Help please: coin door test buttons not working (Black Knight)

[solar value]

Hi all,

It seems that the test buttons on the inside of the coin door on my Black Knight are not working, nothing happens when I push them. The credit switches under the coin mechs work, however, as do the lights behind the coin windows. In fact, apart from the test buttons, the game is working fine.

I have done the obvious things, reseated the coin door connector and looked for loose wires.

Anyone hazard a guess as to what the problem could be or how I would go about diagnosing it?

Am I missing something obvious? Perhaps the button that senses if the coin door is open may be at fault?

Any help greatly appreciated, thanks, SV.

[MartyJ]

Try reseating the CPU board into the driver board

[solar value]

Try reseating the CPU board into the driver board

Thanks Marty, but no change.

[Steevsee]

Try reseating connector 1J4 on cpu board (2nd connector fom left, along top of cpu board.)

[Retropin]

Id be putting a meter across the switch to make sure its operating first, then diagnose why the signal is not being read if need be

[solar value]

OK, I'm back on this, thanks everyone who has contributed so far but unfortunately the problem still exists.

Id be putting a meter across the switch to make sure its operating first, then diagnose why the signal is not being read if need be

Retropin, I have tested the switch and I think it is OK but can you be more specific about how to test it and I'll make sure?

Try reseating connector 1J4 on cpu board (2nd connector fom left, along top of cpu board.)

Thanks Stevesee but no change

[Retropin]

There will be a diode across the switch... test this first. Get your multi meter and set to CONTINUITY ( or beep if you have one)... put your probes on either side of the diode... if OK.. youll get very high reading ( high resistance) with probes one way... swap them over and you should get LOW reading ( or a beep if you have it).
If this tests OK.. then you need to put your RED lead on the side of the switch that has the diode end without the black band on it.. place BLACK lead on other side of switch and then press the switch... you should get a LOW reading to show good contact through the switch

[solar value]

There will be a diode across the switch... test this first.

You mean the diode on the left-hand switch, right?

put your probes on either side of the diode... if OK.. youll get very high reading ( high resistance) with probes one way... swap them over and you should get LOW reading

I'm getting infinite resistance either way, so I guess I need to change the diode?

I've got some 1N4007 diodes fom RTBB which I was going to use on some coils of another game, can I use one of these?

[Retropin]

Infinate reading suggests diode has gone OPEN... need to replace

[solar value]

Hi everyone,

I am back on this after a long break. I have replaced the diode but unfortunately the buttons still don't work.

Is there a way to simulate activating the buttons without actually pressing them so that i can determine whether the problem is with the buttons or somewhere else? Any other ideas?

Thanks, SV.

[beaky]

Hi everyone,

I am back on this after a long break. I have replaced the diode but unfortunately the buttons still don't work.

Is there a way to simulate activating the buttons without actually pressing them so that i can determine whether the problem is with the buttons or somewhere else? Any other ideas?

Thanks, SV.

Unplug IJ4 on cpu
Short CPU board, 1J4, Pin 2 (GND) to Pin 3 (ADVANCE) that is the momentary switch: each time you short these 2 terminals it will simulate pressing the red button with the orange and green wire.
A jumper across 1J4, Pin 2 (GND) to Pin 4 (Auto / Manual) Will simulate the black middle switch being in the up position. No jumper across these 2 will Will simulate the black middle switch being in the down position

Before trying this disconnect the memory protect switch that the door pushes on when it is closed (if you have one fitted) if this is stuck closed it will enable the memory protect and the Advance button will not work.
Also Before trying this try shorting the Green and Orange wire with a screw driver, this will simulate pressing the red ADVANCE button. I have seen these switches fail on many occasions.

The Button with the diode on it is the "HIGH SCORE RESET" Button. No need to worry about this switch at this stage.

[goodolddays]

Its unlikely all 3 buttons would fail at the same time though 

[solar value]

Also Before trying this try shorting the Green and Orange wire with a screw driver, this will simulate pressing the red ADVANCE button. I have seen these switches fail on many occasions.

OK, finally some action (thanks, Beaky). Tried this and it worked.

So that means the ADVANCE button is not working. So I'm guessing I need a new set of buttons. Anyone have one or know where I can get them?

[Retropin]

Any momentary switch will work

[beaky]

Its unlikely all 3 buttons would fail at the same time though 

True,  but if the "ADVANCE" button fails you can't get into diagnostics. I didn't mean I have seen them all fail at once, I meant I have seen 1 stop working many times. 

You might be lucky and only one side of the switch has died and you can use the other pole, Try soldering the wires onto the other set of pins on the switch (i.e solder the green wire to the other bottom pin and the orange wire to the other centre pin) It may give you a bit more life out of the switch until you can get another one.