Is the salary earned from working in the maintenance of electronic devices, which includes musical instruments, permissible, albeit temporarily until another job is found, knowing that there is a serious search for an alternative job?

If the questioner's work is limited to repairing electronic devices and he avoids dealing with musical instruments, then there is no harm in him benefiting from his salary. His work is disliked (makruh) but not forbidden (haram). However, if his work inevitably involves dealing with musical instruments, then he is not permitted to remain in that job unless there is a necessity. In that case, he must remove the wages earned from repairing musical instruments from his salary, unless removing it would place him in a state of necessity. In such a situation, he may benefit from it only to the extent of repelling that necessity. Necessity is defined as a situation where one fears destruction, unbearable hardship, or an inability to achieve the minimum standard of living.