Proscan Plded3996a-c2

[_N_]

Re: Proscan Plded3996a-c2

OK, that means the MOSFET is not switching on and off and it just passes the input Voltage right to the output without producing the boosted Voltage needed for the LED.
So you need to find out what DCV you have on the VCC pin and the GND pin of that 8-pin SMD IC.
Did you download the spec sheet for that IC? If you did, then you should upload it.

yes its in my 1st posting, top of thread along with all the other data sheets.

pin 1: {V.in} gives 12.4V

[budm]

Re: Proscan Plded3996a-c2

OK, sorry I did not go through all the links you provided in the first post, I will download and upload the spec sheet for other people to see for future reference.

[_N_]

Re: Proscan Plded3996a-c2

OK, that means the MOSFET is not switching on and off and it just passes the input Voltage right to the output without producing the boosted Voltage needed for the LED.
So you need to find out what DCV you have on the VCC pin and the GND pin of that 8-pin SMD IC.
Did you download the spec sheet for that IC? If you did, then you should upload it.

pin 1 is Vin gives 12.4Vdc

[budm]

Re: Proscan Plded3996a-c2

OK, we need the DCV on each pin (with ref. to GND pin) of that OB3350 to see if it is active or not.

[_N_]

Re: Proscan Plded3996a-c2

OK, we need the DCV on each pin (with ref. to GND pin) of that OB3350 to see if it is active or not.

k

[budm]

Re: Proscan Plded3996a-c2

It looks like there is no drive output from the IC, the VCC is OK, the OVP is OK, so you can try a new IC.

[_N_]

Re: Proscan Plded3996a-c2

It looks like there is no drive output from the IC, the VCC is OK, the OVP is OK, so you can try a new IC.

k, off to purchase one.
anything else you'd like to verify by chance?

[budm]

Re: Proscan Plded3996a-c2

Nothing else I can think off, if the you at the diagram in the IC spec sheet, that is probably pretty close to what you have on your board, it is just a simple Voltage booster circuit.

[Agent24]

Re: Proscan Plded3996a-c2

Could a fault with the feedback circuit cause the driver to shutdown?

[budm]

Re: Proscan Plded3996a-c2

Since there not enough output Voltage to turn on the LED, the feedback then will be 0 since no current flowing through LED and through the current sensing resistor as shown in the diagram.

[Agent24]

Re: Proscan Plded3996a-c2

Oh yeah... that makes sense, but what if there is something wrong with the current sensing resistor\circuit for the FET?

(I don't know if that is the problem here, asking more out of curiosity actually)

The datasheet doesn't seem to explain much about how the CS pin works and if it's related to the OCP or not.

[budm]

Re: Proscan Plded3996a-c2

Right now the MOSFET's Gate is not getting any drive signal from the IC and I do not see anything standing out to stop the IC from drivng the MOSFET, and the MOSFET is not shorted out which will take out the Source resistor, so to be sure he can check the Resistor on the Source pin of that Power MOSFET.
The CS sense pin works the same as the SMPS IC by sensing if too much current is being flow through the MOSFET, the more current flow the higher the DCV across the Source resistor, when it reach the trip point (per spec sheet, it is 330mV), the drive circuit shutdown.

[Agent24]

Re: Proscan Plded3996a-c2

Thanks, it makes sense now.

[_N_]

Re: Proscan Plded3996a-c2

Part ordered last night, when it arrives ill install and upload pics, it will be a while since no one stocks it other than the people who make it.
Thanks Bud for the help, ill keep ya posted.

[_N_]

Re: Proscan Plded3996a-c2

New part arrived and soldered it all in , no bridges now i get these voltages all measured to Ground pin of the IC. and still no BL helllllp ? ;}

[budm]

Re: Proscan Plded3996a-c2

6, 7 and 8 are now much more different than the old IC. Need to do more thinking here.

[_N_]

Re: Proscan Plded3996a-c2

I left it on for 10 min this mourning and remeasured and now i get slightly different voltage.

1: 12.4
2: 0
3: GND
4: 0.04
5: 0.01
6: 3.6 - 0.60 this one fluctuates
7: 2
8: 2.4

voltages off the main 2 big caps is v164,
also the cap near for the inverter v20.9

[_N_]

Re: Proscan Plded3996a-c2

I was extremely careful in removing everything ,

Curiosity killed the cat, I know,...... I know
But looky looky
ECD029 IC-E-CNA039d139

[_N_]

Re: Proscan Plded3996a-c2

I Just tried to see if the led strips would light using a small tiny H.V.inverter from a colored cold cathode tube for PC Modding, that feeds itself from a pc psu at 12V,
regardless of the horrible /Black-brown states of the back of those LED Pcb strips, they flicker and all do light up (not brightly but they do turn on with the little inverter), Ill heat sink them to the large metal backing before I close it all up using a potting / thermal paste adhesive... WHY the hell didn't they do this at factory the tube costs like $2.14 on ebay sigh.

[Agent24]

Re: Proscan Plded3996a-c2

Be careful you don't electrically connect them to the frame somehow and short them out.