Hello

[Jackeeson]

Hello, I'm new here, and have a question.

I have a Galaxy DX2547 Base operating on AC. Everything operates okay, EXCEPT the meter light. I made an assumption that the lamp was "burned out", but when tested, was okay.

All of the LED lights and other lights work. I traced the red and white lamp wire back to the LED board to the pads marked O/P and L+. There is no continuity reading here when the radio is unplugged and I tested with the switch in and out (on and off). There is no power reading here when the radio is turned on.

I was planning to install a LED light in the meter, when I thought it was just a burned out lamp. But now this problem just adds to the mess.

Any ideas?

 

[2NC995]

My schematic reading ability is mighty rusty...but it looks like the L+ should read line voltage(better said, power supply voltage: 13.8) to ground, and the negative is controlled by q402, which in turn is controlled by the dimmer.

Again, very rusty, but I’d be inclined to see if either pad has line voltage to ground, and then check the emitter of q402 against a positive source, with the dimmer in the proper position.

full schematic: http://www.cbtricks.com/radios/galaxy/dx2547/graphics/Dx-2547_sch_main.pdf

And good luck. There’s a lot of folks here with way more knowledge than I’ll ever have, and I’m sure you’ll get more responses.

 

[RT431]

Welcome to the forum.
Hang loose, someone will be along soon to answer your question.

 

[nomadradio]

The side marked "L+" is the main 13.8 VDC power to the bulb.

The side marked "O/P" is connected to the dimmer transistor for that bulb. Won't show any continuity. You can take the wire loose from "O/P" and touch it to circuit-board ground. Not the chassis metal. Not the same ground circuit.

If the bulb comes on bright, the dimmer circuit is the problem.

73

 

[357magnum]

Welcome to the forum ! Enjoy the knowledge .... & the rest that comes with it !

 

[Jackeeson]

Thanks dledinger, RT431, nomadradio, and 357magnum for the welcome and advice!
I read your suggestions, did a little testing, and here are the results:

Labels: Light=Power
No Light=No Power

With the unit plugged in and the power switch off
1. L+ to Ground =Light
2. L+ to + Power Switch Terminal =No Light
3. O/P to + Power Switch Terminal =No Light
4. O/P to –Ground =No Light

With the unit power switch on
1. L+ to O/P =No Light
2. L+ to + Power Switch Terminal =Light
3. L+ to – Ground =Light
4. O/P to + Power Switch Terminal =Light
5. O/P to – Ground =Light

When the dimmer switch is off=no power to light

When the dimmer switch is on=power to light

Multimeter (DCV) between LED board pads and Power Switch Button/Terminal

L+ to + Switch Terminal=Power/Light
L+ to - Switch Terminal=Power/Light
O/P to + Switch Terminal=Power/Light
O/P to - Switch Terminal=Power/Light

 

[357magnum]

Out of my league , but I'm sure one of the Radio Gurus will see this & help . If nothing happens soon use something to start the thread about the radio problem . Hello might get passed over because of the heading . Just my 2 cents . 73 & God Bless , Leo

 

[357magnum]

Sorry I missed it ! Nomads on this .

 

[Jackeeson]

Out of my league , but I'm sure one of the Radio Gurus will see this & help . If nothing happens soon use something to start the thread about the radio problem . Hello might get passed over because of the heading . Just my 2 cents . 73 & God Bless , Leo

Thanks...I thought about that... too late.

 

[2NC995]

If you have power at L+, or as nomad suggested, have an illuminated lamp by putting the other side to DC ground, then you’re good on the positive side.

What I don’t understand from your troubleshooting is this:

”When the dimmer switch is off=no power to light

When the dimmer switch is on=power to light”

Is that not how it’s supposed to work?

 

[Jackeeson]

If you have power at L+, or as nomad suggested, have an illuminated lamp by putting the other side to DC ground, then you’re good on the positive side.

What I don’t understand from your troubleshooting is this:

”When the dimmer switch is off=no power to light

When the dimmer switch is on=power to light”

Is that not how it’s supposed to work?

Yes. Just trying to point out that the dim/tone switch appears to be working properly, at least as far as power going through (i.e., being controlled by) that part of the circuit.

 

[2NC995]

I see. Still not sure I understand 100%, but if someone put a gun to my head and made me guess, I’d be leaning towards Q402.

 

[Recon]

Hello, I'm new here, and have a question.

I have a Galaxy DX2547 Base operating on AC. Everything operates okay, EXCEPT the meter light. I made an assumption that the lamp was "burned out", but when tested, was okay.

All of the LED lights and other lights work. I traced the red and white lamp wire back to the LED board to the pads marked O/P and L+. There is no continuity reading here when the radio is unplugged and I tested with the switch in and out (on and off). There is no power reading here when the radio is turned on.

I was planning to install a LED light in the meter, when I thought it was just a burned out lamp. But now this problem just adds to the mess.

Any ideas?

Just being curious, what is the age of your 2547? My 2547 died at only four-months old. It suddenly lost power as I was monitoring channel 19 on AM.

 

[Jackeeson]

I see. Still not sure I understand 100%, but if someone put a gun to my head and made me guess, I’d be leaning towards Q402.

Good point. Let me add a few details. This CB set is about five years old. I bought it because it was "the last base CB radio made." I have many other radios that I use.

I only turned it on about 10 times the first year. The meter light was always "dim" but okay. When I turned it on this year, the meter light did not work at all. It was not used for last last four years, and was on my display desk with other radios.

I incorrectly assumed the lamp (bulb) burned out. Logically thinking, if you walk into a room, flip on the light switch and the light bulb doesn't work, you just replace the bulb. If that isn't the problem, then you test the switch, fixture,....

When I opened the radio and tested the lamp, it was okay. So then (what was I thinking?) decided that it must be the LED board. So I ordered a new one and replaced it. Every component that worked before is still working. Unfortunately, the meter light did not magically light up.

The transistor that you mentioned is a new one since it is located on the LED board that was replaced. I tested the old one and it is okay.

I should know better than to just replace parts...guessing--even an educated guess with some testing! I am again guessing that there is a short somewhere in the dimmer circuit as nomadradio suggested.

The only other major component left is the dim/tone switch that controls the light. I know electrical components can fail regardless of use or time, but I can't imagine the switch that was only used about 4 or five times failed. This will be my next area of focus.

Maybe a little DeoxIT or CRC will solve the problem on the dim/tone switch! A new one may be worth trying (if warranted) after some more testing/cleaning.

Thanks again for helping and your additional advice is welcome.

 

[2NC995]

I think it’s ok to change parts on your OWN things, as sometimes it’s cheaper than even having something looked at.

Parts-swapping at a professional level is something else all together!

Hopefully nomad or one of the other professionals has some advice for you!