Sony_Trinitron TV problem!!!

Thread Starter

ranatungawk

Joined Oct 30, 2008
162
Im using old “Sony_Trinitron_KV-2192M3” TV. Since last few days, I found some channels are very unclear or no pictures at all ( see pic 1 to 3 ). Some channels which I watched very clearly (high gain ), can barely watched with shadows (see pic 4 & 5). However I didn’t find any other problems such as “screen width issue issue”, “power off issue”, or TV function problems. So I did following things :

  • Antenna connection (RF) directly connected to the Tuner unit ( BT-EG201) - problem remain same.
  • Tuner was removed from the mother bored and all DRY joists were re-soldered. - problem remain same.
  • Motherboard was re-soldered - problem remain same.

Could you please give me a advice on fixing this ? what should I do next ?
 

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#12

Joined Nov 30, 2010
18,210
The second and third pictures remind me of the frequency of the tuner being slightly out of adjustment. One cause could be in the AGC circuit.
 

bertus

Joined Apr 5, 2008
20,461
Hello,

It looks indeed to a tuning problem.
The sensitivity is low and the AFC is not working correctly.
It could also be there is a problem with the voltage reference (TAA550) of the tuner

Bertus
 

Thread Starter

ranatungawk

Joined Oct 30, 2008
162
Hello,

It looks indeed to a tuning problem.
The sensitivity is low and the AFC is not working correctly.
It could also be there is a problem with the voltage reference (TAA550) of the tuner

Bertus

Does the reference voltage mean the B+ which supply the tuner ????
 

debe

Joined Sep 21, 2010
1,158
Looking at the pictures there appears to be a darker band across the picture. It just might be caused by mains freq in the power supply. If its a smps check that the first electrolytic from the mains bridge rectifier is ok. If its playing up using a DVD player through A/V, then its not a tuner problem.
 

Thread Starter

ranatungawk

Joined Oct 30, 2008
162
In which case - the RF part may be faulty.
Thanks for the advice !! pls tell me, according to Mr debe's comments, can the bad filter cap cause is issue? because i saw B+ voltage go to the RF unit too. however apparently that cap is ok (not get swelled)
 
I think problem is in your tuning circuit which is the out of band of frequency, so it might be a problem of getting clearance. Check with that circuits.....
 

R!f@@

Joined Apr 2, 2009
9,728
Come back after a few hours. I will help you to locate the fault indefinitely.

My god child's graduation is this evening. I will post back after that.

First confirm to me if the problem is there at AV input. Double check with Audio Video Input and post back.
 

Thread Starter

ranatungawk

Joined Oct 30, 2008
162
Come back after a few hours. I will help you to locate the fault indefinitely.

My god child's graduation is this evening. I will post back after that.

First confirm to me if the problem is there at AV input. Double check with Audio Video Input and post back.
thank for your help you sir, there is no any AV input, but only a RF input (antenna- input)
 

R!f@@

Joined Apr 2, 2009
9,728
Seems I have a bit of time to spare.

So this means the fault is at Tuner or IF.

Here is another thing you should do.
Near the tuner there will be an IF pack, Service diagram no, is IF201 / IFB-389

IF Pack is a bit larger than tuner.
Remove it and then remove the shield covering and then resolder every single joint. Do not leave a joint untouched.

Clean the Board with any circuit PCB cleaner to remove the flux, inspect it for solder bridges thoroughly and solder it back.

Remember to clean it and check with a magnifying glass.
Any bridge not removed will cause picture failure and cause more symptoms.

Post back after doing this.

{ed}

I wonder where OP is.
 
Last edited:

loosewire

Joined Apr 25, 2008
1,686
Show a picture with the dvd hooked up,the photo's you have up
all show signal or agc,have you checked with your cable company.
You must have tried an other T.V. on your Input,we don't know.
I would never agree to all the soldering,solder only when you have a
good reason,you will only make more problems.
 
Last edited:

THE_RB

Joined Feb 11, 2008
5,438
It's ripple in the PSU. The Trinitrons have a central caged PSU under the tube neck, slide that out and replace the smaller electros in it but not the very large one.

It's also worth cheking the marked points for the PSU voltages with your multimeter set to AC volts, as this will show ripple.
 

tom66

Joined May 9, 2009
2,595
Usually in these TVs there is a 33V rail which provides power to the tuner. This is used to bias the tuner's varicap diode. Check if this is present.
 

Thread Starter

ranatungawk

Joined Oct 30, 2008
162
Usually in these TVs there is a 33V rail which provides power to the tuner. This is used to bias the tuner's varicap diode. Check if this is present.
Thanks for the advice! I found 12V, B+ voltage goes to the tuner. hope this is the voltage you have mentioned here. can a bad "varicap diode" cause this issue ? could you please see the service manual i have attached herewith.
 
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