Re: LiteOn PA-6601-1A (600w) blows its TOP

T_U you're right the transformer is not insulated at all
and..yeah... GFCI, wikipedia told me it is known this way in the USA

Toast, the scope is a digital cheap one (the analogue is under repair) but it works good. I see only 50Hz near the supply, nothing at higher freq

-Alez

Re: LiteOn PA-6601-1A (600w) blows its TOP

I think that if i feed in the digital multimeter a square waveform running at 130kHz I should see about half the voltage.. where I am wrong?

However I don't see nothing on the scope

RCD=Residual-current device aka "differential switch" aka "life saver" ...

Re: LiteOn PA-6601-1A (600w) blows its TOP

The transformer is connected between pin7 of the TOP and +160VDC. So 160VDC found on pin7 means that the TOP is frozen (and the MOS permanently off), isn't true?
Unfortunately I can't connect the oscilloscope because the probe ground is connected to earth, and even if I have fed the PSU with a 220V to 110V insulating transformer my RCD trips! I don't know if it is safe to disconnect oscilloscope earth from mains plug to do these tests.
So there are more cases:
1. My TOP is already blown
2. My TOP works and my meter...

Re: LiteOn PA-6601-1A (600w) blows its TOP

Thank you Toast for providing me those voltages... are those values taken from a working supply?
The readings at the TOP are quite identical:
Pin 1: 4.9v
Pin 2: 2.5v
Pin 3: 1.1v
Pin 4=0v
Pin 5: 4.9v
Pin 7: 160v
HDC rail: 160v
If I connect a 10k resistor between pin 1 and base of Q856, then pin 5 goes to 0v, but the circuit still doesn't work.

Alez

Re: LiteOn PA-6601-1A (600w) blows its TOP

No, there is no sound. Stuff in the main supply section seems ok. Simply stand by supply does not work, the TOP is freezed by some side circuitry.
I'm using a 220 to 110 V transformer + a 150W bulb shunt. I correctly read 160VDC on the primary power rail capacitors. It's probably some transistor near Q856, but it's not easy to test&replace all as they are smd...

Re: LiteOn PA-6601-1A (600w) blows its TOP



Hi all. I have the same problem. I have replaced the TOP, its cap, Q856 (with a bc557) and OPTO851 (with a sharp pc123). It is still dead...what to replace now?
Seems that Q856 lowers TOP's frequency in stand by mode. A way would be tring to bypass some circuitry as the TOP should work "alone". What do you think?

-Alez...