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Aussie Pinball Forums => Technical Matters => Circuit Board Repair Guides => Topic started by: TUF-427 on February 11, 2014, 01:08:21 AM

Title: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 11, 2014, 01:08:21 AM
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.
Title: Re: Wpc 89 board Display Corruption..
Post by: Strangeways on February 11, 2014, 09:52:03 AM
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.
Title: Re: Wpc 89 board Display Corruption..
Post by: MartyJ on February 11, 2014, 09:27:14 PM
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.
Title: Re: Wpc 89 board Display Corruption..
Post by: andtan on February 11, 2014, 09:36:11 PM
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

Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 11, 2014, 11:43:32 PM
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
Title: Re: Wpc 89 board Display Corruption..
Post by: Homepin on February 12, 2014, 08:14:26 AM
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.
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 12, 2014, 10:28:32 AM
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..
Title: Re: Wpc 89 board Display Corruption..
Post by: beaky on February 13, 2014, 11:06:03 PM
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.

 
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 14, 2014, 01:00:11 AM
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.. ^^^
Title: Re: Wpc 89 board Display Corruption..
Post by: Marty Machine on February 14, 2014, 08:00:52 PM
So, did a new mpu fix it?
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 15, 2014, 02:57:19 PM
So, did a new mpu fix it?

Do you Mean the Asic chip Marty?
Title: Re: Wpc 89 board Display Corruption..
Post by: Marty Machine on February 15, 2014, 07:12:38 PM
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?
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 15, 2014, 09:01:23 PM
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...

Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 20, 2014, 07:42:06 PM
Still chasing this unfortunatly this is the error I get in display test..
Title: Re: Wpc 89 board Display Corruption..
Post by: Homepin on February 20, 2014, 11:43:42 PM
Problem solved - your machine is upside down - didn't you realise that????  %.%
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 20, 2014, 11:57:17 PM
Or my Iphone was <.>
Title: Re: Wpc 89 board Display Corruption..
Post by: Marty Machine on February 21, 2014, 01:30:18 AM
Problem solved - your machine is upside down - didn't you realise that????  %.%
He mounted it on the ceiling so the water would flow down better  :lol :lol :lol :lol
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on February 21, 2014, 10:27:15 AM
Problem solved - your machine is upside down - didn't you realise that????  %.%
He mounted it on the ceiling so the water would flow down better  :lol :lol :lol :lol

Thanks for the informative,on topic replys... ^^^
Title: Re: Wpc 89 board Display Corruption..
Post by: johnwartjr on March 15, 2014, 09:27:05 AM
Run the display test. I see this from time to time, and it's often the 6264 RAM on the DMD controller. Cheap and easy fix! The display test will report the errors.
Title: Re: Wpc 89 board Display Corruption..
Post by: Strangeways on March 15, 2014, 11:35:09 AM
Run the display test. I see this from time to time, and it's often the 6264 RAM on the DMD controller. Cheap and easy fix! The display test will report the errors.

+1

Even re seat the RAM chip and look for any bent pins which can happen when you swap ICs from board to board.
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on March 19, 2014, 10:40:19 AM
Run the display test. I see this from time to time, and it's often the 6264 RAM on the DMD controller. Cheap and easy fix! The display test will report the errors.

+1

Even re seat the RAM chip and look for any bent pins which can happen when you swap ICs from board to board.

Cheers guys,
I have run the display test and it reports Ram address errors.
This is unclear as to weather this is the 6264 on the CPU or on the display driver board,
But by being able to carry the fault across machines by swapping the Mpu board leads me to believe its that board.
Alas williams decided it was best to solder the 6264 directly to both boards so not able to swap easily..
Will have to be cut off and socketed with dip28s

Can you substitute a different speed 6264 to the original?
I think the original chip is 150ns and most available now are 70ns..
Title: Re: Wpc 89 board Display Corruption..
Post by: Homepin on March 19, 2014, 12:14:39 PM
Faster chip speeds are fine - slower is not
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on March 19, 2014, 02:27:43 PM
Faster chip speeds are fine - slower is not

Cheers for that I'd suspected that would be the case but wasn't 100% sure..
Also can get them with a broad operating voltage and some just at nominal 5v..
Title: Re: Wpc 89 board Display Corruption..
Post by: Caveoftreasures on March 19, 2014, 08:18:33 PM
a dumb question.

does the factory manual have a simple trouble shooting section with that error on there with the manufacturers answer as to what it is/needs replacing ?
Title: Re: Wpc 89 board Display Corruption..
Post by: studley67 on March 19, 2014, 08:27:33 PM
if you replace the mpu ram chip.be extra cautious.the tracks and pads are very fine and easily damaged.I have a military soldering background and screwed one up from my "jackbot",hence a new mpu.
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on March 19, 2014, 10:47:41 PM
a dumb question.

does the factory manual have a simple trouble shooting section with that error on there with the manufacturers answer as to what it is/needs replacing ?

That would be nice but doesn't exist in Wpc manuals I've seen.

Maybe williams had something more substantial for Wpc series..

I'm guessing for operators and repair techs it was a case of replacing boards to keep the machines making money and hardcore repairs on the boards were done back in the workshops..
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on March 19, 2014, 10:53:35 PM
if you replace the mpu ram chip.be extra cautious.the tracks and pads are very fine and easily damaged.I have a military soldering background and screwed one up from my "jackbot",hence a new mpu.

Yes not really looking forward to changing it and have been leaving it as the last resort ,
Pretty  well changed everything else related to display operation  I think..
Title: Re: Wpc 89 board Display Corruption..
Post by: beaky on March 19, 2014, 11:48:03 PM
so when you put a substitute mpu board in your machine and you do a display test you dont get an error in display test.
and you put the suspect mpu board in a different machine and do the display test you get the error in the different machine?
if this is the case then the fault has to be on the mpu board.

before replacing the ram chip on the mpu board if you haven't done so already i would be beeping out all the address and data lines between U1, 2, 3 and the cpu chip.
I would find it strange that you would have only a display fault if you had a faulty ram chip on the mpu board, i would expect lamp, switch , solenoid and flasher problems as well.
but anything is possible
 
Title: Re: Wpc 89 board Display Corruption..
Post by: Caveoftreasures on March 20, 2014, 12:08:50 AM
what happens wen u put a proven/other dmd display in the machine, same error as the orig white water dmd's message ?
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on March 20, 2014, 02:21:46 AM
so when you put a substitute mpu board in your machine and you do a display test you dont get an error in display test.
and you put the suspect mpu board in a different machine and do the display test you get the error in the different machine?
if this is the case then the fault has to be on the mpu board.

Yep this is the case..... ^.^

before replacing the ram chip on the mpu board if you haven't done so already i would be beeping out all the address and data lines between U1, 2, 3 and the cpu chip.
I would find it strange that you would have only a display fault if you had a faulty ram chip on the mpu board, i would expect lamp, switch , solenoid and flasher problems as well.
but anything is possible

I've previously socketed U1-2-3 and ensured all pins went to where they were supposed to.
Also had a Cro on all the data and address lines and seem to have activity on all..
Weather it's correct is beyond my testing ability..
It has had the odd random coil fire and flipper flutter in WW with this Mpu board installed..
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on March 28, 2014, 01:05:44 AM
Update socketed and replaced the 6264 chip and installed into the shed pin BSD.

straight to display test ran perfectly for 3 full test sequences..had a game seemed fine..

left machine on for awhile started to notice some artefacts on the Dmd again..

Ran display test arain same old Ram address error..

soooo looks like something gets warm after Machine being on for awhile... ^.^
Title: Re: Wpc 89 board Display Corruption..
Post by: Marty Machine on March 28, 2014, 01:12:30 AM
Sheesh, this seems to be getting nastier each time :-(

Assuming the 6264 is new and/or proven on other machine(s) ????

You may wanna check/replace the bypass capacitor associated with the 6264 and any other bypass caps (especially tantalum types) around other memory chips.
'ghosty data' is usually corrupted ram data when bypass caps go open (or short) and alter the digital 5v signals to 2.5volts into the 'no go zone....

fingers crossed...
Title: Re: Wpc 89 board Display Corruption..
Post by: TUF-427 on March 28, 2014, 02:01:54 AM
Sheesh, this seems to be getting nastier each time :-(

Assuming the 6264 is new and/or proven on other machine(s) ????

You may wanna check/replace the bypass capacitor associated with the 6264 and any other bypass caps (especially tantalum types) around other memory chips.
'ghosty data' is usually corrupted ram data when bypass caps go open (or short) and alter the digital 5v signals to 2.5volts into the 'no go zone....

fingers crossed...

Cheers for the tips Marty yea brand new 6264 chip a little faster than the original but should be good..

I will have a new board by the time Ive finished!
Title: Re: Wpc 89 board Display Corruption..
Post by: Marty Machine on March 28, 2014, 07:27:02 PM
Cheers for the tips Marty yea brand new 6264 chip a little faster than the original but should be good..
I will have a new board by the time Ive finished!
....or no hair left to pull out  ;-)