Ok, so i lifted the three legs of the PWM controller, and there was no voltage on it's OUT pins that are going to the three drivers, even when shorting the VID pins to ground.
Then i put the overclock chip back in, and there is the same voltage on each of the PWM controller's OUT pins (50-250mA - it changes each time that i power it up)
Shorting the VID pins to ground makes no difference.
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Removed the overclock chip, so it's VIDOUT pins are definitely disconnected now
But lower mosfets still don't turn on when shorting VIN pins to groundLast edited by socketa; 02-07-2024, 10:27 PM.
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Yes, i disconnected the PSU and moved the CMOS reset jumper to reset position and then back again
I also flashed the BIOS because it's checksum had changed
So even though i ground the VIN pins that go to the controller which tell it what voltage to regulate at, there seems to be something disabling the chip from outputting signals to the drivers,
Like you say, maybe the overclock chip is telling the controller chip to not output, irregardless of whether i try to force VCORE by grounding the VID pins
I found a schematic of a board with that overclock chip
[URL]https://elektrotanya.com/gigabyte_ga-8knxp_rev_2.0_sch.pdf/download.html[/URL]...Last edited by socketa; 02-02-2024, 01:32 AM.
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Maybe due to this?
Top right and bottom right
[URL=filedata/fetch?id=3208398&d=1706775733][ATTACH=JSON]{"alt":"Click image for larger version Name:\ttop right near lever..jpg Views:\t14 Size:\t50.5 KB ID:\t3208398","data-align":"none","data-attachmentid":"3208398","data-size":"small"}[/ATTACH][/URL] [URL=filedata/fetch?id=3208421&d=1706777047][ATTACH=JSON]{"alt":"Click image for larger version Name:\tTop left.jpg Views:\t0 Size:\t59.0 KB ID:\t3208421","data-align":"none","data-attachmentid":"3208421","data-size":"small"}[/ATTACH][/URL]...Last edited by socketa; 02-01-2024, 03:30 AM.
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The VID pins of the VRM controller chip are direclty connected to the VIDOUT pins of the jumperless overclock chip
It seems like the job of the overclock chip is to override the voltage that the controller chip is putting out.
Shorting pins VID 3&4 of controller chip to ground should give 00111 (1.35V)
But this new PWM controller chip is also not sending out any PWM signal voltage to the drivers.
The three driver chips each have 12V power at VIN, and voltage on drains, and the controller chip has PGood voltage,
and the jumperless overclock chip correctly detects...Last edited by socketa; 01-31-2024, 11:38 PM.
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Yep, have ordered some
Will update when the chip has being replacedLast edited by socketa; 01-13-2024, 11:44 PM.
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I was sure that the high and low side mosfets were shorted to ground
Now, after checking again, it's only the high side mosfets drain and source shorted together, and not to ground
I found the faulty mosfet (was the same position that the previous one went short), and replaced it
Now, with the CPU removed, the board starts, but this time no VCORE, and the VID begins at 11111 (off), and then, over the course of about ten seconds, VID0 falls to low to make 11110, but still nothing on VCORE
When i push the power button with the CPU installed, VID is 11111 (off), but...Last edited by socketa; 01-13-2024, 03:38 AM.
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Did that (sorry, it was VID4, not VID3, that i pulled low to get 1.375V)
There's 12V on the three drivers supply pins
There's 8.57V - 8.64V on the low side gates,
but there's no voltage on the high side gates,
and of course, there's no VCORE
The controller is putting out a signal 10110 (1V)
and when grounding VID4, there is still no VCORE, since there's no voltage on the high side gates
There is no voltage on the PWM OUT pins
Then i accidentally shorted OUT1 to AGND, and it shut down, now the board wont start
It tries to...Last edited by socketa; 01-12-2024, 11:21 PM.
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Yeah, maybe the 3000 CPU was just about dead after the upper vrm shorted,
and it had enough life in it to to POST, but then fully died
This board also has an IT8206R "jumper free overclock controller" that's located next to the VRM controller, and VID 0-4 also go to it
There's five 4.7k pull up resistors
with the PSU and CPU removed, they all measure 3.4kohms in-circuit,
except for VID3's resistor, which is 1.3K
With the CPU removed, there is 1.0v VCORE, which corresponds to what's on VID 0-4 10110
With the CPU installed,...
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Thanks for that
Re-flashing made no difference
Am assuming that i should be looking at the K-8 output voltage chart that's on that datasheet, since the CPU is AMD socket 939
On VID pins 0 to 4 there is 10110 (3V = high),
and that equates to 1.00V
Meter shows about 1.0V
Shorted a few of those pins to ground and had it up to 1.2V and the PCI card moved on to a different code and stopped there
But now i noticed that the mosfets were getting hot, Vcore 800mA, and now the CPU is shorted
Maybe i briefly put it up to 1.55V, and killed the 3000 CPU...Last edited by socketa; 01-10-2024, 08:12 PM.
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I flashed the bios, but still get code 44 on the PCI slot card
the only noticeable difference is that the board now powers down when the power button is pressed,
1.02V VCORE sounds too low to me
...A few hours later , now a hard short has developed across VRM mosfets
...Found, and replaced, the shorted mosfet, and it shorted again as soon as power was applied
...Replaced that one, and now get code D0, and now can't shut down with the power button - VCORE still 1.02V
Am wondering that since i replaced the mosfet with a different brand, maybe i should replace...Last edited by socketa; 01-10-2024, 03:48 AM.
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Now it's all good.
I tried two SATA drives one of them was a DVD drive, and neither of them were detected
After a bit of frustration, decided to try a spare laptop drive, and it was recognized
All that is left to do is to replace the initial VRM SMD capacitor back on to the tiny bit of copper that remains
One thing that i found out is that i couldn't MS-DOS USB boot with later versions of Rufus
Which made me think, for a while, that there was a problem with the motherboard USB
[ATTACH=JSON]{"alt":"Click image for larger version ...Last edited by socketa; 01-06-2024, 02:09 AM.
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Yeah, it's about time,
I thought that there might have being a problem with the CMOS, since it didn't automatically identify the CPU correctly, but when i changed the FSB clock setting to what is was meant to be, then it identified it correctly
The only problem is that it's not seeing the SATA ports, despite being enabled (or disabled) in the CMOS
According to the CMOS setting, "PATA-IDE" and "SATA-IDE" are both controlled by the same VT8237 chip
The IDE port works OK, but there's no SATA in the first CMOS section "Standard CMOS Features" that...
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Now it's fixed
After fixing this nearly soldered joint
[ATTACH=JSON]{"alt":"Click image for larger version Name:\tnearly soldered joint.jpg Views:\t0 Size:\t185.0 KB ID:\t3173140","data-align":"none","data-attachmentid":"3173140","data-size":"full","title":"nearly soldered joint.jpg"}[/ATTACH]...
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Well, i finally reflashed the BIOS and put it back on the board.
Turned on the power ,and no response whatsoever.
The CPU VRM was running before i removed the chip, but there was no code on the PCI analyser card.
But, as i moved the board, it started up, and halted after the second analyzer code
So that was a good sign
Then i noticed that i could cut power by flexing the board
After some more flexing, it went through the entire POST sequence, and the BIOS screen appeared. Yay! [URL="https://www.badcaps.net/#"]😀[/URL]
So, after many years,...Last edited by socketa; 01-04-2024, 04:12 AM.
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Re: Zalman ZM500-GV stops after 40s and 5VSB drops to 2.5V
Fixed
It was either a leaky zener, or possibly a thyristor, in the OVP in the standby feedback (the zeners both still tested correct voltage)
Looks like the 2.5V standby is what happens when the opto is continuously turned on by the latched thyristor
The other PSU was working but had low PSON, so it wouldn't turn off with the mobo power button - but i didn't figure out why because i damage the board, by heating the cm6000 are too much (the PCB separated and cracked).
Also managed to...
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Re: Zalman ZM500-GV stops after 40s and 5VSB drops to 2.5V
The standby chip is good.
And it appears that all of the primary standby components are good also.
The TL431 tests good
I see that the TL431 needs 2.5V in order for it to turn on - could that be related to why there is only 2.5V standby?
There is a thyristor and a zener, in series, connected between the standby rail and the cathode of the TL431.
What is is the function of that additional circuitry?
Should it be latching?Last edited by socketa; 07-31-2023, 03:52 AM.
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