Cobra 25 NW ST Power Problem

[Scott45]

I Have A Cobra 25 NW ST That Look Like It Is Not Getting The Right Amount Of Power. The Radio And Meter And Channel Readout Is Very Dim. I Checked The Dimmer Switch And It Is Ok. There Is 13.8 Volts At The Back Of The Power Plug Where It Comes The Radio. Does Anyone No What The Protection Diode Is In This Radio And How To Check It, Or Have Any Suggestion On What To Try.

 

[dudmuck]

I Have A Cobra 25 NW ST That Look Like It Is Not Getting The Right Amount Of Power. The Radio And Meter And Channel Readout Is Very Dim. I Checked The Dimmer Switch And It Is Ok. There Is 13.8 Volts At The Back Of The Power Plug Where It Comes The Radio. Does Anyone No What The Protection Diode Is In This Radio And How To Check It, Or Have Any Suggestion On What To Try.

The dimmer is VR406, a pot (variable resistor).

You should see your 13.8v on one side of it. There is only pcb trace, wire and a inductor (T2) to the dc power connector. There isn't anything to protect this pot from over current. If the s-meter bulb can take 13.8volts, then try temporarily short the wiper of VR406 to the 13.8v side, if you see full brightness, then the pot is bad.

Not sure myself what "Getting The Right Amount Of Power" means. but you can also check for your 13.8v volts on the collector of TR18, or where R97 & 98 join. also pin-1 of IC1 TA7222.

 

[Scott45]

I Hook Up The Radio To Check Some Of The Stuff That You Have Listed. When I Hooked Up The Radio, It Worked Fine Everything Was Working. I Talked On The Radio For Three Hours And Everything Worked Great. I Don't Know, I Never Saw This Before. Thanks For Your Help And Reply

 

[Switch Kit]

So this means your problem went away ?

 

[loosecannon]

im gonna guess this is happening in a vehicle and say that the problem lies with the vehicle, not the radio.
loosecannon

 

[Scott45]

Yes Switch Kit The Problem Went Away And Loosecannon I Was In The House. I Got A Few Radios In A Trade And I Was Trying Them Out. That Was The Only Radio That I Ever Saw Do That. But The Radio Is Working Great Now With No Problems.