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Genie System 1 displays help needed - FIXED

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By scoots

3 years ago


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  • Started 3 years ago
  • 19 posts
  • 7 Pinsiders participating
  • Latest reply 2 years ago by scoots

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#1 3 years ago

been trying to track down this problem for months (i am strictly an amateur). displays would flicker and eventually died altogether. i replaced the filter caps and C6 on the power supply. repinned the connectors and added additional grounds. no longer blowing the 69v fuse. cleaned up an accidental solder bridge, replaced a couple of blown diodes (CR3/CR4) and the four diodes that make up the bridge rectifier on the power supply (CR6-9). now instead of dead displays i get this:

http://www.youtube.com/embed/4j0Atzy2qm4

checking the displays in the test menu shows no improvement. something is "working" because they change while scoring, but nothing usable. plugging/unplugging the individual displays didn't improve anything. all connectors are good and clean and snug.

noticed Z16 and Z17 (the 7448 decoders) on the MPU were screaming hot, made me wonder, though the game and sound proms were also hot and they still seemed to be functioning fine....

just found this regarding someone else's issue, but seems like it could also apply here:

"Since you said the problems show up same on players 1 and 2 and same on
players 3 and 4 - you need to look at digit strobes, not segment drivers.
Digit strobes are driven by Z18-Z21."

Z18-21 are 7408's

any feedback much appreciated!


#2 3 years ago

scoots

First you need to go here:

http://www.pinrepair.com/sys1/index.htm#display

Great info on the System 1.

Next use the info to troubleshoot.
If you have an O-Scope, all the better.

If you plan on keeping the game you should invest in a Pascal CPU PCB or All in One PCB.
These PCBs blow away the original Gottlieb PCBs.
http://www.flippp.com/eboards.html

Let us know what is going on as you troubleshoot and We'll try to help


#3 3 years ago

In addition, these displays from boston pinball look great. I have them in my Genie and the color is better than the original IMO.

http://www.bostonpinballcompany.com/displays.htm


#4 3 years ago

pdman, already been through that document a bunch of times. if there's anything apropos to my situation that i didn't mention in the first post, i am missing it (as i said, i am new to this). was hoping maybe someone had seen a similar display problem and could comment from first hand experience. i've posted this on three different boards and that site is always the first reply posted....


#5 3 years ago

By chance do you have a display that's shorted?


#6 3 years ago

plugging/unplugging the individual displays didn't change anything.


#7 3 years ago

i do have a logic probe and the schematics, though i've never actually used one. if someone knows what the readings on Z16-Z21 are supposed to look like i could dive in there.

alternately, would it be possible for me to buy the 7448 and/or 7408 chips and piggy back them on top of the existing chips to see if it makes a difference (before i go through the trouble of desoldering the old ones etc)? a friend showed me this technique on a video arcade machine but i'm not sure if it is safe/effective in all applications....


#8 3 years ago
pdman said:

If you plan on keeping the game you should invest in a Pascal CPU PCB or All in One PCB.
These PCBs blow away the original Gottlieb PCBs.
http://www.flippp.com/eboards.html

I will second the recommendation for the Pascal PI-X4 replacement boards. One board replaces the power supply, MPU and Driver boards. It also adds a TON of new features. I'm in the final stages of restoring an old Genie as well. If you're interested, I posted a thread with pics, and a more detailed description of the replacement board and it's features here: http://pinside.com/pinball/forum/topic/tonight-i-picked-up-a-sexy-but-dirty-genie

Good luck~!


#9 3 years ago
scoots said:

would it be possible for me to buy the 7448 and/or 7408 chips and piggy back them on top of the existing chips to see if it makes a difference (before i go through the trouble of desoldering the old ones etc)?

I can see issues using this technique. I wouldn't use it. Also 7448's are fairly hard to find. Many of the surplus electronic vendors still have them.

scoots said:

been trying to track down this problem for months (i am strictly an amateur). displays would flicker and eventually died altogether. i replaced the filter caps and C6 on the power supply. repinned the connectors and added additional grounds. no longer blowing the 69v fuse.

So the 69VDC fuse was blowing all the time?

scoots said:

cleaned up an accidental solder bridge, replaced a couple of blown diodes (CR3/CR4) and the four diodes that make up the bridge rectifier on the power supply (CR6-9). now instead of dead displays i get this:

Has this Pin ever worked correctly for you or has it never worked correctly and you are now trying to fix it? Give us as much info as possible.

From the Video you don't have a lot happening with the displays.

How are the connection fingers on the CPU that connects to the Display connectors?
Are they clean and nice and shiny.
How are the contacts in the display connectors in the harness?

There is a service manual on System 1 here.
Look for GottliebĀ® System 1 Service Manual about 3/4 down the page.
It will have waveforms and such that you should see on the display driver outputs.
http://www.pbresource.com/books.html

Do you have access to another CPU PCB?


#10 3 years ago

the 69v fuse WAS blowing. i think it was due to the solder bridge i left after reflowing a connector pin. it is good now.

when i got the pin everything worked as it should. then one day the scores started to flicker and dim. i thought at the time it was due to the cold weather, but eventually they just went dark altogether. i made a lot of mistakes trying to troubleshoot this due to my lack of experience, but it is back to the point where everything works properly except the displays.

i repinned all the connectors going to the PS. i did not do the other connectors because they are still "factory snug". i am only the 3rd owner of this machine. after a year on location, it spent the next 30 with the guy i bought it from. it is really in excellent original condition and i'm trying to keep it that way. i know buying the pascal or ni-wumph would be the easy way to go about this but i also really want to learn what is wrong and how to correct it.

i do own the genie manual and gottlieb ss manual. i've read all the "big" system 1 sites several times and googled till my fingers are ready to fall off.


#11 3 years ago
scoots said:

i repinned all the connectors going to the PS. i did not do the other connectors because they are still "factory snug". i am only the 3rd owner of this machine

That can mean nothing.
You need to check all the connector and all the PCBs finger contacts.
You have to check for corrosion and any acid damage.

It's the easiest thing to do first and it solves many issues. It is step #1 in troubleshooting System 1 pins.
Do not jump ahead in troubleshooting if you don't check all connectors and contacts first.

Also does the pin boot and coin up?
If it does, what happens to the displays as you score points?

scoots said:

i know buying the pascal or ni-wumph would be the easy way to go about this but i also really want to learn what is wrong and how to correct it.

Fine but do all the easy must do fixes before troubleshooting the electronics.

scoots said:

i do own the genie manual and gottlieb ss manual. i've read all the "big" system 1 sites several times and googled till my fingers are ready to fall off.

The GottliebĀ® System 1 Service Manual is not the same as the individual game manuals.
It goes into much more depth and shows correct waveforms from the CPU PCB and other info that is not in the game manuals.

Trust me, I have worked on and repaired dozens of System 1 games. Do the must do things first before anything else


#12 3 years ago

If you haven't re-pinned the connectors on the displays - I'd do that. When I got the dirty Genie to boot for the 1st time, the two bottom displays (player 3 and 4) looked good, while the top 2 didn't. I did a quick swap of the top displays with the bottom, and it made ALL of them look bad - missing segments, flickering, etc. One of them didn't work at all. After I repinned the display connectors - they worked 100%.


#13 3 years ago

i've been plugging away at repinning the connectors. so far no changes.

does anyone have a chart of what the pins on known working ICs on the MPU should show on a logic probe? i actually have a spare boardset now i could cannibalize.


#14 3 years ago

no one's ever recorded the logic probe readings on a functioning board? how about just U6 when all the scores are sitting at 0?

pretty please?


#15 3 years ago

Scoots,
You'll be better served by rounding up some schematics. The logic is pretty simple. Segments are set up, then a digit is strobed.

However, the video would lead me to believe that your MPU has much bigger problems than the display driver ICs. If you're MPU is original, it might be time to think about a NiWumpf replacement MPU. It might be the 7448s, but it might also be the "spider chip" that drives the displays. In that case, a replacement MPU is where you are headed.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info


#16 3 years ago

...fat fingers, hope this doesn't post twice.

A logic probe will show constant activity once the board boots & the machine is in attract mode on the outputs of these chips...

U6, 7 thru 10, 12 thru 15, 27 thru 35
U (Z) 18 thru 20 & 11, all outputs
U (Z) 12, at least pins 2 & 12
U (Z) 14, at least pin 10.

Are any of these stuck high or low?

scoots said:

no one's ever recorded the logic probe readings on a functioning board? how about just U6 when all the scores are sitting at 0?
pretty please?


#17 3 years ago

... on U6, the " 7 thru 10, 12 thru 15, 27 thru 35" are the pin numbers


#18 3 years ago

THANK YOU, guilford bob!

i will take a look today and report back. i hate the idea of having to replace the original MPU, but if the spider is bad at least i'd know i can stop fooling around with other possibilities.


#19 2 years ago

update:

after avoiding this problem for months, i replaced Z16 and Z17 and displays are working properly again.



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