I have a sony KV-32TS20, which has worked fine for several years. Of late, it has developed some symptoms
On startp all channels are just snow, and no audio, just disturbance.
After about 5-10 mins, the picture and audio kick in, and everything is fine.
It worked like this for a few months. Now, the audio and picture do not kick in at all, and the TV often shuts itself off.
I have seen several posts on this NG about bad solder joints. I have removed the A board from the TV, but am not sure where to look for bad solders. Several years back I had lost audio on the TV and had to replace the small board piggybacked on the A board. Could this new problem be related in the same area?
This is a very old set. I have not worked on one for many years.
I have had some cold solder connections in the AFC and AGC circuits in this set. This is going by your fault description. The AFC and AGC circuits are mainly in the IF module.
On occasion in some Sony models, I have had some component failures in the AGC circuit that is on the main circuit board. In some models there is an additional stage on the main board. The main part is in the IF module.
When soldering in the IF and tuner sections, the effects of working on them can cause mistuning. To re-alighn these, you will need the proper calibration setup, and the information for it. When I've had big problems in these areas, I generaly changed the tuner or IF modules, as necessary to fix the fault.
To perform any detailed work in this set, you will meed tp purchase the service manual. You will also need the means to follow it up.
Thank you for an informative response.Not being too familiar with the electronics of TVs, is the AFC and AGC circuitery located in the "Jungle" section of the A-Board? I have the Sams service manual, but am not sure where to find the details for the AFC and AGC. Any additional information greatly appreciated.
There should be a metal box next to the tuner that contains the IF and AFC circuit. Usually the bad soldering is on one or more of the coils in that box. You'll have to remove the box from the board to get inside it. Andy Cuffe
Need help with a really strange problem. Watching program in ENGLISH and taping on VCR at the same time. Playback VCR and get Spanish broadcast. Both TV and VCR are Sony products. VCR is a Combo VCR/DVD unit.
Please reply to my e-mail snipped-for-privacy@sbcglobal.net
Thanks for your response. I am a little confused on where exactly the tuner is. The main mother board has a silver box soldered on it. This box connects to the co-axial cable via a banana like connector. Is this the tuner?
The mother board also has three vertical boards mounted on it. One of them is the "A board", which has two silver boxes on it too. Are one of htese boxes the tuner?
Pulling out the vertically mounted "A Board" is simple, but I am not quite sure how to dismantle the whole mother board. If the tuner is mounted on the mother board and not on the vertical "A Board", I will have to figure out a way to dismantle the mother board.
If your TV is worth anything to you, after reading your response, I would strongly suggest you call a service centre that services Sony TV sets.
If you start messing around in the tuner and IF sections of your set, there is a very strong possibility that you will most likely increasing the cost of the final repair, rather than saving anything at all. There are a lot of critical components involved in the tuner and front end. Disturbing them, can effect the calibration of the signal path. To work in the tuner and IF sections, the modules will have to be unsoldered from the main circuit board, to gain access to their internal circuit board, if any soldering is to be done. If there are any defects in these modules that is more than something simple, they are normally changed rather than serviced.
These sets can get rather complex to service, require a lot of experience, training, having access to the proper service information, tools, and instrumentation.
There are also some serious safety issues when working in TV sets.
--
JANA _____
Thanks for your response. I am a little confused on where exactly the tuner is. The main mother board has a silver box soldered on it. This box connects to the co-axial cable via a banana like connector. Is this the tuner?
The mother board also has three vertical boards mounted on it. One of them is the "A board", which has two silver boxes on it too. Are one of htese boxes the tuner?
Pulling out the vertically mounted "A Board" is simple, but I am not quite sure how to dismantle the whole mother board. If the tuner is mounted on the mother board and not on the vertical "A Board", I will have to figure out a way to dismantle the mother board.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.