Orion 7880 instruction manual Encoder Test

with, both of these numbers will be +000.0. The first two sets of numbers on the upper and lower lines of the LCD screen are meaningless for the purposes of this test.

If you move the telescope counter-clockwise in azimuth, the number in the lower right should increase, while if you move clockwise in azimuth, the number will decrease. If you rotate the telescope exactly 360˚ in azimuth, the readout should return to the original +000.0 reading.

If you move the telescope upwards in altitude, the number in the upper right should increase, while if you move downwards in altitude, the number will decrease. If the tele- scope tube was perfectly horizontal when you enabled the hidden functions of the con- troller, then the altitude will read +090.0 when the telescope is pointed precisely vertical.

If one, or both, of the encoders are not behaving properly when performing this diag- nostic test, there may be a problem with the assembly of the system, or a problem with one of the encoder boards or discs. Also, be sure to check that all cable connections are secure.

Encoder Test

The encoder test is another diagnostic test that gives information about the performance of the encoders themselves. Select “ENCODER TEST” from the list of hidden functions using the arrow buttons and press Enter.

The LCD screen will now display two lines of data. The top line of data corresponds to the altitude encoder, while the lower line of data corresponds to the azimuth encoder. The first two digits on each line denote the amplitude of the signal from one of the magnetic sensors on the encoder board, the second two digits represent the amplitude from the other sensor on the encoder board. The numbers are in hexadecimal (base 16) digits. Therefore “A” in hexadecimal represents “11” in decimal, “B” represents “12” in decimal, “C” represents “13,” “D” represents “14,” “E” represents “15,” and “F” represents “16.” Whe moving the telescope in altitude or azimuth, you will note that each of the digit pairs rises

and falls. None of the digit pairs should ever go above “F3.” If they do, then the encoder disk is too close to the sensors on the encoder board. This will generally not happen in altitude, but can happen in azimuth.

If you notice that the first or second digit pair on the second line of the display goes above “F3,” then try loosening the lock nut on the azimuth nut of the base by about 1/16 turn. If this does not work, you will need to disassemble the azimuth encoder (azimuth encoder disk, brass bushing, and azimuth encoder board) and reassemble it carefully according to the instructions that came with the IntelliScope Dobsonian telescope itself.

If you notice that the two digit pairs on the first line are going above “F3,” then there is a problem with your altitude encoder assembly. More than likely, the altitude encoder disk is bent.

The three-digit number displayed after the digit pairs on each line is the “radius” for each encoder. This number should not go above about 125 or below about 30. If it does, per- formance may be compromised for the corresponding encoder. If the number goes above 125, then the encoder disk and magnet may be too close to each other. If the number goes below 30, then the encoder disk and magnet may be too far away from each other. Also, if the radius varies by more than 30 counts in a cycle, encoder performance may not be optimal, and you should contact Orion’s Customer Service Department.

The four-digit number at the end of each line is the raw encoder “ticks” in hexadecimal numbers. This information will generally not be useful for diagnostic testing of the encoders.

22