Gottlieb System 1 Display Issue

[nhm]

Ok, so I sold my Pinball Pool last week. After some initial setup issues, everything was running great. The following day, the new owner says that the machine played for about 2 hours, and then the displays went out. I came over and found that the fuse going into the transformer was blown. I replaced the fuse, but now there appears to be very low power going to displays. They are extremely dim and flicker. Displays 1-3 appear to score and work correctly. #4 I can't tell. It may be too dim to see. Same for the credit display. I'm inexperienced thus far at pinball repair, so I went home to research. Here's what I understand may be the cause(s):

Bad transformer
High voltage pot needs adjustment
Filter Capacitor at C6 needs to be replaced
Bad display sucking to much voltage

Here's my plan that I would like you more seasoned pro's to review:
1. Check voltage coming out of the transformer
2. Try adjusting the voltage pot. I don't think this is the issue though, because the diplays aren't just dim, they also flicker.
3. Test the displays by powering the machine up with only one display connected. Repeat for all displays.
4. If everything else checks out, replace the filter capacitor. I could only find one internet source that perfectly described this problem, and it said that the cause was a dry filter capacitor.

If I am missing something please let me know. If this sounds good, please let me know so that I feel more confident that I'm not going to ruin something. Also, where is the best place locally to buy pinball fuses and capacitors? I need some .25 slow blow fuses and a 200mfd 150v capacitor.

Thanks everybody!

[eric]

You have the right idea. Your transformer is probably fine. Try disconnecting J2 and J3 from the power supply and check the display voltages at the header pins of J3:

A2 J3 pin 1 = 60V
A2 J3 pin 3 = 42V
A2 J3 pin 5 = Ground
A2 J3 pin 7 = 4V
A2 J3 pin 8 = 8V

If these look good, reconnect J2 and J3 and disconnect all displays but 1. If the display comes up, reconnect them one at a time until you find the bad one.

***All connecting and disconnecting of connectors MUST be done with the power off!***

[eric]

Great Plains Electronics is a great source for pinball related components. Radio Shack is generally good for fuses (though not very much else).

[oneandasixtenth]

you can get the caps at the rad shack too .... 1/4 amp slow blow fuses are hard to find there but you can get them at the coin op out there on 99w

[revtest]

Sorry just catching up on my thread reading hows this going for you? I see you are in good hands thanks Eric for fielding this.

[eric]

Any updates?

[nhm]

Well....I tested the displays and they are fine. However, my dumbass inadvertently touched something and I think I fried a chip on the board. The machine now will start scoring and not stop until the machine is turned off. At this point it is well beyond my level of repair.

If anybody wants it, I'd let it go for $200. It probably needs a RAM chip replaced as well as the filter capacitor. If you know what your're doing, it's probably pretty cheap to fix if you do it yourself. If you're interested, shoot me a PM. Feel free to drop by if you want to check it out first. It is still in excellent physical condition.

[eric]

Awesome price for how good of shape that thing is in.

[nhm]

If you know anybody who wants this machine, let me know. Should be easy to fix for the right person.