Vestel!

[newtothis]

Have 11.2 volts from the 5v standby... ESR of cap is good, Resistor checks out... Not sure how the NPN works so would that cause this?

[Ltank]

Re: Vestel!

It appears that the transistor has a emitter to collector short. I am on my smartphone and I don't have a pen with me to look up the zener diode voltage rating. Also check the voltage across the zener diode if its correct. If wrong value then it may be causing the transistor to be fully turned on. It has a .7v drop across the on junction.

[newtothis]

Re: Vestel!

11.9v at one side of diode... 0 at the other

[newtothis]

Re: Vestel!

Can an NPN be tested in circuit.. if so its bad...

Base to emitter = red - black _ Closed
= Black - red _ Open

Base to collector = Red - Black _ Open
= Black - Red _ Open

Emitter to collector = Red - Black = Closed
= Black - Red _ Open

I have tested this correctly haven't I?

[tom66]

Re: Vestel!

If you have 11.2V into a 5V standby, I'm pretty sure the main board would have fried!!

[newtothis]

Re: Vestel!

Guess what... I didn't lol... Replaced the transistor and voila works lovely :-)

[Ltank]

Re: Vestel!

I am glad that it worked for you. The voltages told me shorted transistor.

[newtothis]

Re: Vestel!

I am glad that it worked for you. The voltages told me shorted transistor.

Assumed it would be as there is very little in circuit to drop the voltage to 5.

Cheers for your help

[tom66]

Re: Vestel!

wow, quite surprised to say the least that nothing fried! All functions work?

[newtothis]

Re: Vestel!

wow, quite surprised to say the least that nothing fried! All functions work?

Yes absolutely perfect! :S