(Topic ID: 296172)

Gottlieb System 3 Voltage Issue

By RobAquinas

10 months ago

Topic Stats

  • 4 posts
  • 2 Pinsiders participating
  • Latest reply 9 months ago by RobAquinas
  • No one calls this topic a favorite


Linked Games

#1 10 months ago

I have a Gottlieb System 3 Cactus Jack's that plays no music, sound effects, or voices. The sound board and aux sound board both have flashing LEDs. There is no double squelch when the game is powered on. Fuses all test fine. The voltage from the transformer to VR1 on the Auxiliary Power Supply is 16 VAC, a little higher than the 12.6 VAC stated in the manual. The output to the Auxiliary Sound Board is 80 mV instead of 12 V. VR1 gets hotter than a $2 pistol too. The sound test does not work. Pressing the reset switch, SW2, on the sound board does not appear to do anything. I have already replaced VR1 thinking that was causing the problem but nothing changed. I think the only other issue could be one of the 4 diodes on the Auxiliary Power Supply. These traces are extremely delicate, so before I start shotgunning, I wanted to see if anyone could help pinpoint the problem or diode. Thanks!

#2 10 months ago

Step through this section of the Pinwiki: https://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_3#Sound_Problems

Let us know what you find.

1 week later
#3 10 months ago

YeOldPinPlayer thanks for the response. I have read pinwiki extensively. Unfortunately, it gives no guidance on voltage issues. What I have found after replacing VR1 and the 4 diodes on the Auxiliary Power Supply is that it is functioning properly. When I unplug the Sound Board at P2, the reading at the end of both power supply lines to the Auxiliary Sound Board and Sound Board at P2 jumps back to the voltage leaving VR1, +17 VDC. When P2 is plugged into the Sound Board, the reading from VR1 drops to 80 mV and VR1 becomes as hot as molten lava. So, the problem is originating on the Sound Board in the +12 V line, I think. The +12 V line looks relatively simple. It only passes through 2 3403 Op-Amps. I don't know how to test those before just replacing them. Could it be a problem even farther down stream than the Op-Amps that is causing the +17 V to drop to +80 mV and the Voltage Regulator to overheat?

4 weeks later
#4 9 months ago

For anyone else experiencing a similar issue, I replaced the OpAmps at B1 and A5. The voltage returned to normal and the sound works.

Promoted items from the Pinside Marketplace
From: $ 18.00
Apparel - Men
Pinside Shop
$ 15.00
Cabinet - Sound/Speakers
Gweem's Mods
$ 49.99
Cabinet - Toppers
Lighted Pinball Mods
From: $ 3.00
Lighting - Interactive
Professor Pinball


Wanna join the discussion? Please sign in to reply to this topic.

Hey there! Welcome to Pinside!

Donate to Pinside

Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, become a Pinside+ member!