I’ve had some success repairing the PS2 5V boards but on average I only get about 20-30% working again.
In order of easiest/most likely to succeed to hardest:
- Check the external 5V voltage regulator. It’s a LM2937.
- Check to see if the electrolytic capacitors have gone bad. Usually the top vent has popped or leakage around the capacitor base. Will have to separate boards.
- Check for shorted wires
- Separate the boards by removing the Kapton insulation tape and MOSFET heatsinks. Desolder the 14 position .100” connection header. This is by far the toughest because of the no lead solder and many of the pins are connected to large surface areas. The large surface area acts like a heatsink and makes the soldering iron almost useless. Use copious amounts of ChipQuick flux, solder wick, and solder sucker.
- Put on high power magnifying glasses and start looking for obviously fried components.
- MOSFETs like to fail due to static.
- Many of the really small SMD components are impossible to source. They usually have a 3 character code such as A7P, A4T, 352A, W2X. If I’m able to cross-reference, there are usually multiple possibilities and many times out of production. I’ve built-up a collection random components to experiment with
- If there are multiple component failures then the board is almost certainly a total loss. I compare this to a lighting strike where the failure(s) could be anywhere. I use these to experiment with and soldering practice.
Examples
- Repair #12. PS2 5V board with smoke coming from the capacitor area, as reported by the customer. Completely dead. I separated the board and found the 5V regulator wires had shorted and fried multiple components. I replaced a few MELF DO-213AB diodes with a best guess. The only markings were stripes which I found varies. After messing around for a few weeks I gave up.
- Repair #11. PS2 5V board with sounds but no movement. Separated boards and found a capacitor loose. Also found a short in the tender couple board. Put back together and it worked.
Ideas
I have more ideas than I have time but here are a few of them.
- Create test harness for the 14 pin header. Attach to Arduino to run diagnostics.
- Reverse engineer board test points and create diagnostics.
- Recreate PS2 test stand (MTH has one for their repair tech) with Arduino, Raspberry Pi, or similar.
Questions for the Community
- Can PS2 5V boards be swapped between steam and diesel like the 3V boards?
- Does anyone have an internal pinout for the PS2 5V boards, i.e. the 14 position connector or PCB test points? Board schematics?
- A common observed failure mode is a constant relay clicking when voltage is applied. I’ve tried several things but none worked. I assume a relay failure or a transistor/MOSFET not providing enough voltage to keep the relay open. Additional comments wanted.
Please add any comments. I’m also working on three PS1 boards so I may start a separate thread for them.
