Stalker st9f dx no am audio

[tony2803]

Stalker st9f dx am audio and signal really low even with volume all the way up.
Audio and signal dropped off slowly fm and ssb seem ok.
Anyone got any ideas. Thanks in advance.

[Admiral]

Stick it in your favourite forum 'For Sale' for £30 and keep bumping it to compete with Clive who also has 99% of his posts there, and don't forget to post it this time.

[lbcomms]

The grey 10V electrolytics have died of old age and are going leaky. Eventually SSB will die too and often the ones on the PLL will go as well, bricking the radio. Only way to fix it and make it reliable is to replace all the electrolytics, a.k.a. "recapping" the radio.

They occasionally take out a diode or transistor from excessive current, but 95% of the time recapping will cure all faults in those late 70's / early 80's Uniden board sets.

Very common repair.

[tony2803]

The grey 10V electrolytics have died of old age and are going leaky. Eventually SSB will die too and often the ones on the PLL will go as well, bricking the radio. Only way to fix it and make it reliable is to replace all the electrolytics, a.k.a. "recapping" the radio.

They occasionally take out a diode or transistor from excessive current, but 95% of the time recapping will cure all faults in those late 70's / early 80's Uniden board sets.

Very common repair.

I have forgotten to mention that I have completely recapped this stalker only yesterday ( 8/04/17). The fault started before I recapped it.
All new capacitors are Panasonic 50 volt and purchased as a complete kit.

[tony2803]

Stick it in your favourite forum 'For Sale' for £30 and keep bumping it to compete with Clive who also has 99% of his posts there, and don't forget to post it this time.

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[lbcomms]

I have forgotten to mention that I have completely recapped this stalker only yesterday

It's probably had one of its small diodes go, either as a result of the bad baps or just a coincidence.

Do you have a multimeter with a diode check (forward voltage measurement) function, and preferably an oscilloscope?
First thing to do would be to check the diodes, especially those on the middle part of the board (AM audio and AGC detectors).

Less of a chance, but seen occasionally - those shiny green polyester capacitors with the 3 digit value code on them. We see two or three of those old Uniden radios a year with leaky or shorted examples of those.

[tony2803]

I have forgotten to mention that I have completely recapped this stalker only yesterday

It's probably had one of its small diodes go, either as a result of the bad baps or just a coincidence.

Do you have a multimeter with a diode check (forward voltage measurement) function, and preferably an oscilloscope?
First thing to do would be to check the diodes, especially those on the middle part of the board (AM audio and AGC detectors).

Less of a chance, but seen occasionally - those shiny green polyester capacitors with the 3 digit value code on them. We see two or three of those old Uniden radios a year with leaky or shorted examples of those.

Thanks for your reply, will go through it this afternoon and see if anything is faulty.

[tony2803]

I have forgotten to mention that I have completely recapped this stalker only yesterday

It's probably had one of its small diodes go, either as a result of the bad baps or just a coincidence.

Do you have a multimeter with a diode check (forward voltage measurement) function, and preferably an oscilloscope?
First thing to do would be to check the diodes, especially those on the middle part of the board (AM audio and AGC detectors).

Less of a chance, but seen occasionally - those shiny green polyester capacitors with the 3 digit value code on them. We see two or three of those old Uniden radios a year with leaky or shorted examples of those.

Thanks for your reply, will go through it this afternoon and see if anything is faulty.

As reference to this fault. Someone mentioned a Q1 fault not familiar with this Q1. Can someone enlighten me as to what Q1 actually is. Thanks.

[lbcomms]

A little black thing with three legs. with "C1675" written on the front of it.

If it's faulty, receive will be very low in all modes. As you previously said that SSB was OK, that component will also be OK. Your problem will be elsewhere.

[tony2803]

A little black thing with three legs. with "C1675" written on the front of it.

If it's faulty, receive will be very low in all modes. As you previously said that SSB was OK, that component will also be OK. Your problem will be elsewhere.

Thanks for your reply. Ok found fault TR35 transistor had gone down popped a new one in and everything is ok loud rx audio now on all modes.
Thanks everyone for your help and assistance great help all of you.