Element ELEFW40C won't turn on.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

When LEDs are connected in series to form a string, the total Vf of the string can be much higher than the typical TV power supply putting out for the backlights circuit which around 24VDC, so the boost converter is needed.

There are other things that can produce the forward voltage for those LEDs in series though, isn't there? Why couldn't something like a switching voltage regulator? Is it because there won't be enough current then?

[vinceroger69]

Re: Element ELEFW40C won't turn on.

this video may help
https://www.youtube.com/watch?v=Qy8fh-g5DOM

[budm]

Re: Element ELEFW40C won't turn on.

If you have 30 LEDs in series, you will need 90vdc+ Vdrops (15~30V typ.) on the PWM Controlled MOSFET + Vdrops on the current sensing resistor for the constant current power supply circuit.
'Why couldn't something like a switching voltage regulator?'
Boost converter is a switching power supply, LED power supply is constant current source, the current is regulated instead of Voltage. Typical LED current for LED backlights is 200~400mA.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

If you have 30 LEDs in series, you will need 90vdc+ Vdrops (15~30V typ.) on the PWM Controlled MOSFET + Vdrops on the current sensing resistor for the constant current power supply circuit.
'Why couldn't something like a switching voltage regulator?'
Boost converter is a switching power supply, LED power supply is constant current source, the current is regulated instead of Voltage. Typical LED current for LED backlights is 200~400mA.

I think I'm understanding. So even that boost circuit will be producing a high voltage, right? Right now, I don't think it's producing any at all. That diode shows something like 0.2VDC. That should be showing something much higher, around 90VDC or so. Either something in the boost circuit isn't working or the boost circuit isn't getting "activated". I'm starting to think it's not getting activated. If it was, that standby light should be turning from red to blue when I hit the power button.

Do you think I'm right on this? Thanks!

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

this video may help
https://www.youtube.com/watch?v=Qy8fh-g5DOM

The video was nice, seeing how it's done, but where would I purchase the stuff to freeze the eprom? Is there any other way you can think of that I would be able to check that the eprom is corrupt? I believe I found it on the board. I have things (but don't know how to use all of them). I have a logic analyzer that I haven't turned on since I bought it. I have an oscilloscope. They're old. I have the DMM. I have a programmable DC power supply. I have a DCA meter and an ESR meter.

There's gotta be some sort of way to determine if the eprom is working or not. Shouldn't I be able to hook the logic analyzer up to the pins and see data coming out of it? Or use the scope to see data on some pins or something? Or use the DMM to see if there's voltage coming out of the pins?

The chip is an 8-pin IC. It has a funky G for the symbol, then the words AH1422, if I'm reading it correctly. There's red marker on it and there might be something under the red marker. I'm having trouble identifying that chip. It's similar to the one in the video.

**EDIT: I removed the marker and it looks like it's a 25Q16BS1G. I've searched for 25Q16BS1G and they have the funky G symbol, so now I'm going to try to find the datasheet and verify that this is in fact the eeprom.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

Here's the datasheet for the dual and quad serial flash.

[vinceroger69]

Re: Element ELEFW40C won't turn on.

to freeze the eeprom you can get electronics freeze spary but a few of us use air duster spray just hold the can upside down its not as good as freeze spray dosnt last as long etc but usually does the job ok. Its a pity we cant find a schematic for this board as could tell the what voltages are missing etc maybe budm can advise if he thinks the spiflash ic could cause this issue.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

Okay, I don't understand something. When I have the DMM set to measure DC voltage and I try measuring the voltage on that diode, I put the common on one end of the diode, the probe for voltage on the other end, and it measures around 0.237VDC. But when I put the black probe on the GND pin of the serial flash chip and the red probe on that same diode, now I get 37VDC. I don't understand why. But if I measure the other diodes the same way with the black probe on one end of the diode and the red probe on the other, I get much higher readings.

Is this because I'm just measuring the voltage drop when I have the black probe on end of the diode and the red probe on the other end of the diode? If that's the case though, that means those other diodes have really really large voltage drops, doesn't it? When I read 100+VDC on diode, that would mean that one diode actually has a voltage drop of over 100VDC. Is that right?

[diif]

Re: Element ELEFW40C won't turn on.

I find it easier to give EEPROMs a waft of hot air to remove then stick them on a reader.
I've found a couple of faulty ones that weren't detected/read.

They are easy to identify as you have discovered, by the dot of paint on them.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

Yeah, I want to test it first before removing it though.

Also, I found what appears to be a transistor in a SOT-23 package. I've been putting a DMM set to voltage on the transistors pins and just checking if they have voltage. This one though, the two pins on the bottom both have voltage. The first is a little over 12V, the second is a little under 12V. Obviously, the output is 0.0VDC. But is this common? Does that just mean the transistor, if being used as a switch, hasn't been "turned on" yet?

I froze the flash with the can of air (generic duster). It was wet, so I blew on it till it turned frosty. It didn't do a thing though, still doesn't power on.

[diif]

Re: Element ELEFW40C won't turn on.

What's a better way to test it than see if it's readable ? It take a couple of minutes to remove, read and replace.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

I don't any way to test besides reading it, but to read it, I need to purchase equipment that I don't have. I guess I could charge the customer for the equipment, but it'd really suck if that's not the problem. I would have wasted time on getting the equipment shipped to me and wasted money on equipment I didn't need. I guess if you're fairly certain it's the flash chip there, I'll go ahead and order everything. I just figured there was probably a way to check that it's working (maybe that Output pin) with some sort of device...that's all.

[diif]

Re: Element ELEFW40C won't turn on.

A CH341A is about $4. Good for laptops too.

[budm]

Re: Element ELEFW40C won't turn on.

If the diode is for producing the positive output (Negavtive GND circuit), then you put red probe on the Cathode of the diode, black probe on GND (or chassis if the circuit grounded is tied to the chassis), that is how you find out what the output of the power supply is, that Cathode should also be connected to the + of the filter cap.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

A CH341A is about $4. Good for laptops too.

That 4$ isn't bad at all. I think I'll order one, even if that isn't the problem, just so I have one for the future if I ever need one. I might need some cables and software as well. I'd like to find one that has USB port. We don't really have any parallel or serial ports. I'll start shopping around and see what I can find.

[vinceroger69]

Re: Element ELEFW40C won't turn on.

i also have this one too its a good programmer stj has put some updated software on this site for it too
https://www.youtube.com/watch?v=L0ChYNwunUE

Edit software from stj in this thread
https://www.badcaps.net/forum/showth...ghlight=CH341A

[diif]

Re: Element ELEFW40C won't turn on.

That 4$ isn't bad at all. I think I'll order one, even if that isn't the problem, just so I have one for the future if I ever need one. I might need some cables and software as well. I'd like to find one that has USB port. We don't really have any parallel or serial ports. I'll start shopping around and see what I can find.

No cables required. Just plugs into USB. The software is available on this site.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

I was thinking of this one:

https://www.amazon.com/SMAKN%C2%AE-P.../dp/B013Q5P3ES

You say no cables required, but that socket there looks like it's not made for SMD type components but through-hole components. Wouldn't I need something like this:

https://www.amazon.com/CPT-063-Test-...7REF8BBN7T9DD2


And then cables to hook that to those pins on the side of that socket on the programmer? They list that EEPROM programmer as a writer. But I'm guessing it can read as well. I have to check into drivers and make sure I can find them. I'd like Windows 10 64-bit drivers, but if I can't find them, that's okay. What I need is Linux 64-bit drivers and software that will work with Linux. I mean worst case, I can use my wife's Windows 10 64-bit laptop, but I'd prefer to use Linux.

**EDIT: I think I see how it works now. I solder the chip to that little green board, solder the pins to that little green board and then plug the green PCB into the socket.

[Spork Schivago]

Re: Element ELEFW40C won't turn on.

i also have this one too its a good programmer stj has put some updated software on this site for it too
https://www.youtube.com/watch?v=L0ChYNwunUE

Edit software from stj in this thread
https://www.badcaps.net/forum/showth...ghlight=CH341A

That doesn't list the 25Q16BS1G as one of the supported chips...It'd really suck if the flash was good and I ended up frying the chip because it wasn't compatible...

I can't find any that list the 25Q16BS1G as a compatible chip. I'm thinking it might not matter? What do you guys think?

[vinceroger69]

Re: Element ELEFW40C won't turn on.

This is the exact one i had ordered


http://www.ebay.co.uk/itm/CH341A-24-...vip=true&rt=nc

it does list the winbond W25Q16 ic if its the same ic as yours

The main issue is we dont know if your eeproms at fault and if it is you will need the correct firmware for the board that matches the panel etc to re programme the ic ive just looked on shopjimmy and cant see any boards for this tv?