[PS2 TWO] Estudio de Fixes Para PS2 Two

Finally... I finished my part of the puzzle.
Maybe not the way I wanted it to be, but it's simple yet elegant!

We must thank the Matrix team for giving us the first lead to the problem, although I think their diode-fix is worthless. Then thanks to the Ripper team for really giving usefull information about what can go wrong with DVD bus patching and that a Mechacon lockup actually causes the coils to fry. The Ripper team described a safety circuit that should be built that would current limit the coils and another circuit that should detect the lock-up and reset the Mechacon. The Matrix team did it... with the PIC-Fix they made it possible to detect the lock-up and kindof reset the Mechacon... and now here it is... the current limiter a.k.a. "the vanDrunen fix" :

http://vandrunen.net/gallery/PSTwo_vanDrunen_Fix

This is probably the most simple current limiter existing and at first I didn't think that just this would do the job... but appearently it does... I've tested this thorougly even during a Mechacon lock-up!
This current limiter will allow more current through your coils than my initial designs, but it's low enough for your coils to "hold out"... and high enough for the Actuator to still operate within specifications.

In combination with the Matrix PIC-Fix this should definately protect you coils on short and long term. More testing to verify "playability" should be done, but with no or hardly any adaptations this combo can be the definite solution.

Instead of writing the full explanation of the "device" in this thread I'll make a PDF or something... because I think my photo gallery will be overloaded if I don't... and a photo-tutorial can be a bit unhandy!

About the 4x 10 ohms resistors "in series"... OOPS... it's parallel!! I'll fix it.
And I used 4x 10 ohms to make 2,5 ohms, because it needs to be able to dissipate a maximum of 0.75 Watts power. The standard small resistors are designed for 0.25, so that's why I took four. Using 2x 5 ohms or 1x 2.5 ohms is perfect too if you take the "bigger" ones... 2x 0.5 Watt, 5 ohm or 1x 1 Watt, 2.5 ohm.

Thanks for telling me Rebo.71

WilliamG... if your PS2 crashed after the first boot of a DVD-R ONLY and you have a DMS4-Lite chip, then I doubt it was the dreaded Mechacon crash. I measured the possible coil currents during a Mechacon crash with and without diode fix and it didn't make much difference, if your coils would've survived the 2A+ currents you were really lucky.

It came to my knowledge that "other chips" can cause these lockups easily because they don't overcurrent the DVD bus while patching. That's probably the reason why ot was the matr1x team that found a way to "recreate" the lockup so easy... and provide us with this good PIC-Fix .

I didn't say I would make an easy fix, but just one that works and is better than the diode fix and the romeo2 mod... and even this one is not exactely the way I wanted it. It would for instance be better to isolate the supply pin for the part of the actuator that drives the coils only and apply current limitation to only that pin... and put it at 100 mA. My first designs were two current limiters in between the coils themselves, but they are extremely complicated and hard to build... I only used them for testing purposes.

One advantage of this fix over the diode fix is that it doesn't degenerate the Actuators performance... read the ripper-team's documents on this if you want to know why.

One advantage of this fix over the romeo2 mod is that this dynamically lowers voltage to limit currents. You'll have full Actuator performance with full current limitation.

This fix together with the Matr1x-PIC-Fix could be soldered onto a nice PCB that can be easily installed and sold online as a quick-and-easy (tm) solution.

A tutorial on PIC programming will come later this day

2.5 ohm doesn't have to be exactely 2.5 ohm... something between 2.5 and 3.5 is ok. We don't really need 500 mA, but it's not already too much for the coils.

When you look at my install pictures you see that I unsoldered a fuse first. When you solder two wires to the two points where the fuse used to be and hook a current meter up in between, you'll measure currents between 10 and 600 mA with normal operation. When the Mechacon has crashed and the coils are driven at full current the current to the RS2004FS can go up to 2 Amps, it's just not enough to make the fuse PS11 blow. About 200 mA would go to the spindle motor and the power electronics (I don't have exact measurements, I didn't have a scope for this) and the rest would go through one or both coils.

When you would limit the current at less than 300 mA you would see a lot strange responses from the sled and spindle motors, especially during spin-up and disc seek. 400 mA works fine, but gave me some strange noises from the sled motor on a rare occasion... so I kept it at 500 mA... no real "scientifically proven" value, but ok, feel free to experiment.

When the Mechacon crashes and the current is limited at 500 mA I could measure 180 up to 240 mA through the coils when the spindle motor is off, 180 mA is about the same as maximum during normal operation and 240 is the peak during normal operation. With the spindle motor still on at high speeds these currents are lower.

About if it is overkill to do my fix as well as the Matrix fix... the answer is YES . But what if the PIC can't reset your console during a lockup... and what about those 1-2 seconds that your coils experience FULL current before the PIC can reset your PS2.. it all adds up!

Just think of it this way:
I mod quite a few consoles and a lot of those are going to be PSTwo's in the coming weeks / months. I ask about 100 euro's for a DMS4 install, which is a lot, but I give service and a full 3 months warranty. I will apply any patch necessary at no extra cost and at low expense if it will prevent my customers from becoming unhappy customers.

ok.. about using only my current limiter and not the PIC... you could do that, but don't you hate it to get up from your chair and having to unplug the power supply to get it to turn off?

You could do that, of course, I'll do some more endurance testing on some dummy coils to see how long they can stand a 180-240 mA current. Maybe even with my limiter they will still fry after leaving the PSTwo in it's locked up state for half an hour... I didn't get to test such extreme things, but I will.

And about the programmer... I think you're right, but we need the diodes to be connected this way to create a power supply by draining some current from the serial port. The zener diode has been inserted to keep the voltage at approx. 5 volts so you won't damage the PIC. Some current will flow, but those are limited (hard limited by the PC) and the zener will dissipate all excess power. Currents will be between 5 and 20 mA.

I actually built the JDM programmer from it's original diagrams a long time ago in a way I could use it with a pin header. I only rotated and swapped some components around and today I have redrawn it's diagram exactly like I built it on my circuit board. It's a bit easier to "recreate" it from my diagrams but nothing has technically changed

But really.. if you know some quick and easy fix to make the "power supply" more efficient and keep it functionally the same, tell me and I'll change my diagrams. I don't really feel like doing it myself because it works good enough now.

And for all the other people... ANOTHER TUTORIAL

Here's some pics in my photogallery showing you how to connect the JDM programmer and the PIC to the PC and how to use the program "IC-Prog" to flash the PIC with the "Matrix PIC-Fix"

http://vandrunen.net/gallery/PSTwo_Matrix_PIC-Fix