samsung PN64E550 no standby voltage

[martino]

Hello,
TV is dead,no standby voltage,do however have 3.06volt on PS-ON.
This one is kicking me and was hoping to get some help from the experts.
I made a drawing on pic#2 of what I thought was relevant.
Power supply is a BN44-00515A.
I did buy this kit and have replaced the majority of it:
http://www.shopjimmy.com/samsung-bn4...repair-kit.htm

[RCA2000]

Re: samsung PN64E550 no standby voltage

DO not see HOW you could have 3V on the PS-on line with NO standby. After all--the PS-on is derived fro Stby..and gated through syscon to turn on the run supply..

Look again...I am SURE...you will then see some Stby voltages... whether they are correct or constant...you will have to measure for that.

[martino]

Re: samsung PN64E550 no standby voltage

DO not see HOW you could have 3V on the PS-on line with NO standby. After all--the PS-on is derived fro Stby..and gated through syscon to turn on the run supply..

Look again...I am SURE...you will then see some Stby voltages... whether they are correct or constant...you will have to measure for that.

Measured again,
pin#1=PS-ON=3.06volt
pin#2=STBY=0.0 volt

I measured resistance between the STBY pin and GND=135K ohlm.


I too thought ps-on came from the stby voltage,but this thing is proving me I'm wrong,lol

[RCA2000]

Re: samsung PN64E550 no standby voltage

What do the pins that go to the connector that leads to the signal board--what is each of them called ?ONE of them HAS to be supplying voltage to it---for the signal board to THEN give a PS on voltage to the PWB.

[martino]

Re: samsung PN64E550 no standby voltage

see pic
pin#1= 3.06volt,the rest is all zero.

[martino]

Re: samsung PN64E550 no standby voltage

After reading MANY posts here,I found a guy that had the same issue.
He,just like I did,had replaced the IC UC802(circled in pic) and had no STBY and a voltage on PS-ON.
He put the old chip back on and his STBY returned.
Going to do that right now and report back if STBY returns.
If it does I will have to let shopjimmy know that that chip is defective.

[budm]

Re: samsung PN64E550 no standby voltage

Can you read the P/N of that IC? the STBY Voltage is supplied through that MOSFET QM880 so something is not turning on that MOSFET, is kind of strange to Have STBY through MOSFET, but the bottom line is that the main must be getting OTHER Voltage to run right now to produce the PS-ON signal, you will probably have to check the Voltages on the main board connector to see what other Voltages you have right now to feed the main board., unless the power supply has pull-up resistor on the PS-ON pin and the main board is not active to keep the PS-ON Line low = ON (active low) which may be how this power supply board is, LOW = ON..

[martino]

Re: samsung PN64E550 no standby voltage

Can you read the P/N of that IC? the STBY Voltage is supplied through that MOSFET QM880 so something is not turning on that MOSFET, is kind of strange to Have STBY through MOSFET, but the bottom line is that the main must be getting OTHER Voltage to run right now to produce the PS-ON signal, you will probably have to check the Voltages on the main board connector to see what other Voltages you have right now to feed the main board., unless the power supply has pull-up resistor on the PS-ON pin and the main board is not active to keep the PS-ON Line low = ON (active low) which may be how this power supply board is, LOW = ON..

Update:soldered the old chip back in,could not read the p/n,sry,and sure enough the STBY is back,5.3v.
PS-ON is now at 4.3v.

Soldering a 470 ohm resistor from ps-on to gnd sadly does NOT turn on the powersupply Unless I need to activate VS-ON as well to get the 15v etc?
Voltage on main caps remains 164v and no 15volt etc.

Took a pic of board with chip removed for future tracing for somebody.

[Nick's Tvs]

Re: samsung PN64E550 no standby voltage

PS-ON to ground and VS-ON to 5volt line

[martino]

Re: samsung PN64E550 no standby voltage

PS-ON to ground and VS-ON to 5volt line

Did that,no change,main caps still at 164 and no 15v.

So,onto the remainders of the parts in the SJ kit.
In pic I circled the parts I did replace before already in blue.

Now working on the parts in red circle,but the IC on board doesnt show what direction it is in.The new IC has a grey stripe.

[RCA2000]

Re: samsung PN64E550 no standby voltage

"Pre made kits"...do NOT always work the best. I usually try on my OWN...to decide what parts need replaced based upon readings and such and order them ONLY..

On a rare occasion that does not work...I WILL get a kit...

[martino]

Re: samsung PN64E550 no standby voltage

"Pre made kits"...do NOT always work the best. I usually try on my OWN...to decide what parts need replaced based upon readings and such and order them ONLY..

On a rare occasion that does not work...I WILL get a kit...

Agreed,and that's probably the best way to go.
I however am not the most skilled guy when it comes to these power supplies.
I really need to educate myself better on the workings of them.
I measured around,found that most components in that kit to be blown(shorted) on mine and opted to get the kit.
It sucks I cant read the p/n on those IC's,for directional position and also to find spec's on them..

The components in red circle,are they responsible to turn psu on full?
PS-ON via optic coupler to hot side? Or is there more suspects on the cold side?

[RCA2000]

Re: samsung PN64E550 no standby voltage

From what I can tell...the red circled parts are in the BOOST CONVERTER section. This is a ckt. to raise the raw B+ to nearly 400V dc...in the "run" mode...ONLY. it is turned on by an optocoupler from the COLD side....again ONLY...when the Ps is in the run mode.

Can you tell where the PS-on line goes to on the PS? I wish I had a schematic of this PS to help you with. I recently had a PS that had a bad driver chip on the hot side...not really identifiable, numbers rubbed off. Thankfully though..I found a complete PS cheap on the 'bay...

[martino]

Re: samsung PN64E550 no standby voltage

New(not so good) developement

I marked pic with problem area etc.

psu rigged to be forced on.maincaps 164volts. Measured around in hot side,from negative leg of main caps.
AS SOON as I touch the spot I marked as "red probe" with my probe,while black being neg leg maincap,the relay starts clicking on/off in 0.5 sec intervals.(and keeps doing that even with probe removed)It's not pressure sensitive,it's the fact probe touches it.
Voltage on main caps spike to about 400 volts,then drop off to about 210 before it spikes back to 400 in about 15 seconds.

Ok,still in mind that the one IC was defective out of the box,I decided to desolder the voltage regulator to measure out of circuit(was getting low ohm readings)................when I buggered it all up.......sigh.......
I damaged the traced in the area I circled blue and now cant trace out what connects to what.Again,NEVER do solder work at 3am,it will bite ya.

Anyone happen to be working on one of these that can trace it out for me? I been searching for hrs and cant find a schematic for it.
Even bought the service manual for it for $25,but they don't do schematic drawings and board prints anymore. grrrr...

[dick_barton]

Re: samsung PN64E550 no standby voltage

Video on the set at:-
https://www.youtube.com/watch?v=xf0wJPzZK10

[Shane711]

Re: samsung PN64E550 no standby voltage

I have 2 of these TVs I have been trying to fix. Both TVs have blown power boards. So I fixed both boards and the TVs will not work because of the MCV14A IC.

The MCV14A is a programmable IC and so I bought the programmer and could not copy it to a new IC. After a long time of searching I think I discovered that the IC is read protected. How do they do that and how do I get past that?

So I need help from an expert, if I can get this program copied I will share it on here. Takes a special programmer though if anyone is interested in using it.

So how do I get past the read protection?

Here is a web site stating that this IC is read protected.
https://www.scribd.com/document/319446617/Mcv14a

[petehall347]

Re: samsung PN64E550 no standby voltage

see what sort of lock it is and make a key . i know how to look at computer files but not chips . must be similar though .
sorry i couldn't help .

[Shane711]

Re: samsung PN64E550 no standby voltage

This is more complicated than that I think. Might have to have a special computer and then might need a pass key. Bu there should be a trick around that like maybe crossing a pin off or something.