Lucent PSU schemes (Octane)

For discussion of triage and repairs to SGIs as well as general hardware questions
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bkd
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Lucent PSU schemes (Octane)

Post by bkd » Sun Aug 05, 2018 10:25 am

Does anyone know where I can download electric scheme for Octane PSU (first revision, 028-003). I try to recover it but unsuccessful... It seems that it has chain breakage somewhere as it can conduct alternating current but can not conduct direct current. Multimeter shows VERY big resistance but on the other Octane it shows about 500k Ohm. So does on PC (and about that on O2).

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GRudolf94
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Re: Lucent PSU schemes (Octane)

Post by GRudolf94 » Thu Aug 09, 2018 9:28 pm

There are no schematics for any SGI parts, they were all made under NDAs. Standard SMPS troubleshooting order applies, though:
Input, fuse, varistor, rect. bridge, capacitor, switchers, PWM and transformer, then secondary semiconductors, feedback circuit and output filtering.
:Indigo2: R10k@195MHz/64MB RAM/XZ/ATX PSU conversion in the works/acting up
:Indy: R4600@133MHz/128MB RAM/XL-24/Gruesomely plasti-welded together
:Octane: R10k@225MHz/1536MB RAM/SSI

SGI Ultra64...erm, Nintendo64 console :D

and lotsa non-SGI stuff

bkd
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Re: Lucent PSU schemes (Octane)

Post by bkd » Sun Aug 12, 2018 3:25 am

Thanks, I try to follow these steps.

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gijoe77
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Re: Lucent PSU schemes (Octane)

Post by gijoe77 » Sun Aug 12, 2018 6:37 am

I've been wondering - its got to be possible to mod a current PC PSU to fit inside an octane PSU - anyone ever think of looking at this? I have, but I just don't have the right sort of tools/gear to figure out what pins have what voltage on that connector. I suppose one would have to get creative with a working octane/PSU to measure those, but I think I see a path...

does there have to be a load to measure voltage pin by pin? have a the common peg of a voltmeter on ground and then measure pin by pin while a modified system is running? If its non-standard voltages add resistors? In my half sleepy state I can almost see this being an interesting project, but only if I knew this side of electronics and tools a bit more...

bkd
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Re: Lucent PSU schemes (Octane)

Post by bkd » Wed Aug 15, 2018 12:40 am

I think I have somewhere Octane PSU voltages measured by one Nekochan user. I'll search but it won't be too soon.

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GRudolf94
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Re: Lucent PSU schemes (Octane)

Post by GRudolf94 » Wed Aug 15, 2018 6:13 pm

gijoe77 wrote:
Sun Aug 12, 2018 6:37 am
I've been wondering - its got to be possible to mod a current PC PSU to fit inside an octane PSU - anyone ever think of looking at this? I have, but I just don't have the right sort of tools/gear to figure out what pins have what voltage on that connector. I suppose one would have to get creative with a working octane/PSU to measure those, but I think I see a path...

does there have to be a load to measure voltage pin by pin? have a the common peg of a voltmeter on ground and then measure pin by pin while a modified system is running? If its non-standard voltages add resistors? In my half sleepy state I can almost see this being an interesting project, but only if I knew this side of electronics and tools a bit more...
The biggest issue here is finding a PC PSU that will supply rails to the same current an Octane PSU does. Ever looked at the 3.3V IMPACT rail feed posts on the frontplane?
:Indigo2: R10k@195MHz/64MB RAM/XZ/ATX PSU conversion in the works/acting up
:Indy: R4600@133MHz/128MB RAM/XL-24/Gruesomely plasti-welded together
:Octane: R10k@225MHz/1536MB RAM/SSI

SGI Ultra64...erm, Nintendo64 console :D

and lotsa non-SGI stuff

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gijoe77
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Re: Lucent PSU schemes (Octane)

Post by gijoe77 » Wed Aug 15, 2018 6:30 pm

what exactly do you mean when you says rails? I'm not really a power guy, but don't modern PSU supply 12V and 5V (or something like that), can't the 5V be lowered down by putting resistors in the path to achieve 3.3V?

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PA8600
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Re: Lucent PSU schemes (Octane)

Post by PA8600 » Wed Aug 15, 2018 8:23 pm

gijoe77 wrote:
Wed Aug 15, 2018 6:30 pm
what exactly do you mean when you says rails? I'm not really a power guy, but don't modern PSU supply 12V and 5V (or something like that), can't the 5V be lowered down by putting resistors in the path to achieve 3.3V?
A lot of modern PSUs try to put more voltage on the 12v rails than the 3.3 or 5v rails since CPUs and GPUs use those voltages. Even a 1000w PSU will give you what, 25 amps on the 5v rail while they'll put out 80+ amps on the 12v rail.
HP: C3000, B2600, 425T, RX2620, ZX6000, Vectra VA, Omnibook 800CT
SGI: :O2: R10k (dead), :Octane: R12k 300mhz, :320:
IBM: RS/6000 43p, Intellistation Power 275, P5 505, Thinkpad 380D, 390
Sun: Ultra 45, Blade 2500, Blade 150, SS IPC (bad psu)

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jan-jaap
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Re: Lucent PSU schemes (Octane)

Post by jan-jaap » Thu Aug 16, 2018 3:46 am

PA8600 wrote:
Wed Aug 15, 2018 8:23 pm
gijoe77 wrote:
Wed Aug 15, 2018 6:30 pm
what exactly do you mean when you says rails? I'm not really a power guy, but don't modern PSU supply 12V and 5V (or something like that), can't the 5V be lowered down by putting resistors in the path to achieve 3.3V?
A lot of modern PSUs try to put more voltage on the 12v rails
amps, not volts. ;)

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Irinikus
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Re: Lucent PSU schemes (Octane)

Post by Irinikus » Thu Aug 16, 2018 4:26 am

gijoe77 wrote:
Wed Aug 15, 2018 6:30 pm
what exactly do you mean when you says rails? I'm not really a power guy, but don't modern PSU supply 12V and 5V (or something like that)
Rails refer to Power Supply outputs that feed power to multi-staged circuits. (Amplifiers, for example)

9b3b50d92c21ad091893b1feab4c3c5e.jpg
gijoe77 wrote:
Wed Aug 15, 2018 6:30 pm
can't the 5V be lowered down by putting resistors in the path to achieve 3.3V?
You would have to make use of a voltage regulator to reduce the voltage from 5v to 3.3V, as the volt-drop across the resistor would result in a huge buildup of heat and would reduce the output current available for the given voltage. (you would more than likely have to run quite a few 3.3V voltage regulators in parallel to supply the required output current.)

EDIT:

Rather than using multiple voltage regulators in parallel, you could make use of this type of circuit to increase output amperage:

7CIkG.png

Or this example, if you need even more amps:

7812-voltage-regulator.jpg
Image

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