CRT tv blowing fuses after clean

[guskenny83]

Hi,

I opened up an old crt TV today and it was covered in dust, so i got a can of compressed air and gave it a blast. However i accidentally had the can horizontal for part of the time and liquid came out creating a freezing effect..

Now when i turn it on the fuse next to the giant capacitor keeps blowing.

Is there anything anyone suggest i try to fix it? Or have i just ruined it?

Ergh. So stupid.. the air didnt really clean anything anyway!

 

[dorke]

1.First thing to do is take a small 1/2" paint brush and remove the dust
from the board till it is very clean and then try again.
2.It can be that the liquid solidified some dirt causing the fuse to blow.
3.Some close-up photos can help a lot.

 

[guskenny83]

1.First thing to do is take a small 1/2" paint brush and remove the dust
from the board till it is very clean and then try again.
2.It can be that the liquid solidified some dirt causing the fuse to blow.
3.Some close-up photos can help a lot.

Thanks for your quick reply. I am out now getting some more fuses. I will clean it all properly when i get home with a paintbrush and take some photos.

So it is unlikely that any of the components were damaged by the freezing?

Thanks again

EDIT: is there anything you would advise i use/not use to clean it with? I have methylated spirits, would that be okay?

 

[dorke]

At first just remove the dust with a brush.
After that, use a vacuum cleaner with a "narrow head" to suck the dust away(not to close to the components they can be damaged!)

Rubbing alcohol is what I clean with, but only in the places it is needed(solidified dirt etc.)

The freezing itself will not damage a component.
If however it created a short/overload with the dust/dirt a component can be damaged when power is applied.
Same thing goes if connecting the power while the liquid didn't evaporate completely.

 

[73's de Edd]

.



Sir guskenny . . . . . (possibly being of a mere 32 years of age)

The most likely situation that might have happened, was the creation of a "mud path" between the base and collector of the horizontal output transistor.
That would THEN account for the pulling of some serious current drain on the sets power supply, when power is applied, and therewith, popping of the fuse.

With the timely transition to an all "bone dry" board, the condition should dissappear.

Forget putting in ANOTHER fuse, to potentially worsen any component damaging conditions, or further total parts meltdown.

Instead . . . . . commmandeer a table lamp, drop light , etc with a cord and having an AC plug on its end. Put a 100W incandescant lamp into its socket.
Use two clip leads to insert the lamp into circuit, across the now empty fuse clips where the blown fuse was.
Dress the leads so that you can't touch them . . . . . . they HURTZ! . . . . .Baaaaaaaaaaaaaaaad !

NOW when you turn the unit on, if there is STILL being a serious circuit problem, the lamp will light up at its FULL brightness.( No fuse ker-poppen-bangens ! )
Or if things are being quasi-normal, the light will start out bright and drop to a lower operating level, in accordance to the power consumption of the unit.
Or sometimes pulsing if the 100 watt lamp is not letting quite enough power throught to operate the circuitry.. . . . . telling you it wants a TWO HUNNERT WATTS
"bub" in dat socket .

Soooooooooooooooooo your "old crt TV" gives us ZERO help whatever, so come back with the Brand of TV and its Model and or Chassis number so that the
analytical minds here can analyze its circuitry and lead you on a logical path of its troubleshooting / repair.

73's de Edd


.

 

[HellasTechn]

I would also recommend caution when you reinstall the boards in to the chasis make sure they sit properly and no short is created.

 

[guskenny83]

Hi all, thanks so much for your advice. I got home, gave it a bit of a clean with a brush (i will do a more thorough job later) and it seems to work again.. *phew*

Thanks again for the advice, I have a couple more questions but i might make another post about that in a bit..

 

[dorke]

Nice to hear that
Don't clean it to much...just gently with a brush and vacuum cleaner.

CRT TVs work fine with dust since they have openings to dissipate the heat buildup in them.

As they say,
If it ain't broken don't fix it...

 

[guskenny83]

good advice, i have created a separate thread with some more questions if you have any ideas:

https://www.electronicspoint.com/threads/help-making-a-crt-oscilloscope.275531/