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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
Vertical Deflection Problem????

 
 


Wiz
User


Sep 20, 2006, 11:23 AM

Post #1 of 10 (4854 views)
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Vertical Deflection Problem???? Can't Post
Hi, I have a TV made by Techwood some company of the dixons group I think. The model number is 28RF1 and the ircuit board number is 11AK45B5.
When I got the tv, it had a single bright horizontal line in the middle of the screen, I though deflection booster chip (stv9379a), so I replaced that and a picture (blue screen).
However, the picture is not correct, the bottom half of the screen is fine, but from just above the centre is a bright line, followed by a more lines above it, in a kinda strip pattern.
Have I bought a faulty chip, Is the input to this chip from the jungle IC faulty or is there another reason for this to occur.
Any help much apprieciated,
Oliver



techchris
Veteran

Sep 20, 2006, 12:57 PM

Post #2 of 10 (4849 views)
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Re: [Wiz] Vertical Deflection Problem???? [In reply to] Can't Post
the 11AK45 is a Turkish Vestel chassis. it suffered from many faults and vertical scan was one. after changing the ic check for two low value resistors by the heatsink next to the flyback tx. I think about 2.7ohm they feed low volts to the scan ic. one or both will be open circuit.you may find the ic is gone again, hopefully not.


Wiz
User


Sep 21, 2006, 12:46 AM

Post #3 of 10 (4831 views)
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Re: [techchris] Vertical Deflection Problem???? [In reply to] Can't Post
I have found the culprit, R614.
It has burnt the colour off, and the schematic I have is too blured to read the correct value.
Would it be 2.2ohms as R611 (the one next to it)
Also what would cause this to happen in the first place, and how likely is it that something simillar happen again?
Thanks,
Oliver


(This post was edited by Wiz on Sep 21, 2006, 1:24 AM)


rrobor
Veteran

Sep 21, 2006, 12:13 PM

Post #4 of 10 (4817 views)
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Re: [Wiz] Vertical Deflection Problem???? [In reply to] Can't Post
Resistors ar just used as fuses so if its 2.2 ohm use that. the usual issues that cause this fault is 1/ zap from he eht starting up feeding back into the vertical via the yoke. check around the ultor cap is clean, other than that its luck. 2/ supply electrolytics drying out causing high voltage at start up. But that IC is a bit crappy to drive that TV so sorry it fails due to being run close to limit, its what one would expect in a portable TV, not this model.


hackman
New User

Sep 22, 2006, 1:22 AM

Post #5 of 10 (4801 views)
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Re: [Wiz] Vertical Deflection Problem???? [In reply to] Can't Post
If it is using 100@35v /100@25v/10@50v/1@50v/47@50v in the vertical area and is older then 8 or 9 years, replace all those caps (with the same values, observe polarity!!!), as said above, the caps dry out, I would use 105c (not 85c) caps, they cost alot more and usually can handle the heat.
Also observe safety when working on the TV, refer the schematic for safety instructions.
J.


Paulpablo
Enthusiast

Sep 22, 2006, 2:51 AM

Post #6 of 10 (4799 views)
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Re: [Wiz] Vertical Deflection Problem???? [In reply to] Can't Post
Hackman just gave you great advice! Run with it ! But I like rorbrs answer,that should confuse everybody !


(This post was edited by Paulpablo on Sep 22, 2006, 3:00 AM)


techchris
Veteran

Sep 22, 2006, 7:46 AM

Post #7 of 10 (4791 views)
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Re: [Wiz] Vertical Deflection Problem???? [In reply to] Can't Post
they went wrong because they are cheap under rated components in a cheap tv.this is how manufacturers keep the costs down. Once changed I have not had a repeat problem on any(yet) so I guess the replacement ic is better quality than the originals used.


rrobor
Veteran

Sep 22, 2006, 8:13 AM

Post #8 of 10 (4789 views)
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Re: [Paulpablo] Vertical Deflection Problem???? [In reply to] Can't Post
So Sorry man, I write with the hope that my reader has been educated.


Wiz
User


Sep 22, 2006, 11:55 PM

Post #9 of 10 (4779 views)
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Re: [rrobor] Vertical Deflection Problem???? [In reply to] Can't Post
I replaced the resistor with the same value as the one next to it (2.2ohms) and it now seems to work correctly.
The board says 2003 on it, so I doubt that the caps would have dried out that quickly. hopefully it will keep working.
Thanks for all your help
Oliver


rrobor
Veteran

Sep 23, 2006, 10:30 AM

Post #10 of 10 (4775 views)
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Re: [Wiz] Vertical Deflection Problem???? [In reply to] Can't Post
Do not ask for advice if you do not wish to take it. Capacitors rated at 85deg jammed next to a heat sink dry out in a year or so, If you dont have an ESR meter you have no way of telling and as the capacitor costs 20 or 30 cents its not worth the risk. But as you know best, good luck with your projects.

 
 
 


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