A PS1 PSU issue, a reset button, and a lesson learned

A few weeks ago, we sold two PS1 PSU replacement boards on eBay. The buyer, Jan, left us positive feedback and followed up with a detailed message describing an issue he encountered during installation.

He owns two consoles: an SCPH-9001 (NTSC) and an SCPH-7502 (PAL).
The PSU worked flawlessly in the SCPH-9001. However, the SCPH-7502 was behaving erratically. Here’s a summary of his observations:

The good

• The board was seated properly, and the mounting hole aligned perfectly with the case.
• Without the screw, the console powered on normally and worked fine.

The bad

• With the screw in place, the PSU powered on (LED lit up), but didn’t seem to deliver enough power to the console.
• Occasionally, even with the screw, the memory card showed signs of power (he’s using a PSXMemCard Gen2 with a display), but there was usually no video/audio output, and the disc drive didn’t initialize.
• Once, he briefly saw the Sony logo before the system stopped working again.
• It even worked when the console was upside down—but stopped again once flipped.

In summary, the issue was intermittent and position-sensitive.

Figure 1. PlayStation 1 SCPH-7502 (PAL). The yellow circle marks the mounting hole.

We believed the issue was related to the reset button, which is slightly larger than the original one. It’s the same aftermarket component used in other PS1 PSU replacement boards, and we manually trim it before assembling it onto the PCB.

In this particular case, we may not have trimmed it quite enough. As a result, the button could have been constantly or intermittently pressed when the board was screwed into the shell.

To rule out any compatibility issue—or a possible difference between NTSC and PAL console shells—we tested the board ourselves in an SCPH-7502 (PAL). It worked as expected, and we didn’t encounter any issues.

Jan later sent us a message that confirmed our suspicion. He trimmed about 1 mm more off the reset button and voilà—everything started working perfectly, even with all screws firmly in place.

We’re extremely grateful to Jan for his detailed feedback. This issue had only occurred once so far, but we’re actually glad it happened to Jan—because thanks to his clear description and testing, we were able to trace the root cause and address it properly, preventing it from happening again.

This problem had been mentioned in reviews of other replacement boards on the market, but we hadn’t seen a clear explanation or solution until now. Thanks to Jan’s input, we’ve been able to understand and document the issue more clearly.

Looking forward

As part of our commitment to continuous improvement, we will explore alternative part numbers for the reset button. The goal is to find a component that eliminates the need for manual trimming, ensuring a more consistent and streamlined experience for all users moving forward.

Besides, we’ve set up a dedicated test unit with a modified PS1 shell that includes a side window. This allows us to observe the reset button from a side profile during installation and operation, so we can validate not only general functionality but also the mechanical behavior of the reset mechanism.

Figure 2. Yes, there is an opening in the side of the shell.