Tv turns off then instantly cuts off help please

Thread Starter

rastaman46

Joined Nov 17, 2011
75
Cap looks fine its just bent.

Where i get schematics from?

There no burn marks or anything like that.

All id does is once back light kicks in tv cuts off

Regards
 

Thread Starter

rastaman46

Joined Nov 17, 2011
75
More if i turn on its never stops turning on and off just constantly doing this

Mesuared voltages against prints on board all fine all matches up

Regards
 

ScottWang

Joined Aug 23, 2012
7,397
If you check the capacitors then you should check their ESR using ESR meter, if you measure the voltage cross on the capacitor then you should using O'scope to see the ripple voltage, if you can see the ripple voltage then the capacitor was damaged.

TVProblem_rastaman46_AAC.jpg
 

MrAl

Joined Jun 17, 2014
11,389
Hi,

Mine did the same thing, it was the low voltage power supply section, the electrolytic caps.

Check the BOTTOM of the caps to see if there is anything leaking out, it may be brown or dark color and dried up already. You need a good flashlight and try to see UNDER the caps at least partially.
Usually the top bulges too but if the bottom leaked it may not bulge.
I had three bad ones and one good one, replaced all four. It works now.
 

Dr.killjoy

Joined Apr 28, 2013
1,196
Hey let try my luck and what's the model number of the tv ???
What kind of TV is this ?? My times when the voltage is corrrect from the power supply there is a problem some where else .. But generally most issue start with the power supply and the Elec caps and the inverter boards and sometimes the caps on the main board...
 

wayneh

Joined Sep 9, 2010
17,496
Mesuared voltages against prints on board all fine all matches up
Then the problem is likely elsewhere. A service manual would help.

Is this a CRT? I don't see any high voltage components, like a flyback transformer for instance. Common failure. The power supply will shut itself down if it detects a fault. With an LCD, the backlight inverter is a typical failure.
 

wayneh

Joined Sep 9, 2010
17,496
Hi i dont have ESR meter all i have is standard meter
Removed all caps mesuared all fine
I recently worked on a power supply. Some of its capacitors appeared to have decent capacitance (I can only take approximate readings with my meter). But using a DIY ESR I built showed that some had a very high ESR, 40Ω versus 1Ω for their new replacements.

My point: You can't judge a capacitor without an ESR meter.
 

Gdrumm

Joined Aug 29, 2008
684
Fuse.JPG On the left hand side of the picture, the fuse looks compromised.
It appears to have been factory wrapped, and that wrap has melted away, or been cut away.
Have you checked the fuse?
Gary
 
Last edited:

ScottWang

Joined Aug 23, 2012
7,397
Hi i dont have ESR meter all i have is standard meter
Before I bought the ESR meter that i only could measured the capacitance as you did, although the capacitance is right, but the internal resistance could be too high, because the Electrolytic liquid was lost a lot, so i had to unsolder the capacitor and replaced a new one to tried.
 

ian field

Joined Oct 27, 2012
6,536
Cap looks fine its just bent.

Where i get schematics from?

There no burn marks or anything like that.

All id does is once back light kicks in tv cuts off

Regards
Probably a transformer with shorted turns on the backlight inverter - a firm called HR does pattern spares of this sort. They started off making replacement flyback transformers for CRT TVs - I've never had a dud from them.
 

bwilliams60

Joined Nov 18, 2012
1,442
You said you measured all your voltages on the output side correct? if you have done this properly, you should have 24v, 12v, 5v and 3v supplies from this connector. The tv will vary by make and model. If these are okay, I suspect you have issues elsewhere. Do you have a backlight if you leave it on in a dark room or is that out as well
 
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