Three stones Minibox Es battery won't charge
May 12, 2015 at 10:31 AM Thread Starter Post #1 of 17

Ironnick23

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Hey guys. So I have a minibox es and the battery has died. I got a replacement and installed it exactly how the original was v+ v- g. (Red,black,white wire) but it doesn't work unless plugged in.

The orange charge light indicator was working but would shut off, now doesn't come on at all. I may have shorted it.

When I plug it into the ac adaptor and not in the wall the red led comes on, indicating there is a charge in the battery and the wall wart is working.

When plugged in and turned on the blue led light comes on but not the orange and I can use it, but the plug is very susceptible to being in the wrong position and shutting off.

I let it "charge" overnight following instructions elsewhere on this forums but the amp will not turn on without it being plugged in.

I've resoldered joints, and visually inspected it and can't find the issue. I'm very handy with a solder iron but a voltage meter is not my strong suit, I'm looking to repair this thing so I'm not stuck plugging in. What can I do to find where the short is or identify where the problem is located?? Please help
Thank you
 
May 12, 2015 at 11:45 AM Post #2 of 17

cdsa35000

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http://anythingbutipod.com/2009/10/three-stones-miniboxe-review/


Its 18V battery and probably the black and white wire are wrongly swtiched/connected, just switch position.
Use multimeter voltage to measure the amp without the battery, the output V+ = must be around 19-20+V to charge the 18V battery.
 
May 12, 2015 at 6:42 PM Post #3 of 17

Ironnick23

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Okay, so I replaced the orange led with one the same size and color. Now it indicates when its charging again... but still shuts off after a couple minutes. 
 
It is wired like in the photos of the amp in another thread, and on the board it says +(red) -(black) G(white).
http://www.head-fi.org/t/595034/minibox-e-battery-replacement
 
I did try swapping the wires but that didn't work I think. When the wall wart is plugged in the amp but not the wall the light still comes on red, but shuts off when i turn on the amp as opposed to the issue the guy in the thread i quoted is having. 
 
It is x4 3.7 li-ion batteries wired in parallel? I am going to check the connections on all these wires. I bought a pack of 10 batteries so I wanted to attempt this fix myself instead of sending it in. 
 
May 12, 2015 at 9:03 PM Post #6 of 17

Ironnick23

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from wikipedia:
 
"Sometimes one of the power-supply pins will be referred to as ground (abbreviated "GND"). In digital logic, this is nearly always the negative pin; in analog integrated circuits, it is most likely to be a pin intermediate in voltage between the most positive and most negative pins[citation needed]."
 
this being the case, I have wired my 4 li-ion batteries properly to themselves and to the board. 
 
May 13, 2015 at 2:01 AM Post #7 of 17

cdsa35000

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Wait, Did you pry open the original battery pack and using the exact same specified 3.7V Li-ions?
And there 3 wires should be connected to a little Charging Controller PCB board inside the pack, the V- wire is probably the batt. condition/(dis)charging detector/controller.
Battery have only to do with V+ and GND, That detector logic controller decide to (dis)enable (dis)charge the whole battery!
 
May 13, 2015 at 2:15 PM Post #9 of 17

Ironnick23

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I didn't not see a charging pcb board inside the old batteries. Just +\- points on each battery. And wires connecting them in a open circle leaving one negative wire, one positive, and a white from the middle of the batteries to be attached to the amp
 
May 13, 2015 at 3:51 PM Post #10 of 17

cdsa35000

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If not working then not compatible as the origina
Very simple those are crappy Li-Polymer battery, totally different than original round batteries and maybe need different charging logic on printboard and can't be connected/charged to parallel as the original!

Show the pics of the original battery pack opened!
 
May 15, 2015 at 8:55 PM Post #11 of 17

Ironnick23

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Image 1: what is left of the original battery. It is tsy552533 400mAh 3.7v
just 4 batteries wired to themselves with three wires that run to amp

Image 2: New battery wrapped in yellow electric tape. These came with a positive/negative wire attached to each one, I connected them in the exact same manner as the original. 

 
edit: ps. I had to go rummaging through my garbage to get you this pic, I have a modified iPod 5g with blackgate caps, lod, and 120gb sd card. and I modified my sr225i's with a gold grill and antique mahogany..It has been a long time in the making, and I am very eager to get this amp running!
 
May 16, 2015 at 3:54 AM Post #12 of 17

cdsa35000

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What so difficult about this, its not rocketscience, so simple serial battery wiring.

measured voltage from black and red wire is 16.85 and from black to white is 8.5.  

Seems the amp do gives charging voltage, so if leave connected to the battery for few hours, battery should charged and gives14.8V reading.
Possible faults.
1) amp charging logic defect, no charging (ca. 50mA?) current is flowing through batt. , use [mA] multimeter in serial in the batt. chain to measure charging current.
2) batt. pack not good.
3) amp powering circuit from battery entry is defect.
 
May 16, 2015 at 4:48 AM Post #13 of 17

cdsa35000

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This new diagram is more accurate, the opamp is using separated V+, V- and GND ref voltages, so if you measure the voltage correctly.
The multimeter MINUS probe stay to the GND amp point and use the PLUS probe to measur points V+ and V-.
The readings should be with amp power ON, V+ = +8.4V and V- = -8.4V makes total if measured from V- to V+ = +16.8V

With good charged batterypack only the readings: V+ = +7.4V and V- = -7.4V makes total if measured from V- to V+ = +14.8V and the amp should power up!

2n6stbr.jpg
 
May 16, 2015 at 8:58 AM Post #14 of 17

Ironnick23

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Amazing diagram, thank you! Process of elimination, right? When I get home I will double check but I am pretty certain I have the batteries connected in this manner. The wires to the amp are done so like your first diagram. I'll have at it with the multimeter and see what I can find
 
Jun 7, 2015 at 6:34 PM Post #15 of 17

Ironnick23

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I followed your diagram to the T. Wired them up, the multimeter is giving me 16.8 from positive to negative and 8.5 from positive to the middle wire (ground). I have reconnected the batteries to the amp, and the charge indicator light is on. I will follow up after 5+ hours to see if it did anything 
 
 
edit:
Orange light goes off (indicating its fully charged because it is) Turning on amp when plugged in works fine, but when unplugged doesn't power on with the batteries...
This has been my problem from the beginning, and it appears the batteries are fine
 

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