(Topic ID: 298255)

Gottlieb System 1 4v and 8v Low / Dim Displays

By Knxwledge

77 days ago


Topic Heartbeat

Topic Stats

  • 17 posts
  • 3 Pinsiders participating
  • Latest reply 75 days ago by Knxwledge
  • No one calls this topic a favorite

You

Linked Games

Topic Gallery

View topic image gallery

20210807_204622.jpg
20210807_204630.jpg

You're currently viewing posts by Pinsider G-P-E.
Click here to go back to viewing the entire thread.

#4 76 days ago

Just buy a new board!

#6 76 days ago

HECK YEAH!!!
Oh, wait, I no longer sell those boards... um... nevermind.

Seriously, though -- those 3A rectifiers could cause your issue but you said the +5V was working fine. That says the 3A rectifiers were fine. Bad solder joints can do amazing things, though.

Do make sure you are measuring the +4 and +8V while using the digital ground and not the high voltage ground.

#8 76 days ago

Yep, there's your problem.
Pin 5 of J3 is your high voltage ground, pins 4 & 5 of J2 are your low voltage (digital) ground.
Use the negative end of your 3300uF cap to measure this voltage.

Nobody knows why Gottlieb isolated the two grounds. Using the wrong ground for your meter's reference is known to cause voltage to measure incorrectly even though they are working.

#12 76 days ago

That 4 and 8V using the 'other' ground catches a lot of people off guard. All the others look to have been measured properly. I'm surprised none of the FB guys mentioned this.

#14 76 days ago

If you look at the schematics - you will see there are two separate grounds on that board.
Nothing will happen if you tie the two grounds together. In fact, most (if not all) of the replacement boards have the two grounds purposely tied together to avoid this type of problem.

You're currently viewing posts by Pinsider G-P-E.
Click here to go back to viewing the entire thread.

Hey there! Got a moment?

Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside