Worklog Some PS2 Project

[Miggas]

I found another component that although it's in stock, the BOM has a name for that component that I can't find anywhere outside of china, it's the 16.9344MHz oscillator, NX3225GA-16.9344M-STD-CRG-2, it's not in digikey, mouser, TME, etc..., it's actually under the name STDCRG2-16.9344M, it's the exact same component and it took about an hour to find it.

 

[Tschicki]

I found another component that although it's in stock, the BOM has a name for that component that I can't find anywhere outside of china, it's the 16.9344MHz oscillator, NX3225GA-16.9344M-STD-CRG-2, it's not in digikey, mouser, TME, etc..., it's actually under the name STDCRG2-16.9344M, it's the exact same component and it took about an hour to find it.

The part number of that crystal may have changed at some point (?), because all stock I ordered back then is marked with NX3225GA-16.9344M-STD-CRG-2. Searching for it in Digikey or Mouser now redirects to the STDCRG2-16.9344M, which is the correct part and fine to use. I will try to update that in the BOM today or tomorrow!

 

[Miggas]

I was going through the BOM to see if I could find cheaper alternatives to some components and I noticed that there's no caps in the BOM for the 32.768KHz oscillator, did you leave those out for some reason? I've never seen oscillators without caps, I'm going to use 10pf caps here as using the formulas in an adafruit blog post gave me around that value.

 

[Tschicki]

I was going through the BOM to see if I could find cheaper alternatives to some components and I noticed that there's no caps in the BOM for the 32.768KHz oscillator, did you leave those out for some reason? I've never seen oscillators without caps, I'm going to use 10pf caps here as using the formulas in an adafruit blog post gave me around that value.

C1501 and C1502 are marked DNP in the schematics and should ideally not be populated. If you compare with a 79k or 90k mainboard, they are also not populated there - most likely because they are integrated in the RTC.

The RTC will work in both cases (populated or not), but it will drift substantially more when they are populated (in the order of 30s to 1 minute per day). I tried populating them with 10pF or 15pF on the first revision, and that's why I decided to keep them DNP.

Without these caps the RTC still drifts by about 7s a day. If you are already looking for alternative components - this may be fixable using a crystal with lower capacitance and ideally lower ESR. I discovered this a bit too late, these PS2 models apparently use a Rohm BU9861 RTC+EEPROM. The exact datasheet isn't available, but checking Rohm's old datasheets for similar parts gives some hints about a better crystal selection for the RTC (BU9873 for example)