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mix4fix
PostPosted: November 7th, 2025, 1:25 pm 
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I recovered a small portable headphone amplifier. It has no markings on it. I am unable to research it.

It has short male and female 1/8 inch TRS standard headphone cables. It has two lights: a red one when a power supply is connected, and a green one that never lights up. The volume knob that clicks on, and volume goes up.

12VDC wall wart supposedly came with it. When connected., red light illuminates red and green light never illuminates. I tried different 12VDC power supplies.

When I opened it up, it has a batter pack with 5 AAA batteries wrapped together.

My only option is to try considering replacing the battery pack. Five AAA equals 7.5VDC-ish?

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SoundMods
PostPosted: November 7th, 2025, 1:35 pm 
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mix4fix wrote:
I recovered a small portable headphone amplifier. It has no markings on it. I am unable to research it.

It has short male and female 1/8 inch TRS standard headphone cables. It has two lights: a red one when a power supply is connected, and a green one that never lights up. The volume knob that clicks on, and volume goes up.

12VDC wall wart supposedly came with it. When connected., red light illuminates red and green light never illuminates. I tried different 12VDC power supplies.

When I opened it up, it has a batter pack with 5 AAA batteries wrapped together.

My only option is to try considering replacing the battery pack. Five AAA equals 7.5VDC-ish?

This is my best guess. If the batteries are dead, even with the wall wart plugged into it, it may not work. If the batteries are rechargeable and not totally spent (unusable) then give it time to charge.

Otherwise, if the batteries are regular AAA batteries you can replacement them. Or -- remove the batteries and see if the piece will run off the wall wart wart.

I expect that the green pilot light indicates that power is being fed to the circuit -or- that the rechargeable batteries (if that is what they are) are fully charged.

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mix4fix
PostPosted: November 7th, 2025, 1:50 pm 
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It is a battery pack, with five AAA sized cylinders that say AAA on them. They are stacked three and two, to fit in the case. I don't think Batteries Plus would have that pack. I wish it were that simple to swap standard batteries.

I will try that unplugging the battery pack.

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SoundMods
PostPosted: November 7th, 2025, 1:55 pm 
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mix4fix wrote:
It is a battery pack, with five AAA sized cylinders that say AAA on them. They are stacked three and two, to fit in the case. I don't think Batteries Plus would have that pack. I wish it were that simple to swap standard batteries.

I will try that unplugging the battery pack.

You can always buy AAA rechargeable batteries at Home Depot and put together a DIY battery pack.

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Roscoe Primrose
PostPosted: November 7th, 2025, 2:11 pm 
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SoundMods wrote:
mix4fix wrote:
It is a battery pack, with five AAA sized cylinders that say AAA on them. They are stacked three and two, to fit in the case. I don't think Batteries Plus would have that pack. I wish it were that simple to swap standard batteries.

I will try that unplugging the battery pack.

You can always buy AAA rechargeable batteries at Home Depot and put together a DIY battery pack.


If it’s a pack, they may be solder tab AAAs, still easy to come by, but probably not at home depot…. Amazon will have them, and probably batteries plus as well…

Roscoe

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mix4fix
PostPosted: November 7th, 2025, 11:20 pm 
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Went to Batteries Plus. Battery pack is bad - 4.2VDC.

They mentioned a generic battery pack that is 6VDC. They were out of it. Didn't go to any other location.

With the battery removed, and the wall wart plugged in, there is no red light. The next time I am out, I will look for that generic battery pack and give it a try.

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SoundMods
PostPosted: November 8th, 2025, 12:19 pm 
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mix4fix wrote:
Went to Batteries Plus. Battery pack is bad - 4.2VDC.

They mentioned a generic battery pack that is 6VDC. They were out of it. Didn't go to any other location.

With the battery removed, and the wall wart plugged in, there is no red light. The next time I am out, I will look for that generic battery pack and give it a try.

You didn't say if the headphone amp worked at all with the battery pack removed and unit plugged in to the wall-wart.

It is difficult to say what your headphone amp can use in terms of a lower voltage. The 7.2-vdc that it was designed for is only 20% higher than the generic 6-vdc battery pack.

Before spending your money you might want to try jury-rigging a 6-volt battery to see if the headphone is even viable at all.

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mix4fix
PostPosted: November 8th, 2025, 12:55 pm 
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Was told elsewhere that the batteries themselves could be 1.2VDC or 1.5VDC depending on the type of battery.

It red light did not light up with battery disconnected and wall ward plugged in.

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SoundMods
PostPosted: November 8th, 2025, 1:17 pm 
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mix4fix wrote:
Was told elsewhere that the batteries themselves could be 1.2VDC or 1.5VDC depending on the type of battery.

It red light did not light up with battery disconnected and wall ward plugged in.

Good point about the batteries. I forgot that chargeable AAA size cells are only rated at 1.3-volts. I learned that lesson the hard way trying to use them with the camera I used for work.

The camera would "eat those cells for lunch" before I got any real use out them. That's when I discovered Lithium cells.

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