Confusion over Excel 2.4 and Mars 126DFX

[TrevorAustin]

I had a 126DFX in my cab and had hardwired it and got it working but using a mechanical microswitch for coin pulses to my Mister.

I wanted to do it ‘properly’ so I purchased an excel 2.4 board and put pins 1:1 for all 17 pins, power goes to the 126 and coin inhibits work fine, all coins pass.

However I cannot get a coin out pulse on pin 4 (or the meter pin) I tried connecting a multimeter across pins 3&4 and can see a constant 2v, sometimes it fluctuates a little. However pressing the service button or passing coins does nothing, I also tried measuring resistance across those 2 pins and there is no connection either when pressing service on the credit board or passing coins. Am ai missing something obvious?

If I connect my 2 wires from my credit switch to 3&4 I get a string of credits every few minutes but ai think that’s due to having separate grounds which I can sort later once I know it’s working properly.

What have I missed or is my excel board faulty. (It’s constantly flashing its led about once per second but I believe that’s normal)

 

[qjuk]

What are the dip switches set to on bank 3 on the Excel board? (ie., the bank of 6 switches).
Try setting them to Mars parallel, which is 1+3 ON, the others to OFF, if it is not already on that setting.

It is normal for the red LED to flash every second or so on the Excel.

Also, is the Mars 126dfx mech set to run in fixed parallel mode?

 

[TrevorAustin]

What are the dip switches set to on bank 3 on the Excel board? (ie., the bank of 6 switches).
Try setting them to Mars parallel, which is 1+3 ON, the others to OFF, if it is not already on that setting.

It is normal for the red LED to flash every second or so on the Excel.

Also, is the Mars 126dfx mech set to run in fixed parallel mode?

Yes I’ve tried that setting, doesn’t seem to make a difference, and I have no idea if it l’s in parallel, how do I check. Although if it was that shouldn’t the service button on the Excel still give me a pulse?

 

[qjuk]

The 126dfx manual is online here. Page 23 explains how to convert between the different modes.

You are right, the credit board should pulse a credit when pressing the black button.
I’m thinking perhaps the pulse length generated by the Excel is not compatible with your Mister setup?
It’s also possible that the Excel board could be faulty.

I have a spare working Excel board which you are welcome to borrow if you wanted to test your set-up with it. Drop me a PM if you want to take up the offer.

 

[TrevorAustin]

Thank you, that’s really kind of you, where are you based.

Can I confirm that my 126 should be in parallel mode or binary? And presumably I match that on the credit board?

I have been trying to measure the pulse using a multimeter between ground and pin 4 on the credit board assuming that it’s a ground pulse I expected to see continuity, but it doesn’t happen, or I expected to see a voltage change but it’s stable at between 1.8v and 2.0v (seems to change each time I power it on.

Is there a better way to measure it?

 

[qjuk]

I’m in the UK, Devon.

I’ve had another read of your opening post.

First thing to do is make sure the Mars mech is disconnected from the Excel board and the only thing connected to the Excel is 12v (pin1), Ground (pin3) and the credit line (pin4). Does it now give a credit pressing the service button? Depending on the device/machine the credit line is connected up to, the voltage is usually constantly held high (around 5v). When pressing the service (free credit) button, the voltage very briefly drops to 0v, then it goes high again. You can test with a multimeter, put the black probe on pin 3 (GND) and the red probe on pin 4 (O/P1). Did you notice a drop in the DC voltage reading every time you press the button?

You said you are getting around a constant 2v on pin 4. That sounds too low for me. I’m certain the threshold for a lot of devices to recognise the difference between high and low is around 2.5v (I am happy for anyone else to chip in and correct me if I am wrong). Basically it sounds like your credit line is constantly low, therefore the Excel board is not making any difference by grounding to 0v when pressing the service button.

Excel boards are also very fussy when connected to certain devices/game boards. I’m sure it is to do with the ground pulse length generated by the Excel. On some of my pcbs (Tournament Arkanoid is one), the Excel will not credit it, yet a manual microswitch wired on the same credit line works. I sometimes think the ground credit pulse is too short for some things.

The other option is to try a different credit board altogether. Some boards like the Brent Electronic Frontline have an option to change the pulse length.

You said the meter output is not working either. Is it a 12v DC meter connected? It will only pulse on coin counts and not when pressing the service button.

The 126 mech will need to be in parallel mode if connecting it via the 17 pin header on the Excel. The 126 is probably in automatic mode and may or may not work. Have a look through the link I gave above for the information to change to fixed Parallel output. There’s only 3 options. It’s easy enough to change between the 3 output options.

My conclusion is that it sounds to me as if your Mister setup is not compatible with an Excel credit board. I personally would try a different credit board if you can.

 

[TrevorAustin]

I’m in the UK, Devon.

I’ve had another read of your opening post.

First thing to do is make sure the Mars mech is disconnected from the Excel board and the only thing connected to the Excel is 12v (pin1), Ground (pin3) and the credit line (pin4). Does it now give a credit pressing the service button? Depending on the device/machine the credit line is connected up to, the voltage is usually constantly held high (around 5v). When pressing the service (free credit) button, the voltage very briefly drops to 0v, then it goes high again. You can test with a multimeter, put the black probe on pin 3 (GND) and the red probe on pin 4 (O/P1). Did you notice a drop in the DC voltage reading every time you press the button?

You said you are getting around a constant 2v on pin 4. That sounds too low for me. I’m certain the threshold for a lot of devices to recognise the difference between high and low is around 2.5v (I am happy for anyone else to chip in and correct me if I am wrong). Basically it sounds like your credit line is constantly low, therefore the Excel board is not making any difference by grounding to 0v when pressing the service button.

Excel boards are also very fussy when connected to certain devices/game boards. I’m sure it is to do with the ground pulse length generated by the Excel. On some of my pcbs (Tournament Arkanoid is one), the Excel will not credit it, yet a manual microswitch wired on the same credit line works. I sometimes think the ground credit pulse is too short for some things.

The other option is to try a different credit board altogether. Some boards like the Brent Electronic Frontline have an option to change the pulse length.

You said the meter output is not working either. Is it a 12v DC meter connected? It will only pulse on coin counts and not when pressing the service button.

The 126 mech will need to be in parallel mode if connecting it via the 17 pin header on the Excel. The 126 is probably in automatic mode and may or may not work. Have a look through the link I gave above for the information to change to fixed Parallel output. There’s only 3 options. It’s easy enough to change between the 3 output options.

My conclusion is that it sounds to me as if your Mister setup is not compatible with an Excel credit board. I personally would try a different credit board if you can.

Really good info thanks.

I’ll change it to parallel, that’s easy enough from the document. Disconnecting from the 126 will be a pain as it’s 17 different cables rather than a single ribbon cable. But I’ll do that to test.

As it stands I’m definitely not seeing a pulse, even very briefly on the pin 4 connection, it’s a fairly high end multimeter, so when it’s reading 2v it auto sets to up to 9.99x so dropping to 0, even for a very short time, should give a flash of the numbers even if it doesn’t register the 0 in time. But nothing changes at all.

 

[TrevorAustin]

Took it all apart and there is a pulse from the service button, only short and only indicates dropping to about 1v but I guess that’s just the matter reacting too slowly. Then I put it all back together and I think the same is happening on pin 4, but not certain and definitely on the meter. But it’s too quick to be sure. But the fact it’s only 2V control voltage seems weird. I think I might just stick to my bodged microswitch. I don’t like things not working properly but this looks like it’s going to need another bodge via an arduino to get a decent signal and that’s a bigger bodge than the microswitch.