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sound improvement


Background 
The following page describes a procedure to modify your Archos Jukebox 6000 to improve its sound quality. The technical information and original mod was largely supplied by TJ (regenpak) in the ArchosJukeBox6000 forum on Yahoo groups. I have simply repeated part of the modification and detailed it below.

WARNING  The following instructions are given by the author in good faith.  You will invalidate your AJB6000 warranty by performing this modification and if you are unfortunate or careless you will destroy your AJB6000. The author takes not responsibility for the fitness, completeness or accuracy of these instructions.  They are for your information only; follow them at your own risk.  It is not a step by step guide .... it is simply what I did. DO NOT ATTEMPT THIS unless you are comfortable soldering small SMDs.

What you require
Tools to disassemble your AJB (Phillips No0 or smaller, T10 star bit)
Fine point soldering iron
Solder
Single strand wire (to jump to the caps)
4x220uF caps - AVX (Kyocera) TAJC227K004X, Farnell order code 196990, Case code "C",
Solder sucker (depending on your method of disassembly)
Dremel tool (my lazy method of disassembly), or other method of cutting metal
Insulating tape
Patience

Disassembly

Remove the front fascia.  There are four screws, two at the top (headphone jack end) and two more at the bottom (USB end).  Using a small phillips screwdriver remove the screws (tip .... make sure that you use a correctly sized screwdriver, and be careful.  It is very easy to strip the head off the screws). Carefully remove the front fascia by lifting it vertically up.  Now remove the battery covers (a lot easier once the front fascia is removed).  Remove the batteries.  Place all of the bits that you are removing in a safe place / container

Remove the four hard-drive screws on the sides of the AJB6000.  You require a star bit to do this.  Now carefully remove two of the blue bumpers from the USB end.  You will probably bend the metal case a bit getting them off.  It is hard to describe how to remove them.  See the last two photos on reassembly to get an idea.  Essentially you have to squeeze the bumper so you can clear the two parts of the metal case.  Once you have removed the USB end bumpers,  lift the remaining two blue bumpers (marked in red) clear of the circuit board and then wiggle and slide the main body of the AJB6000 out of the metal case.

Turn the main unit upside down.  We now need to remove the hard-drive.  The hard-drive is plugged into the AJB at the headphone end.  To remove it we need to clear the circuit board at the USB end and then disconnect it from the main unit.  Carefully lift the USB end of the hard-drive up and away from the AJB. You only need to lift the drive end to clear the circuit board at the end of AJB

Now using a flat blade screw drive work the hard-drive out of the connector.  Make sure that as you do this, it continues to clear the USB end of the circuit board.  Once you have the hard-drive loosened away from the connector a bit, you should be able to carefully wiggle and pull it out of the connector.  Place the hard-drive somewhere safe.

Remove the insulating plate that was underneath the hard-drive and you will see the main boards of the AJB6000.  We need to remove top circuit board so that we can work on the board underneath

This is the tricky bit. You have two options. You can either remove the metal surround by unsoldering all of the tabs around the AJB (shown by the red arrows above, and possibly some more points since I did not try this) and hence gain access to removing the top board, or you can take the easier route (in my opinion) by removing the tabs themselves. I tried bending the tabs vertically, but found the clearance to tight to lift the top board clear.

I ended up removing the tabs, by cutting them with a Dremel tool and metal cutting disc. I thought this would be safer than trying to cut them with sidecutters or bending them until they broke. Your mileage may vary.

Now that we have removed the tabs (or bent them / or removed the metal surround) we can remove the top circuit board.  This is a two step process.  Carefully work the USB end of the board vertically, so that we unplug a large header underneath.  If you look carefully you can see this. 

Once you have the board clear of the header at the USB end, we need to unplug the headphone end by working the board horizontally away in the direction of the arrow below.  Be careful and do it slowly and you will be fine.  Do not force it! but realize that it is a socket and could be tight.  Place the top board somewhere safe.

Now we can see the main PCB that we are going to solder the additional capacitors in parallel to.  I have marked the two output capacitors.  The ends that I have marked are the ends that I soldered the striped end of the new capacitors to.  I'm sure I will be corrected here, but I could find no mention of polarity on the datasheet for the capacitors, and I haven't looked at the datasheet for the DAC, so I blindly followed the orientation shown in a photo by TJ in Yahoo groups.  From memory tant caps do have polarity so it was correct, nothing blew!

I soldered the capacitors back to back.   Make sure that you have the stripes at the same end! (ie they are in parallel, which for capacitance is additive).

Originally I planned to place the capacitors, sandwiched between the two boards.  Unfortunately when I reassembled the boards, it became apparent that there was not enough room.  While I managed to reassemble the AJB, it was irritate in its operation and the top board had a bit of a curve in it from the additional capacitors.  Not good.  I believe that when TJ performed this mod, he had removed some resistors, gaining enough room to place them between the boards.

I finally decided to place the new capacitors at the USB end, where there was room.  Below you can see two of the capacitors in parallel with jumper leads running to one of the output capacitors

Below you can see the finished modification.  Two 220uF capacitors in parallel, for each channel, jumped to the original output capacitors.  I have covered the new capacitors in green insulating tape.  Make sure that they are covered properly, because they are near the power / charging circuitry.  Make sure that you have the striped end of the new capacitors connected to the marked end of the original capacitors. Additionally add some insulation above where you have soldered the leads to the existing capacitors. This is simply a precaution. Reassemble the AJB reversing the disassembly procedures above. Make sure that you seat the top PCB carefully.

Once I had the hard-drive plugged back in I jumpered some power to the AJB to test the mod. In case you have made a mistake it is a lot easier to go back from this point, as you will find out in a moment when you reattach the blue bumpers!

Slide the AJB body back into the metal case, carefully clearing the top blue bumpers.

Now for the tricky bit!  You need to squeeze the blue bumper together so that you can clear the two projections from the metal case, without bending them to much!

You will also need to reseat the base of the bumper into the case after doing this.  Be patient and you won't bend your case!  Finally replace the top cover and all of the screws.

Done .... sorry I did not do the resistor mod, I find the volume fine.  I apologize for the layout of this page, I realize it will take a while to download all of the photos on a modem connection, but I figured more detail etc was better than less.

Appreciate any comments or corrections ... steve@mctubster.com