hans14914

Loren,

Thanks for that information. I am glad that the failsafe all live in the output stage, that does make it a lot simpler. I didn't know if it was somehow using that UPow pin to signal back to the controller that a fan was dead.

I need to find some time this weekend to probe those Sig pins and log the frequency and map the duty cycle to the workshop operational theory diagram. Will be fun to simulate that output with the signal generator to run the output stage "manually"

Thanks!

GregBBRD

One of my friends called me and asked if I wanted to comment about the electric fan control thread on Rennlist.
There's at least three people, here, that are way smarter than I am about moving electrons around.
And my momma raised no fool.
I'm perfectly content to read.

Lorenfb

It's that simple! Have Mark at 928 International post a video of my test setup running both fans with just a 12V battery and a variable power supply.
Although the fans aren't receiving a PWM signal, a basic square wave signal generator can replace the variable power supply. The signal generator
output needs to be greater than 16-18 volts peak to minimize the power dissipation of the MOSFETs in the amplifier. That replicates the controller
input signal. A simple test like that verifies the basic functionality of the amplifier.

worf928

How many will you sell me at $150?

Lorenfb

Zero! When most realize that the power module is the last module to fail on a 928. Shotgun troubleshooting wastes time & money.

Alan

I think you have overplayed your hand...

Its a good shirt for most engineers, myself included - often with time some humility creeps in

Alan

GregBBRD

Let's try to remember:
Not everyone is a perfect communicator....especially on the Internet, where voice inflections are not present and personalities are a mystery.

While certainly, not any one person is perfect or knows every detail about everything, Loren is worth the time to listen to to and pay attention to.
Loren is a professional electronic module repair specialist....working almost exclusively with the electronic "boxes" in German vehicles.
If you need anything electronic on your 928 inspected or repaired....Loren can fix it.....and generally knows (from memory, without looking at any notes....he's absolutely amazing) exactly how each part interfaces and is supposed to work.
Without Loren, there is a plethora of Porsches that would not be running or correctly functioning, today.
With a "Double E" and a lifetime working in this specialty field, he's a real treasure.

Try and be nice.
We "need" every specialist we can find, to keep our 928's functioning.

Mrmerlin

Thanks for the update Greg