Do you mean ZD1SS1?zd1551
There is no zd1551 in the nomenclature.
Where did you pull this from? The service manual has no mention of this.Hey COALA, that ZD1551 is usually a 5.1V zener diode. You can replace it with a 1N4733A (5.1V, 1W), just make sure it matches the circuit markings.