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Old 15th Aug 2020, 11:59 am   #1
technotel
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Default Realistic Portavision-150 5" colour tv

Hi all
I won this TV and its in very good clean condition.
can any one advise on schematic diagram source? Any info would be greatly appreciated. It has hor hold issue. no adj outside and cant even work out how to get into it lol. Another odd thing, its battery operated as well but no battery compartment that I can see?? I have attached some photos
regard
technotel
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Old 15th Aug 2020, 12:54 pm   #2
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Default Re: Realistic Portavision-150 5" color tv

I think this had a battery holder that clipped ono the back slots - it was quite bulky and heavy, holding ten D-cells!
There were some quite smilar ones by Goodmans and Samsung. The front portion comes off. I think there are a couple of screws underneath and it sort of hinges off - careful of the CRT base! There should be a conventional line hold control and there's also probably a line coil that might just need a slight adjustment.
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Old 15th Aug 2020, 1:40 pm   #3
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Default Re: Realistic Portavision-150 5" color tv

Yes - as Welsh Anorak says, the D battery holder was an additional item that clipped on to the bottom and could be removed when using the TV with a mains adaptor or cigarette lighter plug. Unfortunately it's very unlikely you'll find an original battery box unless you buy another complete TV - but then again these little TVs are practically worthless now, and can be picked up in car boot sales for a pound or two. They're no longer portable since there's no analogue signal, but if you still want to run it on batteries you can buy battery holders and Ni-MH rechargeable batteries to make up your own battery pack, or use one of the small sealed lead-acid batteries, as used in burglar alarms for back up power.

To open it, look for screws hidden underneath the rubber feet. You may also have to pull off the volume / tuning knobs before the case will come apart. I'm pretty sure there will be a horizontal hold adjustment inside, but it may be a coil instead of a potentiometer.

As for the original manufacturer, I was also thinking Samsung but then I noticed it says "Made in Hong Kong". All the old Samsung TVs I've come across were made in Korea so it's probably not made by them. Once you can open it, take some pictures of the chassis - someone on here may be able to identify it.
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Old 15th Aug 2020, 1:58 pm   #4
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Default Re: Realistic Portavision-150 5" color tv

Awesome
Thanks guys. Yes I had decided that it must be a separate battery holder. I removed 2 screws from rear. will look for those screws under the feet. The knobs are proving difficult to remove somehow. Dont want to prise them with screwdriver at risk of marking the case. Thanks again.
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Old 15th Aug 2020, 2:55 pm   #5
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Default Re: Realistic Portavision-150 5" color tv

Try a loop of strong string fed behind the head of the knob, wrap it once around the shaft behind the knob and with the emerging ends on opposite sides of the knob, pull on both ends at once. You may need an assistant (or a spare knee) to hold the set down.
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Old 15th Aug 2020, 3:52 pm   #6
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Default Re: Realistic Portavision-150 5" color tv

I think that set might be clone of a roadstar or I have feeling that there might be a Matsui version , But I never worked on one
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Old 20th Aug 2020, 7:14 pm   #7
technotel
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Default Re: Realistic Portavision-150 5" colour tv

Hi guys
The crt is indeed a Samsung tube. I have adjusted the Hor hold and it actually has a great little pic. I noticed striations though, on left hand side. Why do striations always seem to appear from the left hand side of screen?
I would like to get a circuit for it anyhow.
Any one recognise it from these pics?
many thanks
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Old 20th Aug 2020, 9:11 pm   #8
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Default Re: Realistic Portavision-150 5" colour tv

Quote:
Originally Posted by technotel View Post
Why do striations always seem to appear from the left hand side of screen?
This is due to the fast flyback action, if the damping is inadequate then the flyback pulse (to flyback the scan rapidly to the left hand side of the screen) can cause ringing in the various inductors present at this point, ie. Lopt, Scancoils, line lin coil etc. thus it always appears on the left. The forward scan (to the right) is a fairly slow rising sawtooth wave in comparison and does not usually ring the inductors.
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Old 21st Aug 2020, 9:30 am   #9
technotel
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Default Re: Realistic Portavision-150 5" colour tv

Quote:
Originally Posted by Red to black View Post
Quote:
Originally Posted by technotel View Post
Why do striations always seem to appear from the left hand side of screen?
This is due to the fast flyback action, if the damping is inadequate then the flyback pulse (to flyback the scan rapidly to the left hand side of the screen) can cause ringing in the various inductors present at this point, ie. Lopt, Scancoils, line lin coil etc. thus it always appears on the left. The forward scan (to the right) is a fairly slow rising sawtooth wave in comparison and does not usually ring the inductors.
I guess there is no damping adj for this ? Its been years since I fixed tv sets for British Relay but do recall damping resistors going high ??
Many thanks
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Old 23rd Aug 2020, 1:55 pm   #10
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Default Re: Realistic Portavision-150 5" colour tv

I've had a couple of these sets, & they both suffered with line striations. On mine, I found that some of the problem was capacitive pickup being caused by incorrect dressing of the CRT base leads. Moving them won't totally cure it, but it can sometimes be minimised a little.

David.
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