Hitachi LE49S508

[krygods]

Re: Hitachi LE49S508

Resistance between LED5+ and chassis with the connector in place shows 1 on the meter with it set to 200 ohm.

This is with power off correct?

[krygods]

Re: Hitachi LE49S508

that P/N on the 8 pin IC is really hard to read, I can barely see it with a 30x magnifier and only at a very precise light angle do the characters appear.

It looks to be F28543 but the 8 could be a B and the 5 could be an S

[krygods]

Re: Hitachi LE49S508

New tester arrived in the mail today.

The rectangular capacitor that you asked me to test is C39 on the PSU?

If so here are the readings from C39

Vloss = 0.00%
950.5nF
ESR 0.00 ohm

[krygods]

Re: Hitachi LE49S508

The 8 pin IC definitely says F2B543

[budm]

Re: Hitachi LE49S508

I did find anything on that P/N F2B543.

[krygods]

Re: Hitachi LE49S508

I cleaned the chip with IPA and am finally able to read the P/N OB3350CP

Attached is the datasheet I've found

[budm]

Re: Hitachi LE49S508

Check the DCV between the Vin pin 1 and the GND pin 3 to see if the IC is getting the DCV to run it.
And also all the Voltages of other pins against GND.

[krygods]

Re: Hitachi LE49S508

Measures 0.12 DCV

[CapLeaker]

Re: Hitachi LE49S508

That's not enough voltage to run that LED PWM controller IC.

[krygods]

Re: Hitachi LE49S508

Sorry bud I didn't see that you asked for voltages between the rest of the pins and gnd.

Let me go ahead and check those right now.

[budm]

Re: Hitachi LE49S508

No need at this point since you are not getting the correct Voltage for the Vin pin 1 (Measures 0.12 DCV) any way.
Need to trace out where that Vin pin 1 goes to on the board.

[krygods]

Re: Hitachi LE49S508

All pins measure 0VDC against GND (Pin 3)

[budm]

Re: Hitachi LE49S508

please see post 31.

[krygods]

Re: Hitachi LE49S508

Ok, let me see what I can figure out. This will be my first time tracing a circuit so lets see what happens.

[krygods]

Re: Hitachi LE49S508

Ok here is a better picture of the area I'm tracing out and a picture that I've traced over using a graphics program.

Am I headed in the right direction?

I'm assuming that some the the circuit eventually jumps to the top of the board, how do I determine when this happens?

[budm]

Re: Hitachi LE49S508

What resistance do you get between Vin pin 1 and the Ground pin?

[krygods]

Re: Hitachi LE49S508

Resistance jumps to around 150 ohm for a split second and then drops back off

[budm]

Re: Hitachi LE49S508

150 Ohms? I expect in the it to be in K Ohms range.
Looking at the board layout, pin 1 is connected to one end of the '100' R112, the other end of R112 is connected to a jumper RJ8, the other end of RJ8 is connected to RJ7 (000), the other end of RJ7 is connected to the LED current sensing resistors (5 of them connected in parallel) which are connected to GND. So pin 1 of that IC cannot be the Vin pin.
See if I am correct, the pictures have glares so it is hard to see all the traces.

[krygods]

Re: Hitachi LE49S508

Sorry for the crappy picture with the glare I'm slowing learning how to take macro shots.

Here's a better picture because I'm a little confused as to what is going on here but it is slowly starting to make a little sense how things are connected.

The way I see it Pin one goes to R112 the other side of R112 goes Q11?

[budm]

Re: Hitachi LE49S508

OK, that is better.
"The way I see it Pin one goes to R112 the other side of R112 goes Q11?" yes, it goes to the Collector of Q11 (PNP), the Emitter looks to be connected to RJ14 (please verify), but that is where the picture is cut out. Is the other end of the RJ14 connected to the connector 12V PIN?
What is the resistance reading between Collector of Q11 and GND?
Q11 looks to be used as the switch to supply the Voltage to pin 1 of the IC.
I think it is either C34 is bad or the IC is bad to have 150 Ohms reading on Vin pin 1 of the IC.
I think we are getting close to the problem.
BTW, Q12 (NPN) get the BL-ON (>2V = ON) command at the Base to be turned on (Collector Voltage goes LOW) which the is then turn on NPN Transistpr Q11 (12VDC is fed into the Emitter, the 12VDC output is on the Collector) to supply the VCC to the IC Vin pin 1.
You do have BL-ON (>2VDC) for sure, right?