Hello everyone here,
I'm an engineer trying to repair my neighbor's Indigo2.
Symptoms are, machine only starts until playing the startup sound, but no graphics appears, and the LED stays constantly amber.
From previous experience with aging (PC) power supplies, I opted for taking out the PSU of the Indigo2.
Espscially as my neighbor mentioned that the system needs switching on TWICE since quite a while to get started at all.
On opening, I only identified one electrolytic capacitor with a little bit of brownish residue, and changed that one right away.It's on the +12V apparently.
Only now as I get to the 5V, it has a very poor quality, with ~1V undershoot and ~+1.5V overshoot, so there is certainly something not good any more.
See attached scope shots.
However, adding just some capacity to 5V (4700µ Low ESR), to (temporarily) compensate for eventual capacity loss, didn't change anything. 5V seems also reasonably stable and sustained when swithcing off; a connected HDD runs for a couple of seconds after mains unplugged. So I guess the 2200µ cap's are not at fault.
Now, in lack of schematics, I would be grateful for some hints which components to address next, and what to try to get the regulator back on track. Still I guess it's some faulty capacitor, but I just can't change them ALL on suspicion. Maybe it's a smaller one having lost its HF capabilities?
Thanks in advance for any useful hints!
mistermusixx
I'm an engineer trying to repair my neighbor's Indigo2.
Symptoms are, machine only starts until playing the startup sound, but no graphics appears, and the LED stays constantly amber.
From previous experience with aging (PC) power supplies, I opted for taking out the PSU of the Indigo2.
Espscially as my neighbor mentioned that the system needs switching on TWICE since quite a while to get started at all.
On opening, I only identified one electrolytic capacitor with a little bit of brownish residue, and changed that one right away.It's on the +12V apparently.
Only now as I get to the 5V, it has a very poor quality, with ~1V undershoot and ~+1.5V overshoot, so there is certainly something not good any more.
See attached scope shots.
However, adding just some capacity to 5V (4700µ Low ESR), to (temporarily) compensate for eventual capacity loss, didn't change anything. 5V seems also reasonably stable and sustained when swithcing off; a connected HDD runs for a couple of seconds after mains unplugged. So I guess the 2200µ cap's are not at fault.
Now, in lack of schematics, I would be grateful for some hints which components to address next, and what to try to get the regulator back on track. Still I guess it's some faulty capacitor, but I just can't change them ALL on suspicion. Maybe it's a smaller one having lost its HF capabilities?
Thanks in advance for any useful hints!
mistermusixx
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