Originally Posted by lenkrauss
Have an Autohelm ST4000+ that works but has dim LCD display with burn mark.
Any idea where I might check for a used replacement display head? Or for someone to repair mine? Also, I might be able to locate a used display with a good LCD that could be swapped for mine. Any idea what this swap labor might cost and who or what kind of tech could do it? Can anyone comment on whether such a swap is feasible -- have no idea as to how the LCD is connected to control circuit board.
You can find broken instruments (people usually blow the FETs in there by shortcircuit and inadequate fusing) on ebay fairly regularly, with good LCD. The st4000+ and the st5000+ has the same display, so you can go for either.
It is very simple to replace the LCD, five minute job, and you only need a small Phillips head screwdriver. You can safely try it, even if you don't have much experience in it.
First remove the 8 screws on the back of the instrument. You may need to peel off the gasket to reach them. Then carefully pull apart the case. Grab the center cylindrical part on the back and the front of the case and pull. It may need some force. When it comes apart, be careful with the wire to the buzzer, as it is glued to the back. Pull off the connector.
Next, unscrew the three screws on the bottom part of the circuit board. Then lift the board. The LCD may be stuck to it, be careful not to drop. From here it is trivial, there are some parts, the frame of the LCD, the flexible striped connectors, the diffuser, just observe their place and order.
Put the replacement LCD in, and doing everything in reverse, assemble. It takes more to to write than to do it, and once you open the instrument, it becomes clear what to do.