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China MIN DONG TV-MD 14/22 repair
perjmolsen:
Just noticed a thing....
A cap is missing... seems top have broken off due to corrosion...
Now the question... what type could that have been.. ::)
princess prin prin:
A ceramic cap (like the blue ones) across frame ground and secondary ground. Low capacity (1n to 4.7n) and 400V or 1KV.
Suck all the solder from the yellow pin on the flyback and connect the bulb to the trace and a ground point and lift the jumper in the white circle.
If still no voltage check that you have around 300VDC across the legs of the big cap with green top and if you have voltage there it could be a bad voltage regulator IC (5-pin IC screwed to the heat sink).
perjmolsen:
--- Quote from: princess prin prin on January 13, 2019, 09:37:46 am ---A ceramic cap (like the blue ones) across frame ground and secondary ground. Low capacity (1n to 4.7n) and 400V or 1KV.
Suck all the solder from the yellow pin on the flyback and connect the bulb to the trace and a ground point and lift the jumper in the white circle.
If still no voltage check that you have around 300VDC across the legs of the big cap with green top and if you have voltage there it could be a bad voltage regulator IC (5-pin IC screwed to the heat sink).
--- End quote ---
Hi
Big thanks for all your information :)
I have done as you say, but no volt.
I can massure 298V across the big 150uf 400V ud cap.
I have also tried to change the cap to a new one - but same result.
So it might be the 5 legged IC KA2S0765 - I have already changed it but i might be defect - i think that i have some more laying around.
perjmolsen:
Halleluja :cheers:
I got 113 V now
What i did
Changed the KA2S0765 IC one more time
Also changed the small cap (47uf 50v) after the big cap- the old one measured (45uf esr 1.1 ohm)
Powered it on and now I have 113V at the yellow circle at the flyback.
SO.... Then i think that i need to put it back in reverse order?
1.
Solder the yellow pin back at the flyback
Connect the jumper
Test if i have B+ at middle leg where HOT need to be put in
If test OK then
2.
Put HOT back in
Test if i got static and picture ?
princess prin prin:
Don't connect the jumper yet. Do the lightbulb test at the HOT collector (with HOT out of circuit). If you have steady light and b+ voltage put the HOT back in and reconnect the jumper and test the chassis. Don't keep the yoke connected to the chassis.
The horizontal inductance on the label seems quite high for the resistance. I would expect it to be half of that.