I had the exact same board, it died on me after I managed to get it to post a few times. I replaced all of the caps, in particular near the power delivery (470 micro farad I think). A lot of them were completely empty, not busted open, just bone dry. Didn't fix it for me though, but it might work out better for you.

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is the same as the P5BV3+ except it uses the VIA 596 southbridge instead of the traditional 586B.

Tried both ISA and AGP GPUs, no POST.

No beeps, absolutely nada. Tested ALL MOSFETs on the board (4 of them) and all tested good. Tried a lot of CPUs, including ceramic Pentium and Pentium MMX, Cyrix 6x86 and even AMD K5.

Any ideas?

PcBytes wrote:

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is t […]
Show full quote

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is the same as the P5BV3+ except it uses the VIA 596 southbridge instead of the traditional 586B.

Tried both ISA and AGP GPUs, no POST.

No beeps, absolutely nada. Tested ALL MOSFETs on the board (4 of them) and all tested good. Tried a lot of CPUs, including ceramic Pentium and Pentium MMX, Cyrix 6x86 and even AMD K5.

Any ideas?

When you figure it out let me know 🤣. I would love to be able to resurrect my board too. Maybe a busted transistor or something? You can end up replacing every surface mount component on the board before you figure out what it is.

mothergoose729 wrote:

PcBytes wrote:

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is t […]
Show full quote

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is the same as the P5BV3+ except it uses the VIA 596 southbridge instead of the traditional 586B.

Tried both ISA and AGP GPUs, no POST.

No beeps, absolutely nada. Tested ALL MOSFETs on the board (4 of them) and all tested good. Tried a lot of CPUs, including ceramic Pentium and Pentium MMX, Cyrix 6x86 and even AMD K5.

Any ideas?

When you figure it out let me know 🤣. I would love to be able to resurrect my board too. Maybe a busted transistor or something? You can end up replacing every surface mount component on the board before you figure out what it is.

As far as it goes I have replaced nearly all major capacitors in the following order - all CPU caps were replaced from 1000uF 6.3v to 1500uF 6.3v OST pulled from a dead ASRock board, and the rest are 1000uF 6.3v OST pulls from the same board and the result was the same - no POST, no BEEP.

There are still some small TEAPO capacitors left (100uF 16v, SEK series) as well as 5 10uF 25v TEAPO caps left, with one being near the VIA596 southbridge.

Transistors aren't the problem as I've tested them with a DMM and they are fine. I'll try replacing all 17 tiny capacitors and see. I am eager to fix this board as it has 1MB cache, which would pair absolutely nice with a K6-2 500MHz.

PcBytes wrote:

As far as it goes I have replaced nearly all major capacitors in the following order - all CPU caps were replaced from 1000uF 6. […]
Show full quote

mothergoose729 wrote:

PcBytes wrote:

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is t […]
Show full quote

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is the same as the P5BV3+ except it uses the VIA 596 southbridge instead of the traditional 586B.

Tried both ISA and AGP GPUs, no POST.

No beeps, absolutely nada. Tested ALL MOSFETs on the board (4 of them) and all tested good. Tried a lot of CPUs, including ceramic Pentium and Pentium MMX, Cyrix 6x86 and even AMD K5.

Any ideas?

When you figure it out let me know 🤣. I would love to be able to resurrect my board too. Maybe a busted transistor or something? You can end up replacing every surface mount component on the board before you figure out what it is.

As far as it goes I have replaced nearly all major capacitors in the following order - all CPU caps were replaced from 1000uF 6.3v to 1500uF 6.3v OST pulled from a dead ASRock board, and the rest are 1000uF 6.3v OST pulls from the same board and the result was the same - no POST, no BEEP.

There are still some small TEAPO capacitors left (100uF 16v, SEK series) as well as 5 10uF 25v TEAPO caps left, with one being near the VIA596 southbridge.

Transistors aren't the problem as I've tested them with a DMM and they are fine. I'll try replacing all 17 tiny capacitors and see. I am eager to fix this board as it has 1MB cache, which would pair absolutely nice with a K6-2 500MHz.

I replaced every capacitor on my board and it still didn't come back to life 🙁. It's like you said, fan spins, with no beeps or any indication of what could be wrong.

mothergoose729 wrote:

PcBytes wrote:

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is t […]
Show full quote

I have the K6BV3+/66 rev B2 and I experience the same issues, although in my case, the CPU does warm up as it should. Board is the same as the P5BV3+ except it uses the VIA 596 southbridge instead of the traditional 586B.

Tried both ISA and AGP GPUs, no POST.

No beeps, absolutely nada. Tested ALL MOSFETs on the board (4 of them) and all tested good. Tried a lot of CPUs, including ceramic Pentium and Pentium MMX, Cyrix 6x86 and even AMD K5.

Any ideas?

can you clearly tell me how to test those 3 leg with one shorter leg mosfet? i have multimeter but i cant figure out how to know if mosfets are good or bad

mothergoose729 wrote:

I replaced every capacitor on my board and it still didn't come back to life 🙁. It's like you said, fan spins, with no beeps or any indication of what could be wrong.

i pulled the bigger caps and tested them with a capacitor tester i bought on ebay. most of them were fine just one didnt have a reading. and changing it did not fix the motherboard.

its a really nice motherboard because of the cache, but for quality if it just dies looks like a piece of junk from dfi

of cpu does not get warm without heatsink there has to something not powering it or the mosfets

There is a jumper set for AT/ATX power plug. Have you checked that it was set accordingly to which PSU you are using ?

Deksor wrote:

There is a jumper set for AT/ATX power plug. Have you checked that it was set accordingly to which PSU you are using ?

yea, jumper is set to ATX and im using an atx power supply
if i set it to at with an at power supply , its the same problem

Cga.8086 wrote:

can you clearly tell me how to test those 3 leg with one shorter leg mosfet? i have multimeter but i cant figure out how to know if mosfets are good or bad

Set your multimeter to continuity.
With black probe on the MOSFET's gate tab, place red probe first on drain. It should give an infinite reading. Placing the red probe on the source tab should make your multimeter beep.

Repeat the same to each MOSFET. A bad mosfet (in my experience) will either show infinite on both drain and source, or beep on both drain and source.

also use pc post card, they are super cheap nowadays, and measure all voltage rails on the powered on motherboard

It's not so easy to heal a motherboard if you have got only a multimeter.
First of all it's better to check if jumpers have been set correctly.
Then look (with magnifier) if there aren't any scratches on top and bottom of the MB, damaged components.
If you haven't got a POST card try to connect a speaker and start the MB with no RAM. The MB has to beep a RAM error.
Using voltmeter mode you could measure CPU voltage (against GND rail) on a pin of big choke near CPU socket while the MB is turned on. But be careful not to short something. Does CPU voltage correspond to the settings?
What about a BIOS chip? Is it pushed correctly into a BIOS socket?

Roman555 wrote:

It's not so easy to heal a motherboard if you have got only a multimeter. First of all it's better to check if jumpers have been […]
Show full quote

It's not so easy to heal a motherboard if you have got only a multimeter.
First of all it's better to check if jumpers have been set correctly.
Then look (with magnifier) if there aren't any scratches on top and bottom of the MB, damaged components.
If you haven't got a POST card try to connect a speaker and start the MB with no RAM. The MB has to beep a RAM error.
Using voltmeter mode you could measure CPU voltage (against GND rail) on a pin of big choke near CPU socket while the MB is turned on. But be careful not to short something. Does CPU voltage correspond to the settings?
What about a BIOS chip? Is it pushed correctly into a BIOS socket?

I did that on my K6BV3+/66 (same as P5BV3 except no AT/ATX jumper and uses VIA 596 southbridge):

Checked jumpers (and DIP switches), all set according to manual.
Checked board multiple times, no scratches, just a few marks of thermal paste which I already cleaned.
Connected speaker, started MB without RAM. No beeps.
Checked voltage, got 3.2V (Pentium ceramic chip) on choke near BIOS socket. (that's its placement)
Reseated BIOS mutiple times.

None of these has brought the board to life. I even went ahead and submerged the board in 99% IPA and still nothing.

PcBytes wrote:

.....
None of these has brought the board to life. I even went ahead and submerged the board in 99% IPA and still nothing.

But your instance not equal this. Although symptoms could be the same the cause may be different.
Before looking for EEPROM flashing tools (incl. hot swapping) and an oscilloscope it's better to do easy things.

Use a multimeter on beep continuity mode and test for shorts on the 5v,12v etc rails using the motherboard side AT connector. Test these against the middle two black ground AT rails. (you can also do the same on the ATX connector).
I had two off these boards fail in 2002 and both were shorted to ground on the 5V rail according to a multimeter.
Unusually the motherboards did not power on and then turn off quickly which normally happens with a short. They just stayed powered on with no post.
Then I used an ISA/PCI diagnostic card and it showed 5V was good but 3.3v was what had actually shorted (which was derived from 5v). Helped to narrow it down.

AvalonH wrote:

Use a multimeter on beep continuity mode and test for shorts on the 5v,12v etc rails using the motherboard side AT connector. Test these against the middle two black ground AT rails. (you can also do the same on the ATX connector).
I had two off these boards fail in 2002 and both were shorted to ground on the 5V rail according to a multimeter.
Unusually the motherboards did not power on and then turn off quickly which normally happens with a short. They just stayed powered on with no post.

Yes, I agree, these measurements are very helpful too.

AvalonH wrote:

Then I used an ISA/PCI diagnostic card and it showed 5V was good but 3.3v was what had actually shorted (which was derived from 5v). Helped to narrow it down.

The 3.3v rail is absent in old PCI slots. But 3.3v rail is necessary for SDRAM, CPU I/O Voltage, chipset and so on.
What about this MB I think MOSFET that is near DIMM makes 3.3v for everything but AGP. There is a LDO near AGP that supplies 3.3v for AGP graphics card.

Roman555 wrote:

PcBytes wrote:

.....
None of these has brought the board to life. I even went ahead and submerged the board in 99% IPA and still nothing.

But your instance not equal this. Although symptoms could be the same the cause may be different.
Before looking for EEPROM flashing tools (incl. hot swapping) and an oscilloscope it's better to do easy things.

I'm trying all the easy stuff.

I just checked the mosfets using a AT PSU (ATX simply won't start no matter what PSU I use) and I have noticed that there's a ticking around the MOSFETs between the SDRAM slots and the ATX power plug. This becomes more evident as the following happens when I measure with my DMM on any of them:

-Drain will produce a intermittent beeping
-Source will either yield ticking or a continuous beep with ticking in the background

Further testing revealed:
-one or two of the MOSFETs might have failed, and it's the one near the edge of the board around the ATX plug - red probe of DMM on source reveals that the resitance slowly increases to infinite. The one next to it confirmed this (it's healthy btw) because placing the red probe on its Source prosuces a steady long beep, and shows no resistance.

K6BV3+/66 mobo btw.

PcBytes wrote:

I just checked the mosfets using a AT PSU (ATX simply won't start no matter what PSU I use)

ATX not starting means protection kicks in - on of board rails is shorted

PcBytes wrote:

and I have noticed that there's a ticking around the MOSFETs between the SDRAM slots and the ATX power plug. This becomes more evident as the following happens when I measure with my DMM on any of them:

-Drain will produce a intermittent beeping
-Source will either yield ticking or a continuous beep with ticking in the background

?? you measured continuity on powered on board?
what are you measuring exactly? drain and what? source and what?
the only thing you should measure is drain-source junction, you can simulate turning mosfet on (after desoldering it) by briefly charging gate, but its usually not needed as mosfets love failing short

PcBytes wrote:

and I have noticed that there's a ticking around the MOSFETs between the SDRAM slots and the ATX power plug. This becomes more evident as the following happens when I measure with my DMM on any of them:

-Drain will produce a intermittent beeping
-Source will either yield ticking or a continuous beep with ticking in the background

?? you measured continuity on powered on board?
what are you measuring exactly? drain and what? source and what?
the only thing you should measure is drain-source junction, you can simulate turning mosfet on (after desoldering it) by briefly charging gate, but its usually not needed as mosfets love failing short[/quote]
Here's a photo of the section I measured.

The nearest to edge of board MOSFET I am feeling is shorted - measuring the Gate-Source junction I get a rising resistance, while the same test done on the other MOSFET next to it will result in a beep (low resistance). Both MOSFETs are the same brand and model - NEC 2SK3296.

Disregard the wire going from the Drain tab to the 8 pin IC - I did that to bypass a trace I accidentally broke.