959 DX GALAXY-NO SOUND

[NZ8N]

Pin 2 and The Cathode of D75 are the same trace. This will only see a voltage
( ~ +8v) if in Transmit mode through R216 (10k), and if TB is not on. This "mutes" the audio amp IC in TX, except in TB, then it unmutes it by Q36 clamping the Mute on TX voltage.

You say C177 is bad? This is the capacitor that feeds the output of the TDA chip to the speaker.

 

[Eldorado828]

Gentlemen, I want to give you all a great big thank you for your help in getting this galaxy back to working.

I'm happy to report that after replacing c177 and a few others around the audio chip, we now have audio in all modes and full functions checks shows we're 100 percent.

Another lesson from the fine folks at wwdx, my gratitude to you.

I had a cap kit that was ordered for a 959 but hadn't been used and was able to rob some caps for the cause. I'm thinking it's probably a good idea to recap the whole board as preventative maintenance. Got an email in to forum member @Klondike Mike today for a 939 kit and said he'd let me know.

Crazy that it's all this little fellows fault!

 

[loosecannon]

congratulations!

always great when you can actually point to a bad component.
that is a strange cap to have go out though.

what year was that radio manufactured?

Im also wondering if that radio spent most of its time plugged in to an external speaker?
and if so, what impedance was that speaker.

i'd like to find out whether we are dealing with a part that got stressed or if we are seeing the beginning of the end of life for the caps used in a certain vintage of Galaxy radios.
LC

 

[Eldorado828]

congratulations!

always great when you can actually point to a bad component.
that is a strange cap to have go out though.

what year was that radio manufactured?

Im also wondering if that radio spent most of its time plugged in to an external speaker?
and if so, what impedance was that speaker.

i'd like to find out whether we are dealing with a part that got stressed or if we are seeing the beginning of the end of life for the caps used in a certain vintage of Galaxy radios.
LC

L.c., I bought the radio about 2 months ago brand new old stock. It wasn't until last week that I took it out of the box, broke the tape and plastic to do a functions check on it when the flaw was discovered.
It came from a wholesaler who said it came directly from Galaxy so somewhere in some warehouse it's been sitting all these years. It's production date is 01/08 so it's a pretty early production for the 939. My guess is the age of the caps or faulty and the factory didn't catch it??

Yes, it's a good feeling when a guy can fix his own stuff. You all were instrumental in it though.

 

[loosecannon]

thanks for that info.

I would say that more than likely what you bought was a radio that was supposed to be a factory refurb, or a factory return that somehow made it back onto the market without ever getting fixed.

if you never saw the radio working since you've had it, i would bet that the cap was bad from the get go.
LC

 

[nomadradio]

That radio is a bit young to need a full re-cap. The "awkward age" when those caps begin to fail one by one is 20 to 30 years, depending on mileage.

Never thought I'd say that a radio made in the RCI Malaysia plant was better in any way, but be thankful it wasn't built in Vietnam. They're still learning how and it shows.

73