ABIT KV8Pro: Vtt mod

[Goldlocke]

OK, I want to figure out the Vtt mod for the KV8 Pro rev1.1. I already contacted master Hell-Fire.
Winbond W83303D again.
There are no other ICs around DIMM slots. Only mosfets.

[Goldlocke]

OK, here we go with the voltage measurements:
I hope Hell-Fire or anyone can help me, figure this out!

[Goldlocke]

OK, the only pin that shows ~ 1.3V is that one. Vtt in bios shows 1.33V - multimeter reads 1.30V here.

[Goldlocke]

I think I could follow the trace from Pin#7 (Vtt sense) up to this area. The trace goes to the back of the board and to the front again I think. There are some 1.30V readings on these mosfets and on resistor R19 too.
Does this help?

[Hell-Fire]

Originally posted by Goldlocke
I think I could follow the trace from Pin#7 (Vtt sense) up to this area. The trace goes to the back of the board and to the front again I think. There are some 1.30V readings on these mosfets and on resistor R19 too.
Does this help?

Do a resistance check on pin #7 to see what you get.

I would think that replacing R19 with a 200-1K ohm VR would do the trick.

The VR would need to be set to 0 ohms before soldering on the R19 pads.

I would do a connectivity test between R19, the FETs beside it where you read Vtt, and pin #7 on W83303D.

[hipro5]

IF the trace goes from pin 7 of the winbond IC to the Mos-Fets DIRECTLY , then sorry M8 but you HAVE to cut the trace and do the the mod of the IC7(-G) mobos.......That's the only way to do it.......

EDIT : IF you can read on R19's BOTH ends the 1.3Volts,then you are just lucky........
Replace it with a 10 Ohms resistor and on the right leg of it(as shown in pic) solder a 200 Ohms trimmer 25 turns to ground and you're ready......

[Goldlocke]

To you both: Thanks for joining this thread.

@ Hell-Fire: OK, Hell-Fire you outlined the correct trace.
Resistance check with mobo turned off? I read 366ohms ground to Pin#7. I also read 365ohms on both sides of R19 (dunno if thats relevant?).
I read 1701ohms on Pin#7 with mobo turned on. I also read 1701ohms on both sides of R19, when mobo is turned on.

How do I perform a connectivity test plz? sry for noobness!
Can I do this with the acoustic continuity test of my voltmeter?
edit: OK, did the "beep test". And my multimeter beeps every time I connect Pin#7 and the 1.3v or 1.28v points I labeled below!

@ hipro5: I read 1.30V on both sides of R19. And the 2 dots beside it. I only have to make sure, I am following the correct trace from Pin#7 up there.

[Goldlocke]

btw, Vtt mod is my priority because the GURU software allows Vdimm adjustment to 3.28V. I will try Vdimm mod later, when Vtt has succeeded.
If anyone needs the datasheet of W83303D - I can email it to you. (But I think you 2 already got it a long time)

[hipro5]

LAST one........IF R19 "beeps" with the 7 pin of the winbond IC , then you can remove it and do the mod as described above....

[Goldlocke]

Yes, R19 beeps at both ends.
So what is 10ohm fixed resistor for? Safety reasons?
Oh, and I have to start with low resistance on the trimmer, right?

Hey guys! If that works - gimme your Paypal accountnumbers!

[hipro5]

Originally posted by Goldlocke
Yes, R19 beeps at both ends.
So what is 10ohm fixed resistor for? Safety reasons?
Oh, and I have to start with low resistance on the trimmer, right?

Hey guys! If that works - gimme your Paypal accountnumbers!

NO.....You have to start at high resistance on my mods(IC7-G) based VTT......IF you solder ONLY a trimmer in R19's place , then YES trim it at low resistance......

[Hell-Fire]

Since R19 is a zero ohm resistor, its just there to bridge a gap more or less.

You can remove it and solder a 200ohm to 1K ohm VR set at zero ohms to start with. Raising the resistance will increase the voltage in the loop for Vtt.

[Goldlocke]

OK, removed R19. Soldered 187ohm in place. Changes Vtt by nothing.
I will try higher VR...

[Hell-Fire]

If you still have R19 handy, check its resistance to make sure it was a 0 ohm resistor.

[Goldlocke]

Yes, it's 0 ohms. There's also a 0 printed on it.

[Hell-Fire]

Do you not have a VR handy for this versus using a fixed resistor?

187 seems to high to begin with.

[Goldlocke]

Look at my pic! It is a VR. I went from 0 - 187 ohm. no change. Shall I try the 1k VR?

[Hell-Fire]

Originally posted by Goldlocke
Look at my pic! It is a VR. I went from 0 - 187 ohm. no change. Shall I try the 1k VR?

LOL..sorry about that. Only took a quick peek as I have the solder iron in my hand.

Yeh, may as well try the 1k, although I would think that 187 ohms should have increased the Vtt.

I will have to relook this over later today after I ship some items out.

[hipro5]

Originally posted by Goldlocke
Look at my pic! It is a VR. I went from 0 - 187 ohm. no change. Shall I try the 1k VR?

Unsolder the trimmer and measure the line if it "beeps" with the pin 7 of the IC.......

[Goldlocke]

HAH! I just checked resistance of the new VR with mobo working.
-> It did change Vtt temporarily in bios! (When I made contact with the multimeter). Of course it went up and down, but it changed!!!
I will try 1k VR...

Originally posted by hipro5
Unsolder the trimmer and measure the line if it "beeps" with the pin 7 of the IC.......

I unsoldered VR, so that short wires were alone. Now only 1 line beeps (the 1 nearer to the IC).

edit: hmm,...even 1k VR didnt change a thing. So, what is the difference between making contact with the multimeter and using simply the VR???

edit2: checked other thing: When I leave to line open without the VR the board does not post. When I connect the 2 wires directly to each other, the board posts and shows default Vtt. So R19 indeed was just a bridge.
But why does an increase in resistance not change the Vtt?

[Goldlocke]

YESSS! WE DID IT!!!
I can now change Vtt way beyond 1.60V.

hipro5's way was the right one!

10ohm fixed instead of R19 and then 200ohm VR from there to ground. Of course the pic only shows the testing setup, not the final mod.

Hipro5 I love you! Ok, I love you too Hell-Fire!

It is indeed a "greek summer of 2004" as your President put it hipro5.

[Hell-Fire]

I fail to see why a fixed resistor is needed for this mod.

Although Hipro also used fixed resistors in his guide to the IC7 boards (for Vtt & Vagp mods), they were not needed there as well.

I straight thru VR should have done the trick as well.

The way I am looking at that above, it would prob still work just to remove the whole setup in the above pic and solder the VR between pad #1 and the FET leg reading Vtt.

Hipro, could you clarify this for me as it may help me with future mods. Resistance is resistance, and when a zero ohm resistor is removed, its no different than cutting a trace and introducing a resistance into the circuit loop to increase voltage.

[Goldlocke]

maybe the clue is the connect-to-ground-part?

[jess1313]

Hell - what do you think, his got the pics & diagrams down pat. Thats some sweat camera you have there, nice work with the voltage readings to.

[hipro5]

Originally posted by Goldlocke
YESSS! WE DID IT!!!
I can now change Vtt way beyond 1.60V.

hipro5's way was the right one!

10ohm fixed instead of R19 and then 200ohm VR from there to ground. Of course the pic only shows the testing setup, not the final mod.

Hipro5 I love you! Ok, I love you too Hell-Fire!

It is indeed a "greek summer of 2004" as your President put it hipro5.

WAY TO GO M8.....

I'm glad I could help you out with this..Keep on......

Thank you...