Games of Nevada Draw Poker - game isn't being displayed

[Chris-socal]

Wait, to test the thyristor use diode tester when board is powered off. There should be no continuity from middle leg to either outside leg. But the two outside legs will test as shorted. I just confirmed that in a brand new component out of circuit. 

Chris

[James33244]

Thanks for checking that, when checking with diode mode are you measuring the voltage drop through them or are you on ohms measuring?

[James33244]

Unsure if there Is multiple replies by me as it looks like my replies are not posting. I am unsure which one is the main computer chip but I did try and check the thryistor which had 12vdc on all 3 pins. From what I believe Is pin 1 and pin 2 I have low resistance which is 40ohms. Between the middle pin and the plate I have continuity which I believe is normal and what I believe to be pin 2 and 3 I have 98ohms which I believe is normal but unsure. So it looks like pin 1 and 2 are shorted but not positive. Also I can measure voltages and grounds to compare it to your board where your ic were blown.

[Chris-socal]

Diode tester. If all 3 pins are shorted there is a problem.

[James33244]

I'm just checking voltages and grounds in hopes we can compare to see where I'm loosing my video signal. On connector p4 which goes to the crt monitor below are the voltages I read when powered on and connector unplugged from crt.
Pin 6: Brown 11.5v a/c
Pin 5: Grey 11.5v a/c
Pin 4: Black 11.5v a/c
Pin3: Blue 11.3v a/c
Pin 2: Green 11.3v a/c
Pin1: Red 11.3v a/c

[Chris-socal]

That doesn’t look right, it kinda indicates the game board isn’t sending a video source. Are you using the black wire as common? Since you give a reading from the black wire I don’t think you are.
Each of the colors should be similar but slightly different.
The two syncs might have a very low reading.
Since my board isn’t working either I don’t think my numbers will help. I seem to recall video source is in the .8 to 4.5v range, using black as common.
Vertical and Horizontal are different. If your meter has a Hz setting use that.

Update…I found and attached the input spec voltage from the manual, I wasn’t too far off; 0-4v

Chris

[James33244]

I was not using the black pin 4 as common. Those specs are very helpful and I will recheck. I do not have a manual for this machine however I have a manual for a similar machine (mvp-7) if that helps any different than the manual you have.

[Chris-socal]

I don’t know of any manuals for this specific game.
That image came from the Electrohome manual, which is available. I finally got my monitor working pretty good, its not a great picture but good enough…..if I could get the game working!
I assume your monitor is a G07-FBO.  Every one I have seen has that monitor.
Either way, they would all use the same video pattern.

[James33244]

I believe my monitor is a g07fb0. When testing from the blakc pin to pin one and so on voltages are as followed:
1.1v
1.1v
1.3
1.3
Just updating as I forgot to mention my speaker does work just beeps very loudly and won't turn off unless unplugged.

[Chris-socal]

You would measure the pins like below, black is your common to each. If I saw exactly 1.3v on all the colors I suppose the screen would be solid white, about 1/3 full intensity. Not sure where V and H sit.
R
G
B
V
H

As for the sound circuit, it could be the audio amp shorted or simply getting a rogue input from the driver, it could be a problem with the amp or it could be an error tone being thrown out by the computer. Who knows.
You can power the board using a benchtop power supply, 24v dc to the pins where the red and black wires come in on the back connector.
8vac comes into he connector on the side…the two pins on the bottom…closest to you with board in the machine (you can trace them to the rectifier on the opposite side of the board. Im not actually sure why they bring AC onto the board and then rectify it, I would think its just for bulbs. Who knows. Once you power it up you can take a logic probe and look at high and low on the logic chips and see if data is moving. Or you can look at the schematic of the sound chip and remove the source and see if the tone hangs around.
Im no expert though, I can’t get mine to do anything. Im getting close to parting it out. It just isn’t worth the mental bandwidth.

Chris

[Chris-socal]

Hi James

If you have time can you tell me what these connectors pictured mate with? I found two more sets that were connected to the wrong mate and caused a resistor to short out. Hopefully that is all that shorted. I also found a 74lLS367 that was defective, I actually pulled and tested every logic IC. After doing that I started getting signs of life…but not much because of the frying resistor.

1. There is a 9 pin with a variety of colors coming from the main loom in the back
2. A 4-pin with purple, orange and blue
3. A 4-pin coming from the coin mech (green,green,brown,orange)
4. There is a hole on the right side of the cabinet. Is there a reset key on this machine?

If I could see the mate to each of these it would help me a ton.

Thanks a ton. 

Chris

[James33244]

No reset key that I know of. Mine does not have a hole in the side of it also that 9pin connector you showed is disconnected on mine and looks like it is not used. As for that smaller four pin with the blue,purple and orange mine is hooked to an all black wire connector which is connected to two money counters in the top back wall of the machine. As for for coin mech one it is connected to a orange, blue/yellow, brown/black, and two blue/orange wired connector located behind that white panel on the front door.

[Chris-socal]

Thank you!
That explains a lot! That connector was connected to the coin switch!
Problem is, I can’t find a proper mate for the coin switch.

[James33244]

Here are some photos of how that connector looks. If needed I can tell you where the machine side wires go.

[Chris-socal]

Oh, That is how mine is connected. But that wire going to the meters is not connected on mine.
One other thing I noticed on yours….you need to check that coin switch. Mine is connected to the two outside tabs, which on my switch is Open with momentary contact.
On my switch the middle and left tabs are NC, normally closed, which would tell the machine the coin switch is stuck. I wonder if that is why you have an error tone?

Check your switch with a meter, they can vary.

Chris

[James33244]

Sorry for the delayed response I still haven't fixed my machine but were you able to get anywhere with yours?

[Chris-socal]

I had to put it in storage, I plan on dissecting the circuit at a later date but it could take me a few months to figure stuff out on it. I a, actually working on some boards I put in a “one day” pile a few years ago! LOL