English Amiga Board - View Single Post - Dead A1200 (+5V only 287Ohms against ground)

04 June 2017, 13:44

I'm trying to figure out if I can fix an A1200. Got a working power supply from an A500 and one from another A1200. When I connect them to this defect A1200, both power supplys make strange noises (one is ticking and the other gives a high frequency noise). Obviously something seems to be pulling too much power. I'm measuring on the +5V (Pin 1 of CN8) against ground only something like 287Ohms which seems to be too low. For testing purposes I just removed the C811 (1000uF) to make sure that this one isn't making a short circuit, but that's not the case. Well now its getting difficult - it could be anything beeing powered by the +5V. The Board is Rev 1.D. Schematic diagram can be found here: http://www.amigawiki.de/dnl/schematics/A1200_R1.pdf
Curious if anyone could problably point me in the right direction. Maybe something that often likes to cause problems and pulls the +5V down?

04 June 2017, 13:44	#1
Alen Posts: n/a	Dead A1200 (+5V only 287Ohms against ground) I'm trying to figure out if I can fix an A1200. Got a working power supply from an A500 and one from another A1200. When I connect them to this defect A1200, both power supplys make strange noises (one is ticking and the other gives a high frequency noise). Obviously something seems to be pulling too much power. I'm measuring on the +5V (Pin 1 of CN8) against ground only something like 287Ohms which seems to be too low. For testing purposes I just removed the C811 (1000uF) to make sure that this one isn't making a short circuit, but that's not the case. Well now its getting difficult - it could be anything beeing powered by the +5V. The Board is Rev 1.D. Schematic diagram can be found here: http://www.amigawiki.de/dnl/schematics/A1200_R1.pdf Curious if anyone could problably point me in the right direction. Maybe something that often likes to cause problems and pulls the +5V down?