AG Neovo X-17A

[budm]

Re: AG Neovo X-17A

Are the two Diodes (SS14?) to the right of Q801, are the Cathode on the left of the as shown in the picture?
If Q801 is not being driven, I do not expect to see 1.11V at the Drain of Q801.
Another Voltage reading that does not make sense is the FB voltage at PIN4 (8.5V), since if the out put is not working, how can it has that high voltage feedback from the output, see page 5 of the data sheet of U801.

[sabre504]

Re: AG Neovo X-17A

Hi
yes both ss14 and cathode to Q801 as others were and as marked on the board

[jetadm123]

Re: AG Neovo X-17A

It looks like the TPC8104 is a good match for the RSS050. I do agree with budm that several of the voltages on Q801 don't make sense:

1) have you verified there are no shorts on Q801?

2) from the diagram in post #21, please verify the R1 and R2 equivalents on your board are within specs?


If 1) and 2) are both good, then it might very be that U801 needs replacing.

[budm]

Re: AG Neovo X-17A

I looked at the block diagram of U801, please take the resistance reading between pin6 (Drive pin) and the Vin pin 1 to see if the internal MOSFET is damaged and caused the output drive pin6 to be stuck high.

[sabre504]

Re: AG Neovo X-17A

Hi i will check these things later
sorry time difference means delayed replies sometimes
Paul

[sabre504]

Re: AG Neovo X-17A

Hi
reading from pin 1 to 6

X1 ,X10 or X100 all read the same (see pic)

But cant find any shorts on mosfet

[budm]

Re: AG Neovo X-17A

It goes up to the red marker on the meter? or the needle just stays down on the left side?
I still think there is problem with the IC due to some of the voltage readings you had indicated earlier.

[sabre504]

Re: AG Neovo X-17A

Meter only goes to the red mark i put on there save writing out 3 readings (lazy i know).

I also think that U801 is probably defective but looking at the damage that was done its possible there may be other components failing .

I will have to try and track down another ic or a similar one and then see where it goes .
Thanks for input so far

[budm]

Re: AG Neovo X-17A

The meter should not move at all since the MOSFET should read open circuit between Source and Drain.
That will explain why you are getting about 11V at the drive pin all the time.

[sabre504]

Re: AG Neovo X-17A

Hi
seems that Hong Kong and US are the only places for original part with a 3 week wait from either so may order a couple extra.
Cant find a cross reference part tho

[sabre504]

Re: AG Neovo X-17A

Hi
have had to order the part so will update when it arrives (3 weeks)

Thanks for all the help so far
Paul

[sabre504]

Re: AG Neovo X-17A

HI all update on this iit is now working

Replaced U801 and was rewarded with power light and no signal reading on the screen .

This unit has s-video and composite as well which are both working and vga and dvi inputs working .

Also had to replace a fuse and cap on the inverter .

Parts replaced
Q801 used a TPC8104
U801 used a AIC 1578
2 x SS14 Diodes
ZD801 used a 6.3v zener diode

And while opened up i changed 1 16v 470uf and 3 x 1000uf 10v on the power input side.
I have had it running now for about 12 hours using a dvd player via the s-vid connection with no problems .

Thanks to all for the inputs and advice have attached a pic of it working

[jetadm123]

Re: AG Neovo X-17A

Good work! Glad to see the repair went well.

[sabre504]

Re: AG Neovo X-17A

Thanks strangely enjoyed repairing this one bit more of a challenge than just the usual caps and some soldering .

Hopefully this thread will help some others

[budm]

Re: AG Neovo X-17A

Great job!