PS1 won't read memory card, might be a fuse

General information to do with the PlayStation 1 Hardware. Including modchips, pinouts, rare or obscure development equipment, etc.
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TheFilyng
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PS1 won't read memory card, might be a fuse

Post by TheFilyng » June 6th, 2024, 11:06 pm

Hi, first post here, I hope I'm in the correct place.

I've recently bought a new PS1 (model scph 7002) since the one I bought previously had a faulty drive/laser (ended up fixing it by cleaning it, but anyways).

I bought this new one in impeccable state, but when I tried to use my memory card in it, it wasn't detecting it. Games don't detect it, and the memory card menu doesn't as well. I initially thought the memory card was dead (since it's a 3rd party one), but I tested the memory card on the other PS1, which is also a scph 7002, and it worked wonderfully, it was reading it. I've been reading multiple posts about it and seems like it might be a fuse (PS605???), but from what I've read that usually fixes the PS1 not being able to detect controllers, this PS1 detects the controller perfectly, it's just the memory card that fails to read. Furthermore, I've also cleaned the Memory Card contacts.

What could possibly be? Should I go the PS605 replacement route? I would preferably not want to resolder anything, so if there are any tips or suggestions on what could it be, let me know.

Adding a picture of the board with the modchip just in case is relevant at all: [

P.S. I've ordered a Bitfunx PsxMemCard just in case I try that and works for some reason. I was going to order it anyway, but it's useless if the PS1 is not reading mem cards at all.

Thanks in advance!

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Post by nocash » June 7th, 2024, 9:04 am

If you think that it's a fuse then you do need a multimeter to check if the fuse is broken, and if so, yes, that would require soldering.

But, the controller and memory card are using the exact same signals and supply voltages, so it's pretty much implossible that one works & the other doesn't work, and even if so: it seems fruitless to look for fuses on the mainboard.

I would guess that it is a very simple mechanical problem. Anything like: Forgot to connect the memory card? Inserted it upside it down? Haven't tried the second memory card connector? Dirty contacts on the memory card /socket? Broken solder points on the memory card socket? Tried to disconnect the controller, if that's causing the problems?

PS. As you have two scph-7002's, swap the front panel and power power supply to track down what's wrong.

PPS. There's also the 7.5V supply, normal memory cards don't need it, but some third party ones might need it. If that's broken then vibration motors in analog controllers would also fail to work.

TheFilyng
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PlayStation Model: SCPH-7002

Post by TheFilyng » June 11th, 2024, 12:36 am

nocash wrote: June 7th, 2024, 9:04 am If you think that it's a fuse then you do need a multimeter to check if the fuse is broken, and if so, yes, that would require soldering.

But, the controller and memory card are using the exact same signals and supply voltages, so it's pretty much implossible that one works & the other doesn't work, and even if so: it seems fruitless to look for fuses on the mainboard.

I would guess that it is a very simple mechanical problem. Anything like: Forgot to connect the memory card? Inserted it upside it down? Haven't tried the second memory card connector? Dirty contacts on the memory card /socket? Broken solder points on the memory card socket? Tried to disconnect the controller, if that's causing the problems?

PS. As you have two scph-7002's, swap the front panel and power power supply to track down what's wrong.

PPS. There's also the 7.5V supply, normal memory cards don't need it, but some third party ones might need it. If that's broken then vibration motors in analog controllers would also fail to work.
Thanks for the reply! I just managed not only to find, but to "fix" the issue.

I opened up the PS1 and checked the continuity for the PS605 fuse, and it was working perfectly. So I was wondering what might be the cause then, and I learned (as you mentioned) that the controller port not only uses the PS605, but it also uses the PS602 fuse for +7.5V for the rumble motors, and when checking the continuity for this fuse, it was blown. Apparently memory cards don't use that rail, but 3rd party memory cards do! And of course, my memory card was 3rd party, so in order to fix it I had 2 options:
  • Replace the PS602 fuse
  • Find a compatible memory card that uses the PS605 +3.5V rail.
I went with the second option and ordered a PsxMemCard (which is based on PicoMemcard) and now everything works wonderfully, since it uses the +3.5V rail (PS605) and not the +7.5V one (PS602).
Hope this helps someone!

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Post by nocash » June 11th, 2024, 7:07 am

Cool, glad that it's working (or bypassed). If you want to replace he fuse someday, there are schematics (with parts lists at the end of the document) for several older/newer PSX mainboards (see the Downloads section on top of the forum page).
From what I've learned recently, only the rating in Amperes matters (the Volts don't matter because fuses have close to 0 ohms, so there's always the same voltage on both sides of the fuse).
When using a differently sized fuse, just take care that it won't be dangling around, or cause shortcuts with the shielding plate or other components.

TheFilyng
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Post by TheFilyng » June 11th, 2024, 9:07 pm

nocash wrote: June 11th, 2024, 7:07 am Cool, glad that it's working (or bypassed). If you want to replace he fuse someday, there are schematics (with parts lists at the end of the document) for several older/newer PSX mainboards (see the Downloads section on top of the forum page).
From what I've learned recently, only the rating in Amperes matters (the Volts don't matter because fuses have close to 0 ohms, so there's always the same voltage on both sides of the fuse).
When using a differently sized fuse, just take care that it won't be dangling around, or cause shortcuts with the shielding plate or other components.
Awesome, thanks for the info. Will probably replace the fuse down the line so this info is very valuable. Ty!

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