2 fluctuating volts. All the diodes on the coin door board checked OK (checking both ways so it allows flow in one direction).

The lamp matrix shows the Start Button as Row 4 (Q87 transistor) Column 8 (Q91 transistor). The same chart shows Q87 as J133-5 and Q91 as J138-9. A different Lamp Circuit chart shows those transistors going to J133-5 and J138-9 on the playfield and to J135-5 and J136-3 to the cabinet.

I'm confused then as one side of the start bulb is connected to J6-4 on the coin door interface. It is labeled in the schematics as Lamp. It shows it running to J1-2 of the coin door interface and then back to J133-9 on the power driver board. J133-9 is shown in the lamp circuit diagram as Q83 which is a different lamp matrix row.

Basically I'm not sure how the circuit that lights the start button is supposed to be. I'm still learning to read / understand the schematics. I may be misinterpreting something or maybe the schematics are wrong.
 
Found that connectors J133 & J135 on the power driver board must be completely interchangeable. They were reversed according to the schematics. Changed them but doesn't appear to matter as things work the same either way.

The bulb and socket are fine. Hooked up a battery pack to the terminals of the socket and the bulb lit up.

Traced J136-3 from the power driver board to one of the terminals on the start light socket. No issue there.

Traced J135-5 from the power driver board to connector J1-2 on the coin door interface board. pg. 3-3 of the schematics show this as sourced from J133-9 on the power driver board which I had noted earlier did not make sense. I assume the schematic is wrong as the lamp matrix shows J133-9 powering lights on the playfield. I also traced J133-9 to lights on the playfield.

The coin interface board schematic shows J1-2 going to J6-4. The second start bulb terminal is connected to J6-4. This is noted as "lamp" in the schematic.

If I connect J135-5 to the second terminal of the start bulb it lights up while in attract mode and flashes with the rest of the playfield. Is that normal or should start be solid? Does anyone know why the coin door interface board appears to be involved with the lighting of the start bulb? I'm thinking there is something wrong with the coin door interface board.
 
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Pulled the coin interface board. Reflowed all connections in the start light circuit (2 pins and a diode). Tested the diode again. It seemed fine. Tested the same as the other 6 on the board and would only allow flow one way. Tested the start light with the game on and it did the same thing (did not light).

Pulled the board again and replaced the N4004 diode. Tested it again with the game on and it works!!!!

It does flash in attract mode and goes solid while playing a game.

With a meter, prior to replacing the N4004 I was getting about 8 - 9 volts between J135-5 and J136-3 but a drop to about 1.5 volts after it went through the coin interface board. After changing the diode I get the same results so meter wise I did not see any impact to what I did. I've read that these games actually turn the bulbs on very fast even when they appear solidly lit so assume that explains the voltage fluctuation; however, not sure what the deal was with the old diode.
 
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