Display Inop

[Tripple Nickel]

Just picked up a Cobra 25 LTD 40 channel @ local yard sale, dirt cheap, has awesome Mod + Ears. Works great except no signal or light in display. Is it simple fix ?
555 :drool:

 

[Tripple Nickel]

Just picked up a Cobra 25 LTD 40 channel @ local yard sale, dirt cheap, has awesome Mod + Ears. Works great except no signal or light in display. Is it simple fix ?
555 :drool:

BUMP......Let me refraze, the channel display is working as well as the Trans/Rec red/green light. Great operating radio, just no LIGHT/METER not working. I know someone must have had a similar problem, let's hear from you.
555.........

 

[sonoma]

more than likely the bulb is just burned out and the meter is problably sticking. pull the meter out and clean it and there is 2 screws on the pivot point for the needle. sometimes you can just move one of the screws just a little and the meter will work unless the spring is shot on it. one other way to check the meter is take a analog ohm meter and touch it across the 2 terminals on it and reverse the leads back and forth and the meter will swing as you move the ohm meter laeds back and forth.

 

[Beetle]

more than likely the bulb is just burned out and the meter is problably sticking. pull the meter out and clean it and there is 2 screws on the pivot point for the needle. sometimes you can just move one of the screws just a little and the meter will work unless the spring is shot on it. one other way to check the meter is take a analog ohm meter and touch it across the 2 terminals on it and reverse the leads back and forth and the meter will swing as you move the ohm meter laeds back and forth.

If you do this, put the VOM on a high resistance scale. The more resistance in line, the less current through the meter movement. A typical Rx1 range resistor is just a couple of ohms. Use the highest range your meter has.

And don't "reverse the leads back and forth". All you're trying to do is see if the movement has continuity.

 

[sonoma]

If you do this, put the VOM on a high resistance scale. The more resistance in line, the less current through the meter movement. A typical Rx1 range resistor is just a couple of ohms. Use the highest range your meter has.

And don't "reverse the leads back and forth". All you're trying to do is see if the movement has continuity.

if you put a analog ohm meter on a needle gauge it will sweep the needle on the radio meter . this way you will know if it works or not. that is why you reverse the leads so it will sweep the radio meter if it will work.
just like checking a capacitor. you reverse the analog meter leads and it will show if the cap is good or not.

a digital ohm meter will not sweep the radio meter to see if it functions. just check ohms and if the spring is bad it will still show ohms but not work.

 

[Tripple Nickel]

Thank's BEETLE/SONOMA, I was beginning to think no one would reply. In all the radio's I've had since early 60's, I have never opened one up, I just don't trust myself touching something wrong. This is a really good sounding radio and has a lot of audio and modulation. The meter/light does not effect the operation, just wanting to see if it's a simple fix. Do you recommend any kind of electronis spray ? I could do that, all I have is a digital meter with blk/red lead. Any info would be appreciated. 3's to ya.
555

 

[sonoma]

since you only have a digital meter. check for voltage at the bulb and see if it is there. if you look at the top and bottom of the meter you will see a small screw on the pivot of the needle. sometimes you can just take jewelers screw driver and move the screw just a small amount and the needle will break loose. if not you can find new meters from sellers on the sight or on ebay for your radio. the bulb just fits in the side of the meter. does the meter try to move at all in trans or receive? you might be able to shake the meter and see if it will move at all.
just take the meter out of the radio and check it. it is so simple to do.

 

[Beetle]

if you put a analog ohm meter on a needle gauge it will sweep the needle on the radio meter . this way you will know if it works or not. that is why you reverse the leads so it will sweep the radio meter if it will work.
just like checking a capacitor. you reverse the analog meter leads and it will show if the cap is good or not.

a digital ohm meter will not sweep the radio meter to see if it functions. just check ohms and if the spring is bad it will still show ohms but not work.

And if you connect the analog ohmmeter to the terminals of a DC meter, the applied voltage may be enough to push too much current through the coil, thus making what might have been a good meter into a burned-out one. Either polarity. One way should force the needle into the full-scale stop and the other way into the zero stop. UNLESS there's enough resistance in line. It won't "sweep" anything; it'll go from zero to full scale and then to burnout REALLY quickly, depending on the meter sensitivity.

I've worked on enough meter movements to know that yes, you can connect a DC source (such as an ohmmeter) to a meter's terminals, but you need to include a means of limiting the current.

 

[Tripple Nickel]

Good info you two, I won't be poking around anything that would futher damage the meter, maybe a bulb ok. BTW, do you take the TOP off th change the bulb ? I'm hoping it's just stuck, the transmit/receive lights works perfect. Is this a common problem for this Radio?
555