Sharp EL 640 repair

From: dudley
Email: dmail@singnet.com.sg


I am trying to repair two of the talking calculators for blind folk who rely on them. Problem: The 'talking' only occurs when they are in an aircon room around 22C. (outside temp 28C in Singapore). The display is ok. I have found that slightly heating or cooling the large glass diode at the top end of the circuit board can affect the 'talking' and I suspect this diode is the problem but do not know the type/number. Can anyone help?? I should be able to get an appropriate diode here in singapore if I know what to ask for.