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Old 23rd Dec 2019, 11:32 am   #21
simpsons
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Richard

This TV is not for the simple hearted and having the Schematic is the next step whilst although Ben said, “making sure it isn’t (just) the Scart connector”, the off screen picture suggests otherwise.

In fact although your thread say GREEN NOT WORKING, the off screen picture post 10 quite clearly shows GREEN TEXT. It also shows RED TEXT so is the blue content of the picture missing from the decoder matrix and video drive or, is it a display problem?

Maybe your test meter will give you some of the answers.

Whilst it might be the electrolytic you mention, its function is unknown unless the schematic is at hand.

In addition, the white lines shown when the set was working, illustrate an over advanced A1 voltage which can only be adjusted in accordance with the service manual otherwise the grey scale will be wrong which would result in black and white pictures being given a coloured tint.

May I suggest you show colour bars on the screen and post them so that the fault can be narrowed down following the green flash. These can be from a laptop connected via the HDMI socket or if using Talk Talk as your internet provider, their Test Channel.

Ask RED to BLACK for a photo copy of the schematic or a scan for all to see so that members can help you further.

Chris
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Old 23rd Dec 2019, 4:51 pm   #22
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Hi Chris, thanks for the reply,

The green text and colour did disappear at first, along with a very bright green dot in the centre of the screen when it was switched to standby via the remote. It came back somehow as then the green text was visible on the screen.

I've got a beta alignment tape with colour bars on it so I'll connect a VCR to the TV and take a photo of the results and post on here.

Thanks again
Richard.
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Old 23rd Dec 2019, 8:29 pm   #23
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Quote:
Originally Posted by simpsons View Post
Ask RED to BLACK for a photo copy of the schematic or a scan for all to see so that members can help you further.
No need to ask me

The manual is available to freely download from Elektrotanya here : https://elektrotanya.com/samsung_s64.../download.html

At about 21meg in size it is not possible to upload here.

This manual may not match Richards set exactly but should be near enough for his purposes, there are many subtle differences between the myriad of suffixes to the Samsung base model number.
The core chassis is usually very similar though, certainly close enough to help with repair/diagnosis, just don't follow the component values verbatim out of the manual, whatever value is actually fitted to the set should be used instead.
Some models have very slightly different features as well.
Still better than nothing with the above caveat born in mind.
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Old 23rd Dec 2019, 8:40 pm   #24
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Ah, thanks for that, Red to Black. I'll take a look at that over the coming days. Firstly I'll need to post a picture of the set displaying colour bars so it will show what's happening.

Thanks again,
Richard.
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Old 24th Dec 2019, 10:21 am   #25
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Richard

Can you confirm the component reference for the bulging capacitor?

Chris

Last edited by simpsons; 24th Dec 2019 at 10:48 am.
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Old 24th Dec 2019, 11:19 am   #26
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Hi Chris,
It's CF04 on the CRT PCB. 160v 10uf 85°c. I received some new caps in the post this morning so later on when I've got some free time I'll install it.

Thanks,
Richard.

Last edited by Snarf81; 24th Dec 2019 at 11:21 am. Reason: Added info
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Old 24th Dec 2019, 6:53 pm   #27
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Default Re: Samsung WS-32Z419D CRT TV green not working.

I've just changed that bulged cap. Not much difference unfortunately.
I've taken pictures of colour bars and a picture with the colour turned off through the osd and it's got a red tint to it still.
I've also taken a picture of what I presume is the red gun SiL IC.

Silly TV!

Thanks all
Richard.
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Old 24th Dec 2019, 7:00 pm   #28
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Default Re: Samsung WS-32Z419D CRT TV green not working.

If the A1/G2 is mis-adjusted this can lead to this sort of problem on this range of sets, as yours developed suddenly with other symptoms though I personally suspect the crt itself.
Do have a look at the manual and in particular the service mode wrt setting the G2.
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Old 24th Dec 2019, 7:54 pm   #29
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Default Re: Samsung WS-32Z419D CRT TV green not working.

The crt will be getting low at that age and normally any adjustments are done through the "service menu" with the original type remote.
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Old 24th Dec 2019, 7:55 pm   #30
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Default Re: Samsung WS-32Z419D CRT TV green not working.

I'm not surprised that the capacitor you changed had no effect as it was decoupling a 12 volt feed to the Velocity Modulator.

Is it me or arn't the colour bars just about correct? I thought the fault was a missing colour!

The grey scale is wrong, that is all.

From the circuit description, there is spot switch off suppression, which I haven't had time to see how it works on this set which may have some bearing on the fault condition but for me to get around the problem just now its an A1 G2 issue.

Does the grey scale alter at different beam current. Viz, light and dark scenes?

The service manual shows how to set the A1 G2 using a scope and also the CRT cathode voltage BUT BEWARE the slightest tweek only will be needed clockwise or anti clockwise from where it is, always looking at a monochrome image. Use correction fluid or similar to mark a reference point to return to.

It is unusual for it to be necessary to make a re adjustment but there you are.

Alternatively, you could leave the A1 G2 adjustment as is and if the grey scale is wrong for light and dark scenes, you might just back off the blue black level BUT make a note of the original setting.

If you are not confident in making adjustments do look up web descriptions of the effect the adjustments make.

Chris
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Old 24th Dec 2019, 7:57 pm   #31
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Quote:
Originally Posted by simpsons View Post
Is it me or arn't the colour bars just about correct? I thought the fault was a missing colour!
My thoughts too.
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Old 24th Dec 2019, 8:20 pm   #32
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Default Re: Samsung WS-32Z419D CRT TV green not working.

The reason I suspect the crt itself was partly due to the suddenness of the onset of the fault, plus the addition of the green flyback lines and "background" type fault posted in earlier pictures in this thread, this was a classic symptom of intermittent H-K shorts on certain Samsung and Philips tubes in the latter years of Crt sets.
I have seen Samsung tubes fail this way in the past.
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Old 24th Dec 2019, 9:43 pm   #33
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Is it just me, or is the purple cast on the greyscale image only showing up in those colours -- black, blue, magenta and red -- that do not contain any green? And if it's not just me, is that significant?
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Old 24th Dec 2019, 11:42 pm   #34
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Julie

You are right. Richard for Blue adjustment read increase Green background.


Red to Black's experience is worth noting and explains the sudden change in greyscale. Let's hope that any adjustments made will last for some time.

Good luck and thank you Julie for seeing my error.

Chris
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Old 25th Dec 2019, 12:09 am   #35
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Quote:
Originally Posted by simpsons View Post
I'm not surprised that the capacitor you changed had no effect as it was decoupling a 12 volt feed to the Velocity Modulator.
That doesn't sound quite right, a 10u 160V for that? I'd have expected it to be for the cathode drivers, in which case it could cause clipping (streaking/bleeding) when defective.

However, since the bars look right, I'd try and adjust the G2 tension and/or the bias settings in the service menu.
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Old 25th Dec 2019, 3:11 am   #36
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Capacitor CF04 does indeed decouple the VM chip, but is for the 142V line, so that explains why it is rated @ 160V.
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Old 25th Dec 2019, 1:25 pm   #37
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Default Re: Samsung WS-32Z419D CRT TV green not working.

The colour bars show that green seems to be ok, on mono it looks like the green cathode bias is too high to me.

Lawrence.
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Old 25th Dec 2019, 3:11 pm   #38
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Default Re: Samsung WS-32Z419D CRT TV green not working.

The problem with these type of RGB output stages is that they sample the cathode current from each gun of the CRT during black level and are a pain to fault find, hands up all those who have had problems getting a simple TDA3562/3566 to output a display.To work correctly everything has to be right including the CRT and the screen voltage setting on some sets is ultra critical, without access to a 'scope it makes life difficult.

My way of tackling it without one would be as follows, it's a bit rough and ready but it might prove a point. As mentioned earlier before you start it's very important to put a precise mark on the position of screen control on the LOPT so it can be returned to the exact original position if you lose the display.

In a darkened room first select a scart input with nothing connected to it and turn the brightness and contrast to minimum, wait until the on screen display disappears so you have a totally blank screen and gradually increase the screen control, usually clockwise until you see a raster with flyback lines. Reduce the screen voltage until the raster is Just extinguished. Also mark the two focus controls and swing them from one end to the other, there should be little or no change but if a raster with flyback lines reappears then there could well be inter-electrode leakage in the CRT gun. Now recheck with a greyscale and see if there is any change.

Don't advance the screen setting too high as you may cause a trip circuit to operate shutting down the set, if that does happen just switch off and reset the pots to their original positions then start again.

John.
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Old 25th Dec 2019, 6:26 pm   #39
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Default Re: Samsung WS-32Z419D CRT TV green not working.

If you are careful a Gentle tap on the crt neck can very often show up a duff crt.
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Old 26th Dec 2019, 6:23 pm   #40
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Default Re: Samsung WS-32Z419D CRT TV green not working.

Hi everyone.
Thank you all for the advice and replies.
I'm going go try and adjust A1 G2 as a few of you have suggested. I can't seem to find where it is in the service manual or on which PCB I should be looking on. As I said before, I'm a total CRT novice. I'll mark the adjustment pots with a thin sharpie pen so I can put them back correctly.

Many thanks
Richard.
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