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Asus P5A not working

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First post, by Nemo1985

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I recently bought an Asus P5A, rev 1.04, I have a 1.03 already which instead works.
I noticed that the cpu won't get warm, I measured that the power consumption is pratically the same when the cpu is installed or not installed.
Debug card shows: ----
All lights are up except for the 5v, this is the same behaviour I get on the working card.
Capacitors are not bulged, the card has no visible physical damage.

Any help to troubleshoot the issue?

Thanks

Reply 1 of 42, by fool

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I would measure these two regulator output voltages. You can do it without CPU. Just check that Vcore jumper is set to something, like 2.1V.
Orange = Vcore
Yellow = VIO
Green = 5V reg input

Last edited by fool on 2023-02-04, 14:27. Edited 2 times in total.

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Reply 2 of 42, by Nemo1985

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Thank you for the tip, I can do it straight away I just have 2 dumb questions:
Orange arrow measured v1.42 (it started from v0.8 and slooooooowly went up).
Yellow arrow measured v1.47.

That with v2.1 voltage setting, same values if I use an higher vcore setting.

Where could be the problem? Capacitors?

Reply 3 of 42, by fool

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Orange is Vcore and 2.1V is OK. But I was wrong with the CPU, for VIO (yellow arrow) measurement CPU must be inserted. Otherwise they are about the same value.
Also try to change GND point if value looks strange.
What CPU are you using?

Toshiba T8500 desktop
SAM/CS9233 Wavetable Synthesizer daughterboard
Coming: 40-pin 8MB SIMM kit, CS4232 ISA wavetable sound card

Reply 4 of 42, by Nemo1985

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fool wrote on 2023-02-04, 13:39:

Orange is Vcore and 2.1V is OK. But I was wrong with the CPU, for VIO (yellow arrow) measurement CPU must be inserted. Otherwise they are about the same value.
Also try to change GND point if value looks strange.
What CPU are you using?

What gnd do you advice? I'm using the ps2 ports metal case.
I use a Pentium 133 v3.5 with the cpu installed they both measure v0.82x
So apparently the voltage goes down as the load goes up?

Last edited by Nemo1985 on 2023-02-04, 14:03. Edited 1 time in total.

Reply 5 of 42, by fool

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Yes, I got that. USB/PS2 port cover is fine.

That pentium is common rail and interconnects Vcore and VIO.
For what it sounds, Vcore supply is possibly missing and draws VIO down with it.
It would tell more if you have dual rail CPU f.ex. MMX or K6(-2).

Toshiba T8500 desktop
SAM/CS9233 Wavetable Synthesizer daughterboard
Coming: 40-pin 8MB SIMM kit, CS4232 ISA wavetable sound card

Reply 6 of 42, by Nemo1985

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fool wrote on 2023-02-04, 14:01:
Yes, I got that. USB/PS2 port cover is fine. […]
Show full quote

Yes, I got that. USB/PS2 port cover is fine.

That pentium is common rail and interconnects Vcore and VIO.
For what it sounds, Vcore supply is possibly missing and draws VIO down with it.
It would tell more if you have dual rail CPU f.ex. MMX or K6(-2).

I've tested a k6-2 350 (v2.2)
Orange arrow measured v0.359
Yellow arrow measured v1.432

Also asus p5a as +3 voltage selection (for dram, chipset, agp i\o cpu buffer) which is actually jumpered for v3.5 (but it can be higher).

Reply 8 of 42, by Nemo1985

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Yes it is v5.04x for both... I think the problem it's that the cpu doesn't get any power?

Reply 9 of 42, by fool

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Those two PWM controllers HIP6013 near both transistor pairs switches transistor to generate selected output voltage. Clearly something is wrong with the control. Look for missing or weird looking components around them.

I haven't heard of poor capacitors in P5A? Of course doesn't mean it's impossible....

Toshiba T8500 desktop
SAM/CS9233 Wavetable Synthesizer daughterboard
Coming: 40-pin 8MB SIMM kit, CS4232 ISA wavetable sound card

Reply 10 of 42, by Nemo1985

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Uhm it seem everything is in order

Reply 11 of 42, by fool

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I would check these next, just to be sure they have supply voltage etc.

HIP6008
-pin 14 (VCC) 5 or 12V
-pin 10 (PGOOD), may not be connected

HIP6013
-pin 14 (VCC) 5 or 12V
-pin 6 (enable), should be above 1V regulator to be enabled

Toshiba T8500 desktop
SAM/CS9233 Wavetable Synthesizer daughterboard
Coming: 40-pin 8MB SIMM kit, CS4232 ISA wavetable sound card

Reply 12 of 42, by Nemo1985

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I missed your answer about the capacitors, I can confirm that noone of the socket7\ss7 boards I had ever need a recap but they are usually the first thing which is suggested to change.

Thank you very much for your help here are the values, i'm still using the k6-2 cpu:

HIP6008
-pin 14 (VCC): 12,17
-pin 10 (PGOOD): zero (probably not connected as you suggested)

HIP6013
-pin 14 (VCC): 12,17
-pin 6 (enable): 5,027

Reply 13 of 42, by bloodem

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If I were to take a wild guess, I'd say that you're probably dealing with a shorted transistor and / or a shorted voltage controller.

1 x PLCC-68 / 2 x PGA132 / 5 x Skt 3 / 9 x Skt 7 / 12 x SS7 / 1 x Skt 8 / 14 x Slot 1 / 5 x Slot A
5 x Skt 370 / 8 x Skt A / 2 x Skt 478 / 2 x Skt 754 / 3 x Skt 939 / 7 x LGA775 / 1 x LGA1155
Current PC: Ryzen 7 5800X3D
Backup PC: Core i7 7700k

Reply 14 of 42, by Nemo1985

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bloodem wrote on 2023-02-04, 17:22:

If I were to take a wild guess, I'd say that you're probably dealing with a shorted transistor and / or a shorted voltage controller.

That was my first thought when I noticed the cpu didn't get warm...
Any suggestion how to find it? I tried to keep the motherboard on for some minutes and then touching components to check if there was anything hot but I found nothing.

Reply 15 of 42, by bloodem

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Well, you need to check resistances. Look at the voltage controller's datasheet and check all pins for potential shorts. If one pin turns out to be shorted, trace the connection and see where it leads. If it's connected to one of the MOSFETs, then... don't even bother with identifying if the MOSFET or the controller is to blame: just replace both (I would replace both MOSFETs and the controller if this turned out to be the case).

Once you remove them, you can then see which one was shorted. They usually tend to fail simultaneously (either the MOSFET kills the controller or vice-versa). 😀 Either way, I would not risk it and would replace them all with new parts (after making sure that the short is gone, of course).

1 x PLCC-68 / 2 x PGA132 / 5 x Skt 3 / 9 x Skt 7 / 12 x SS7 / 1 x Skt 8 / 14 x Slot 1 / 5 x Slot A
5 x Skt 370 / 8 x Skt A / 2 x Skt 478 / 2 x Skt 754 / 3 x Skt 939 / 7 x LGA775 / 1 x LGA1155
Current PC: Ryzen 7 5800X3D
Backup PC: Core i7 7700k

Reply 16 of 42, by Nemo1985

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Uhm i'm sorry but i'm not so savy when I have to use the multimeter, so I need some clarifications.
Should I touch every pin with the red probe while the black is on the ps2 ports case and check resistance?
That with the motherboard turned off?

Those are taken from the datasheets:

The attachment HIP6008.jpg is no longer available
The attachment HIP6013.png is no longer available

Reply 17 of 42, by bloodem

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Nemo1985 wrote on 2023-02-04, 17:41:

Uhm i'm sorry but i'm not so savy when I have to use the multimeter, so I need some clarifications.
Should I touch every pin with the red probe while the black is on the ps2 ports case and check resistance?
That with the motherboard turned off?

Pretty much, yes! 😀
The motherboard shouldn't be connected to power when you do these tests.

1 x PLCC-68 / 2 x PGA132 / 5 x Skt 3 / 9 x Skt 7 / 12 x SS7 / 1 x Skt 8 / 14 x Slot 1 / 5 x Slot A
5 x Skt 370 / 8 x Skt A / 2 x Skt 478 / 2 x Skt 754 / 3 x Skt 939 / 7 x LGA775 / 1 x LGA1155
Current PC: Ryzen 7 5800X3D
Backup PC: Core i7 7700k

Reply 19 of 42, by Nemo1985

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Values for HIP6008 values from pin 1 to 16:

>3k
10.78m
23.48k
0.3
7.53k
4.881k
10.85m
11.90k and then goes up

0.2
9.70m
55.06k
7.91m
38,06k
38,06k
9.81m
First time Goes up to 55k and then down, remeasured gave 2m and goind down

Crazy means that the multimeter start with a low value and then it goes up up up up, while the other are like stable value (they may change of 0.01)

HIP6013:

10.30m
6.13km
11.26m
0.L
3.605k
13k
0.3
453
7.87m
38,05k
0.L
0.L
0.L
38,05k
Last edited by Nemo1985 on 2023-02-05, 08:53. Edited 8 times in total.