| Click here to select a new forum. |
| Q605 / LC475 Half dead psu can make you think sound is dead. |
Posted by: uniserver on 2015-03-05 04:05:58
The PSU that i normally use to test LC's is a re-capped one.
but i forgot, in messing with my personal machines a week ago the good one got swapped with one that was not already serviced.
Witch caused me some issue, but, just another tid bit to toss in the bucket.
|
Posted by: Elfen on 2015-03-05 07:52:08
Interesting.
|
Posted by: uniserver on 2015-03-05 15:12:22
if i had to guess i would say, the -12 rail died.
|
Posted by: Elfen on 2015-03-05 17:20:28
12V? More interesting, I thought 12V was mostly for the hard drive and RS-232 Serial Protocols, but 5V for the chips.
Teach me more!
|
Posted by: uniserver on 2015-03-05 17:22:27
yeah the negative 12 volt rail.
|
Posted by: uniserver on 2015-03-06 15:57:58
Well i was close… the LC475 / Q605 does not have a -12 volt rail… It has a -5v rail… and if that goes out you get no sound and maybe other stuff as well ( serial ports )
And as elfin mentioned before, He had situations where the metal in his LC power connector was rotted away. That can also be bad, looks like -5v is on the end right near C129, so i bet if cap go made it to that terminal, could get rotted out. Killing your -5v rail as well.
|
Posted by: techknight on 2015-03-06 16:29:34
Well when I am testing Mac II, SE/30, I dont need any of the negative rails.
I need the 5V, and the 12V. Thats when I get sound and everything. But youll loose communication, and I am unsure of floppy drive requirements.
The machine wont run without 12V, and it definitely wont run without 5V. The 12V i assume is part of the reset management circuitry, which explains why it needs it. And its for sound as well.
|
| 1 |