Wpc 89 board Display Corruption..

[TUF-427]

Hey All got another curly one,

this time its A Wpc89 board that seems to corrupt The display,

Puts lines and artefacts on the Display.

First thouught display board but its the cpu doing it,

can transfer board into another machine and it brings the fault with it.

Anyone got any ideas on this thus far Ive changed U1-2-3 chips on board which should be the most likely suspects with no Joy..

Reseated Asic,Processor and game rom without change,got a new Asic coming will try to change that next..

Peter.

[Strangeways]

Strange problems like the one described would sound like the ASIC Chip. Everything else seems to be covered - ROM, RAM, CPU and cables. Maybe look for solder splashes around the ASIC socket.

[MartyJ]

I would have initially thought cables (data lines)...But problem stays with board on different cable(s)..

Just check the pins and that nothing (ie solder dag or similar) has not got caught in them.

[andtan]

Hey peter,

I recently had issues with my Getaway showing vertical lines on the DMD which would flash in time with the score flashing.

For the life of me I can't remember which ribbon cable I wiggled first, as I was leaning over the playfield and had my daughter watching the screen, but it was one of the two ribbon cables on the left hand side of the DMD Controller board (J601, J602) which end up at the CPU board at J201, and J202.

In my case it appeared to be a bad connection at the DMD side. It's possible you may have issues at or before the header pins on your CPU board at (J201, or J202), as that would definitely result in the problem moving from pin to pin.

Hope that helps.

Andy

[TUF-427]

Thanks for the Ideas Guys,

It did seem Like a connection problem at first,

Its on a machine I had just picked up too which Im sure it wasn't doing it when inspected and tested 

Waiting for a New Asic chip to turn up From RTBB and will revisit it again.

Ive closely inspected the board for solder etc but will have another close look under that Asic socket..

Peter

[Homepin]

I'm also going with cables - they are 20 years old and this type of cable gets pretty flaky when unplugged/plugged a lot.

A new set isn't expensive - I would start there.

[TUF-427]

I'm also going with cables - they are 20 years old and this type of cable gets pretty flaky when unplugged/plugged a lot.

A new set isn't expensive - I would start there.

Agreed , First thing I tried was a full set of ribbons from a known working machine,also a display driver board,then a display,All to no avail

So Swapped Mpu boards and Fault was transferred to new Machine, And Faulty one works fine with the other Machines Mpu..

So its Pointing towards THe Mpu....

So Far I have changed U 1-2-3 which are a pair of 74LS244 and 74LS245, and Reseated Processor chip and Asic and Game roms been swapped a few times..

[beaky]

I did a repair on a board that had a broken pin on one of the ribbon cable headers,
it was broken below the plastic so it still stayed in place.
if the asic chip doesn't fix the problem then i would be beeping all the pins on the headers (parts side) to the relevant pins on U1, U2 and U3 to make sure you don't have a broken trace or pin.

 

[TUF-427]

I did a repair on a board that had a broken pin on one of the ribbon cable headers,
it was broken below the plastic so it still stayed in place.
if the asic chip doesn't fix the problem then i would be beeping all the pins on the headers (parts side) to the relevant pins on U1, U2 and U3 to make sure you don't have a broken trace or pin.

 

Good call Andrew, I think ive probaby already belled most of them when I did the sockets for U1-2-3 ICs but wont hurt to recheck..

[Marty Machine]

So, did a new mpu fix it?

[TUF-427]

So, did a new mpu fix it?

Do you Mean the Asic chip Marty?

[Marty Machine]

So, did a new mpu fix it?

Do you Mean the Asic chip Marty?

No the MPU,......the last thing you said was your "faulty" board with "working MPU" works fine, so youre looking at getting another MPU......or did you drift between Asic & MPU meaning the same chip?

[TUF-427]

Ok cool sorry I should read my posts a bit more closely before pressing the submit button 

Story so Far..

Basically I've got a Dead Wpc CPU/Mpu board out of a machine I'd recently purchased.

I substituted a known working Wpc CPU/Mpu board into that machine and the Pin works perfectly.

So in effect this proves that the fault is on the machines original Mpu board.

So I'm trying to find the problem on the original Mpu board

I've changed the buffering ICs at U1-2-3 without change.

I've sourced an ASIC chip that I've just installed and powered the board on The bench.

It seems to be toggling all the data on the J201 and J202 headers so going to try back in the machine shortly...

[TUF-427]

Still chasing this unfortunatly this is the error I get in display test..

[Homepin]

Problem solved - your machine is upside down - didn't you realise that????