Uniden BC350A won’t turn on when connected to 12V transformer

[MURSman]

Hi all, I’m new to the site and I have some questions that I best should ask here.

I have a BC350A scanner mounted in a remote location, and I would like to power it off of a 12V step down transformer, the problem is I can’t get the scanner to turn on, despite everything being wired up correctly.

When powered off the regular wall connector, it works fine, but the location it’s at does not have a receptacle for plugging in the wall connector, so I have to use the outputs on the transformer.

Is there some type of switch or fuse preventing it from turning on or something?

 

[mmckenna]

so I have to use the outputs on the transformer.

Describe this transformer in detail.
Got a link, photo or other information on it?

 

[hiegtx]

To add to mckenna's comments, if you just have a "transformer" at your remote location, and nothing else, you're, in effect, trying to run the scanner on AC current, not DC. You need somethingto take the AC output of a transformer, and change it to DC, in order to run the scanner.

 

[10-43]

Your description is rather confusing. It is at least an incomplete description. Outputs on the transformer? What exactly does that mean? Are you connecting directly to the transformer? The output of a transformer will always be AC. The wall wart outputs DC. If the wall wart is heavy, it has a transformer in it and rectifier to convert AC to DC. It may have a voltage regulator or it may not, but the output must be 12 v DC. If you have connected 12 AC to the scanner, it may have damaged it. Does it still work with the wall wart?

If the wall wart is very very light it will not have a transformer, but will have a voltage rectifier and a solid state dc to dc voltage converter.

If the location does not have an electrical outlet, where is your 12v stepdown transformer getting the input power from?

 

[wtp]

AC Adapter (Model AD-140U)
DC 13.8V Power Connector Connect the DC power cable here. Note: Use only the specified AC Adapter or DC power cord.

 

[10-43]

AC Adapter (Model AD-140U)
DC 13.8V Power Connector Connect the DC power cable here. Note: Use only the specified AC Adapter or DC power cord.

.

A photo worth no words.

If you are plugging that into the AC outlet and then to the back of the scanner and the scanner wont turn on, the AD140U is defective and you cannot repair it. But your original description implied otherwise.

 

[wtp]

there are a couple of words on the top of the page..
now we know what the output from the original is.

 

[trimmerj]

Need a rectifier and a filter cap to use a AC xformer for a dc supply. Wouldn't hurt to add a 7812 regulator to the ckt

 

[wtp]

a couple of these should do the trick...

 

[MURSman]

Hey all, sorry for the confusion on context for the transformer.

Here’s a link to the exact transformer. It’s a AC to DC transformer, 120V/240V AC input, 12V DC output.

https://a.co/d/5aBQ69U

 

[jwt873]

How did you connect it? The AC input is obvious, but for the DC output you should be using the V+ terminal and the center ground terminal. (The V- is used for bipolar applications, which you don't need). Also, before using it, I'd be checking with a meter to make sure it is 12V..

 

[RMason]

When powered off the regular wall connector, it works fine, but the location it’s at does not have a receptacle for plugging in the wall connector, so I have to use the outputs on the transformer.

The BC350A only runs off of 12VDC. I assume that the wall connector you refer to is a wall wart (ac adapter) similar to what wtp posted above. If it works with the wall wart, but not the AC/DC transformer you are using, it suggests that there is most likely an issue with either the transformer or the wiring.

Have you measured the output of the AC/DC transformer to ensure it is delivering 12VDC?
Have you verified that the center pin is connected to positive?

 

[mmckenna]

Do you have a volt meter you can use to check the output?

Make sure it's running somewhere between 12.5 and 13.8 volts. There's an adjustment potentiometer on the right side of the terminal strip for adjusting voltage.

Make sure your polarity is correct. Positive must go to the center pin of the power socket on the back of the scanner.

That power supply should work just fine for what you are doing if it's functioning correctly and wired correctly. You'll need the volt meter to determine that.

 

[MURSman]

The wiring is all correct, the wire with the grey dashes is the negative, and the normal colored wire is positive. I don't have a volt meter at the moment that can measure below 120V, but I connected another 12V device to it and it powers it just fine. I played around with the potentiometer and didn't do anything as well.

 

[mmckenna]

but I connected another 12V device to it and it powers it just fine. I played around with the potentiometer and didn't do anything as well.

Without the means to test the output voltage, and based on the low cost of this power supply, I'm going to go with the possibility that it's not functioning correctly.

Until you have a multimeter you can check it with, you might want to disconnect everything and wait.

This is essentially the Baofeng of Multimeters, but it's a place to start:

7-Function Digital Multimeter

Amazing deals on this 7 Function Digital Multimeter at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

If you sign up for their news letters, there's (very, very) often a discount coupon, or they just down right give them away for free.

 

[RMason]

I connected another 12V device to it and it powers it just fine.

Did you use the same wiring to power the other device?

Be sure to check the voltage at both ends of the wiring - at the barrel connector to the scanner as well as at the output of the AC/DC converter

 

[10-43]

The switching power supply requires AC house voltage same as the AD-140U. What is the need for using the switching power supply? Either one is capable of the required voltage and current.

That switching power supply is a shock hazard as long as the AC inputs are exposed. That type of power supply is intended to be housed in an enclosure.

 

[MURSman]

Alright, got a multimeter, and output Voltage is 13.02 Volts DC, and it's also the same at the connector that plugs into the scanner. Input is 119.5 Volts AC.

 

[mmckenna]

Alright, got a multimeter, and output Voltage is 13.02 Volts DC, and it's also the same at the connector that plugs into the scanner. Input is 119.5 Volts AC.

OK, is that with the scanner connected and powered on?

 

[MURSman]

OK, is that with the scanner connected and powered on?

Both on and off. Still not turning on when you turn the power knob.