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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
Need help Sharp 21V-K200S wont turn on

 
 


dboy23
Novice

Feb 6, 2008, 9:36 AM

Post #1 of 7 (169 views)
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Need help Sharp 21V-K200S wont turn on Can't Post
Hello TV experts,
My TV wont turn on (stby only). When I turned ON the main power botton, the led is on red (standby) and when I turned ON the power on the remote, the led is green for a few seconds only and then it goes back to standby (led red). I need to turned off and on the main power button before I can change the led to green (but for a few seconds only). I checked the board, I found out that the vertical IC have cold solder, I resoldered it and still the prob occurs. Pls help what other parts/components to check. Thanks in advance!
Note: when the led is on green (few seconds only), no picture on the screen and sound.



dboy23
Novice

Feb 7, 2008, 12:02 AM

Post #2 of 7 (159 views)
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Re: [dboy23] Need help Sharp 21V-K200S wont turn on [In reply to] Can't Post
I also noticed that there's a humming sound on the transformer when it is still on standby mode. Anyone here have diagram of this model 21V-K200S?


dboy23
Novice

Feb 29, 2008, 6:55 AM

Post #3 of 7 (127 views)
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Re: [dboy23] Need help Sharp 21V-K200S wont turn on [In reply to] Can't Post
I already have TV diagram (pls see attachments, power supply only). And I found out that R511 (1.5 ohms near FBT to 24V Vcc of Vertical IC) was open. After replacing this resistor, then turning on the TV, this resistor burned. I tried to remove the vertical IC and replace again the R511 resistor and check the 24V Vcc line of this IC and I measure around 30V instead of 24V (note: CRT is detached to the board when measuring). Anyone could explain why I measure 30V instead of 24V when vertical IC was removed? Does vertical IC influenced the FBT input? And also 185V (YBN1) is only 100V. Pls advise.

Note: 115V and 12VA on the 1st page are already ok. IC751 input and output are also ok.

I dont know how to upload the sch in this site.
pls download the sch here-->
http://www.tv.quuq.org/forum/index.php?topic=734.0


techchris
Veteran

Feb 29, 2008, 11:47 AM

Post #4 of 7 (122 views)
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Re: [dboy23] Need help Sharp 21V-K200S wont turn on [In reply to] Can't Post
the voltage was higher because it was not under load conditions .check the diode in series with the resistor is not short circuit.did you change the ic anyway?


dboy23
Novice

Mar 1, 2008, 5:40 AM

Post #5 of 7 (116 views)
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Re: [techchris] Need help Sharp 21V-K200S wont turn on [In reply to] Can't Post
Thanks techchris!
The diode is ok. I will buy and replace this vertical IC.
Do you have an idea about the 100V instead of 185V on YBN1?


rrobor
Veteran

Mar 1, 2008, 10:07 AM

Post #6 of 7 (114 views)
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Re: [dboy23] Need help Sharp 21V-K200S wont turn on [In reply to] Can't Post
The set will have blanking if there is no vertical as a means of protecting the tube so wait till you fit your IC before you start looking for other things. Also there is always a voltage doubler in the vertical this is 1 diode and an electrolytic with a range from 68uF to 100uF change that, also make sure the tube is clean from the ultor cap to the yoke.


dboy23
Novice

Mar 7, 2008, 12:58 AM

Post #7 of 7 (86 views)
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Re: [rrobor] Need help Sharp 21V-K200S wont turn on [In reply to] Can't Post
after replacing the vertical IC and R511, the TV is now OK.
YBN1 voltage is now 185V when the board is connected to the CRT (if not connected, it is still 100V).

Thanks to techchris and rrobor and to this site!

 
 
 


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