Stalker IX DX AMC/ALC not working

[13EL121]

Hi friends,
Got a poor Stalker IX DX which I bring back to working condition. Had to replace all electrolytics etc...
But AMC and ALC are at full blast and can not be regulated. Checked all transistors for ALC and AMC but they are OK. Any ideas would be appreciated.
Thanks, Ralf

[13EL121]

Sry double post due sql error. Please delete.

[cb4ever104]

There's a lot of ways to do this Ralf , so you'll need to go through the diagram . I've seen people do some strange things to radios to max these out . The best one was someone put one of the transistors in backwards to disable the circuit

[ch25]

Measure resistance between collector TR48 and emitter of TR33.

[13EL121]

Right friends, will have a closer look and measure some voltages. Have a working Stalker9 here.
This was a poor radio. After some love, rewiring the NB ANL and PA switch and new caps ist working again, but AGC and AMC pots do nothing.
Thanks for the tip of resistance between Transistors. Will check tomorrow.

[astradyne]

Have you checked the A1012 for voltage out? When these go open circuit they usually cause the issue you mention.

[13EL121]

Yes, preowner swapped the 1012 to a BD244 or something, but voltage switching and output regulation via VR in AM FM works.

[13EL121]

Measure resistance between collector TR48 and emitter of TR33.

Restance between both is 3,3k Ohm. Swapped TR48 back to a 2sa1012. Now more SSB power, but AMC and ALC still at full blast.

[ch25]

stalker_ix_dx_sch-unlocked.jpg

There must be something wrong in that area.
Chris

[13EL121]

I hope so Chris.
Strange thing. TR31 measures ok too. Next step are the Diodes. But in circuit they seem to be OK.

[13EL121]

Many thanks guys for the input. Just found the fault. There was a solder bridge near mic Socket. That shorted TR31 i think. I removed the solder bridge and resolderd both points. AMC and ALC now working fine again.
Radio is now back on air and working excellent.

IMG_20191112_210123.jpg

IMG_20191112_210237.jpg

73s Ralf

[cb4ever104]

Good stuff Ralf . I usually learn how individual circuits work when I get those kinds of faults .

[13EL121]

Thanks Paul, it was hardly to see. I cleaned the PCB with isopropyl alcohol, so I could better see the solder joints. It was very nasty, but now it works fine.