(Topic ID: 285075)

Target Alpha Fixing Itself?

By BadgeringBadger

2 years ago

Topic Stats

  • 4 posts
  • 3 Pinsiders participating
  • Latest reply 2 years ago by srcdube
  • Topic is favorited by 2 Pinsiders


Linked Games

Topic Gallery

View topic image gallery

76EF1485-DA83-4B0D-A1E3-FD2D43A6A074 (resized).jpeg
G Relay Circuit (resized).png

#1 2 years ago

While the game sat for about two months unplayed and unplugged, I've probably put 40+ games on it in the past week, without any major issues outside of one - Rarely (5 games out of the 40+ I've played this week) when draining the ball down the middle, the machine would get into a weird state where the flippers would still work, but the pop bumpers would not pop, and nothing would score. It's like the machine knew the ball drained, but didn't want to start the end of ball bonus count. Every time I'd press the new game button it would go through the reset button, and start a new game like nothing happened.

Well, every time but one, as two days ago I drained the ball down the center, and nothing happened. I pressed the start button, and nothing. I powered off the machine, let it sit for a few minutes before I started it back up again, and had a dark playfield (backglass lights still lit up, tilt light illuminated, and pressing the button to start a new game didn't do anything. I powered it off, looked around inside for anything obvious, started it back up again, same result. I shut it off and ordered a multimeter.

This afternoon, I figured I'd start it up and have one more look at it. It was still stuck in 'tilt mode', but I pressed the start button, and a new game started. Well, almost a new game. It went through the full start sequence (reset the score to 0), but started me on ball 2. I played another five games (and a 4 player game) just to make sure all was good, and outside of one drained ball not starting the end of ball stuff, everything was flawless.

So, two questions:

Any idea what was stopping me from starting a new game?

What should I be doing to try to solve the rare occurrence of a drained ball not starting the end of ball sequence? I've started recording my games to see if there's a common scenario (I almost suspect it happens when I hit a drop target and drain down the middle), but I haven't figured it out yet.


Name of game, manufacturer and year: Target Alpha / Gottlieb / 1976

Did it ever work in your Possession?: Yes, owned since May

Where did the game come from?: Arcade, shopped before delivery

Have needed MODS been done?: Not aware of any. None needed?

Are any aftermarket boards installed?: No

What was the last service you performed?: None while in my posession

Battery Corrosion: No battery?

LED or Incandescent lighting?: Incandescnent

Blown fuses: Visual check appears good

Smell: Old wood smell

Obvious Past Work Performed: Shopped before delivery. Game set to free play by an extra wire somewhere, but I forget exactly how it was done.

Do you have a Volt Meter?: No

Can you solder?: It's been a while, probably can

Location: Twin Cities, MN

#2 2 years ago

I see that you bought the game in May, when it was summer. These sorts of things can happen to EMs in northern climates when winter rolls around. The humidity plummets, which makes the switch stacks contract. This can affect the reliability of their make/break action. This is why it is important to make sure all switch stacks are screwed down tightly before making any adjustments. If they are not tight enough, the adjustments will go out of alignment when the climate shifts.

When the ball drains and no bonus happens, it sounds like your “Bonus Score Control Relay” might not be energizing. It is closely tied in with the circuit for the O relay, which is what sends the ball into the shooter lane. It sounds like this is happening when you successfully start a new game, so that rules out some of the contacts in their shared circuit as culprits in this problem.

If I had to venture a guess, the make/break switch on the DX relay and the make/break switch on the 15th position for the bonus unit might be the problem. You can see these two switches annotated in red below. The yellow line is the complete circuit for how the G relay initially gets energized.

G Relay Circuit (resized).pngG Relay Circuit (resized).png
#3 2 years ago

Thanks for the info. Once my multimeter arrives I'll take a look at that area and see what I can find

#4 2 years ago
Quoted from BadgeringBadger:

Thanks for the info. Once my multimeter arrives I'll take a look at that area and see what I can find

In a prior post, someone recommended to me a "lightbulb tester" to debug stuff on EM's... not a tester for lightbulbs, but a tester made of lightbulbs. Rig up something that can handle about 30v, and it's a great tool for tracking down problems, especially intermittent ones.

I took an old string of dollar store Christmas mini lights where the bulbs are in series, and cut off the first three sockets (so I'd have a nice long cord to connect them in the pin). Shrink tubed the three bulb sockets together, and replaced the bulbs in the sockets with three 12V bulbs (that was the largest I could find off the shelf) so that they could handle about 25V-30V. Cut off the plug and put on alligator clips. Clip one end to a ground (one is right beside the game counter at the front), and clip the other to the signal your tracing.

Great tool for tracking down the kind of stuff you're looking it, as it responds quicker to pulses than a DVM does. Added bonus I found out when I started using it; not only does it show you if a signal is getting through or not; if it's getting through but is a shitty signal, then the lightbulbs are dimmer, so switch needs to be cleaned. Strong bright light pulse on one side of a switch... weak dim light pulse on the other side of the switch.

Recently debugged a problem where coin stepper relay seemed to be firing, but wasn't advancing the stepper, lightbulbs showed a weak dim pulse, but on the other side of the motor switch driving it, it was bright and strong. Cleaned that switch and problem resolved. Also had an intermittent problem with the bonus stepper very occasionally not advancing correctly, then rectumfying itself; but it has a lot of switches in it's path. I connected the lightbulb tester to one signal, and put the lightbulbs on top of the playfield on the right side over the shooter lane, and put it all back together.... when the intermittent problem came up again, I could see on the lightbulbs if something wonky was going on with the signal I was monitoring... I'd just keep moving it along the path until I finally found the one that was flakey.

I'm currently trying to debug a problem where on one score wheel, I'm occasionally getting the 10,000's number rolling over two numbers instead of one. When I connected my lightbulb tester to the relay, I can see that whenever it jumps two numbers instead of one, I'm getting some kind of quick double flicker on the lightbulb... the switch from 1000's 9th position is either flakey, or something else is occasionally giving me two quick pulses instead of one on my 10,000 relay. I'd never find something that subtle with a DVM.

Best and cheapest tool I have in my EM arsenal now!

76EF1485-DA83-4B0D-A1E3-FD2D43A6A074 (resized).jpeg76EF1485-DA83-4B0D-A1E3-FD2D43A6A074 (resized).jpeg
Promoted items from the Pinside Marketplace
From: $ 12.99
Cabinet - Other
The Pinball Scientist
From: $ 33.00
Gameroom - Decorations
Rocket City Pinball
From: $ 1.00
Playfield - Other
Rocket City Pinball
1,100 (Firm)
Machine - For Sale
Springfield, MA
From: $ 4.00
Cabinet - Other
Space Coast Pinball
From: $ 4.99
Cabinet - Decals
The Pinball Scientist
Great pinball charity
Pinball Edu


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, subscribe to Pinside+!

This page was printed from https://pinside.com/pinball/forum/topic/target-alpha-fixing-itself and we tried optimising it for printing. Some page elements may have been deliberately hidden.

Scan the QR code on the left to jump to the URL this document was printed from.