PSP Power Supply Update

PSP (Original) Main Board (Power Supply)I was probing around a bit more and I’ve found the obvious problem, and it’s not the transistor. The power connector to tI can envision what happened now: an unregulated supply – works fine for just charging the battery, the current is low and the TPS65250 has a wide input voltage range. But, upon power up current demands go up, voltage drops, and this tiny connector melts because it can’t handle the current. It surprised me this would happen before the input fuse blew – bad design I guess, should have used a connector rated for higher current since the connector is on the supply side of the fuse. It took longer to find since I never suspected this, but, was fairly easy to fix. Next time check the simple things first.

NEC Versa LX secondary battery

battery2Battery uses weird Sony Energytec US103463 prismatic cells — haven’t found a suitable replacement cell — let me know if you have a source; until then, it’s filed under “battery”.

I love that laptop, and it’s great battery life. I kept asking myself why no-one makes new slower, low power laptops with new technology (except they’re moving towards it again with the XO and eeePC). The versa gave me 7 hours of portable computing (or more with standby), while most new laptops give you 3 hours. I couldn’t find anything smaller than the versa for a good price when I got a new laptop in 2005.

PSP Power Supply

PSP (Original) Main Board (Power Supply)Tom gave me his PSP after frying it by using the wrong powersupply. The micro fuses were okay, so onto the SMPS! It’s self contained – up in the top left corner in the picture, but, on the other side of the board. I didn’t take a picture of that size for some reason. So, this supply is based on a Texas Instruments Power Management IC, TPS65250. Anyways, closest datasheet I could find online was for the TPS65050 series. I assume the rating are simply a bit different, or this is OEM’d. I’m thinking right now that the main switching transistor is shot…and since those SMD transistors are basically impossible to identify – since they never seem to have any text on ’em – I just pull random ones off of old broken computer motherboards and assume they’re close enough….they all have been so far.

A Canadian-made road bike cica 1979. 24″ frame, new wheels, rear sprocket, eggbeater pedals. My start to real distance riding. We did about 3000km summer 2007.

sekine1

sekine2

Mobile Pro 900 Linux and Serial Port

mobilepro2┬áThe NEC MobilePro 900. A beautifully sized and featured Handheld PC circa 2003. A venerable performance beast when compared to its earlier brethern – although doomed to run WinCE out of the box. This thing packs a 400MHz Intel PXA255, 64MB RAM, 32+32MB flash, touchscreen, unimpressive although adequate 8.1″ DSTN HVGA display, PCMCIA and CF slots, USB host port and built-in modem into an extremely portable ~ 9.7″x5″x1.2″ package. Plus, it sells used for less than it’s earlier siblings for which linux ports exist, and boasts a 10 hour battery life undmobilepro1er standard productivity.

Lets make one run linux, and then lets make it useful!
Picked up a beat-up unit off ebay cheap, and promptly replaced the built-in modem with a serial port — small, careful soldering here, although a technically simple mod! It already has a built-in serial port; but, few cables exist, and ordering the connector (Honda RMC-EB9F1( )-BSLA3-MA1) is expensive.

Tools:

HaRET

Inside:

firmware: p530 v6.0
 build date: oct 4 2004
 PIC firmware ID: 3.18.7
 Bootloader Version: 3.4
 bSquare

windows for handheld pc 2000: build 9546-126
 core system version 3.0
 internet explorer version 4.01
 pocket outlook version 3.1

ROM: 2003/05
 ROM Rev: Minerva TR5.4
 ID: 002E0006-40D4-00D1-F800-123456781234

intel pxa255a0c400
 l4340393

x2:
 NeoMagic
 NMC1110A-LQ144C
 0439h102 1998
 201076

microchip
 pic16lf877
 h04 pt

ta550cpfb
 48t
 cvv9

42j4n9k
 max3243c

x2:
 samsung
 k4s561632e-tc75

epson
 s1d13806f00a1

f c39af
 lcx32245

wim
 xwm8731
 43aewrv

isp1161a1
 cd1992
 tpno42
 6e

x2:
 128j3c150
 5427a789
 z4272014b

m systems
 Disk on Chip Plus
 m03831-d32-v3-x

 bottom::

sigma:: r3064xl
 f13675-0309

ltc1628cg

Cypress AN2131SC “Evaluation Board”

freecypressUSB to 25-pin parallel “file transfer cable.” I saw someone tossing this out, and through the transparent shell, I could see too many components for a simple USB bridge chip. Conveniently, the IO is broken out for you, power supplied though USB and, it has a USB interface for your new age convenience. Because the software is stored in an external EEPROM, it’s simple to invoke the built in development bootloader — ground the SCL pin (I added a switch) to bypass the external software. Now, if you want to read or reprogram the EEPROM, just flip the switch back.