iAudiophile.net Forums


Go Back   iAudiophile.net Forums > Hard Disk Players > Cowon X7

Post New Thread  Reply
 
Thread Tools Display Modes
Old 03-22-2012, 19:50   #1
brianh
Junior Member
 
Join Date: Jul 2011
Location: Sydney, Australia
Posts: 29
Default Info Re: X7's that won't turn on

My X7 has suffered this fate after 2 months in the drawer. After making a phone call, I have some info from the Aussie distributor about this issue that also affects other models (O2, A2 & A3 I think? He also told me that this will appear on their website as soon as he can get to it).

I know there was an older thread on this but as the info is new, I thought it better to put it where it can be seen....

Apparently when the battery goes below a certain level, the device enters "Safe Mode" - in this mode, the battery will only accept charge at 10% of normal rate, hence why it takes so much longer to get to full charge once this happens..... charge, charge and keep charging was the advice given to me, then if that fails, I need to send my unit to them - thankfully just the local distributor - who will attempt a reset with a proprietary COWON program (can't be distributed to customers unfortunately) and if that doesn't work, then the next step is to replace some circuitry to get it alive again.

I am only guessing that this issue is related to these models being HDD units, and the FW being designed to prevent damage to the battery from being over-drained, due to HDD activity when at low charge....... having a "safe mode" would also explain why it won't come to life again until the battery hits a set level of charge - as to whether it's a good design decision or not, well.............

I've been charging my X7 for 12 hour periods over several days. My unit is just out of warranty so I opened it up.... as the charging hadn't worked yet, I wanted to make sure there wasn't a dodgy connector/solder joint or wire loose, and to measure that voltage was actually going in.... (took some pics too) - the battery is currently at 3.60 volts. It's marked as "3.7V 1920mAh" and I was informed it can hold up to 4.2 when fully charged, so I will need to leave it over the weekend and check again on Monday before hitting the panic button. I might also try to measure at what point it comes back to life - assuming I'm that lucky.......

If I find somewhere to load the photos I took, I will post some images of the internals.......I hope the information above helps anyone else who finds themselves in the same situation.....

Last edited by brianh; 03-22-2012 at 19:54..
brianh is offline View brianh's Photo Album   Reply With Quote

Advertisement [Remove Advertisement]

Old 03-22-2012, 20:26   #2
paulr
Senior Member
 
Join Date: Mar 2006
Posts: 438
Default

If you charged it for several hours/days and it's still at 3.6v then either the charging circuit is wonky (i.e. battery is not being charged) or else the battery itself is kaput. If you've got an external cellular phone battery charger you could try charging the x7 battery up with that (it will take a long time because cell phone batteries are smaller) if you can deal with the wirinng. Or use a more serious li ion charger if you have one. If you've got the battery out of the player, can you measure its exact dimensions and any numbers printed on it?
paulr is offline View paulr's Photo Album   Reply With Quote
Old 03-22-2012, 21:14   #3
brianh
Junior Member
 
Join Date: Jul 2011
Location: Sydney, Australia
Posts: 29
Default

Hi Paul,

3.60 Volts is the first/only measurement I have, so I don't have a baseline - given that it was very flat to start with and that safe mode limits the charge rate severely, 3.60V might be an OK figure, I'll just need to keep an eye on it to see whether it changes or not and how fast.

I could easily attach a bench power supply or Li-ion fast charger to charge it faster, but I want to see how the unit responds to charging with the supplied charger first, so I have some data that may be useful for others. The supplied charger is rated at 3.0Amps, so it can only charge at 300mA at the fastest, depending on the voltage drop and design of the charging circuit..... if nothing has changed by Monday, I will be de-soldering the +ve battery wire and charging the battery independently as you suggest, then re-attaching & seeing what difference it makes.

The battery has the following text printed on it:
"BAK 703769P
0G06 7.10Wh
+ 3.7V 1920mAh"

There is also a small QR code that I can't get my phone to scan.

EDIT: Here's the website for that battery - last one on the list...
http://www.bak.com.cn/products2.aspx...teID=47&page=3

Dimensions: 69L ( this includes 7mm taken up by connectors) x 35W x 7D.

The battery seems to be mounted on its own metal bracket that is affixed to the case. I haven't been game to prise it loose or remove it yet, as the wiring is tightly laced *under* the HDD mount..... I want to avoid causing myself any additional problems at this stage......

Cheers,
Brian

Last edited by brianh; 03-22-2012 at 21:44..
brianh is offline View brianh's Photo Album   Reply With Quote
Old 03-23-2012, 00:49   #4
paulr
Senior Member
 
Join Date: Mar 2006
Posts: 438
Default

Do NOT charge a li ion battery with a bench supply. Use a proper charger. That should charge at constant current (say 0.3C) til the cell reaches 4.2V, then constant voltage til the current decreases to zero. I'd advise against soldering to the battery if you can help it too. Just go in through the JST connector (the thing that's likely to be at the end of the wiring). Those connectors are available at sparkfun.com among other places and maybe you can improvise some connection to the one currently on your battery. You may be able to find a replacement cell of similar measurements and capacity at powerstream.com or batteryspace.com.

3.6v open circuit is a pretty low state of charge. Maybe you really do have to send the player in for service.

Last edited by paulr; 03-23-2012 at 00:58..
paulr is offline View paulr's Photo Album   Reply With Quote
Old 03-23-2012, 05:45   #5
brianh
Junior Member
 
Join Date: Jul 2011
Location: Sydney, Australia
Posts: 29
Default

It's OK, I know not to connect to any stock supply - I am aware of proper charging rates for various types of battery chemistry, I am qualified in electronics with many years of field service behind me.... but thanks for the warning, as I hadn't made this clear and you weren't to know from my posts. I have supply gear that allows me to set and monitor both the current and voltage, and if needed I can get my hands on a specialised charger.

The 3.6V I measured was in circuit, I haven't disconnected anything as yet.... The X7's internal layout is battery laid transverse (top end) , HDD laid transverse in the middle, and a stacked double cct board at the bottom end. I've been measuring where the battery wires attach to the top of the stacked cct boards.

I also realised on the drive home that if I were to de-couple the battery and temporarily connect a supply to that point, then gradually increasing the voltage to 4.2V should allow me to identify what the "trigger" point is for restoring the X7 to normal mode - from there, re-connecting the battery should allow the unit to work - and charge - normally again, assuming that the battery is not kaput as you mentioned.

The unit hasn't been used a great deal and it should be fine. It wasn't giving any indication of battery problems, but given the number of "sudden" failures I've seen reported for units that should otherwise be reasonably healthy, one has to suspect the possibility of a bad batch of batteries..... and with the battery disconnected, I could also test it as per specs on the BAK website to confirm its health or otherwise....

I did manage to measure the charging current using the supplied 5V 3.0A wall charger, and at the moment it is sitting at about 2.0mA...... no wonder it is taking so long. I can't discount that this is due to the FW "Safe Mode"'s crippled charge rate, but it still sounds very low...... the supply is at 1.5V above the battery when loaded, there'd also be some drop due to the charging circuitry especially if it's throttling things down..... I'll do what tests I can over the weekend and report any findings.

I'm not discounting that I may need to get it serviced, but given my service background I will be throwing everything I have at it before I reach that point.

Cheers,
Brian

Last edited by brianh; 03-23-2012 at 05:51..
brianh is offline View brianh's Photo Album   Reply With Quote
Old 03-29-2012, 23:26   #6
brianh
Junior Member
 
Join Date: Jul 2011
Location: Sydney, Australia
Posts: 29
Default

Latest update.... I just dropped the X7 off at the distributor for repair (no easy drive, we're on opposite sides of Sydney...).

I charged the battery directly (not through the jack) at 4.2 volts according to the BAK battery specifications. The battery charged up to 4.19V and a few days after disconnection, holds 4.17 volts - so it isn't dead.

After further consultation with the distributor, it seems the main board/FW is preventing the unit from recognising the battery is OK & enabling operation again.

Even though the unit is ojust over 12 months old, I have approached the distributor about having the unit repaired under statutory warranty as it is not fit for its intended purpose - it does not do what it can be reasonably expected to do, i.e. when flat, it should accept being charged and operate again. The distributor is receptive to this and has also mentioned that they have advised Cowon that this aspect of the FW should be removed.... obviously to no avail. If Cowon start getting claims under consumer law that cost them $$ to fix, perhaps they'll reconsider, given that it is probably quite easily addressed by a FW update.

The law I'm quoting appplies to units purchased prior to January 2011 - the post January 2011 law gives even more protection. Please check your individual circumstances.
I'll also post this last para in the other post about this issue, in case no-one sees this one..... Aussie X7 owners should be aware of this approach if they experience this issue as our consumer laws most likely give them protection.

Last edited by brianh; 03-29-2012 at 23:34..
brianh is offline View brianh's Photo Album   Reply With Quote
Old 03-29-2012, 23:42   #7
Enzyme
(A)rrogance (B)reeds (I)gnorance
 
Enzyme's Avatar
 
Join Date: Jan 2011
Posts: 979
Default

great info there m8, cant believe the 2ma charge rate ><

i wonder if the statutory rights in korea are different, for a decent sized company they seem to take a lot of risks otherwise, what with false claims on batteries and lots of dodgy stock, might explain the lack of push into the world market.

would love to get my hands on that cowon program
Enzyme is offline View Enzyme's Photo Album   Reply With Quote
Old 03-31-2012, 02:23   #8
Flip Martian
Member
 
Join Date: Jun 2011
Posts: 140
Default

When mine bricked for the same reason, luckily I'd bought it from amazon. Even though it was several months old, they were prepared to swap it for a new one. Except they had no stock, so offered a full refund with no quibbles. Amazing service. Used the money to buy one elsewhere. No other player like it!
Flip Martian is offline View Flip Martian's Photo Album   Reply With Quote
Old 05-21-2012, 23:12   #9
brianh
Junior Member
 
Join Date: Jul 2011
Location: Sydney, Australia
Posts: 29
Default

Bump - I've just spoken to the distributor here in Aus who has managed to repair my unit under warranty and is posting back to me today. He also advised that the engineers are still working on the issue so we may yet see a fix for this - don't give the X7 away just yet!!
brianh is offline View brianh's Photo Album   Reply With Quote
Old 05-22-2012, 01:18   #10
Flip Martian
Member
 
Join Date: Jun 2011
Posts: 140
Default

Good to know, thanks for passing that on. I wonder if they're working on making the touch screen input more accurate too?! With those 2 things sorted (and after installing 3rd party GUIs), it would be pretty much perfect...
Flip Martian is offline View Flip Martian's Photo Album   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 05:16.



Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.


Copyright © 2006-2014 CrowdGather |  About iAudiophile |  Advertisers | Investors | Legal | Contact