Repair tip - Beeping on startup potential cause.
This is not a question but more of a repair tip should someone encounter this problem.
iMac 21.5 inch EMC 2638
Symptoms: Beeping on startup which would typically indicate bad RAM , issue not resolved swapping RAM modules or replacing did not solve the issue nor did PSU swap.
Removed logic board and did bench test with logic board and test power supply , resulted in no beeps and normal startup. Same RAM installed etc.
Cause: Traced to J6600 connector which is the headphone , mic socket connector lower right on the logic board. PP3v3s0 was shorted with this connector plugged in causing the beeps on startup.
Replaced socket and tested OK.