Hello Dan
Thanks for your reply.
This seems to happen a lot , I ask a question……and then I find the answer.
The ASD 3S157 is for the Late 2013 iMac 21.5”.
https://web.archive.org/web/201803162029...
I managed to find and download the ASD EFI part and run a quick test.
Onscreen there were only 2 sensor error mesages;
sensor - temperature — (TL0p) LCD proximity (test 1) sensor verifies that sensor reads within the sensor limits. ERROR — senosr is reading below the low limit
sensor - temperature -- (TL1p) TCON local (test 1) sensor verifies that sensor reads within the sensor limits. ERROR - sensor is reading below the low limit
This relates to a couple of previous questions I’d asked on ifixit regarding the same machine. All resulting from originally opening a machine to change the HDD. With the LCD reconnected. Nothing appears on screen. However using a mini display port to HDMI cable. Plugged into an external TV, there’s a picture to work with.
iMac 2638 21.5" display not working after HDD changed