Unplug and plug back in all connectors from speakers to back box, with power off. If your are getting some sound might just be a loose connection. May be worthwhile to try replacing the pot, the only cost about 4$ at ratshack.

Congrats on the your first pin. I agree with Steve and start with the connectors. Also check out this link

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Sound_Boards

It has trouble shooting tips for your sound board.

Edit: check out this as well. Same page just further down.

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Sound_problems

Wow... good price. Not the best looking pin made but for the price you got a good deal. Take a look at the links I gave you. It would be a good idea to read through the whole document. It has a lot of good information. If you get stuck be sure to ask more questions. There are a lot of helpful people on this site.

I'm working on a Rock right now with no sound. Press the red button on the sound board. If you hear something from those, then your set up (speakers, amp, etc.) is good. Somehow my amp connector was corroded so I had to hard wire I the amp up and was able to get test sounds from there. Next step would be to do this series of tests:

Testing the Data Pathway, Easy Method.

After the sound/speech board itself is tested (as described above), it's best to test the pathway from the CPU board to the Driver board to the Sound/Speech board. This will test the chips and connectors in this pathway. There is no sense changing chips if the connectors are at issue, or vice versa. And this test will identify these problems in a very easy manner.

Step 1: Test the Sound/Speech board. This is described above. If the sound/speech board is missing any sounds S1 to S16, stop now. Fix or replace the sound/speech board.

Step 2: At the driver board find chip Z13. Game on and in attract mode. Using an aligator test lead with one end connected to ground, touch the other end of the lead to Driver board chip Z13 pin 2 (s1), pin 4 (s2), pin 6 (s4), pin 7 (s8). A game sound should be heard for each sound S1 to S8. These are the output pins of Z13, so this tests the connection from the driver board to the sound/speech board. If any sound is missing, check the driver board A3J5 connector (upper left) pin 6 (s1), pin 5 (s2), pin 1 (s4), pin 7 (s8). If OK examine the sound board connector A6J1 pin 8 (s1), pin 9 (s2), pin 11 (s4), pin 12 (s8).

Step 3: At the driver board find chip Z13. Game on and in attract mode. Using an aligator test lead with one end connected to +5 volts (I use the POSITIVE lead of CPU board capacitor C1 next to connector A1J1), touch the other end of the lead to Driver board chip Z13 pin 1 (s1), pin 3 (s2), pin 5 (s4), pin 9 (s8). A game sound should be heard for each sound S1 to S8. These are the input pins of Z13, so this tests the chip Z13 on the driver board.

Step 4: (Does not work for Black Hole.) At the driver board find chip Z3. Game on and in attract mode. Using an alligator test lead with one end connected to ground, touch the other end of the lead to Driver board chip Z3 pin 7 (s16). A game sound should be heard for sound S16. This is the output pin of Z3, so this tests transistor Q10 (MPS-A13) and the connection from the driver board to the sound/speech board. If this sound is missing, replace Q10 and check the driver board A3J2 pin 9 connector (lower right). If OK examine the sound board connector A6J1 pin 2 (s16).

Step 5: At the CPU board find chip Z31. Game on and in attract mode. Using an aligator test lead with one end connected to +5 volts (I use the POSITIVE lead of CPU board capacitor C1 next to connector A1J1), touch the other end of the lead to CPU board chip Z31 pin 6 (s1), pin 3 (s2), pin 11 (s4), pin 8 (s8). A game sound should be heard for each sound S1 to S8. These are the output pins of Z31, so this tests the connection from the CPU board to the driver board. If any sound is missing, check the A1J4 to A3J1 connector.

Step 6: At the CPU board find chip Z31. Game on and in attract mode. Using an aligator test lead with one end connected to +5 volts (I use the POSITIVE lead of CPU board capacitor C1 next to connector A1J1), touch the other end of the lead to CPU board chip Z31 pins 4&5 (s1), pins 1&2 (s2), pins 12&13 (s4), pins 9&10 (s8). A game sound should be heard for each sound S1 to S8. These are the input pins of Z31, so this tests the chip Z31. Note you are touching the aligator test lead to *two* pins of the Z31 chip at the same time. This is an ADD chip, so for the output to trigger both chip legs must go high at the same time.

On my machine, I got very little response from these tests and tried replacing z31 and z13. Next step, I guess would be to repin the connectors. I found that I'm getting the "check sum error 7B3D" after the memory test in test mode so I'm going to try a new game ROM first (I mean, why not take the illogical path only to find out it was simply the connectors )

100$ is a steal! There is a pretty sweet alternative translate based on the artwork from the old film metropolis floating around if you hate that art.

I had one

http://www.flickr.com/photos/56198463@N02/8371751769/

Never succeeded to lit the robot ..in fact the switch of varitarget was ko.
My friends, my wife hate the glass, hate the gameplay so i agree to sell for a low price (350 Euros)

I sold the machine Then i had some regrets...

But my friend Loos gave me definitelly his machine to repair.

In progress..waiting a MPU

Now i love it.

Genesis was my first pin. Yaers later, I still play it. Once you get it tuned up, it's a really great straight up pin. The back glass is sooo chessy, I love it! Best of luck with it.

Nice job on getting the sound working. Your ball problem sounds like your out hole switch isn't working. Put your pin the switch test mode and make sure that switch works. If not check the switch and make sure its adjusted properly. Also check the wires and make sure one didn't break off. Tug on the wires gently and make sure they are solidly connected.

I don't have any System 80 games and don't know the menu system. But your manual should be able to tell you how to get to the test menus. In the test menus there should be a switch test. It will tell you what switches are closed. It will probably just show the switch numbers and you have to look in the manual to see what switch number your out hole is. When a ball goes into the out hole make sure the switch registers as closed in the switch test. If it doesn't then most likely it's not adjusted properly or one of the wires have come loose. Or it could be the switch is working fine and your coil isn't working. You can do the same type of thing and put it in coil test to test the kickout coil. If it doesn't work in the test then it probably has a loose wire. Your coil will be numbered similar to the switch and your manual will show which number is for your kickout coil.

Hopefully someone with a System 80 game can chime in and describe the menu system better. But it should all be in the manual on how to get into it.

Give a little tug on the wires to the sockets and make sure they have a good connection. Inspect the socket and see if it looks corroded or look like its falling apart. Clean the inside of the socket. They make a socket cleaner that looks like a very long pencil eraser that you can pick up at any pinball parts place. Its worth the dollar or two as a lot of sockets just need a quick cleaning. If you don't have one take some fine grit sandpaper and put it on the end of a pensil and twist it around the inside of the socket to clean it. If it still doesn't work check to make sure you are getting voltage to the socket with a MM. If voltage is good then you need to replace the socket. If voltage isn't good then you have a break in the wire somewhere that you will need to trace back.