Defender Control Trouble

xxstatic

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When in test mode it shows the "UP" and "FIRE" being selected, checked the leaf's and that is not the case, disconnected the whole cp and ran the test again, still shows the same as being pressed.
Anyone have an idea on what is wrong?
 
Sounds like a bad interface board. I had a similar issue in my Stargate. Power off the machine, unplug the interface board and power back on. See if you still get the switches as being on. If not, then you know it is a bad interface board.

- Mike
 
Sounds like a bad interface board. I had a similar issue in my Stargate. Power off the machine, unplug the interface board and power back on. See if you still get the switches as being on. If not, then you know it is a bad interface board.

- Mike

I took the interface board off and powered back on, showed all of the switches including ones I had never seen as on, going to reinstall the interface board and see if it goes back to normal.
 
Bah...reinstalled interface board and it still shows the fire and up as activated.....how much is a refurbed interface board?
 
Bah...reinstalled interface board and it still shows the fire and up as activated.....how much is a refurbed interface board?

When you're in test mode, open the back door and wiggle the ribbon cable on the interface board. I bet your switches go crazy opening and closing. Time to replace that ribbon cable.

Edward
 
When you're in test mode, open the back door and wiggle the ribbon cable on the interface board. I bet your switches go crazy opening and closing. Time to replace that ribbon cable.

Edward


Bingo!

Who has ribbon cables? :)
 
I can try the vise method, how does one replace the ribbon cable? It looks like the 20 pin end is soldered into the pcb? I don't want to just yank this out then right??
The connector on the I/O board has 2 parts - the bottom is soldered to the board, the top snaps to the bottom, sandwiching the ribbon in between. Be very careful when removing the top part of the connector, if the connector won't snap together it won't work, and if the bottom part is broken you'll need to desolder the old one and get a replacement from Bob Roberts. Once you remove the top of the connector, you can pull the ribbon out of the pins on the bottom half. The pins are somewhat V-shaped (similar to a telco punch down block if you've ever seen one of those) and as the wire is pushed into the pin, the edges displace the insulation and make contact with one of the conductors of the ribbon. So you can sometimes fix a flaky ribbon just by giving it a squeeze in the vise and pushing the ribbon back into the pins.
 
The connector on the I/O board has 2 parts - the bottom is soldered to the board, the top snaps to the bottom, sandwiching the ribbon in between. Be very careful when removing the top part of the connector, if the connector won't snap together it won't work, and if the bottom part is broken you'll need to desolder the old one and get a replacement from Bob Roberts. Once you remove the top of the connector, you can pull the ribbon out of the pins on the bottom half. The pins are somewhat V-shaped (similar to a telco punch down block if you've ever seen one of those) and as the wire is pushed into the pin, the edges displace the insulation and make contact with one of the conductors of the ribbon. So you can sometimes fix a flaky ribbon just by giving it a squeeze in the vise and pushing the ribbon back into the pins.

Ok have the ribbon cable ordered and should be here tomorrow from Bob, any tip's or trick's on how to remove the existing?
Guess I should wait until the new one is here, should give me a better idea on how it's held together.
 
Ok have the ribbon cable ordered and should be here tomorrow from Bob, any tip's or trick's on how to remove the existing?
Guess I should wait until the new one is here, should give me a better idea on how it's held together.
The connectors used on these boards aren't all identical, so you have to figure out how they come apart by looking at the one you're working on. Before you disassemble the new one, make sure there's enough slack so you can cut off the end of the cable that was inside the connector - you don't want to try and re-use the "holes" in the ribbon (there's normally tons of slack). Also, note where pin 1 is - there's a red stripe on one edge of the cable that indicates pin 1. Make sure you install the new one with the stripe on the same side as the old one. The article at arcadesolution goes over all this pretty well - BTW he refers to this board as a wedge board.
 
One more thing, make sure you pad those vise jaws! I usually use soft wood, you want to avoid having the jaw of the vise directly on the pins on the bottom of the board.
 
The connectors used on these boards aren't all identical, so you have to figure out how they come apart by looking at the one you're working on. Before you disassemble the new one, make sure there's enough slack so you can cut off the end of the cable that was inside the connector - you don't want to try and re-use the "holes" in the ribbon (there's normally tons of slack). Also, note where pin 1 is - there's a red stripe on one edge of the cable that indicates pin 1. Make sure you install the new one with the stripe on the same side as the old one. The article at arcadesolution goes over all this pretty well - BTW he refers to this board as a wedge board.

Ok, found out the trick is to use a very small screw driver and get a little leverage on the seam at the corner of the connector, work slowly from each side and it will come off.

Voila!


New ribbon cable should be here tomorrow from Bob. :)
 

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Ok, found out the trick is to use a very small screw driver and get a little leverage on the seam at the corner of the connector, work slowly from each side and it will come off.

Voila!


New ribbon cable should be here tomorrow from Bob. :)
When you lift this cover off and remove the ribbon cable from these pins, you are setting up to replace the cable by pressing a new cable back in. If you plan to use a Bob Roberts replacement cable, you will be desoldering/soldering the entire assembly.

Try locating a compatible cable and header only; pressing is easer and less error prone than the desolder/solder route.

Saltbreez
 
When you lift this cover off and remove the ribbon cable from these pins, you are setting up to replace the cable by pressing a new cable back in. If you plan to use a Bob Roberts replacement cable, you will be desoldering/soldering the entire assembly.

Try locating a compatible cable and header only; pressing is easer and less error prone than the desolder/solder route.
He can use just the ribbon and CPU connector from the part he gets from Bob. If there's enough slack he could even slice it right off at the connector without even taking it apart first (not that you get much more if you do disassemble it after removing the "used" part). It's easier than desoldering those suckers.
 
Just for s&g I pulled the other end apart (it's going into the trash anyway) and cut about an inch of the ribbon cable off each end, reinstalled both ends carefully clamping them as instructed in the vise, put it back in the machine and got the same two buttons (up, fire) as closed in the test mode :(

Hoping the ribbon cable is majorly the problem and not the pcb itself....
 
Well got the cable from Bob, installed it and I get the same thing :(

Thinking the pcb is the problem, any thoughts?
 
Still a good thing to change that cable out though.

Just to recap -
When you unplug the interface board all together you say ALL the switches show as closed in test mode. So you either have no signal from the PIA on the interface or it's something on the main board itself.
Do you have another PIA chip you can swap onto the interface board?
(can't recall if those are normally soldered on or socketed)
You may be able to swap the one from the ROM or sound board for testing.
(I've seen bad PIA's work fine in other locations depending on what address lines that particular location needs, etc)

I'm by NO means a techy wiz on board repairs though, so maybe some of the vets can chime in.
 
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