Sony Trinitron KV-27S30 with black screen and blinking 4 times.
Need some help on this one. I have traced this to no 13v feed to IC541. No 13v from the flyback. I do not know what feeds the flyback transformer. I am having difficulty chasing the power supply voltage in the wiring diagram. If anyone has feedback on this, I would appreciate it. I do not want to just start throwing parts at the unit. I did find one terminal on the flyback that showed 146v. Appreciate any advice.
Thanks
Ed
ok First off, Your error is a vertical stoppage, for some reason the vertical deflection has ceased operation. in regards to your 13 volt measurement; you need to measure the 13 volts before the tv codes, once it codes, the 13 volts will be gone. there are actually two power sources for ic541(vertical output ic) a +13 volts coming in on pin 2, and a -13 volts on pin 4. If your problem was in the flyback it would code differently. So i believe going further back is the wrong direction now. what has likely happened is that is that ic541 has shorted (there is no way to test to be sure) when this ic goes it will open up R567 and/or r561 both are a .47 ohm resistor, they are fusible, so check them with your ohm meter and see if one is open. if so you know for sure ic541 is bad. With this set you may have another problem learking, if after you replace ic541 and any open resistors, the unit fails again. there is a strong likely hood that the yoke is bad. In most tv's this is a rare problem, but with this set it can be a real issue.
here are the sony part numbers
IC541 = 875998058
r567/561 = 124937711
yoke = 845148611 (replace only if ic541 fails again)
You asked about the flyback and it's drive, Q502 connected to pin 1 of the flyback is the drive transistor that will produce the pulsating dc voltage that will drive the transformer, Pin 2 has the B+ drive voltage this is a dc voltage measuring about +140 usually(i did not get the exact voltage for this set that i stated a typical voltage) In order for the transformer to operate you must have that dc voltage on pin 2, and you have to have the horizontal pulse coming in on the base of Q502 - allot can go wrong to prevent this basic operation, including the prevention of the horizontal drive by the micro because of an error as well as any number of other issues. But the tv usually will give you a different code.
Thank you for your feedback. It is invaluable. I will measure those two resistors and go from there. I will replace IC541 and the resistors. I will let you know.
Thanks
Ed
I have a Sony KV-27S40 and i'm kinda new to this whole repair thing (mostly because i'm to cheap to let some else repair it) but mines has the black screen with no sound and 4 blinking lights so i'm assuming it's the IC541 also. I checked r561 i got a reading so i'm assuming it's still closed but i can't seem to find r567 to check that one. am i on the right track or am i shooting in the dark?
What kind of a reading ? .47 ohms, if it is quite a bit higher then it could be bad. Your set used the same parts listed above. But it is good to check, because the cause and cure can be different between different model numbers. In your case what i said above apples to your set as well. Try the vert output (ic541). it is a cheep fix if it works. most of the time it will.
adixon3 - Except for the yoke, your model does not have this unique problem