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Novice Challenge

Most Frustrating... Faulty LCD in handset

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On another thread a member had just replaced his EQ6 controller board and handset after some incident that rendered both faulty.  I dropped him a PM to see if he had the old faulty parts and if he was willing to send them to me so I could do an autopsy on them.  He agreed, and I bunged him a few quid via Paypal to cover cost of postage.

They arrived mid week and I have just had time this evening to take a look.  I was hoping that the issue with the handset was going to be a blown component, like a diode or voltage regulator which when replaced brought the thing back from the dead, but sadly not the case.  Opening up the handset the board looked in great condition with no signs of burning or exploded parts.  I tested all the diodes and one displayed a short with around 15 ohms.  Thinking this was going to be the cause I removed it and tested it out of circuit, which showed the diode to be fine, with the short still existing on the board.  So I decided to plug power lead in and see if anything got hot.  At 12v it drew a few milliamps, everything remained cold, but the LCD was just a red screen.  The handset did beep after a few seconds suggesting it had issues finding the mount, so I wanted to see if the issue was just the screen or if the flash memory or the PIC processor was not running.  I connected my old skywatcher serial cable via a true RS232 to USB convertor, loaded up the firmware updater software and holding down the 8 and 0 buttons whilst plugging the power in I got a single beep to signify it was in the mode ready to communicate with the PC.

Having selected the correct com port I was able to read back the firmware version.


Excellent, so the processor is running fine... but what about the flash memory....  I downloaded the latest V3 firmware from the SK website and having selected the file hit the update button


And it was checked after the upload which confirmed the flash memory was fine


So it looks like its the old chestnut of a defective LCD screen.  I did occasionally see faint hieroglyphics but very faint and random, even after cleaning and reseating the ribbon cable.  The problem is that these 16 x 2 COG parallel LCDs are proprietary, and impossible to get a replacement.  So regretfully whilst we've got a result for the autopsy, the diagnosis means I can't bring this one back from the dead.

I'm hoping the issue with the mounts control board is blown serial ports on the two 16F886's so replacing those with two new reprogrammed ones will bring that back to life... we'll see



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