Need help troubleshooting srk v2 fet +1 driver (srk special firmware)

I’m having difficulty diagnosing the problem. When batteries are inserted and the tube attached the light is always on and will not turn off. When pressing the button to change levels all of the lower levels have the same intensity and only the upper four levels change. I have cleaned the board, visually inspected for debris or solder that might be causing a short and for bad solder joints. I removed the thermal sensor leads and switch. Any ideas what might be causing this?

So, no ideas? Could someone point me to a circuit diagram for this driver? If I had that I’d be able to figure it out. Google was no help. I may be a bit out of practice but with a diagram it would definitely be easier than component level troubleshooting of an xray machine or spectrum analyzer (when I did so I had such diagrams readily available).

it sounds very much like the 7135 is short circuit, unsolder it and check light
the 7135 is for lower modes
the FET for high modes

If LED - is shorted to ground anywhere either on the board or by the reflector, the driver control is bypassed and you get direct drive and no modes at all. So what he said, likely the pwm pin on the mcu(pin 5) or the Vdd pin on the 7135(right hand pin with tab at top) is shorted to B+ locking the 7135 on(no pwm control).

I suspected the problem might be the 7135. A diagram would help in determining what kind of resistance values I should be getting from b+ to the pads but I am reading a short between the vdd and out pins.

I removed the 7135 and it is working as expected - fet modes only switching and powering off properly. Time for another purchase from mtn.

Can you measure the voltage on the 7135 when the driver is operating on lowest level
The middle leg is ground right goes to diode and left to MCU
The left should have different voltages for different levels

Sometimes when soldering 7135 it can get short by solder tin on the back

I already pulled the 7135. If all goes well I’ll be placing an order from mtn at the end of the week. My Panasonic Viera suffered a probable power board failure so I prioritized purchasing a multimeter to aid in troubleshooting.