Defender: 'Thrust' always on

MonsterBash

Well-known member
Joined
Mar 13, 2009
Messages
1,269
Reaction score
65
Location
Lancaster, New York
So I move my Defender a couple times in the last month..when I finally got it home I got the infamous rug test over and over. It was working fine for 6 months before the move.

I reflowed the pins on the Main PCB, ROM and Interface board and got the game back. Now the thrust is 'stuck' on.

I removed the wires to the thrust button and no change.

I removed the ribbon cable from the interface board to the PCB while the game was running and the thrust still stayed on.

I did double check the interface board and it looks fine after reflowing the pins. mesure the resistors and all were fine

I don't have any extra boards for defender. I could try the interface board from my Robotron but I'm pretty sure they are different

Any ideas on this one?

Edit to add: All other controls including the coin door switches work fine
 
So I move my Defender a couple times in the last month..when I finally got it home I got the infamous rug test over and over. It was working fine for 6 months before the move.

I reflowed the pins on the Main PCB, ROM and Interface board and got the game back. Now the thrust is 'stuck' on.

I removed the wires to the thrust button and no change.

I removed the ribbon cable from the interface board to the PCB while the game was running and the thrust still stayed on.

I did double check the interface board and it looks fine after reflowing the pins. mesure the resistors and all were fine

I don't have any extra boards for defender. I could try the interface board from my Robotron but I'm pretty sure they are different

Any ideas on this one?

Edit to add: All other controls including the coin door switches work fine

If you have a Logic Probe, start with Pin 9 on IC3 of the IO Board.
 
I did trace pin 9 real quick before I had to run out the door.

Does it make sense that even after the ribbon cable is remove the input stays the same?

Compare the input of pin 9 (Thrust) to say the input of pin 3 (Fire). They should be the same. When you push the button it should change the input.

The Resistor pack might be bad, R13 might be bad, IC3 could be bad, IC6, or IC1 could be bad. I would start at R13 and work your way backwards. You should be able to compare the inputs and outputs of Thrust to those of Fire.
 
Do here's an update...

The thrust started to 'sputter' today when I was working on it...at times it almost stopped completely. If I pushed the thrust button (or ground pin 9) it would go back on

What I did find out is if remove the ribbon cable from the main PCB while it was sputtering...it would stay on solid. I would assume then the PCB is getting some input from the interface board.

So with the Interface card hooked up to the PCB if I wiggle the ribbon cable I'll get random smart bombs and hyperspace. Thus I think I have a cable issue.

I'm gonna dig around for and IDE cable and see if I can't replace it..else I'll start a hunt for a new card

Of course I have no idea where my prob is. I cleaned up everything over the weekend...thus I can't find it =)

Compare the input of pin 9 (Thrust) to say the input of pin 3 (Fire). They should be the same. When you push the button it should change the input.

The Resistor pack might be bad, R13 might be bad, IC3 could be bad, IC6, or IC1 could be bad. I would start at R13 and work your way backwards. You should be able to compare the inputs and outputs of Thrust to those of Fire.
 
Do here's an update...

The thrust started to 'sputter' today when I was working on it...at times it almost stopped completely. If I pushed the thrust button (or ground pin 9) it would go back on

What I did find out is if remove the ribbon cable from the main PCB while it was sputtering...it would stay on solid. I would assume then the PCB is getting some input from the interface board.

So with the Interface card hooked up to the PCB if I wiggle the ribbon cable I'll get random smart bombs and hyperspace. Thus I think I have a cable issue.

I'm gonna dig around for and IDE cable and see if I can't replace it..else I'll start a hunt for a new card

Of course I have no idea where my prob is. I cleaned up everything over the weekend...thus I can't find it =)

Try taking a pair of pliers and CAREFULLY squeezing the header. Those can come lose and you'll get flaky connections.
 
If you bring up the switch test, what you will find is that with the I/O card removed all the switches will be on. This is the normal operating condition. With the I/O card plugged in and no buttons pressed, all the switches will show as off.

Here is a link to recrimping the ribbon cable connectors. Just ignore the initial part about replacing the cables until you have had a chance to try recrimping them first. http://arcadesolution.com/ribbon.html

ken
 
So I replaced the cable and it fixed the random smart bomb ~ hyperspace issue but i still have the thrust almost always on.

Good call on the switch test...I'll check it out this weekend...I got a full dance card tomorrow
 
Last edited:
So coming back to this..

According to this site
http://www.robotron-2084.co.uk/techwilliamshardwareid.html#robotronjoust

I should be able to use a Robotron interface board (PN 5772-09680) in a defender...but.. the original defender interface board will not work in the Robotron? Or am I reading the notes wrong?

An yes..the switch test showed the thrust pulsating on


You can use a Joust/Robotron I/O board in a Defender. The pins on the cards are mapped in reverse of each other, but the PIA mapping is the same to the CPU.

picture.php


You just need to flip each I/O conector over and jam them on to make them fit. If you look at the diagram you can see that the pin numbers are reversed , but the mapping to the PIA ports are the same (pin 1 3J3 = PA0, pin 10 3J3 = ground in both cases. Same on 3J2).

ken
 
Great..I do have an extra robo interface board. Not sure the part number but will check it when I get home.

I'm assuming since there is no incoming power I shouldn't have an issue if I don't hook them up correctly the first time?

You can use a Joust/Robotron I/O board in a Defender. The pins on the cards are mapped in reverse of each other, but the PIA mapping is the same to the CPU.

picture.php


You just need to flip each I/O conector over and jam them on to make them fit. If you look at the diagram you can see that the pin numbers are reversed , but the mapping to the PIA ports are the same (pin 1 3J3 = PA0, pin 10 3J3 = ground in both cases. Same on 3J2).

ken
 
best rule of thumb when switching boards on any machine.. power it off first and unplug it...then do the swap and power the game back up. It will save you some considerable headaches.
 
I don't see how the IO boards would be compatible since the Ribbon Cable connector 3J1 has a different pin out between the boards. The +5V and GND are reversed.

Code:
         Robotron    Defender
3P1-1    D4          D4
3P1-2    NC          NC
3P1-3    D7          D7
3P1-4    NC          NC
3P1-5    D6          D6
3P1-6    R/W         R/W
3P1-7    D5          D5
3P1-8    RESET       RESET
3P1-9    D2          D2
[COLOR="Red"]3P1-10   GND         +5v[/COLOR]
3P1-11   D1          D1
3P1-12   D0          D0
3P1-13   D3          D3
3P1-14   E           E
3P1-15   IPIA        IPIA
[COLOR="red"]3P1-16   +5v         GND[/COLOR]
3P1-17   A0          A0
3P1-18   A1          A1
3P1-19   A           A
3P1-20   A3          A3
 
So I dug out my extra Robotron Interface card (5772-09680-xx)..removed the header keys from the harness and installed it in the non-backwards way and it didn't do anything. I tried it this was cuz the board labeling (1-10) was the same on both boards.

So I tried flipping the harnesses 180 degrees (orange wires from the CP) as originally instructed and wahla! I now have all buttons normal thrust!

I'd really would like to know what's wrong with the other interface board...damn thing are so basic. All the resisters OHMed out good and there only like 4 ICs on the thing

Probably not worth messing with

Thanks again!



Great..I do have an extra robo interface board. Not sure the part number but will check it when I get home.

I'm assuming since there is no incoming power I shouldn't have an issue if I don't hook them up correctly the first time?
 
That's weird as there is no +5 going to this board at all

I don't see how the IO boards would be compatible since the Ribbon Cable connector 3J1 has a different pin out between the boards. The +5V and GND are reversed.

Code:
         Robotron    Defender
3P1-1    D4          D4
3P1-2    NC          NC
3P1-3    D7          D7
3P1-4    NC          NC
3P1-5    D6          D6
3P1-6    R/W         R/W
3P1-7    D5          D5
3P1-8    RESET       RESET
3P1-9    D2          D2
[COLOR="Red"]3P1-10   GND         +5v[/COLOR]
3P1-11   D1          D1
3P1-12   D0          D0
3P1-13   D3          D3
3P1-14   E           E
3P1-15   IPIA        IPIA
[COLOR="red"]3P1-16   +5v         GND[/COLOR]
3P1-17   A0          A0
3P1-18   A1          A1
3P1-19   A           A
3P1-20   A3          A3
 
You mentioned reflowing the pins on the interface board before all this trouble started?

I'd go looking for a solder bridge on that board somewhere.
 
I don't see how the IO boards would be compatible since the Ribbon Cable connector 3J1 has a different pin out between the boards. The +5V and GND are reversed.
It must be an error in one of the manuals. I can't imagine it would work with 5v and ground reversed, and why would they change only those two pins when revising the board, leaving all the signals and stuff the same?
 
It must be an error in one of the manuals. I can't imagine it would work with 5v and ground reversed, and why would they change only those two pins when revising the board, leaving all the signals and stuff the same?

Good question. All the schematics I've looked at show Defender being different then all the rest.

I'm sure an adapter could be built to make them all interchangeable.
 
Back
Top Bottom