Sony KV-1404AS Tuner Drift

[smyback]

kv-1404as

The KV-1404AS is a 34cm Sony Trinitron TV from the early nineties, with a basic OSD and no remote control.

The AS in the model number probably refers to the Australian model? So the basic model is the KV-1404.

It has a problem with "Tuner Drift":
* After changing channel need to manually adjust tuning to get clear reception, but eventually the tuner will drift.
* During channel search the tuner almost locks on to each channel but then continues searching without locking. Unable to program ANY new channels.

Anyone seen a problem like this?
Anyone know where I can find the service manual?

 

[Rope]

Your problem seems to be not in the tuner but in the so called AFC detector network in the IF amplifier. If it is not tuned or broken the symphtoms are exactly the same. I'll search for the shematics and send you with some hints how to check the AFC network.

 

[audio_tv]

Normally the problem is solved changing the capacitors of around the tuner.
Some times it is necessary to change the capacitors inside the tuner.

 

[resgrt]

Change your if(transformer)tuner or adjust .First of all resoled the if and ic.

 

[IQBAL KHAN]

hi all
can you mail me the complete problem i can solve it
private message me

 

[VSMVDD]

this fault is caused by a dirty afc switch

usualy this switch is located on the tunner channel adjusters cover plate
via a nodule of plastic that actuates the switch

so maybe the cover is missing or more often the switch
turns jet black and fully oxidized,

 

[IQBAL KHAN]

hi there do you the schemetic
if not see the lc tuned tnak ckt
it may have number on it like XXX-XXX
JUST REPLCE IT ADJUST IT IT WILL BE GOOD