Check the mosfet first as that is the one thing about these cards that can give hell a run for its money, also the caps as they are getting pretty old on these cards.

Yes, I am going to check the voltage regulators as soon as I figure out how to do that.
I have a diode meter but I don't know what readings I am looking for ?

nforce4max wrote:

Check the mosfet first as that is the one thing about these cards that can give hell a run for its money, also the caps as they are getting pretty old on these cards.

I am getting conflicting readings on these components so I am going to replace the low voltage regulator and 2 caps.

(2) 10UF 10mfd 16V 4 x 5mm SMD Solid Aluminum Electrolytic Capacitors.
https://www.ebay.com/itm/US-Stock-20pcs-10UF- … ksid=m570.l1313

(1) SEMTECH EZ1585CT Linear Voltage Regulator Positive Fixed 1 Output 3.3V 4.6A
https://www.ebay.com/itm/5-SEMTECH-EZ1585CT-L … 872.m2749.l2649

Update:
I desolder the voltage regulator and 2 capacitors and I think I found the problem.
Leaking Capacitors corroded the circuit board. ( Capacitors # C18 and C19 ).
I need to clean and repair circuit board and replace pads.
I have the new components which cost a total of less than $1
So I need to perform delicate surgery on this circuit board.
I need to create some NEW pads from 1.4mm copper foil and bond to circuit board with high temp epoxy.
reconnect traces with solder and solder NEW components.

I found this video which details how to repair circuit board.
https://youtu.be/vx50YtEC2S8?t=131

Update:
So I pretty much determined that the regulators are bad.
I was not exactly sure what reading to be looking for so I just purchased the components anyway.
They only cost less than $2 total.
Then I compared readings of the NEW components with the old ones on the Voodoo.
both regulators are bad.
SEMTECH EZ1585CT
and
SEMTECH EZ1582CM

Now to reassemble.
cross your fingers.

What voltages were they outputting on the card in its powered-up state? I'm wondering if just the traces on the board are bad. I had these type of caps go bad on my Mac SE/30. They ate up a bunch of traces, which I had to rewire.

feipoa wrote:

What voltages were they outputting on the card in its powered-up state? I'm wondering if just the traces on the board are bad. I had these type of caps go bad on my Mac SE/30. They ate up a bunch of traces, which I had to rewire.

Yes, I have some old mac classic logic boards that need re-caps too.

On one of the Voodoo cards 2 caps went bad and corroded the PCB and 4 pads. I still need to repair. Waiting for 1.4mm copper foil to rebuild pads.
On the other Voodoo the two regulators are bad for sure. Some diodes are reading bad but I think it is because of the regulators.
I am going to take it one step at a time.

As for the readings, I just compared the readings from the NEW components to the old ones on the Voodoo's with a meter.
Check each leg of the regulators and compare readings.
Also check each cap and diodes and traces.

See photo above.

Guys, I am ready to start to repair these Voodoo cards. I have two cards with the same problems.

The problem:
was the regulators over heated and caused the capacitors to burst and leak onto the PCB destroying the pads and traces.

My solution:
I want to repair these cards by soldering wires between the regulator legs and PCB traces. I want to use electrolytic capacitors instead of surface mount capacitor.
What do you think. What is the beast type of capacitor to use and what voltage do the capacitors need to be ?

HI guys,

I have the exact same card that started by small artifacts, progressed to no vga output but card stiff detectable to completely dead, no longer detected. I suspect the mosfet is dead, as it is cold to the touch when the card in running. The original SEMTECH EZ1585CT fixed 3.3V 4.6A is obselete and the ebay link above gives me an adjustable version, which I don't like to use. Will this model be a good repalcement ? Specs seem to be the same..

Analog Devices Inc.
LT1585CT-3.3#PBF
IC REG LINEAR 3.3V 4.6A TO220-3
https://www.digikey.ca/en/products/detail/ana … -3-3-PBF/891630

I would like some validation on my reasoning, as well as the replacement part.

Thanks in advance.

The regulator you mentioned from LT should work fine. Pinout is the same and the parts are "basically the same", but from different manufacturers. You can check if the old regulator is working or not by measuring the output voltage.
If you have a DMM handy, you can measure the voltage on the Tab of the regulator (where the screw is mounted to) against ground (shielding of the VGA output). You should read 3.3V there. Any other value would be suspicious and would indicate an issue with the regulator.

Thank you Tehsiggi,

It's a good think you got me to check. I put a DMM to it and found that I am getting 5V in and 3.3V out (on the tab and center pin), as per the pinout. So this rules out the Mofset altogether. So I continued and looked at the voltage regulator for the processor chip and the output reads 1.246V. So the card is getting power, it's just not being detected anymore.

Note that after all of that testing, I noticed that if I leave the system long enough, I can feel the mosfet getting hot.

I can't help to think that the card shown by Intel486dx33 shown above looks so clear and without damage, yet it had a leaking C19 capacitor anyway.

What can I check next ? Should I replace all caps ?

I will load up some pictures in the next post, so that you guys can look at the card components more closely

Thanks,

First 5 images

Last 5 images

gnn wrote on Today, 01:00:

So I continued and looked at the voltage regulator for the processor chip and the output reads 1.246V. So the card is getting power, it's just not being detected anymore.

1.25V is less than half of what it should be. The Voodoo 3 chip needs about 2.6V to work properly. So something is definitely wrong there - either the regulator is dead, or something else is shorted (hopefully not the core itself).