Galaxy dx2547 modulation limiter location

[KneeBiter]

Picked up a dx2547 that I believe someone removed the limiter as it is way over modulated in AM and SSB with mic gain up. AMC and ALC pot has no effect. Any pointers where to look for a snipped or removed component? Model with switching supply and mosfets ept069611a. Looks like q57 is missing. Could that be it?

 

[Eldorado828]

Q39

 

[Eldorado828]

Then here I believe @ r264 some do a resistor diode combo mombo for swing.

 

[KneeBiter]

Then here I believe @ r264 some do a resistor diode combo mombo for swing.
View attachment 62240

R264 and q39 are both in place.

 

[Eldorado828]

Are the resistors next to ic7 the stock values(r176,r178)? There's a audio mod done there too.

 

[KneeBiter]

Are the resistors next to ic7 the stock values(r176,r178)? There's a audio mod done there too.

They are stock. Looking at the trace side everything looks clean. No hacked solder work to point me. Just where the board is marked q57 looks a little like melted Flux but clean and there is no q57 in place.

 

[KneeBiter]

They are stock. Looking at the trace side everything looks clean. No hacked solder work to point me. Just where the board is marked q57 looks a little like melted Flux but clean and there is no q57 in place.

Looks like q57 should be there and is supposed to be a 2sc945. I'll put one in and see what happens.

 

[Shadetree Mechanic]

Vr 16 is the modulation limiter adjustment. Q57 and associated components make up the modulation limiter.

 

[Eldorado828]

@Shadetree Mechanic nails it, it's gotta be it.
Hmmm was the perpetrator trying to hide his bad practices by choosing a component that was less obvious?

 

[NZ8N]

I used to see 4, 6, or 7 components cut or removed in a lot of radios when I was working for a shop. I put the components back in and repeaked the radio by scope pattern. We called these other shops "Chop Shop CB Shops". My contention was, it's like a dog on a chain. if the chain breaks at the beginning, or the middle, or the end, the dog gets loose, and digs up the neighbor's yard. Again. Why break the chain in 5 places? They copy off of each other.

 

[Handy Andy]

ALC is SSB side, so there may be one more mod you'll have to locate...

The Q57 is AMC - not ALC - so if ALC is affected, look for more work...

Like Q50...see if it is there...

C174 and D78 - By Q57 (your missing part) would be also suspect.

 

[NZ8N]

The EPT0696 boards are after my time, I used to see similar in EPT3600 and the RCI 2950 (1st gen and 2nd gen) before the DX series came out.

These are the components I would see cut or removed in any combination. Or desolder one leg. Or the equivalent from the earlier boards.

 

[KneeBiter]

View attachment 62246

The EPT0696 boards are after my time, I used to see similar in EPT3600 and the RCI 2950 (1st gen and 2nd gen) before the DX series came out.

These are the components I would see cut or removed in any combination. Or desolder one leg. Or the equivalent from the earlier boards.

I put a 2sc945 out of an old washington 8719 parts chassis I had. Fixed the AMC. I tried the ALC pot and it is in fact working. It just doesn't have the adjustment that I am familiar with. It's almost like it does nothing the first 3/4 of the way then its on. Kind of the same with ALC. But they are working now. I was told by my buddy in California that I received this radio from that it had the work done at a very reputable shop who's name I will not mention from Southern Cali. Channel mod is clean. Clarifier mod is clean. Nothing else seems to be tweaked so I think we are good now. Will see what locals say next time they are on. Thanks for the help.