Bally 6 digit display ghosting problem

Quoted from Ralph67:
Check R5 should be 100k give or take 10% , Check for solder splashes?
I would put a socket in for the chip , if you have not already .
I would replace both the digit driver and the level shift transistors. Q3 MPS-A42 (Level Shift) and Q9 2N5401 (Digit Driver) ,This pair control the 100"s digit that's ghosting .
These are cheap and might be the problem , worth keeping these Transistors handy when working on these Bally / Stern displays
good luck

Thanks for the tips. Sorry if I wan't clear, but the ghosting is affecting all digits. R5 and the other resistors are in spec. I'll also order some transistors.

#5 8 years ago

EHL

lyonsden

Quoted from schudel5:
This for a Stern, but check anyways.
https://pinside.com/pinball/forum/topic/tech-stern-meteor-ghosting-displays

I don't think my problem is the wiring harness as the problems come from one board. But let me know if there is something that I am missing.

#6 8 years ago

Ralph67

Pinside member

10y 52,300 304

OP
Quoted from lyonsden:
Thanks for the tips. Sorry if I wan't clear, but the ghosting is affecting all digits. R5 and the other resistors are in spec. I'll also order some transistors.

Yes I know what you mean , one bad display can affect all others ,
Get a few spare chips and sockets to suit ,
I've had luck repairing these , some a bit harder to fix than others , but i thinks the problen may be the driver transistor Q3 , but i usually replace both the driver and the level shift transistors of the "Digit" that is playing up .
Good luck again ...

#7 8 years ago

AMS

barakandl

nvram.weebly.com

12y 132K 10,413

Is that a latching problem? The latch pulse is out of time or not the right length resulting in ghosting??

If you have a scope handy, see if latch strobe for the offending display matches working displays.

#8 8 years ago

EHL

lyonsden

Quoted from barakandl:
Is that a latching problem? The latch pulse is out of time or not the right length resulting in ghosting??
If you have a scope handy, see if latch strobe for the offending display matches working displays.

Good idea, but I am one without a scope. I'll see if I can get a friend to help out.

#9 8 years ago

AMS

barakandl

nvram.weebly.com

12y 132K 10,413

OP
Quoted from lyonsden:
Good idea, but I am one without a scope. I'll see if I can get a friend to help out.

There is probably a pullup resistor on the display and the MPU too (would be in the top left corner of MPU). Make sure a pull resistor on the latch strobe didnt get physically damaged. That is the best reason i can come up with for a latch strobe issue.

These displays all share the same information, the latch just tells the display it is time to read the signals. It all goes really fast, so something out of time could cause this.

I know i have dealt with this specific issue before, but I dont remember exactly unfortunately.

#10 8 years ago

BTF

PinballManiac40

Pinside+ Frequent

Can you post a picture of the backside of the display?

I've repaired several displays. Often times I found broken solder joints on both the 20 pin male connector pins and even on the male glass pin solder joints. You need to check all the solder joints on all the displays.

#11 8 years ago

EHL

lyonsden

There are some pretty ugly solder joints going to the display. I did give them a reflow with an iron, but didn't remove and redo (which I can do). Unfortunately, there does look to be some bad damage in places.

IMG_4997.jpg

IMG_5001.jpg

IMG_5002.jpg

IMG_5003.jpg

IMG_5004.jpg

#12 8 years ago

BTF

PinballManiac40

Pinside+ Frequent

Always best to remove much of the old solder as you can before adding new solder. Reflowing what is there can create cold solder joints, just like on glass male pins (counting from pin #40 being labeled on the left) I see an issue on pins 37, 35, 32, 31, and pin 2.

No worries on the pads missing that do not have traces going to them.

#13 8 years ago

EHL

lyonsden

I was wondering if the problem was in the display or in the board, so I desoldered the display and plugged in the board. The ghosting still persists when the board is plugged in, so I think the problem is somewhere on the board. Attached is a photo of the board highlighting the holes where the display would be connected and the topside of the board.

IMG_5006.jpg

IMG_5007.jpg

#14 8 years ago

EHL

lyonsden

Quoted from PinballManiac40:
Always best to remove much of the old solder as you can before adding new solder

Absolutely. I was being lazy. Now I am man on a mission, armed with a desoldering gun.

#15 8 years ago

BTF

PinballManiac40

Pinside+ Frequent

OP
Quoted from lyonsden:
I was wondering if the problem was in the display or in the board, so I desoldered the display and plugged in the board. The ghosting still persists when the board is plugged in, so I think the problem is somewhere on the board.

Then continue on with barakandl's instructions.

#16 8 years ago

EHL

lyonsden

Success! Thanks PinballManiac, you put a fire under me to clean up those solder joints put down by someone else. I removed the solder from the header, resoldered cleanly (thanks in no small part to TerryB's soldering guide), and reinstalled the board without the display. No ghosting. Soldered back in the display and everything works like a champ. Also, thanks barakandl and ralph for the helpful suggestions, too.

IMG_5009.jpg

#17 8 years ago

Ralph67

Pinside member

10y 52,300 304

Nice to see you fixed it , Yes as others have said always best to remove all the old solder first , then re-solder the pins , it's the only way to make the solder stick properly, and if it still wont take because of the corrosion , install new header pins .
Ralph

#18 8 years ago

BTF

PinballManiac40

Pinside+ Frequent

In this case the problem was the solder joints at the glass display. Pictures at the beginning of the post show that he had already installed new header pins. So when looking at display issues, including a dead display, ghosting of segments or whole digits, one digit stuck on and various other display issues, it always best to look for bad solder joints on both row of pins (glass display and the header pins the wiring plug into) before looking for a component failure.

#19 8 years ago

SLM

Slim64

Pinside member

9y 61,550 2,034

Quoted from PinballManiac40:
In this case the problem was the solder joints at the glass display. Pictures at the beginning of the post show that he had already installed new header pins. So when looking at display issues, including a dead display, ghosting of segments or whole digits, one digit stuck on and various other display issues, it always best to look for bad solder joints on both row of pins (glass display and the header pins the wiring plug into) before looking for a component failure.

His issues were fixed at the header pins.

The rest of your post is spot on!

#20 8 years ago

EHL

lyonsden

Quoted from PinballManiac40:
In this case the problem was the solder joints at the glass display. Pictures at the beginning of the post show that he had already installed new header pins. So when looking at display issues, including a dead display, ghosting of segments or whole digits, one digit stuck on and various other display issues, it always best to look for bad solder joints on both row of pins (glass display and the header pins the wiring plug into) before looking for a component failure.

My problem was at the header, not the display. In a previous post, I took of the display and the problem persisted (ghosting on the other displays). Once I removed the solder and resoldered the header, the problem went away with the display STILL removed from the board (no ghosting on the other displays). Then I reattached the display and the problem was still fixed (no ghosting on the other displays.)

#21 8 years ago

EHL

lyonsden

However, the solder joints for the display were not in good shape and I am glad I redid them, too.

#22 8 years ago

BTF

PinballManiac40

Pinside+ Frequent

The display pins looked more of the issue than the header pins did in the pictures to me. Good reason to inspect all pins under a magnifying glass.

#23 8 years ago

EHL

lyonsden

Quoted from PinballManiac40:
The display pins looked more of the issue than the header pins did in the pictures to me. Good reason to inspect all pins under a magnifying glass.

They definitely looked pretty bad.

#24 8 years ago

BTF

PinballManiac40

Pinside+ Frequent

Did you check all the other displays as well for bad solder joints?

#25 8 years ago

EHL

lyonsden