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Old 11th Sep 2020, 8:26 pm   #1
IKC2E51R8
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Default Sharp CA10 green blob on screen.

Hi everyone

My Sharp CA10 set did a weird thing ive never seen it do before, Im watching a film on it as we speak and had it paused for a minute, when i went to resume it i noticed that two 3rds up the screen just off centre to the left was a large-ish green blob (as if a Magnet was placed in front of the screen is the best way to describe it) before i could even get off the bed to take a closer look i noticed it started to fade and within id say a minute it was completely gone and the screen back to normal.

Has anyone got any ideas what the cause may be and should I be concerned that something is about to fail in it.

In general this set has been very reliable (unlike its dreaded grandfather the CS chassis) Ive had to replace the Lopt twice in it but other than that its always ran perfect.
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Old 11th Sep 2020, 8:38 pm   #2
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Default Re: Sharp CA10 Green Blob

It just did it again, this time bigger and more towards the left.

In the two pics you can see it in the first one then the second pic is about a minute later and it had faded away on its own
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Old 11th Sep 2020, 9:40 pm   #3
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Default Re: Sharp CA10 Green Blob

Some kind of degauss problem?
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Old 11th Sep 2020, 10:02 pm   #4
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Default Re: Sharp CA10 Green Blob

Set seems to degauss fine, it seems to be coming and going while the set is running, never on the right side only the left, its done it about 5 times now, i shut if off and left it to cool down a bit and ive just started it back up now so I'll see if it does it again
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Old 11th Sep 2020, 10:18 pm   #5
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Default Re: Sharp CA10 Green Blob

Well its done it again this time its much bigger and is only going away slightly if ypu change channels a few times but its not going completly now. Again only on the left side and it develops slowly over a period of about 2 mins.

Theres obviously no speakers or magnets near the set and it ran fine when i used it last weekend just tonight its started doing this. Its strange, never seen a crt do this
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Old 11th Sep 2020, 11:09 pm   #6
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Default Re: Sharp CA10 Green Blob

Sorry for the multiple posts..

Found the fault on eServiceInfo

"green patches/strange colours (usually on bright scenes)"
- CRT shadowmask warping on excessive beam current. Enter service mode, select page 00 and set POS 04 (brightness) to 24; POS 05 (saturation) to 2C; POS 06 (contrast) to 4B"

Ive changed those values to the ones in the solution and theres still no change, unless its something else causing it but it exhibts the same symptom as above.

Could it be the shadow mask warping due to excessive beam current? If so where should i be looking as the aoftware changes didnt help, it must be a component gone bad

Ive noticed its reactionary to scene changes, if the scene changes to a slightly darker scene it begins to fade and then eventually goes away but if i pause it on an image that has a brighter portion on it (for example a white shirt) the green patch begins to form in that area as in the attached pic
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Old 11th Sep 2020, 11:12 pm   #7
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Default Re: Sharp CA10 Green Blob

Seen this once where a set had a fall. The shadow mask must of fell out of it's expansion guides, hopefully that's not the case here.
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Old 11th Sep 2020, 11:16 pm   #8
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Default Re: Sharp CA10 Green Blob

I hope not either but I dont see how it would be possible, its only used on the weekends when i stay with my dad and its never moved or touched. Worked perfect for hours last week without an issue. Right now the picture is perfect but if i pause it it will start forming that blob again
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Old 11th Sep 2020, 11:39 pm   #9
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Default Re: Sharp CA10 Green Blob

I’ve got a Sanyo set from 2003 which does this too, bright areas cause the colours to end up all over the place, but if I switch to a blank channel with a blue screen the colours slowly return to normal. It’s done it from new though, I actually returned 2 of the same model for the fault! Never did get to the bottom of it, I did guess that it was shadow mask warping due to excessive beam current, I thought maybe adjusting the screen pot on the LOPT might help, but never got round to it. Could it be worth reducing the brightness and contrast a bit and seeing if the problem reduces, or goes away?

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Old 12th Sep 2020, 12:23 am   #10
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Default Re: Sharp CA10 Green Blob

Tried turning down the contrast and brightness and turning Optical Picture Control on and off..no change. It baffles me that in all the time Ive had this set its never done this, literally just started behaving this way tonight thats why im thinking a component has failed
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Old 12th Sep 2020, 11:36 am   #11
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Default Re: Sharp CA10 Green Blob

Looking like something has maybe let go that supports and attaches the shadow mask to the faceplate. Beam current is causing expansion and upsetting alighnment more than usual because of it possibly. Replacement CRT i think ...if you can find one.
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Old 12th Sep 2020, 1:08 pm   #12
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Default Re: Sharp CA10 Green Blob

Quote:
Originally Posted by michamoo View Post
Looking like something has maybe let go that supports and attaches the shadow mask to the faceplate. Beam current is causing expansion and upsetting alighnment more than usual because of it possibly. Replacement CRT i think ...if you can find one.
Could that just happen though without any outside force to cause it?

I played another film afterwards and it only did it once in a scene with a lamp in it, other than that the rest was fine, the picture on it is still excellent, the fact that it comes and goes would it more likely be a component failure rather than the CRT itself, if it was the shadow mask would the fault not be constant and affect all scenes rather than just bright scenes?
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Old 12th Sep 2020, 1:10 pm   #13
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Default Re: Sharp CA10 Green Blob

Quote:
Originally Posted by michamoo View Post
Replacement CRT i think ...if you can find one.
I have one you'd be welcome to - trouble is, it's in Madrid!
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Old 12th Sep 2020, 1:17 pm   #14
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Default Re: Sharp CA10 Green Blob

Quote:
Originally Posted by ben View Post
Quote:
Originally Posted by michamoo View Post
Replacement CRT i think ...if you can find one.
I have one you'd be welcome to - trouble is, it's in Madrid!
I Have another CRT of the same type in another CA10 i have in my grandmothers house but im still doubtfull its the tube seeing as its so intermittant.

Having said that I'll bare that offer in mind for the future
Does the one you have use the Philips Tube or the Videocolour one?

I havnt taken the back off it yet or anything to see if theres anything obvious thats happened, wanted to get a few opinions on what it could be before diving in and investigating
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Old 12th Sep 2020, 2:07 pm   #15
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Default Re: Sharp CA10 green blob on screen.

Try temporarily disconnecting the degaussing coils and see if the fault still puts in an appearance, could possibly be a faulty degauss posistor, worth a try,
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Old 12th Sep 2020, 2:45 pm   #16
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Default Re: Sharp CA10 green blob on screen.

agree with steve1010uk advice usually the posistors rattle about when u/s worth trying the posistor first .otherwise duff tube
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Old 12th Sep 2020, 3:52 pm   #17
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Default Re: Sharp CA10 green blob on screen.

I'll try disconnecting the degaussing coil later and i'll play the exact same video on it and see how it does. Really hope its not the tube, not in the mood to have to do a tube swap and then trying to dispose of the other tube would be a pain. Hope it wont come to that
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Old 12th Sep 2020, 5:28 pm   #18
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Default Re: Sharp CA10 green blob on screen.

I have seen that fault as described, it is a problem with the shadow mask. I have seen this more than once, on the sets i had if you slap the front of the screen with the palm of your hand you can sometimes see the fault. Norman
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Old 12th Sep 2020, 5:38 pm   #19
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Default Re: Sharp CA10 green blob on screen.

Quote:
Originally Posted by Norman Raeburn View Post
I have seen that fault as described, it is a problem with the shadow mask. I have seen this more than once, on the sets i had if you slap the front of the screen with the palm of your hand you can sometimes see the fault. Norman
I'll try that once home from work and see what happens and report back, it does sound more and more like it is the shadow mask...
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Old 12th Sep 2020, 7:45 pm   #20
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Default Re: Sharp CA10 green blob on screen.

The early G11's (Philips 660) used to do it all the time. We would tell the customer, "It's a feature - not a fault me dear"
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