Sony Trinitron KV-24WX1U no picture.
 

Hi all

I was given this set today by an elderly couple, and was assured it was working. I got it back home, plugged it in and all I'm getting from it is sound but no picture, not even the green OSD. When it's turned on, the corners of the screen flash momentarily but the screen just seems dead. I've had the back off to clean out all the dust and dog hair and I have noticed that the tube is lighting at the base, so I'm assuming the tube isn't dead?

Is this a common fault with these models? What should I check please? Bear in mind that I'm a novice with crt tv's and the only test kit I have is a multimeter currently :-[
I'd really like to get this going as it's a nice size and fits in the dark depths of the corner of my living room.

Many thanks.

Re: Sony Trinitron KV-24WX1U no picture.
 

The A1 diode and safety res can fail , not 100% sure whether on this model or not. Worth a check though.

Re: Sony Trinitron KV-24WX1U no picture.
 

Dry joint on the field output IC? especially it the set has been disturbed. Can't remember the type but I think it may have been in the TDA817x family, look for a small 7 pin Heptawatt package IC.

John.

Re: Sony Trinitron KV-24WX1U no picture.
 

This set has the BE3D chassis fitted, it uses a STV9379 field output chip, IC500.

Re: Sony Trinitron KV-24WX1U no picture.
 

Thanks for reminding me, same type of package though. Refresh my memory but did the ICC9 use a STV9379FS? I'm sure I remember it from some Thomson chassis.

Re: Sony Trinitron KV-24WX1U no picture.
 

The Ferguson version of the ICC9 used the TDA8172 no suffix, it was the ICC7/8 that used a TDA8178F, I am fairly sure this became NLA later and was replaced by a STV type chip with a small Mod to do, I will still have this information somewhere but I would need to dig it out, depending on which/whose kit you bought IIRC some had a few extra bits and gave superior performance, ie. one of the cheaper kits gave fold over and linearity problems (from off the top of my head).

Edit: here you go C/O the TV mag

Re: Sony Trinitron KV-24WX1U no picture.
 

The SONY BE-3D television supports their Error Code service aid and in addition there are Sony Service Tips. Unless you have already done so, I would familiarise yourself with the Service Codes and Service Tips.

You will need the original remote control to access the service menu.

Sight of the service manual is necessary before any work is undertaken in order to communicate to members. This is available FOC through the usual provider.

Good luck

Chris

Re: Sony Trinitron KV-24WX1U no picture.
 

Thanks for the suggestions, I'll get the back off the TV again later today and look for that field output ic and go over the connections.

Chris,
I've downloaded the service manual and tried accessing the service menu with the remote but as nothing is shown on the screen I can't go any further in that respect.

I'll report back later once I've had another look at it.

Many Thanks

Re: Sony Trinitron KV-24WX1U no picture.
 

Hi Richard

Members experience with "stock" faults will be a blessing.

I wonder though if the following can help:

Certain error codes are shown by the LED at the front of the set flashing a number of times.

For example Jungle/chroma no acknowledgement 6 flashes, Multiple devices no acknowledgement 19 flashes.

This is explained on page 29 of the service manual.

Good luck

Chris

Re: Sony Trinitron KV-24WX1U no picture.
 

Hi Chris,

Thanks for the info.
There are no blinking led's, when it switched on the standby light goes out as normal.

I'm going to take a look at that field IC later and re solder any dodgy looking connections.

Thanks

Re: Sony Trinitron KV-24WX1U no picture.
 

Normally if there is Frame fault with these set stby light will flash 6 times
if you are going to check the frame out ic connections it might be a good a
idea to make certain that the boot strap Capacitor is discharged b4 soldering
iron short it to input pin and damage's I/c.
Looking at the Line Output Transformer there are two presets on the back
the bottom one is A1 / Screen voltage Carefully mark how this set now turn it
slightly clock wise , can you now see a dull blank screen please let us know
result
regards Derrick

Re: Sony Trinitron KV-24WX1U no picture.
 

I've had a look and re flowed the joints on the field output IC but to no luck. Still no picture.

Derrick,
The only pre-set I can see on the LOPT is the one pictured. I marked the position and slowly turned it clockwise but still nothing. I've put it back to the original setting. Hmmm.

Thanks

Re: Sony Trinitron KV-24WX1U no picture.
 

I think this is wide screen set , are there two focus controls on the tube base
then the on on the lopts as in picture is one I was talking about
are you able to measure voltage's on the 3 cathodes on the crt R G B
also can up cheek the A1 voltage ( be careful with is one you meter might not
like it ) Hamish Boxer in post 2 makes a point about the A1 voltage . As I do not have circuit digram I cannot be able see how this voltage obtained but let us know what any voltage on the crt base are
regards
Derrick

Re: Sony Trinitron KV-24WX1U no picture.
 

It is a wide-screen set, 24inch screen.

I have a pdf download of the service manual if anyone wants to have a nose at it, and can email it over.

I'll measure the RGB voltages in a little while and post the results.

Where is the A1 diode and safety resistor located please? On the Crt base PCB or the main board?
I'll report back with the voltage readings soon.

Thanks!

Re: Sony Trinitron KV-24WX1U no picture.
 

A1 diode and res , normally main panel near LOPTX. When found check with the set OFF.

Re: Sony Trinitron KV-24WX1U no picture.
 

The voltage on the RGB on the Crt base are as follows.
R 456v AC. 209v DC
G 456v AC. 209 DC
B 456v AC. 209 DC

G1-2, 0v
H2, 0v
H1, 0v
G1-1, 0v
G2, 0v

Hamish boxer,
The picture attached, is that the A1 diode and resistor?

Cheers

Re: Sony Trinitron KV-24WX1U no picture.
 

That could well be the diode and res, it is a long time since I replaced those I must add. See what they read (diode on Diode test range) Res on Ohms' range of the meter. The diode type eludes me and I think it was a Sony special possibly.

Re: Sony Trinitron KV-24WX1U no picture.
 

Rightio, the diode is measuring 1400 on the diode test setting, the resistor isn't measuring at all. It's just reading 1 on all Ohm range settings.

Re: Sony Trinitron KV-24WX1U no picture.
 

Resistor R830 is a 1k 1W fusible resistor and feeds D809 which is type RGP02-20EG23, this is the A1 (Sony calls this G2) supply on the main board from the lopt as in your picture above.
D809 is a high voltage fast acting type, what used to happen is the HV tends to sometimes track across this diode, usually underneath which you can't see until you remove it from the board. Sometimes you can see what looks like a deep scratch/channel on the body of the diode (underside) where the tracking has occurred this is what causes fusible R830 to go open circuit, rather than D809 going short circuit most of the time.

Replacement of D809 and R830 is the only reliable cure, IIRC it was best to leave the replacement D809 stood off the PCB slightly by a couple of mm ie. not pressed fully flat.
I cannot remember now if Sony later changed D809 to a better type.

Edit: C821 is the decoupler/smoother for the A1/G2 supply, I cannot ever remember that blue disc capacitor ever causing any problems in that position on this chassis, nearly always been tracking across the diode itself as the root cause of R830 going open.

Re: Sony Trinitron KV-24WX1U no picture.
 

The diode should read around .6 normally and not convinced the res is a 1 Ohm.Of course possible in circuit readings are throwing up wrong values.
Have a look around the LOPTX and see if you can see anymore diodes , just in case this one goes off to the RGB outputs.
I do not have a circuit or I could identify the correct components for you.

Beat me to it and you do have the correct components and yes , replacement removes all doubts. Not sure whether I still have this diode or not in my old stock.