DX-979 Short/Open problem

[SLR_65]

Hi Guys,

Playing with my radio today and when I hooked my new SWR meter up I had no audio when I turned it on. I'm using it as a base so as I moved things around to check connections it suddenly came on. It seems to be working but just missing audio when it happens as the meter reflects noise/signals and if if I key up it does transmit, though talk back doesn't work.

Fiddling with it I found if I press in the on the lower right side towards the back where the power cord and stuff comes in I can make the audio come in and out. I took the cases off, they aren't shorting anything. The speaker wires aren't pinched and the connector is seated. When I press in on that corner I can barely feel it flex and can't really see it move. I don't see anything shorting or opening, I cut the wiring harness loose and still the issue.

About all I can think of is there are some transistors screwed to that side rail and a couple seem to have insulators under them, I wonder if one is shorting somehow when it flexes?

Anyone ever have an issue like this?

Thanks!

Steve

 

[Robb]

The intermittant connection might be the audio chip along the rail; it may need to be resoldered . . .

 

[Sideways]

Are you using, or have you tried an external speaker?

 

[SLR_65]

Bingo Rob!

I took a quick look at the pcb parts placement diagram...IC8 is the audio chip and it was on the rail 2/3 of the way back - right were the problem seemed to be.

The soldering on those leads looked poor to start with, Dairy Queen peaks on all of 'em, and the solder seemed funky, didn't flow well when heated up. I imagine it's some new low lead stuff or something.

I solder sucked them all and put a dab of fresh solder on 'em and the problem is gone!

A quick tip here - a friend of mine is a Pharmacist and he found that a glass medicine dropper tip will fit into a rubber desoldering bulb. In some bulbs you may have to put a wrap of tape around the tip to get it to fit tight. They work GREAT as they are smaller in diameter and fit into tight spaces much easier than the original tip. They also develop a good suction. When it gets clogged with solder just hold a lighter under it and the solder will melt and you can suck it on up into the bulb. Eventually it will break as the temper gets taken out of the glass by the heat, but it takes a while for that to happen and they are cheap and the performance gain they give is worth it.

I got a good deal on this radio, I have a feeling I know why now! LOL! Oh well, no harm, it was a an easy fix...with a little help from my friends!

Thanks again!

Steve

 

[SLR_65]

Sideways - thanks for the input! I was using the internal speaker and I didn't have an external handy, though it was a good idea and I probably would've given that shot during troubleshooting if Rob hadn't made his suggestion.

Thanks guys! You made my night!

Steve

 

[Sideways]

Glad you got it fixed Good tip on the medicine dropper, ill have to try that