AIWA TV-21ST2 keeps blowing STR S6307

[poorboys_louie]

str-s6307

TV is dead at first, i've found out that B+ diode(UF5405) is short.i've also check for other short near the HOT section.after replacing the shorted diode i tested the unit but it only lasted for 5mins then the unit is dead again.now, str s6307 is shorted and fuse blackened.also B+ diode UF5405 is shorted.

i tried replacing the same components but it keeps blowing.anyway i've checked the board for other shorted components but found nothing except for uf5405 and regulator....any suggestions?

 

[tendi]

aiwa tv-21st2

Check your B+ filter capacitor it may be shorting after a while. Also check the small capacitor across(parallel)the B+ diode.

Good luck...

 

[TLL]

str s6307

If i understand correctly (+b= 13---145 v?) and +b is u`r main voltage from secunder, and the tv was ok for 5 minutes,then do this...
Replace every condensator(electrolitic ones) in primary(there should be 3-6),check 300 v capacitor(if ok do not replace),replace b+ capacitor(should be ~100uf/160v).And of course change the blown diode and str...
The capacitors in the primary if they lose value could cause the increase of the power supply and causing to blow u`r b+ diode,and then the str....(this is the cause for u`r failiure...power supply increase...).
Also chek (if the tv set has optocupler feed back from secundary to primary this controls the level of the power supply) the feed back circuit for blown tranzistor or rezistor.

Best of luck.

 

[poorboys_louie]

tv-21st2

sorry for the late reply, thanks guys i appeciate your help..

i found out that the B+ diode was leaky(RU2), I tested it out of circuit.

Now the tv is working fine..

 

[xaccto]

S6307, I suppose pin 1 is the main switcher
this diagram I found

Yes its a TV fault. When its switched on, very briefly observe on pin1 switching (I think)
then nothing.
Any tips to debugging this circuit ?

If I may also plug for a schematic diagram for a Panasonic TC-59R2 C150Chassis.
Its a nice TV for a CRT, so if I can repair it for next to no $ that would be great,
don't reckon its worthit paying for a service manual for something thats actually obsolete and a commodity, so if I can get one free ?? thanks.