Technical Innovations

Manufacturer of Home-Dome and Pro-Dome Observatories

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Trouble Shooting

Below are a number of Trouble Shooting issues which come up on a regular basis.


  1. The dome sticks at points when it is rotated
  2. The ED motors will not turn the dome.
  3. The shutter has problems opening and closing
  4. The ES cable is tangled on the windlass
  5. The ES cable is frayed at one or more places
  6. The shutter will not open from outside with the PS switch
  7. The shutter will not open from outside with the DDW key
  8. The dome leaks when it rains
  9. There is a hole in the dome where drilled incorrectly
  10. There is a scratch or rub mark on the dome finish
  11. The DDW board is "dead"
  12. DDW will not connect with the computer
  13. DDW will not read TheSky6 file for slaving
  14. The DDW hand control will not operate the dome
  15. Slaving the dome with DDW is accurate only in certain areas of the sky
  16. Will more Troubleshooting Topics be added?




 Frequently Asked Questions

The dome sticks at points when it is rotated

The most critical aspect of Home-Dome/Pro-Dome construction is making sure that when the final bolting down takes place the base ring is "in round" (within the stated tolerances) and that the circumferences of both the base ring and DSR are correct (within stated tolerances). An out of round dome is the most common cause of sticking points during rotation. The other common issues are side rollers over-tightened (and will not freely turn), carriage bolts used where flat head bolts are called for, objects between the DSR and base ring reverse flange (dropped bolts for example), and wheels that are positioned such that they the rub against the cutout when rotated. This topic deals with hand rotation. If you problems with motors rotating the dome (when it rotates freely by hand), that is discussed in topic #2. 

A linked document "Rotation Diagnosis"  goes into greater detail  


The ED motors will not turn the dome

A dome that rotates freely by hand should not have an issue with properly installed ED motors turning it. The first thing you should do is visually check each motor to make sure that a belt is not broken, a drive wheel is not loose and binding, and that the motor assembly is properly installed to allow even contact with the bottom side of the DSR. A frequent problem is that the tension of the motor drive wheels up against the DSR is not high enough. This tension is held by the pivot arm spring so try moving the chain a link or two closer to the attachment hook. Also check the wiring between the motors. Since DC motors are polarity driven you could wire such that one turns CW at the same time another is turning CCW. The ED instructions note that you should check the motor operation when first wiring and before the motors are pushed up into place against the DSR.


The shutter has problems opening and closing

Shutter or latch engaging problems are nearly always caused by the edge of one item catching the edge of another.  To solve, simply examine closely the location of each shutter as the problem occurs, and identify the offending points. Fix by beveling, sanding or adjusting the interfering edge properly

Shutter or latch dis-engage problems are more complex and explained in the below document.    

A linked document "Shutter Diagnosis" goes into greater detail


The ES cable is tangled on the windlass

During the installation of the ES system, the "split bolts" remain in place until the open and close cables are strung and positioned with the proper amount of tension. The springs at the termination points of each side maintains this tension during the open and close cycles. If the tension is released on one side (or both) the result will that the cable will come out of the grooves and become tangled. The only option is to go to the windlass assembly and feed the cable by hand back into the grooves. This will require using one hand to keep some tension on the wire outside the travel nut, while using the other to feed and push the cable in place.    


The ES cable is frayed at one or more places

Cable frays are nearly always caused by the cable "catching" on a sharp edge. The cable is stainless steel boat/aircraft cable and is very strong, even if one or two (of the sixteen) strands are broken and exposed. The first step is to trace the cable path and feel for any edges, obstructions or loose fittings (which could pinch the cable as it travels).Fix any of these conditions detected, then test running the cable. If the location of the fray passes through the "travel nut" and onto the windlass shaft, the cable will need to be replaced. If the location is outside the windlass assembly and does not catch on any pulleys it most likely will be ok. Just check from time to time to make sure it is not getting worse. 


The shutter will not open from the outside with the PS switch

The PD6, 10 and 15 are normally entered by opening the shutter from the outside, opening the door, then walking unimpeded into the dome. When DDW is not installed, the PS (power supply) is normally mounted facing out, with holes drilled in the wall section for the key lock and shutter toggle switch. If the switch will not open the shutter, the first to check is that the key lock is turned on and there is 110 or 220v AC power going to the PS. The red led will give an indication that the unit is receiving power. Check the AC power circuit breakers, and if possible do a test on the same circuit (possibly an exterior light or power outlet). If power is definitely going to the PS, then it is not making it to the ES motor itself. The point at which this "break" can occur is the sliding contact coils and plates. As noted in the instructions, these need to be cleaned every month or two with the plastic scrubby that was provided (or can be purchased at most grocery stores). The buildup of dust and "grime" can eventually prevent power transfer. The second condition would be where the coils are right at the edge of the plates but not making good contact (the dome stopped not precisely at "Home" or high winds to the side of the dome caused a small shift). In both of these cases, try rocking the dome back and forth a couple of inches by pushing on the dome shutter flanges and shutter edges. In many cases this will re-establish contact between the coils and plates.   

In the instructions, it is strongly suggested that you wire an "emergency entry" circuit. This is done by running a wire pair directly from the shutter motor terminals to two bolts to the outside (the bolts securing the rear shutter panel are a good choice). If you find yourself in a no power situation, or the condition described above, 12v DC (car/boat battery works great) can be applied directly to these bolts to open the shutter enough to get inside and diagnose and fix the problem. Make sure you have tested positive and negative before hand so that the power application move the motor in the open direction and not close.

The last resort for entry into the dome when neither of the above work or are available is a "forced entry". The earlier design ES systems have the open cable terminate at a bolt in the lower right hand side (facing the dome) shutter opening dome flange. Clamp vice grips on the cable below the bolt (to be able to hold tension on the cable by hand) and then loosen the bolt and release the cable. With the cable tension held, (this is easiest with two people), force the shutter up - while "feeding" a corresponding length of cable - until the shutter clears the top of the door. At this point, place the cable back into the bolt/nuts and tighten. The door can now be opened and entry by ducking under the front shutter to "repair" the problem. With the newer ES system (tension springs on both cable ends), one person will force the shutter up high enough to open the door (that person must continue to hold the shutter as excessive force has been placed upon the spring) while a second person opens the door enters then closes the door. The shutter can then be allowed to return to the close position, past the top of the door.     


The shutter will not open from the outside with the DDW switch

This situation is very similar to the condition above (PS Key and Switch). In the case of DDW, only a key entry switch goes through the wall to the outside. The power supply is left in an "on" state with power constantly to the DDW board. Much like the previous issue, the first step is to verify AC power to the observatory. If there is power, and the DDW is not responding, go through the exact steps described immediately above.   


The leaks when it rains

The Technical Innovations domes are designed to be VERY weather tight - not only to protect your equipment but in cases of domes mounted on structures, protect the building beneath. A water leak is a direct result of improper installation, failure to seal all the exterior seams with the silicone provided, or bolts not tightened properly. The first step is to be inside the dome when it rains to witness the exact point(s) of entry. This will allow the identification of steps to take to solve the issue - most generally sealing with the silicone places not adequately covered at the time of installation. If there is a leak around a bolt which cannot be tightened further, go ahead and cover the bolt head outside with the silicone. 


There is a hole in the dome where drilled incorrectly

We have tried to make he instructions as clear as possible, but it is not unusual for a hole to be drilled in the wrong place. This results in not only an unsightly hole, but an opening for weather entry. The quickest, and in many cases the least noticeable, is to just "fill" the hole with a short bolt and nut/washer inside. In many cases, it will not even seem out of place. If that does not seem to be a good option, the hole can be filled and finished. A great product for doing this is the fiberglass based automotive filler called "Bondo", which can be purchased at nearly all automotive stores. Once the hole has been filled (Bondo has very good instructions), the surface can be sanded smooth and matching gel-coat (call us) can be touch/painted on the surface.  


There is a scratch or rub mark on the dome finish

The outside of the dome (inside also for that matter) is a finish of a material called "gel-coat". It is a very hard and durable material, but can still get rub marks and scratches. The first attempt at removing these should be with a cloth and acetone. The acetone will not harm the gel-coat, but is very effective at removing other substances marking the surface. Scratches can often be removed with an automotive "polishing compound" (not "rubbing compound - which is too abrasive), and a power buffer.     


The DDW board is "dead"

The DDW board is wired directly to the "Unswitched" (hot) terminals in the PS power supply. This means that anytime the PS is on (key switch on front), the DDW will also be on. When checking if the DDW is powered up, the box should be opened and the main board scanned to see if the "Heartbeat" light is on (a red led which flashes on and off about once per second - a heartbeat rate). If this led is not lighting, check the two circuit breakers - the push button breaker on top of the PS box and the small slide switch type in the lower left hand corner of the DDW circuit board. If re-setting both of these does not start the heartbeat light you will need to test the power terminals with a voltmeter to verify power (normally 12-14 volts) is coming into the system. If there is power at the +12 and GND screw terminals and the board does not "light up", there is a problem and it will need to be pulled and sent to Technical Innovations for repair.     


DDW will not connect with the computer

The computer connection to DDW (6 pin RJ11 modular jack) is an RS232 serial (9 pin) connection with the computer. As such an RJ11/B9 adapter (provided with your DDW system and marked "PC1") is needed at the serial connection point. If no serial connection is available, DDW works with all USB t serial adapters and hubs. There are two small green led lamps just above the "PC" modular jack on the DDW circuit board. The top one should light anytime power is on to DDW. This indicates the internal RS232 communication is established. The led closest to the jack will light once a physical connection is made with the computer. This does no indicate that communication has been established. Once cables are properly attached, the main communication problem tends to be assignment and linking to an available COM Port on the computer. In Windows "Device Manager" you should be able to identify all COM assigned ports figure out which is physically attached to the DDW cable. Once you know this COM id number, go back into the DDW software configuration settings and "assign" this COM number to the DDW software.   


DDW will not read TheSky6 file for slaving

Nearly all problems with DDW reading the output file from TheSky6 deals with setup issues. First, the software must be the "Professional Edition" (which incorporates export files). Once TheSky6 is installed you must setup and "start" the export data file (a text file called "Telescope Position File.txt")  This is accomplished by opening the program, selecting the drop down option "Telescope" and selecting the option "Server Settings". Selecting this option will open selection box of the same name. Near the bottom of the box is an option titled "Log current telescope position to:" with a preceding check box. Make sure that a check on entered in this box. Go back to the main sky screen and send any slew command to the telescope. This will create the file, which will then be automatically updated by the software. On the DDW side, o into "Configure" and select "Telescope Slaving" in the upper left. From the "Setup Telescope Slaving" selection screen choose (by clicking the button) the "Use TheSky Level IV Telescope Log". Make sure that the proper path to the Telescope Position File is entered (this is normally the path below:    C:\ProgramFiles\SoftwareBisque\TheSky6\data\user\TelescopePosition.txt     


The DDW hand control will not operate the dome

When the dome does not respond to commands from the DDW Hand Control unit proceed with the following steps. First, open the DDW box and make sure that the DDW is on and that the "Heartbeat" light is flashing on and off. Make sure that the local/off/remote switch is set to either local of remote. Check the hand controller to see that the red power light is on. Try swapping the gray communications cable with another (all TI gray cables are wired straight through and are interchangeable. If still not responding check with Technical Innovations as repair services may be required. 


Slaving the dome with DDW is accurate only in certain areas of the sky

There are several elements making up successful dome slaving. First and foremost is the accurate input into DDW of observatory location and time values. DDW compensates for less than optimal telescope location within the dome through a series of offsets. The DDW instruction manual goes into detailed descriptions of making these measurements and entry into the software configuration. Once these elements are correctly set the dome slaving will be very accurate.  


Will more Troubleshooting Topics be added?

Yes. This section of the web site is intended to be a dynamically updated area which will continue to expand as different topics are encountered at a frequency indicating they would represent a useful addition to the page.