more Rockbox things on the german homepage of Uwe Freese

Attention: Be careful when modifying your Jukebox. I don't guarantee anything. If you destroy the device, it's your fault. It's always a good idea to practice modifying devices and especially soldering with old worthless electronic parts.


Buffer Animation
buffer animation
in real-time
(128kbps)

Modifying the Archos Recorder to Have 8MB RAM


All Archos Jukebox models have 2MB RAM which is mainly used for buffering mp3 data. An unmodified device can buffer about 50 seconds of music in 256 kbps or 100 seconds in 128 kbps. That means the harddisk spins up very frequently, fills the buffer and then turns off again.

The Hitachi SH1 CPU can work with 8MB. This doc describes how to replace the original 2MB chip with a 8MB model.

Beware: This is not an easy job. The RAM is only 21x10mm big, has 50 pins with a pitch of 0,8mm.


Main Advantages of Having 8 MB


hynix DRAMWhat's to Do


Support in Rockbox


Real Measurements

I've measured the battery consumption with my 8 MB-modified AJB Recorder20. I used a CVS version from 2003-01-23, compiled without demos and without games, 1.726 / 7.726 MB were free, I measured about 600 values/s with a 10 BIT A/D on the serial port, one buffer cycle.
Result: The runtime is extended 15-30 percent!

128 kbps 2 MB 256 kbps 2 MB
128 kbit/s, 2 MB used, avg. 131,4 mA
256 kbit/s, 2 MB used, avg. 179,2 mA
128 kbps 8 MB 256 kbps 8 MB
128 kbit/s, 8 MB used, avg. 113,7 mA (15,6% longer runtime)
256 kbit/s, 8 MB used, avg. 136,1 mA (31,6% longer runtime)

(click images to enlarge)

The values are not precise absolutely. There's a factor in it that I set manually and approximated the value my multimeter showed. But the relative differences should be precise.


All descriptions below are especially for the recorder.



Disassembling the Recorder


My Way of Removing the DRAM

Matthias described removing the DRAM with heat fans (with special nozzles). I don't have such fans. And I'm also afraid of destroying something with the heat.

So I tried to remove SMD ICs with a cutter and it worked very well. Please, try this technique with an old motherboard or other hardware lying around.

removing the DRAM with a cutter 1
using a cutter to remove the DRAM
removing the DRAM with a cutter 2
cut the pins one after another,
don't destroy somthing on the board
removing the DRAM with a cutter 3
how it looks like after cutting the pins
removing the DRAM with a cutter 4
after removing the IC, you can
unsolder the remaining part of the pins
removing the DRAM with a cutter 5
the pins on the right side
are already removed here
removing the DRAM with a cutter 6
how it looks like after removing all pins
(there are some left at

the bottom in this picture)


Connections of the New DRAM

Here's an overview where the pins of the DRAM should be connected to. Read also the doc from Matthias and the PDF files at the Rockbox site describing the old DRAM, the CPU and your special model of new DRAM.

Connections Overview


Connections on the Board Before Soldering the DRAM

Main Board of the AJB
1) the address pins of the CPU
2) wires under the new DRAM
3) the vias for address A10+A11


1) the address pins of the CPU

No, you don't have to solder here. But you should check where the address lines of the CPU go.

address pins of the CPU 1address pins of the CPU 2


2) wires under the new DRAM

This wires connect the left pins (NC before, now A0+A1 from DRAM) to the right pins (on the board). I used one single copper wire out of an isolated coil wire.

After soldering them, I added some glue (for paper) near the solder pads where the DRAM will be connected later. So the wires shown in the picture cannot move even when the soldering pad is heated up again. At the right side, the pins of the new DRAM must not be connected to the board anymore. I used some paper based tape to isolate the pads additionally.

wires under the new DRAM 1wires under the new DRAM 2


3) the vias for address A10+A11

On the other side of the board there's the flash rom. Address lines CPU_A11 and CPU_A12 go there. Locate the vias you can see at the picture and test if they are really connected to the appropriate address pins of the CPU. Then solder thin isolated wires to them. You can see that I removed the isolation at the end of the right wire. That's to make it thinner. The DRAM is lying on this wire later and there shouldn't be such a thick wire between DRAM and board. Be sure not to create a short-circuit here!

vias for address A10+A11


Preparation of the DRAM

Bend pins 12, 13, 14, 31, 32, 37, 38, 39 up. Be very careful wird bending the pins up. Bending them up and down more than once will break the pins.

Then add a very little bit of tin at the bottom of every single pin.

Preparation of the DRAM 1Preparation of the DRAM 2


Solder the DRAM to the Board

Solder two pins on opposite edges first. Then I suggest to solder pin19 + 20. After this, you should test if these both pins are connected to the correct address lines of the CPU and are not short-circuited. If you solder the whole IC and then finally recognize that the wire unter the IC has moved and short-circuited, you have to unsolder the whole DRAM!

Solder the DRAM to the Board 1Solder the DRAM to the Board 2


Voila!

The result of the whole action can be seen here. The transparent thing in the picture is a piece of plastic from a cable tie. It's held by double-sided tape. Now the harddisk cannot push on the wires around the DRAM later.

Result


Questions, Annotations, Problems?

For general questions and support for your Archos Jukebox and if you have problems with your device, use the Archos Technology homepage.
For discussions and bug reports about Rockbox use the Rockbox mailinglist and the Rockbox site at Sourceforge.
Concerning this mod or the other stuff on my page, you can write me an email.