[redshifter]

my d777 discman has an external 2x aa battery pack, but it covers the line-out. so i built a battery pack thet plugs into the dc jack on he discman. the pack is 4x aa--is this a problem that i used 4x aa instead of 2x aa batteries? also, i had to guess the red wire was the positive, because it worked when i tested it. would it work if the polarity was reversed? can i be damaging my d777 with this pack?

 

[ppl]

Some Sony portables have an over voltage sensing circuit however i would not risk using over three cells and rechargables at that (lower voltage than Alk) or just find a 2 cell holder
and sleep well at Night

 

[Duncan]

The jack in question runs at 4.5v... so i'm not totally sure that you'll be doing it any favours running at 6v, and probably fewer still running at 3v...

 

[redshifter]

ok, sounds like i should rethink this. so for now, i'm going to use the battery pack only to recharge the gumsticks. i noticed that if i used 3 aaa batteries i would get 4.5 volts. is there a way this could work, or do i always need to run them in even numbers?

 

[Duncan]

You can run with three batteries with no real problem (providing that they're alkaline / lithium... lets not forget that using rechargeables will only give you 3.6v from three cells - or (rethinking myself) 4.8v from four cells...)

You'd need to know the drain characteristics of the batteries (example - lithiums hold their peak voltage a lot longer than alkalines) and, more importantly - what the voltage rise / fall at the jack will do to the player...

Do you have one of the [Sony] 4.5v DC adapters, so as to measure the voltage swing? - if it peaks at 6v, and drops as low as 3v when under load, then you could use your four AAA cells with no problem at all... and your initial thoughts would be perfectly fine...

(I guess, the other alternative is to work out a clip for a 3v battery pack to clip onto the brass contacts that the normal battery pack connects to, rather than using the DC input?}

 

[redshifter]

thanks, i've been thinking of a way to use the brass contacts, but nothing elegant has come up yet. i'll check the voltage of the sony wallwart with my multimeter tonight. the other option would be, is there a circuit i could put inline in the power line that would regulate the voltage, sort of like a power resistor?

 

[redshifter]

i have a preliminary d777 mod i'm considering. please let me know if you think this will work.

i am going to install a 2nd power jack inside the unit, which will come out the hole in the back where the d777 battery pack normally latches on (on the left). this plug will then be attached internally to the wires that lead to the brass battery contacts. this way, i can use an external 2xaa battery pack and not have to worry about voltage fluctuations. what do you think?

 

[stereth]

If 2x AAs work just fine, you could rewire your 4xAA holder to a series-parallel configuration. Same voltage as two batteries but twice the life.

 

[Jahn]

2 AA should work just fine - I had an AIWA batterypack with that config and it snaked right into the jack perfectly - could use it and the line out at the same time and the D-777 sounded perfect.

 

[redshifter]

Quote:

Originally Posted by Jahn 2 AA should work just fine - I had an AIWA batterypack with that config and it snaked right into the jack perfectly - could use it and the line out at the same time and the D-777 sounded perfect.

really? because i was worried that 3v into a 4.5v jack would harm the electronics.

i may try that, stereth, if it turns out using the power jack is ok.

 

[Jahn]

Yep, a nice clean sound - no smoking or fussing at all coming from the D-777. But then again this was a Aiwa battery pack made for the minidisc player I used to own - maybe it had something going on inside it that helped convert or something, i'm no genius when it comes to that.