Just acquired a Gottlieb System 80A Touchdown game.
I (we) are just getting started with it. So far I have replaced all the capacitors on the boards.
I have also replaced the three bridge rectifiers in the bottom of the game and re-pinned the main board connector.
So far when we turn it on we get all the GI lights working and two displays have a 5 on them, the small display in the center and the player 1 display.
All fuses checked and replaced. Have not messed with any ground cables yet.

But my biggest question is what I should put in the bottom of the game capacitor wise. Someone has twisted together two caps, each with a value of 35V and 3300 MFD.
I did order a kit which came with the following two screw top capacitors. One is a tall 30V 12000MFD and the second is a shorter 50V 4800MFD.
Is one of these supposed to go here??? (See Photo below).
I am working on getting a manual but do not have one yet.
Also any tips on getting this thing further along are appreciated.

IMG_0839.JPG

Here is another photo that better shows where this monster is located.

IMG_0836.JPG

I read all of Pinwiki before I ever got started, I seem to remember them saying to replace the old caps.
Two caps had leaked and I saw no reason to leave them in. The others were replaced because they were over 30 years old and I already had the board out.
Seemed like a no brainer, maybe I was wrong.
One of the three bridge rectifiers was cracked, so once again I was already in there, why not replace the other two?
We will get to work on the grounding soon and I just got a manual paid for this morning.
Thanks for the responses, if I am doing something wrong, I want to know, and I'm sure I will need more help later on down the line.

I did not take it as rude. I was just answering the questions as they were asked.
I am not at home to look, but there was one on the sound board and one on the main power board. Also the Zener diode above it on the main board was toast, so I replaced it as well. I will let you know specifically which ones when I get back home.
I am really just wondering the most what to replace that twisted mess of capacitors in the bottom of the cabinet with. Hopefully the manual will tell me exactly what should be there.
I am not sure where the HV bridge is located.

Just got home. The cap on the power board was C2 and the diode directly above it which was CR7.
The CR7 was toasted. I did not replace R10 with a higher ohm and you are correct, pulling the board off the heat sink was not much fun.
Thanks for the info. Sounds like my tall cap I got in my kit, the 30VDC 12000MFS is what I need to put in place of the hacked version I have currently.
I guess my machine does not use the other 50 volt cap, but I will check the schematics when I get them.

I would tell you which cap on the sound board was blow, but they are not labeled. I will post a photo if I can and circle the parts effected.

I circled the two areas in red that were damaged.

IMG_0830small.jpg

I have already replaced that heat sink. The photo was taken as the game was given to me.
I did talk about replacing the heat sink, but that was in another thread for the Gottlieb system 80/system1 club.
Good catch though.

I do plan on replacing the battery at some point as well. So far no signs of any leakage.
Tomorrow I will do the grounding mod on the power board, cpu board and driver boards.
Luckily I have the good kind of attachments in the lower cabinet that do not require having to do the ground mods down there.

Just finished the ground mods on the power board and the CPU board.
I have not done the driver board yet because none of the Ninja photos or videos have a close enough shot of just where he is putting that wire.
Any way I tested the J2 plug on the Power board and have 5.00 volts coming off of it.
Then I tested the J3 plug and have 63.9 volts and 46.3 volts on pins 1 and 3.

Kind of at a loss as to what to try next. On power up I still just get all the GI lights in the backbox and the playfield lit up.
Also I have two insert lights stuck on and a 5 on player 1 display and a 5 on the small display in the center.
No coin up or game start yet.

Thanks. I'll do that shortly.

Ok. Got 8.47 volts on the 8volt test point.

With the plugs unplugged except the display plugs I get the same problems. Here are some photos of my CPU. One overall photo and two close ups of the top half and the bottom half.

image-212.jpg

image.jpg

image-270.jpg

Ok

All removable IC's removed and sanded.
Unfortunately, no difference.

I already have the reset board unplugged as the Ninja suggested

Yes q4 is fine. Just the flash

Also forgot to mention I had already added the two extra wires to the interconnect.

I can get the battery off no problem.
The problem would be that I only have a multimeter, no scope.

Ordered a logic probe and they sent me a logic pulser. arrrrgh.

Got the two IC chips on order Chris.
They should be in next week.
Thanks for helping out like you did.

Got my two IC chips installed today.
Bingo!!!!
The game plays for the first time.
All displays came to life, credits worked, game started, sound works as does all scoring.
Only three problems to fix.
Top left pop bumper does not work. Fuse is good and coil tests ok. Maybe the little board?
Also the game has two kickout holes next to the flippers and neither one works.
And the last biggest problem is that the controlled playfield lights do not work.
I have two standup target lights that cycle back and forth and sometimes between balls the playfield lights will flash for a brief second and then go back out.

Thanks to CNKay for the phone call to diagnose which chips needed replacing.

Sure.
They were Z5 static ram chip S5101-L
and Z10 open collector inverter SN74LS05N

According to CNKay the Z5 chip is often blown and is very susceptible to static electricity.