Sony KV-25XBR no picture

[Dave M.]

I have no reception from the tuner, but video-in gives me a picture.

I'm asking if anyone knows a common problem and solution for this so I can
be more prepared at the site.

Thanks.

 

[Art]

Check for all the necessary voltages at the tuner including the +33VDC. Tap
lightly on the tuner to see if there is any indication of probable bad
solder connections within it. Etc. BTW is it a "Snowy Raster" or a totally
blank raster? Snowy will indicate that the tuner is attempting to function,
at least amplification of rf noise is happening. Check for obvious cracked
connections, pc traces, etc.

 

[Dave M.]

I will check for white screen, white screen with RF noise or black screen
and get back to you.

Thanks

--
Dave M.


Most recent retrofit updates and experiments, etc:

http://home.rochester.rr.com/mrdave/mdflamp.htm
http://home.rochester.rr.com/mrdave/mdfdetent.htm

 

[JURB6006]

Do you know how to solder ? And I mean solder well.

Two metal boxes, they got boards in them, take them out and very very carefully
resolder them.

IF in doubt take it in. It's actually one of the cheaper jobs you'll have done
on a TV (in a shop) unless you wreck it trying.

JURB

 

[Dave M.]

-Do you know how to solder ?
-unless you wreck it trying.


Excuse me? I'm a senior tech. I was asking for the typical problem and
solution to save time and hassle, since I'm not bringing my shop to the
repair site. However, I DO appreciate your tip.

Thanks

 

[JURB6006]

Excuse me? I'm a senior tech

Sorry about that, but I couldn't assume anything due to the general nature of
your question.

Actually now that I think about it, the KV-25XBR only has the tuner box. Later
Sonys had an IF box too, and it was a source of considerable trouble. Always
had to solder the pins of the coils. When it gets really bad you might even
have normal snow off channel, but completely black, or white video when a
signal is present. (beat frequency of VCO and carrier swamps composite video
buffers)

The KV-25XBR had the IFs on the one main board. (left side from the back I
think). It is under a shield, but you only need to resolder (maybe), and the
foil side of the board is right there. It is the same thing, resolder the coils
that tune the AFT and VCO, and hit the audio one while you're in there.

You might have a different problem if you don't have normal snow when off
channel or no input. Also I do know where to get parts for those things. I
actually have a signal board complete, but the donor has no picture so I don't
know it's good.

I also have the print for a KPR-4110 which shares the same chipset, and damnear
the layout too, if I can find it I can scan the IF and video switching sections
and email them.

All I can say about that set is before taking drastic measures, like getting a
print etc., is to solder, solder and then solder somemore. Component failures
have been really rare in my realm on these sets.

Dave, you could be a better tech. than me, sans experience on that family of
Sonys. I meant no disrespect, but I can't assume anything. These are excellent
sets and well worth saving. I think soldering has a 90% chance of working.

If not post back here.

JURB

 

[Art]

May we therefore presume that you have checked all the operational voltages
at the tuner and confirmed that they are all there?? If so then the
recommendations of resoldering the probable cracked connections is a viable
suggestion.