"COM LINK FAILURE". IGT VISION . SOLUTION ?

[gordy]

The voltage on the good machine is 2.997.  Keep in mind I had swapped most components from the good one over to the bad one -even the MPU. then I put the good MPU back in the good machine because it had all the right game chips in it.  NOW, I just put the MPU from the bad machine into the good machine, got Ram Error etc and finally Com Link ........ like in the bad machine. If the MPU from the bad machine is a good board, should it have worked in the good machine even if it had the wrong game chips in it?

[stayouttadabunker]

Okay...
Here's how you rule out bad chips.
I think both MPU boards are okay.
Put the good chips from the working Good machine and ATA card into
the problem Machine and see if you can get past the "COM LINK Failure" message.
Do the several open/closing of the door too with these chips if you have to.

If you still can't get past the "COM LINK Failure" message with good chips...
then you've pinpointed the problem - it's in the harness.

Troubleshooting a machine is an art! lol

[brichter]

The battery at 2.997 is marginal, the one reading 2.86 is a goner.

I'd replace both.

[gordy]

Have continuity from the known good LCD to the known good  lower PDU. There is one major component that I haven't put in yet and that is the backplane which will be arriving soon . Will keep you all posted.

[stayouttadabunker]

Sounds good gordy! 

[cowboygames]

Gordy, have you tried the battery? If you don't have a replacement you can hook 2 AA batteries in series and wire them in for a test.

[Jim]

Gordy     if I were you, I would get my known good machine up and running first. then I would sub the MPU board on the good machine with the one from the suspect machine, transfer all necessary chips so that you won't have other issues to deal with(clearing the machine due to mismatch etc.) and just see if you can get the machine up and running. If you can't or get the same errors then the problem would appear to be in that board. 

As with any swaptronics  you risk damage to the good machine.

I have machines that operate with battery voltages ranging from  2.4vdc to  2.86vdc , very few actually have a 3vdc reading.

Jim 

[gordy]

Both machines have fresh batteries.  The good machine has always worked --even with many components from the bad machine The MPUs were also swapped as detailed earlier. Thanks.

[stayouttadabunker]

Okay forget hardware for a moment - you have continuity with the COM harness.

When you put the known Good software into the problem machine - you
still got the "COM LINK Failure" message?

Does the software from the Bad machine work in the Good machine? 

[gordy]

As indicated on an earlier page the MPU from the good machine  was put in the bad machine and vice-versa . Both gave Com Link Failure  When switched back to their original machines the bad was bad and the good was good.  Since I dont know one chip from another I better wait until the new mother board comes to see if that is it.

[stayouttadabunker]

Okay good.
I have a question though...when you put the BAD MPU into the Good machine,
did you also move the ATA card along from the Bad machine's LCD computer
top PCMCIA slot into the Good machine too?

If you didn't - the Good machine should have given you an "Incompatible" error message -
rather than a "COM LINK Failure" error because we know the Good machine doesn't give
that error when the correct ATA card and MPU is in there.

Follow me?
That's why I think the MPU boards are fine.
You might be swapping MPU's but not taking the correct ATA card along.

Do both machines contain the same games or are they different games and ATA cards?
By the way, the ATA card I'm talking about is the silver card
 that goes into the top PCMCIA slot of the LCD computer.

[Jim]

Gordy   we are just trying to establish what compoments are good and which are bad. we have not established that the suspect MPU is good or bad. it doesn't work in the bad machine and it doesn't work in the good machine. the only chips you have to transfer from one board to the other are the following:
U-21=base eprom (sb000061), U-46= game 2 eprom,  U-19 = game 1 eprom, and perhaps U-44 version chip. If the version chip is the same then you shouldn"t have to swap it. Since this board is the brains of the entire machine it would be nice to know if it is good.

I think your problem is with your door optics loop. 

[stayouttadabunker]

I purposely put in an incorrect ATA card and look at what came up onto the VFD display!  

You have to move the LCD computer ATA card along with the MPU when swapping gordy!  

[gordy]

The games are Dbl Diam Mine and Wild Cherry Pie.   Switched the chips at U21  U19  U46. The Version chip was not changed  because they were both the same. Switched the Cards in the top of the LCDs too.  Put the MPU from the bad machine into the good machine and very soon the COM LINK FAILURE came up in the LCD and stayed.  Turned OFF/ON and the same result.    Put the MPU from the good machine into the bad machine  and the same routine with " mismatch, ram error, hold 2-3 sec. etc " and same message in the LCD . OFF/ON  gave the same result.     Put everything back in it's original condition  and both machines  acted like nothing had happened.

[stayouttadabunker]

...Put everything back in it's original condition  and both machines  acted like nothing had happened.

Which means - The Good machine is still "Good" and the Bad machine is still "Bad" right?

I wonder why?
1) The Good software doesn't work in the Bad machine.
2) The Bad software doesn't work in the Good machine.
3) You've swapped everything so far.
4)  I have no clue...  


The software from the Bad machine doesn't work on the Good MPU in the Good machine either?
Maybe the Bad software is ...uh....bad? 
Do you have equipment to read the ATA card and SB chip?
It should be checked out...
I can do it if you send it to me and I will look at it and
see if I can get it to run on my machine?
Keep the good software...I'm only interested in seeing if the "Bad" software is..."bad".

[gordy]

Right. The bad is still bad and the good is still good. Will receive a new backplane in a couple days to try. Will let you know.  Thanks

[gordy]

Put in new door optics, too,but to no avail.

[a69mopar]

possible short somewhere. I'd look throught the harnesses or maybe disconnect all the lighting, bv, printer etc.  if it starts then hook up 1 by 1.

Merry Christmas.
w

[gordy]

Finally, it works. It was the CPU ! It was bad. A new board worked  ! I'd like to thank the many members who pitched in to fix this vexing problem.

[stayouttadabunker]

I glad you got it working Gordy!