Spots on display, not pixels

[reavy]

Michael told me the limit was 70° C, so I set the toaster oven for 70 and let it preheat throughly before adding the calculator. It took 8 total hours for the spots to be completely gone. There was one instance where the spots appeared cleared until the LCD cooled completely, and one spot returned.

[pauli]

A second cooking in the range 80℃ to 90℃ an the last dot has come good. My DM 16C is happy again.


Pauli

[lbrott]

When I received my DM15L, it too had spots on the display. I was able to remove them by:

• Remove the 4 black screws from the back of the calculator, then remove the back
• Remove the battery
• Remove the two silver screws and remove the circuit board from the case
• Preheat a scientific hotplate to 80C and wait for it to stabilize
• Place the circuit board face down onto the hotplate so that the display is in direct contact with the hot surface
• Prop the long edge of the circuit board with a thin wood wedge to keep the circuit board parallel to the hotplate surface
• The hotplate surface temperature dipped to 78C for a minute, then overcompensated to 82C for a minute
• When the hotplate surface stabilized to 80C again, a 60 minute timer was started
• After an hour, the circuit board was removed from the hotplate
• The display was completely black, then quickly turned many shades of blue / gray as it cooled
• Within minutes the display was at room temperature and all the spots were removed

An image of the setup:
"https://drive.google.com/file/d/1ATwgjS ... sp=sharing"