Theatre of magic

 

Star Trek left the building to day and I got an AC/DC and an Attack from Mars instead. The Teathre of Magic looks a bit empty. I disassembled the upper side of the playfield until I came to the pop bumpers and it’s so much easier to work with those when the playfield is out of the cabinet. Having it outside also gives easier access to all other mechanisms at the lower side for disassembly and cleaning.

 

These bumpers have taken some serious beating and will be rebuilt with new skirts and bodies, the right one also need a new lamp socket. It’s quite common that the leads break on these but repairing it with wires as it has been done here isn’t the best solution.

 

This bumper have been taken apart and then been reassembled the wrong way round, the metal yoke should be at the other side of the fiber yoke, it did also miss the rod washers. Another of the bumpers had a broken metal yoke, the three bumpers really need an overhaul.

 

 

This is another reason for taking out the playfield, the front left corner of the cabinet has cracked. I think it’s just the leg and leg bracket that keeps it together. One of the side rails are also lose and I need to remove of the back box to reattach it. It will be easier to take care of the broken corner when the cabinet is all naked so it will have to wait for a while.

 

This is a bit odd. Someone has cut the cables to the coin switches and attached another cable that goes through a small PCB which is then wired in to the driver board in the top box. I haven’t got a clue of why this has been done, I will reconnect the switches as they should be and get it to work the proper way.

Theatre of magic

The main reason for this game to be here is a problem with the trap door. It’s lifted but then falls back again before the ball is ejected. The trap door is controlled by a flipper coil with a high power winding to lift it and a low power winding to keep it open. Since it is a flipper coil I first suspected it was driven by the fliptronic board and the problem should be found by the hold transistor, but that was way wrong. It is instead controlled by two transistors at the power driver board. I checked the voltage at the collector at the holding transistor and it was nothing at all there. I should have been able to measure +70v at the collector as long as the coil isn’t energized. Since there was no voltage at all at the transistor I went down under the playfield and measured at the coil and there was no voltage at the hold winding tab either. The cause turned out to be a bad soldering where the coil wire is connected to the soldering tab. I removed the whole trap door unit from the playfield to make a proper repair at the work bench. And since I had it out of the playfield I took it apart to clean the parts.

 

 

While working with it I found a couple of other problems. Two screws were missing at the micro switches where the balls line up, a wire was almost loose at the VUK micro switch and somebody had been oiling one of the plungers. Never oil anything in a pinball unless the manual clearly state that it should be oiled. When the oil is fresh it might look like it did the trick, but it will soon gum up and cause a lot of problems.

 

  

The trap door unit is now refurbished and ready to go back in to the playfield. But it will have to wait, there is a lot of other bits and pieces at the playfield I have to go through first. 

 

Star trek, the next generation

The guns are now back at the playfield, with the new wire looms. As I wrote earlier I made some changes to the LED’s  in the guns, but I had to give it up. The LED’s gave the red light dome an amber color which looked all wrong. But the biggest problem was the ghosting, so I used 555’s instead and now it lights with the right color and no ghosting.

 

I did also use LED’s as replacement for the four colored lamps in the top left corner. The light is fine but there are some ghosting problems also here. The green led in the picture is actually turned off but it is still glowing. I haven’t yet decided what to do about it. I could keep the LED’s, replace them with colored 555’s or 555’s with colored rubbers.

 

The VUK’s was disassembled and cleaned before reattached to the playfield. I checked the soldering of all optos but I need to figure out a way to test each of them once the units are in the play field. 

Cleaning the underside ball guide was quite a project. It wasn’t the dirtiest unit I have seen, but close. It was a couple of hour’s job and it came out quite nice in the end. The plastic ball guide has a repair by the Neutral zone entry. It’s nicely done by metal and there is no reason to do anything with it, but I think the cause for the damage are that people have lifted the playfield with the balls still inside causing them to fall back from the VUK’s and slam in to the end of the plastic ball guide.

 

The left stand-up target by the Beta quadrant ramp had a broken rivet. It was replaced by a screw and nut, an easy fix.

 

The trigger in the gun handle felt a bit odd and I took it apart to see what’s wrong with it. It was the return spring that was broken. I replaced it with a new spring and the trigger was OK. 

The left flipper button didn’t work in the video mode and the cause was a broken opto. I could see that the LED was lighting by using a camera and watching it in the display, but there was no output signal from it at all. I must say that being able to turn to the left gave the vide mode a new dimension J

And the most important fix of them all, moving the batteries to an external holder. I removed the old holder completely to make sure nobody makes the mistake to insert batteries in it. Leaking batteries are the single most common reason for a CPU board to be scrapped.

Star trek, the next generation

The upper playfield is now almost ready, it’s just the canons and the apron that’s missing. The apron has to wait until I have had the ball trough out of the playfield for cleaning and the canons are still a work in progress at the workbench.

 

Everything that can be taken apart have been taken apart for cleaning and polishing and all metal parts and guides have either been polished or cleaned by the glass bead blaster.

 

 

 

 

 

This LED did annoy me quite a lot while playing the game before disassembly. It shone between the targets and right in the face. I’ve shaded it by a piece of shrink tubing. I’ll see what it looks like when playing later on, maybe I need to make another kind of light shield for the LED.

I have inspected the soldering at the different parts and found this at the backside of a lamp board. It is not shorted yet but it is close and the cable strand is now removed.

The canons are still at the work bench. One canon had a cable replaced and I have seen balls loaded but not detected a couple of times which can be due to problems with other cables in the cable loom. I have made new cable looms for both canons to make sure broken wires isn’t causing problems.

The canon housings is quite worn. One of the red light filters was loose and there are some cracks, but it’s not bad enough for having them replaced. Since one of the light filters was loose I thought I should upgrade them to have a red light domes instead, I think it looks much better.

There was LED’s inside the canons but even though it is wide angle LED’s they do not spread the light enough to light up through the filter. I took the LED apart and remounted it in 90 degrees to get it to shine the right way.

What’s left to do is cleaning, polishing, reassembly and connecting the new wire looms, then they will be back at the playfield again.