universal tdk inverter.what is the little white thing ?

[petehall347]

Re: universal tdk inverter.what is the little white thing ?

yes its confusing but it was working and now it isnt so something has gone wrong .
q1 has to be on to send that high side p channel fet gate low so it switches the 12v on ..well that's how it seems to be to me .

it makes me wonder if there is a pass through on the main board that should feed 2v to r63 switching the fet on and the inverter at the same time .

[petehall347]

Re: universal tdk inverter.what is the little white thing ?

the thing is that i have lit the screen with an another inverter and the system is not being shown on the screen so something is amiss there . the processor warms up .the 5v and 3.3v are ok . and the 12v .
am thinking of removing the cmos battery overnight in case its something as silly as that

[R_J]

Re: universal tdk inverter.what is the little white thing ?

yes its confusing but it was working and now it isnt so something has gone wrong .
q1 has to be on to send that high side p channel fet gate low so it switches the 12v on ..well that's how it seems to be to me .

it makes me wonder if there is a pass through on the main board that should feed 2v to r63 switching the fet on and the inverter at the same time .

I did ask about the circuit near C337, what is the component coming from the 12v trace going to the plug, and where does it connect to the inverter (which pin)

[petehall347]

Re: universal tdk inverter.what is the little white thing ?

c337 is missing .the trace has been cut to the fet . that board pin goes to pin 2 inverter so same as pin 1 . i cant understand why its been cut ,i did try connecting it at one point but nothing changed , it was working at that point . u28 is a p channel fet . IRF7406

[petehall347]

Re: universal tdk inverter.what is the little white thing ?

i forgot to mention when the unit is first turned on the 12v at inverter tries to go up but only for less than a second .. will see what the gate is doing at power on .

[R_J]

Re: universal tdk inverter.what is the little white thing ?

Is it possible that that cut trace from the 12 volts also connected to the R63 and inverter on/off?

[petehall347]

Re: universal tdk inverter.what is the little white thing ?

that does not appear possible but i will study it more .
i have been playing with it .
i put 1k resistor between pin 1 and pin 3 mainboard same as 1 and 5 inverter . then made the fet gate low giving 12v ok but inverter pin 5 only going to 200mv .

[R_J]

Re: universal tdk inverter.what is the little white thing ?

I suspect the inverter is damaged, something must be killing the voltage on the on/off line. It looks like there is a 100Ω (101) off pin 5 (inv), does the other end go to a transistor?

[petehall347]

Re: universal tdk inverter.what is the little white thing ?

will have to get a close up pic . back out over to the workshop again ..

[petehall347]

Re: universal tdk inverter.what is the little white thing ?

couple of better pics i hope .
oh i tried unplugging the inverter and absolutely no voltage centre pin main board .pin 3