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Galaxy DX-2547 No audio

L

Larbian

Member
Nov 23, 2018
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0
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Can someone help me out to where to get started please

This dx2547 powers on with all lights and the meter sits at the low end and bounces slightly. Kind of like no antenna is connected
With stock mic, no transmit, meter does not move. I tried 3 different mic's.
Made in Malaysia after 2000.

I see no evidence that someone was inside trying to modify.
I connected a speaker to the PA and when mic is keyed, it squeals loudly even with volume turned all the way down. Nothing out of ext speaker.

I jumped pins 1 and 3 at the mic connection and the meter jumps. That's all.

Here's the strange part. I disconnected the antenna and when i pushed the center pin in, the meter went up to half way but when I started screwing on the outer ring of the PL-259, the meter drops down to nothing.

I also am having trouble locating the IC8 audio amp but if PA squeals, it wouldn't be the amp right?

Thanks
 
Last edited:

First thing to find out is if the radio is receiving on the channel that's selected.

If not, the radio's PLL has lost its grip on the channel frequency. That alone will inhibit the transmitter. FCC rules require that the transmitter must shut down any time the radio's frequency comes "unlocked" from the channel selector.

If you are not receiving on the selected channel, fixing the radio's PLL will be necessary before you can persuade the radio to transmit.

If the receiver really IS on the selected channel, next thing to do is find another radio and a coax jumper.

Put your second (monitor) radio to the same channel and key the 2547's mike.

You should hear a carrier from the 2547. If you do, the radio may have a failed power stage in the transmitter.

If not, back the outer ring down off the far end of the coax jumper and use the tip of the plug as a "sniffing" antenna. Hold it near the driver transistor of the 2547 and see if you can hear a transmit carrier that way.

What comes next depends on what you find up to this step.

73
 
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Thanks Nomad... I will try these steps this evening after work.

I might also add that using a handheld .... with the PL-259 just inserted in to the 2547 and not secured by the ring, and sitting half way on the meter scale, I keyed the mic on a hand held using the same channel and the meter on the 2547 jumped up to 3/4 of the scale ( sorry I can't remember the meter scale on this unit) and stayed there until I release the PTT on the handheld.
 
please do not let me side track you from doing the tests that nomad is asking for, but i would like to know what the RX/TX LED is doing?

it should be green on receive and turn red when you key the mic.
is that the case?
LC
 
hi loosecannon..... no color change when mic keyed that I noticed but I will pay closer attention and jump the 1 and 3 pin again and see.
 
I have a watt meter that has pep but no dummy load. Tried to make one but didnt work out . SWR on my last base was under one so I would think that it can't be far off with this radio.
 
the RX/TX light should start to tell the story.

if it's green and doesn't change when the mic is keyed, that would point to the radio being out of lock.

if it just goes out, that would point to the RX/TX switching circuit.

again, don't let me distract you from the tests that nomad is asking for.

knowing whether or not you are receiving on the channel you show on the display is important to know.
LC
 
Thanks Loosecannon .... you are not a distraction.

How does it come out of lock?
How to relock it?

Is that from the VCO?
 
Ok Nomad.... using an astatic desk mic, I press the ptt, the green rx light turns red and meter goes up on modulation and can hear the carrier on my hand held along with a slight squeal.
A friend a mile away on channel 13 could not hear me.

The radio frequency counter stayed at 27.115 for 2 hours and once in awhile went to 27.1151. No big deal right?

Still no sound from speaker on rx.
I jiggled everything on the boards

Also, starting out the counter was at 27.1148, so I used the clarified to adjust to 27.115
 
All the below questions are just to establish absolutes not trying to be redundant.

It was not clear that you tested the Public address to make sure it was/wasn't working but I assume it is not?

Using your handheld I assume that you can't see any received signal on the meter of the 2547 when you transmit close to the radio? If you have to just use the center pin on the coax while testing with the handheld

You say a friend a mile away could not hear you but could that friend see a good signal on his end?

Just to make sure: Is it transmitting on all channels at about the same power? at least check 1 and 40 if it's doing OK on 1 and 40 it most likely is fine. small differences between 1 and 40 are fine.

The absolute answers to the above can help to greatly reduce the possible areas to look at.

OldTech
 
The pa when I tried previously with stock mic just squealed. Without thinking I did not try with the desk mic.

Now the stock mic did not turn the tx light red or display any carrier or modulation on the unit meter.

The friend did not see or hear any transmission.
I connected an swr/watt meter inline and and showed no tx at all.

I tried the center pin when transmitting with handheld but nothing on the 2547 meter.

Thanks again for the diagnostic help.
 
I have a Galaxy 2547 it had receive but modulation drops off the meter goes to zero but if I shut the radio off for a few minutes and back on it will modulate and I can talk could you tell me the problem
 
Ok, need a little more to go on...

You "had" receive - ok...

But Modulation drops off the meter goes to zero - ok...

Now I have to stop here a moment - when you unkey, do you still have receive? (You hear stuff from the speaker)

Or...

Does the radio just goes "dark" as in no power? (lights dimming or going completely out - like it's ready to blow a fuse)

One issue is with PLL and / or Regulator overheating...it's a shutdown issue like overheating...a main PCB issue...

The other issue of this problem, is a similar symptom - it's further back, towards the wall outlet - as in the power supply is letting you know it's time to quit. This type of problem is from the MAIN power supply feeding this dinosaur...age is showing...

Not that you wanted it to....
 

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