PS1:Controller Fuses

General
There are two separate power supplies on the controller ports - one is a nominally 3.3V supply used to run the controller logic and the other is nominally 8V used to run the vibration motors in Dual Shock type controllers. The same supplies also run to the memory card ports, and the official Sony memory cards only use the 3.3V supply. Some 3rd party controllers and memory cards internally run from 5V, which they regulate down from the 8V supply, so if you have a situation where a 3rd party controller works but the official Sony one doesn't then it may be caused by a blown 3.3V fuse. If you find that the official controllers work (but without rumble) and some 3rd party ones don't then it may be the 8V fuse.

Original grey models
These all use a type of solid-state fuse made by KOA called "Chip Circuit Protectors". They can be identified by the use of reference designations starting with "PS" and a number on the top that represents the nominal fusing current. This is different from most fuses, which are typically marked with the rated operating current. The types used in the PS1 are as follows: The two fuses associated with the controller ports are PS602 (CCP2E20) for the 8V supply and PS605 (CCP2E15) for the 3.3V supply. For completeness, the functions and ratings of the other fuses are as follows: If the console has a parallel expansion port then the same PS602 fuse that supplies power to the controller ports also powers the 8V on the expansion port. This is a common reason for GameShark/Action Replay carts not working, since they internaly drop the 8V to run the 5V flash.
 * CCP2E15 - Marked "15", fusing current = 1.5A, operating current = 600mA
 * CCP2E20 - Marked "20", fusing current = 2.0A, operating current = 800mA
 * CCP2E50 - Marked "50", fusing current = 5.0A, operating current = 2.3A
 * PS601 800mA (CCP2E20) - 8V supply for BTL driver (spindle and sled motors + focus and tracking actuators).
 * PS603 800mA (CCP2E20) - 8V supply to 5V regulator running video + audio DACs
 * PS604 2.3A (CCP2E50) - 3.3V supply to main logic

Slim "PSOne" models
Things are slightly more complicated here, because there were multiple changes to the power supply system and in some cases this changed the way the fusing worked, so it's necessary to know which version of board your console contains. These are normally identified with a -xx number at the end of the board number, although confusingly the -71 board omits this and instead changed the PCB reference to "PM41 (2)" - there is also a -81 revision, which is also a PM41(2), but now actually says "-81" as well.

First release -11 board
This is the closest to the old versions of the console - the main difference is that all the fuses are now on the 7.5V primary power and hence the 3.3V fuses PS604 and PS605 are omitted and replaced with a single fuse on the input to the 3.5V regulators. The controller port and the main logic have separate regulators, but share a common fuse. On this board, all the fuses are 800mA and the same CCP style fuses are used as before.
 * PS004 800mA (CCP2E20) - Supply for controller 8V
 * PS601 800mA (CCP2E20) - Supply for BTL driver (same as old boards)
 * PS602 800mA (CCP2E20) - Supply for controller 3.5V (but on 8V rail before regulator) - note this was CTR_8V fuse on old boards
 * PS603 800mA (CCP2E20) - Supply for 5V regulator (same as old boards)
 * PS606 800mA (CCP2E20) - 8V supply to 3.5V regulators

Intermediate production -21/-31/-41/-51/-61 boards
These still used the KOA CCP style fuses, but added a primary input fuse and moved some things around a bit, including the removal of the dedicated controller 3.5V fuse.
 * PS004 800mA (CCP2E20) - Supply for controller 8V
 * PS600 2.5A (CCP2E63) - Main 7.5V input fuse (added)
 * PS601 800mA (CCP2E20) - Supply for BTL driver (same as old boards)
 * PS603 800mA (CCP2E20) - Supply for 5V regulator (same as old boards)
 * PS606 800mA (CCP2E20) - 8V supply to 3.5V regulators - this now includes the controller supply

Later production -71/-81 "PM41 (2)" boards
These changed to a different style of 1608 SMT fuse - they are no longer as distinctive and just resemble SMT resistors, but can still be identified by the "PS" prefix on the reference designation. The separate fuse for the 5V regulator was also removed and connected directly to the output of the PS600 primary power fuse. Note that on all the units past the -11 shorting the 3.3V rail on the controller will just blow the main 3.3V fuse and stop the console from working at all.
 * PS004 800mA (1608 SMT) - Supply for controller 8V
 * PS600 2.0A (1608 SMT) - Main 7.5V input fuse (rating reduced to 2A)
 * PS601 800mA (1608 SMT) - Supply for BTL driver (same as old boards)
 * PS606 800mA (1608 SMT) - 8V supply to 3.5V regulators - this now includes the controller supply

Short version
On the PSOne, loss of the 8V rail (no rumble) can be caused by a blown PS004. Loss of the 3.3V rail (no controller function) can be caused by a blown PS602 on the -11 boards, but on the later revisions there is no dedicated controller fuse and PS606 should be checked.