# Houdini captive ball servo troubleshooting and replacement. **Source:** American Pinball **Type:** video **Published:** 2023-09-20 **Duration:** 16m 48s **Beat:** Pinball **URL:** https://www.youtube.com/watch?v=Q9A-8-E37Jw --- ## Analysis American Pinball technical service video providing comprehensive troubleshooting and replacement procedures for the captive ball servo mechanism on Houdini pinball machines. Dave Brennan walks through diagnostic steps using the service menu, connection verification, and detailed disassembly/reassembly instructions. The video emphasizes that servo failures are rare and serves as a reference guide for owners who may encounter issues. ### Key Claims - [HIGH] Servo failures on Houdini's captive ball mechanism are very rare occurrences — _Dave Brennan opens video with explicit statement about rarity of failure_ - [HIGH] The servo interface board is located at the bottom right corner of the playfield — _Technical walkthrough with visual identification during live demonstration_ - [HIGH] The captive ball servo is connected to position one on the servo interface board (position zero is the curtain) — _Explicit labeling shown and explained: 'zero most the rightmost connection is the stage curtain and the one position is the captive ball'_ - [HIGH] The P-ROC board communicates with the servo interface board via a connection at the bottom left of the cabinet — _Physical connection identified and demonstrated in video_ - [HIGH] Replacement captive ball servos are available from americanpinball.com parts and accessories section, pre-calibrated and assembled with the captive ball — _Direct instruction given to customers for procurement_ ### Notable Quotes > "it's a very rare occurrence to have one of these servos fail so rest assured that this video is out there as a reference should you ever have issues in the future" > — **Dave Brennan, American Pinball**, Opening > _Sets context for video purpose and establishes servo reliability_ > "so if you have it's not moving what you can do is you can unplug the zero position switch or servo and plug in the move the captive ball from the one position to the zero position and what we're trying to do is we're looking at eliminating the possibility of the servo interface board as being at fault" > — **Dave Brennan**, Mid-section troubleshooting > _Key diagnostic technique for isolating whether issue is board or servo_ > "if you're your ball now moves then we can point at the servo interface board as being an issue if it doesn't still doesn't move then it is an issue with the servo itself" > — **Dave Brennan**, Troubleshooting logic > _Clear decision tree for determining root cause of failure_ ### Entities | Name | Type | Context | |------|------|---------| | Dave Brennan | person | Owner/Tech Service representative at American Pinball providing official troubleshooting guidance | | American Pinball | company | Pinball manufacturer producing Houdini machine; providing technical support and parts | | Houdini | game | American Pinball pinball machine featuring captive ball servo mechanism in stage | | P-ROC board | product | Control board that communicates with servo interface board in Houdini | | Servo interface board | product | Board located at bottom right of playfield that controls servo motors for curtain and captive ball | ### Topics - **Primary:** Technical support and troubleshooting, Houdini machine maintenance, Servo mechanism replacement - **Secondary:** Parts availability and sourcing, Machine reliability and failure rates ### Sentiment **Neutral** (0) — Educational and professional technical content. No emotional language or controversy. Tone is informative and reassuring about rarity of failures. ### Signals - **[community_signal]** American Pinball providing detailed technical support video and educational content for machine owners, demonstrating ongoing commitment to customer service (confidence: high) — Comprehensive troubleshooting guide with visual walkthrough, parts sourcing information, and direct contact information provided --- ## Transcript owners Dave Jeff Brenner with American pinball tech service today I'm going over troubleshooting and replacement steps for the captive ball Servo on Houdini's stage mechanism let me preface this by saying that it's a very rare occurrence to have one of these servos fail so rest assured that this video is out there as a reference should you ever have issues in the future so without further Ado I'm going to go through the steps to check if your Servo is working or not as well as where it's plugged in and how it communicates with the servo control board as well as the P rack board and then finally how you get at the servo should you ever need to replace it first we're going to take a look at the service menu options to test the servos of the stage so open your coin door hit the black enter button go into tests and then scroll over using the red buttons to the stage and just like it says on the screen use your flipper buttons to cycle through the various tests the first two are going to be the curtain so if you hit the right flipper button it's going to open the curtain if you hit the left button it's going to close the curtain so you can do that back and forth but we're not looking at the curtain today we're looking at the captive ball so as you continue to hit the right flipper button you're going to see the captive ball move up and down in its various positions if you do not see the captive Ball moving at all then there's an issue with the servo on the underside either it's come disconnected or there's an issue with the servo itself so now we're going to lift the play field and take a look at those connections with your play field lifted fully vertical and resting on the backbox you can get a better look at the servo driver board it's located at the bottom right hand corner of the play field let me zoom in here and we'll take a closer look at the connections here you can see that the Servo interface board is uh got a LED on indicating that it has five volts of power this is the power connection with the red and black wires going into it so we know that it has power and the servos are connected at the top left of the board with the white and black wires so it's two black going to the top and one white towards the bottom and you can see the connections at the top of the board they're labeled zero one two three um going from right to left and the zero most the rightmost connection is the stage curtain in the one position is the captive ball so in this case we're talking about the captive ball Servo so if you have it's not moving what you can do is you can unplug the zero position switch or servo and plug in the move the captive ball from the one position to the zero position and what we're trying to do is we're looking at eliminating the possibility of the servo interface board as being at fault so now you will go through the same process of running through the tests and you want to see if the servo for the captive ball now moves with the functions of the curtain opening and closing so go back to this in this test menu and move the curtain back and forth if you're your ball now moves then we can point at the servo interface board as being an issue if it doesn't still doesn't move then it is an issue with the servo itself so now one more thing I want to show as a connection is the communication between the P Rock board and the serval interface board so this needs to be securely connected and this is connected down at the bottom left hand corner of your cabinet and I'm going to zoom in on that connection so you can see what that looks like so it's right here is that connection so but this if this is connected then both your curtain and your captive ball should be working just fine for communication if you have now verified that your Servo for the captive ball isn't working you'll need a replacement so what you'll need to do is go to americanpinball.com go do parts and accessories there are two options for the captive ball and curtain make sure you select the captive ball when you're buying this and it will come with the captive ball already attached to the calibrated servo now for the task of getting at the servo itself the biggest part is removing the subway here and you'll see that there are some u-shaped brackets that have some optos attached and really the easiest way for these since these are riveted to the subway the easiest way to get these off is there's a metal clip retaining bracket that slides over the opto and you can just pull the opto off just Clips in there you can do this for both sides so if you want to mark them you know or number them with a piece of tape or something like that so you know where they go but once you put them back it doesn't really matter if you put them top or bottom they'll still work the same so you just slide these brackets off set them off to the side they're all the same and then you can pop the Servo or the optos out of the bracket just let those hang so do that for all of them now for this part um there's a whole metal bracket here for these three optos of the right lock and you have the lock coil attached to it so you can disconnect the lock coil and then you'll need to take a quarter inch nut driver and unscrew the metal bracket now that that's out of the way the subway can be unscrewed from the play field and you'll see that there's several quarter inch nut driver screws wood screws that need to be removed in order to get the subway out you'll also need to disconnect the servo plug for the captive ball so you can get that Servo out so I'll unscrew all these screws [Music] foreign [Music] now with the subway out of the way you'll take a 11 32 driver and take off this metal bracket that's also in the way of the captive ball servo to unbolt the servo motor from the stage mechanism you'll need to hold the keep nut or the nylon lock nut with a open-ended wrench and use a stubby screwdriver to loosen the screws finally got the thing out so now that you have this out you can take your new Servo and follow the reverse process put it back through the shaft back through the washer here and button everything back up let's verify that the servo is working how it's supposed to take the captive ball plug and plug it into position one on the servo board and you should start to see it move I'll go into the coindoor service menu go into tests go over to stage and then use your flipper buttons as we did before and move through the captive ball positions and verify that the servo is now working now from here you can bolt everything back up follow the reverse order put your Subway back in and you should be off and going if you have any questions along the way on anything that I didn't cover in this video please reach out to me at the email or phone number listed at the bottom of the screen thanks for watching _(Acquisition: youtube_auto_sub, Enrichment: v3)_ --- *Exported from Journalist Tool on 2026-04-13 | Item ID: 508a05f9-0af4-47e3-a95b-d4bbec5cbdf2*