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I really need help with a POWER question (warning-technical)

post #1 of 12
Thread Starter 
i have a sony d-777 pcdp player that i need help with options on how to power.

here are the existing options:

1) internal NH-9WM "gumstick batteries". they only last a few hours.

2) external battery pack that holds 2 aa batteries. it covers up the line out.

3) power cord. it uses a sony ac adapter AC-E455B output DC 4.5v 500mA. not useful for portable.

now, i would just keep using the battery pack except it covers up the line out (i have an amp on the way).
here are my ideas for powering the d-777:

1) buy more gumstick batteries. at UP TO $30 each this is an expensive option (the d-777 takes two).
---the NH-9WM is the supplied gumstick. the NH-14WM is a longer lasting version, but i have read that the d-777 uses a timer to charge the battery set to the 9WM specs, so it wont charge the 14WM fully. i wonder if after charging the 14WM you could unplug the power cord, plug it in again (reset the d-777's internal charging timer?), and continue charging the 14WM until it is full? also, is it true the gumsticks recharge themselves from the external battery pack when it is attached?

2) buy an external battery pack which connects by wire. this seems like the most obvious option, but i need something very compact.

3) turn the supplied battery pack into an external battery pack. the supplied battery pack has two contacts that connect to contacts on the back of the d-777. is there a way to connect by wire the contacts on the battery pack to the contacts on the d-777? better yet, can i take the power cord, cut off the wall wart and attach the wires to the battery pack contacts and plug the other end directly into the player?

i'm hoping duncan or some electronics expert can help me with this. don't let me spend $60 on new batteries, and even more important, don't let me fry my d-777!!
post #2 of 12
Well, having had my D777 open, I know that it WOULD be possible to re-wire the connectors for the external battery pack so that you could have it running unattached from the main unit.

Yes, it is very true that the NiMh batteries get partially recharged off of the batteries in the external unit!

I'm not overly sure that the D777 does run on a timer... I've charged up my NH-14WMs many times in the D777, and it takes ages to recharge, and the area under the battery compartment gets quite hot... then, the unit runs for between 20-30 hours per charge, which isn't too bad?!

Modifying the external battery pack... no can do, the principle is good, but if you look at the newer players that DO do that, you'll see that as well as using the mains connecter, they also clip onto a secondary connector which uses (so far as I know) a 3v line, rather than the 4.5v line of the standard mains supply... obviously the D777 doesn't have this extra connector

If you're really dead set on doing this, then why can't you get a standard mains connector, plug it into a 4 way AA battery pack (hopefully a parallel version so that you only need three batteries so as not to overload the 4.5v line) - That way you should get the same effect? - As to how long the batteries would last? Hmm... not very long in my opinion

There is one very final thing you could do, if you're a dab hand with a soldering iron, and you don't mind a couple of (THIN!) wires poking out of the side of your D777... but, thats another story.


If you DO open up your D777 to try and modify the external power supply DO NOT move the laser assembly... after 6-7 years, the rubber feet that the assembly sit on are a little perished, and you wouldn't want them to... erm... collapse
post #3 of 12
Thread Starter 
thanks ducan.

what do you think of the idea of simply running wires from the contacts on the battery pack to the contacts on the d777?

also, do you think i can run wires from the contacts on the battery pack to a plug and just plug it right into the power jack on the d777?

both of these option do not require opening the unit up.

thanks again.
post #4 of 12
You could try that, But I don't think that there would be enough surface area on the contacts for a good hold (solder)?

The line out connector is hard-wired onto the PCB as well, so you can't cheat and have that running externally...

The other way that might work if you were desperate for battery power without the external connectors, would be for some very thin, and VERY flat wire to come out of the internal battery compartment, and connect that to your 3v source?

How many hours do you need the D777 to run for realistically between docking it at home?

Thats one thing i'll be glad about when i get my D-EJ1000 next Wednesday, its got a really clever docking cradle... trés cool
post #5 of 12
Thread Starter 
realistically i would have it run 2 to 3 hours before a recharge. the problem is the gumsticks seem to be inconsistant in how long they run. perhaps biting the bullet and just getting a spare set is the way to go. i am reluctant to open the unit, or make any non-reversable mods to it.
post #6 of 12
To me in that case, It sounds like your 1000mah batteries have had their day... Mine, i've treated them with kid gloves since day 1 (luckily i've had my D777 from new) and they still hold 7-8 hours charge.

I can't believe the price of batteries in the US, thats pretty bad considering that I could buy three for every one that you buy
post #7 of 12
Hi Redshifter
I run my Sony 925 from a 5v bat pack regulated to 4v for the cd
[it shares the pack with a dac]

I supply the 4v straight into the 4.5 v transformer jack.
I have never powered it any other way.
This bypasses the infinity super long life[or whatever] power saving circuit but my pack is 3800mah so I dont care!
Hope this may help.

post #8 of 12
Thread Starter 
i've had my d-777 since new as well. any advice on how to take better care of gumsticks? as far as handling them i have used great care. do you know of any uk retailers that will ship gumsticks to the us?

thanks, setmenu. i'm also considering a battery pack, but it needs to be pretty small.
post #9 of 12

All I can tell you about my batteries is that I've always charged, and then discharged fully before recharging apart from that, nothing amazingly out of the normal.

and, ironically, I very much doubt that ANY UK stores would find it viable to ship the gumsticks over to you... for example, if i bought 2 now, that would cost me $20, but then for registered (insured??) post, that'd cost up to (depending on carrier) another $20 to send to you?!
post #10 of 12
Thread Starter 
heh. the cheapest i found in the us is $22 each. with shipping it comes to $51us. still $11 cheaper from the u.k. why, sony, why?

duncan, what does letting the the battery discharge completely do to prolong the useful life of the battery? i read somewhere the concept of battery "memory" is an urban myth.
post #11 of 12
I don't actually know Redshifter...

I know, going back to the days of NiCad batteries that there was a memory effect phenomenon... as to why... who knows? and I guess i've always been wary since then... so, all of my batteries have always been run into the ground before re-charging.

I guess its worked in principle... admittedly now, i use the 14WMs in my D777 but the 9WMs are still in use in my D-EJ825, and they give that about 35 hours of use... so not bad at all
post #12 of 12
Thread Starter 
well, i just sent in my order for the wm14 batteries. oh well, it's only money.

thanks again for all the help!
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