AC-Adapter for Battery operated device

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francesco
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AC-Adapter for Battery operated device

Post by francesco » Sun May 18, 2014 10:39 am

Hi, I've been researching this and cannot find any info on this.

I have a label printer that can only work with batteries (eight 1.5V batteries and will not take rechargeables). I have tried various 12V AC-adapters (with a steady 12V output) without any success.

How can I make this work?

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Lenp
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Re: AC-Adapter for Battery operated device

Post by Lenp » Sun May 18, 2014 4:19 pm

If you are using 12v AC output that is the issue.
How many batteries are used 8 would be 12vdc if they are series connected. Check the internal wiring of the batteries to be sure they are not split into different circuits. Also with DC, POLARITY IS CRITICAL Measure the adapter output when properly connected and if it drops too low you need an adapter with a higher current rating.

Len
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francesco
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Re: AC-Adapter for Battery operated device

Post by francesco » Sun May 18, 2014 8:29 pm

Oh yes, I am using 12V DC and one of them had a 4A output. Polarity checked to be correct.

The batteries are all in series and checked wiring (1 wire at each end of the series).

Also, if the batteries and 12DC power is connected the printer turns on and i'm pretty sure it only uses the batteries for power.

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dacflyer
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Re: AC-Adapter for Battery operated device

Post by dacflyer » Mon May 19, 2014 3:43 am

sounds like your jack might be the issue..are you sure it is the right size plug going into the jack ?

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Re: AC-Adapter for Battery operated device

Post by francesco » Mon May 19, 2014 4:45 am

Jack is fine because there is voltage at the circuit board when the batteries are not there.

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jwax
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Re: AC-Adapter for Battery operated device

Post by jwax » Mon May 19, 2014 7:03 am

Perhaps the label maker manufacturer and model number would help. Have you contacted them?

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Lenp
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Re: AC-Adapter for Battery operated device

Post by Lenp » Mon May 19, 2014 8:21 am

Francesco

Whoa! I just realized that you mentioned that the unit will not use rechargeable batteries and later said there was a jack. So, what's the jack for? I'll bet the unit will use rechargeable batteries and that the jack is the charger input but not an operating power source. Plugging the adapter probably disconnects the printer so the batteries will charge. Just hook the adapter directly to the battery springs, be mindful of polarity, to see what happens.

Aside form that at a deeper level, volts are volts and amps are amps, regardless of where they come from. The device doesn't know the difference. You could be missing something unless the printer is really quirky about an over/under voltage condition or maybe the power supply is unfiltered which may not be obvious with a meter. Try adding a large value capacitor parallel to the DC power, or if you have the gear, scope the output and look for big ripple voltage.

Give us the make and model!

Hint:
If the battery spring connection works and you don't want to make a permanent connection just get two plastic or wooden dowels that are the approximate size of the battery. Use a small screw, threaded into the end of each dowel to make the connection to the battery clip and the wire from the adapter. Pop them into the first and last cell positions watching for polarity.
Plastic plumbing pipe works for D and C size and the gray plastic riser tube works for AA and AAA cells in most cases.

Len
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francesco
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Re: AC-Adapter for Battery operated device

Post by francesco » Mon May 19, 2014 10:02 am

Lenp,

I wouldn’t say that it doesn’t work with rechargeable batteries if I hadn’t tried it with fully charged batteries. The typical rechargeable is only 1.2V so that may be a reason why they won’t work.

This unit is a Brother P-Touch 2600. It had a separate circuit board for 12V DC power that fed directly in to the mainboard. This circuit board is now dead, thus, the printer works only on batteries. Besides, if there is a jack, it could be because I added one.

I rewired the DC jack directly to the battery terminal (mindful of polarity). I tried seven 12V power supplies ranging from 1A to 4A. Out of these, the only one that worked was the 12V (17A) output of a PC ATX power supply. While this works, it is not a practical solution.

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jwax
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Re: AC-Adapter for Battery operated device

Post by jwax » Mon May 19, 2014 10:42 am

That labeler may just need a large surge of current, or else it will "stall". Maybe a huge capacitor across your power source?

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Lenp
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Re: AC-Adapter for Battery operated device

Post by Lenp » Mon May 19, 2014 10:50 am

None of this makes much sense!
francesco wrote:Besides, if there is a jack, it could be because I added one
This model has a DC 9.5V jack on the right side!
francesco wrote:it had a separate circuit board for 12V DC power that fed directly in to the mainboard.
Why 12V when the AD60-AD24 Brother adapter is 9.5V?
francesco wrote:12V (17A) output of a PC ATX power supply.
Needing 17A is absurd.

There are big problems in the unit or ...Well who knows!
Len
Len

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francesco
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Re: AC-Adapter for Battery operated device

Post by francesco » Mon May 19, 2014 1:23 pm

Lenp wrote:
francesco wrote:Besides, if there is a jack, it could be because I added one
This model has a DC 9.5V jack on the right side!
Lenp wrote:
francesco wrote:it had a separate circuit board for 12V DC power that fed directly in to the mainboard.
Why 12V when the AD60-AD24 Brother adapter is 9.5V?
Doesn't matter. The DC power circuit board is not working and has been bypassed.

Lenp wrote:
francesco wrote:12V (17A) output of a PC ATX power supply.
Needing 17A is absurd.
That is what I said. The point of that "test" was to see if it works.

Lenp wrote:There are big problems in the unit or ...Well who knows!
I know there is nothing wrong with the printer since it works fine with batteries.


What I don't know is why it will work with a PC's ATX power supply and not with a standard DC power adapter.

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Lenp
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Re: AC-Adapter for Battery operated device

Post by Lenp » Mon May 19, 2014 3:38 pm

When it runs with the atx supply how much current is drawn and is there a voltage drop. Compare that with the other adapters. Make the measurements at the battery terminals.
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

francesco
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Re: AC-Adapter for Battery operated device

Post by francesco » Tue May 20, 2014 5:15 am

I thought when I had tested it a few months ago the voltage did not drop but I just tried to test it now and the power supply detects a short and shuts off. Printer still operates fine on batteries.

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haklesup
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Re: AC-Adapter for Battery operated device

Post by haklesup » Wed May 21, 2014 11:52 am

most common causes would be

1. The jack is not intended to power the printer, only to charge the batteries. This is common with some shavers for example, plug it an and it still runs slow until the batteries charge a little more.
2. in a prior attempt to select a power adapter, you may have tried one reverse biased and blew the reverse bias protection diode near the power input, it may get onto the board but the directed away from the active circuits

francesco
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Re: AC-Adapter for Battery operated device

Post by francesco » Wed May 21, 2014 12:31 pm

haklesup wrote:most common causes would be

1. The jack is not intended to power the printer, only to charge the batteries. This is common with some shavers for example, plug it an and it still runs slow until the batteries charge a little more.
2. in a prior attempt to select a power adapter, you may have tried one reverse biased and blew the reverse bias protection diode near the power input, it may get onto the board but the directed away from the active circuits
How is that possible when the jack is wired directly to the battery compartment output terminals?

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