sony kv-27526--no power


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sony kv-27526--no power

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wane
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Jun 15, 2012, 1:01 AM

Post #1 of 19 (2942 views)
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sony kv-27526--no power	Can't Post

hi all
I am working on this tv and the power supply has no voltages on the outputs.I am getting 161v on the main caps and on some of the parts in the primary side of the power supply.The power supply is on a board by it self shouldn't there be some low voltage on the output while the power supply is disconnected from the main board?Any pointers or help will be appreciated.

jts1957
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Jun 15, 2012, 9:37 AM

Post #2 of 19 (2936 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

Sure about that number? Could the "5" be an "S?" Unimpressed

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Location: Far, Far Away

wane
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Jun 16, 2012, 8:19 PM

Post #3 of 19 (2928 views)
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Re: [jts1957] sony kv-27526--no power [In reply to]	Can't Post

yes you are correct it is an S

jts1957
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Jun 16, 2012, 8:52 PM

Post #4 of 19 (2926 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

http://www.encompassparts.com/..._new/SON/KV27S26.pdf

Check condition of: R607, Q601, Q602, Q501, Q502 & solder joints on T501.

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Location: Far, Far Away

wane
New User

Jun 16, 2012, 11:20 PM

Post #5 of 19 (2922 views)
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Re: [jts1957] sony kv-27526--no power [In reply to]	Can't Post

ok i got it to power up but after 20 mins the screen is losing brightness.
sometime the LED blinks 2 times befor i see a picture and sometimes it blinks 8 times.this is after i press the power button.
where should i look now?
Thank for the help

jts1957
Veteran

Jun 16, 2012, 11:47 PM

Post #6 of 19 (2921 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

Your not saying what you did to restore operation doesn't help.

On a set that old I'd recommend checking ALL boards for defective solder joints, especially at heavy components, plug-in connectors, regulator ICs, and in your case, the CRT filament path.

These are the series of Sony's that have the AKB (IK) circuit that a weak CRT will trigger. (LED will blink until IK circuit is happy and allows picture to appear)

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Location: Far, Far Away

(This post was edited by jts1957 on Jun 16, 2012, 11:48 PM)

wane
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Jun 17, 2012, 12:10 AM

Post #7 of 19 (2917 views)
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Re: [jts1957] sony kv-27526--no power [In reply to]	Can't Post

I replace R607 it was open.I have resolder the power supply,vert and HOR sections already.
This tv has more than two problem.sometimes it will just show a bright blue screen with retrace lines and
shut town

mel
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Jun 17, 2012, 8:08 PM

Post #8 of 19 (2911 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

Cneck the solder joints on the CRT board, especially pin 10 and R1784. If OK, tap the CRT neck the check for an internal CRT short.

wane
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Jun 18, 2012, 11:59 PM

Post #9 of 19 (2904 views)
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Re: [mel] sony kv-27526--no power [In reply to]	Can't Post

I resolder the CRT board no change.R1784 is reading good.I tap on the neck but it had no effect.Am i looking at a bad CRT here?

mel
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Jun 19, 2012, 1:55 AM

Post #10 of 19 (2897 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

The symptoms sound like an intermittent heater to cathode short. You can fix this by isolating the heaters from ground which method is described elsewhere on this site or Google it.

wane
New User

Jun 21, 2012, 11:28 PM

Post #11 of 19 (2876 views)
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Re: [mel] sony kv-27526--no power [In reply to]	Can't Post

the method i find seems to be a temporary fix.I dont want to reaturn the tv to the customer with a tem fix.Any idea what the right way to do this is?

mel
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Jun 22, 2012, 2:08 AM

Post #12 of 19 (2873 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

Isolate the heater from ground and rewire it with two turns of wire around the core of the flyback as described elsewhere in the site. Since it involves modifying circuitry, I wouldn't do it to a customers set without notifying the customer first.

wane
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Jun 23, 2012, 1:58 AM

Post #13 of 19 (2861 views)
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Re: [mel] sony kv-27526--no power [In reply to]	Can't Post

so i have to reconnect the heater to ground using that wire?

jts1957
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Jun 23, 2012, 6:18 PM

Post #14 of 19 (2849 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

Isolate CRT heater pins. (Float them).

Take a wire and connect one end to either isolated CRT heater pin, wrap this same wire twice around flyback core, then connect the remaining end of the wire to the other isolated CRT pin. Wink

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Location: Far, Far Away

(This post was edited by jts1957 on Jun 23, 2012, 6:18 PM)

wane
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Jun 23, 2012, 10:20 PM

Post #15 of 19 (2840 views)
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Re: [jts1957] sony kv-27526--no power [In reply to]	Can't Post

ok that mod work only for the brightness.After 20 mins of playing the blue screen with retrace lines shows up again but not as bright as it was befor,set also did not shutdown like befor.
H1 and H2 are the pins i isolated and reconnect using the wire.
is this screen completly gone??

(This post was edited by wane on Jun 30, 2012, 2:17 AM)

wane
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Jun 30, 2012, 2:19 AM

Post #16 of 19 (2797 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

no hope

Ron.M
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Jun 30, 2012, 5:02 PM

Post #17 of 19 (2783 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

wane;.....

Don't give up just yet...
I'm checking something out....
Need to download service manual & get back to you...
Need 2~3 hours...
You may not have a bad CRT !!!!

Later...Ron.M.... Cool

...
Veteran & Retired TV technician

Ron.M
Veteran

Jun 30, 2012, 6:56 PM

Post #18 of 19 (2773 views)
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Re: [wane] sony kv-27526--no power [In reply to]	Can't Post

wane;....

OK , I now have the manual....
IF you are still interested , I'm willing to try & nail down your problem...
1st thing I'm going to ask you to do is:...
With the set 1st turned on , take readings from connector CN1761 on the CRT module...
Start at pin #1...
When the TV goes to "blue screen with retrace lines" (About 20 mins) take the readings again...
PLEASE post both sets of readings...
THANKS... Smile

...

CN1761=;..
Pin#1=Red Drive
Pin#2=Green Drive
Pin#3=Blue Drive
Pin#4=+9 vdc
Pin#5=Chassis ground
Pin#6=Ik , Do not worry about this pin...

Have a GREAT day & weekend.... Sly

...

Later...Ron.M.... Cool

...
Veteran & Retired TV technician

jayaram_c
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Nov 14, 2012, 3:06 AM

Post #19 of 19 (2520 views)
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Re: [Ron.M] sony kv-27526--no power [In reply to]	Can't Post

hi,

was there any update in this case. I too have the same problem.

http://www.tv-forums.com/cgi-bin/gforum.cgi?post=152071;#152071

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