Samsung 42 inch Plasma - Sound chimes no video

[smartjohn]

I picked up this 42 inch Samsung PN43E450A1FXZA plasma that has no picture. Low voltages are fine Vs and Va peak up to correct voltages for several seconds then decay down to under 10 volts. Isolating all boards from SMPS made no difference. Red power light flashes after startup chime sounds. At this point I am suspecting the power supply board and ordered one. Any suggestions are welcome.

[Alastair E]

Re: Samsung 42 inch Plasma - Sound chimes no video

More likely there's a couple of IGBT's short on the Y-SUS board or maybe buffer-chip causing trouble.
--Remove buffer-board and retry with everything else connected...

If the psu gives Vs/Va for some seconds--Doubt its that causing trouble... Its being shut-down by cont/mainboard due to fault condition, usually in the sustains or buffers

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

Thanks for the tip! I will certainly give that a shot. This model has one huge Y buffer board so it will be an easy test. I suspect it may likely be that since isolating the Y-SUS did not fix the fault. Although a quick tips guide I found in Tom's library said that Vs is generated on the Y board in some fashion. so it may still be y-SUS related. I'll report back after further testing.

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

Alastair, you were right! My $13.00 SMPS did not fix the issue. I will try pulling the buffer next to see Vs comes up stable. The good news is that boards are pretty cheap for this entire set! So worst case, I have an extra power supply...

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

Also, one interesting note: When testing the one of the IGBTs in circuit on the Y-SUS board, it did not switch off abruptly as a normal test would indicate, but the LED on my test jig did a slow "decay" to off when i turned the gate voltage off. This could be something else in circuit but I found it to be odd ?

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

Pulled the buffer board and same results: Vs Va both jump high to normal and decay immediately to almost 0. I tried the main board isolation test by removing the power connector at the main board and jumping the power_on pin to ground pin. No luck. Should have given me a test pattern but same drop in Va Vs occurred. I am now focusing on the YSUS board with testing.

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

I found a diode on the Ysus that appears to be shorted. Can someone help with identifying the SMD code? 8728 Thanks!!! appears to be a PMDS package.

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

The SMD code is actually "87" and the package is SOD-106. I have another thread going to track this down in the general topics forum, but no luck so far. I believe he answer maybe in "Turuta SMD Databook 2014" if anyone has a copy and could check.

[tw2005]

Re: Samsung 42 inch Plasma - Sound chimes no video

The SMD code is actually "87" and the package is SOD-106. I have another thread going to track this down in the general topics forum, but no luck so far. I believe he answer maybe in "Turuta SMD Databook 2014" if anyone has a copy and could check.

Sounds like a ROHM product

RFN2L4S

400V 1.5A

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

So, sometimes a wild goose chase ends with the Golden Egg goose! On my efforts to repair YSUS board # LJ41-10136A, I found diode D5126 with SMD Code 87 was in fact the 400V 1.5 Rohm diode. However, when i pulled it out, it tested OK out of circuit. So, a little further investigation revealed that it was paralleled across Q5017 an IGBT (FGD4536) (1st image). I tested the IGBT and found it was shorted! Just so happened I had several of these from another project. I soldered D5126 back in place and replaced Q5017. Bingo! Diode test across D5126 now read OK. So I put the Y-SUS back in for the 1st smoke test. As before startup chimes, but no video. Voltages still spike then fall off right away, same as before.

At this point I assume the new IGBT is fried, so I pull the board for more testing. But Behold..It's OK.... hummmm.

[tw2005]

Re: Samsung 42 inch Plasma - Sound chimes no video

probably need to go deeper and look at all the devices around it including driver ICs , smaller SMD parts like resistors, transistors, diodes.

Only 1 shorted IGBT, ?

I think given the cost of a whole board s it worth it? Hows the Xmain? Gone over that?

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

Again, a little more investigation revealed another fault. Q5016, another IGBT (IRG7R313) appears to be shorted. But looking a little further, I see it is also parallel with a larger diode pack D5014 (F10A400HD) a 10 amp, 400Volt TO-252 device (see Image). So not to be fooled again, I un-soldered only the the collector tab of Q5016, and it tested OK. So this time IT WAS THE DIODE !! HA!! D5014 tested 300 ohms in one direction, and about 600 ohms the other. I did not have another F10A400HD laying around, but I did find a suitable diode for just for testing, an FSU05A40, 400Volt 5 Amp diode. This is not my permanent fix BUT ONLY for TESTING! I ordered an STTH10R04G-TR from DigiKey as the permanent fix.

Bottom line IT WORKS !! to summarize the fix: Q5017 (IGBT FGD4536) was shorted and D5014 (F10A400HD) was shorted. A couple of $2.00 parts max and I’m up and running. Thanks to all that helped me track down the diode that was not bad, but eventually led me to the answer.

[tw2005]

Re: Samsung 42 inch Plasma - Sound chimes no video

Again, a little more investigation revealed another fault. Q5016, another IGBT (IRG7R313) appears to be shorted. But looking a little further, I see it is also parallel with a larger diode pack D5014 (F10A400HD) a 10 amp, 400Volt TO-252 device (see Image). So not to be fooled again, I un-soldered only the the collector tab of Q5016, and it tested OK. So this time IT WAS THE DIODE !! HA!! D5014 tested 300 ohms in one direction, and about 600 ohms the other. I did not have another F10A400HD laying around, but I did find a suitable diode for just for testing, an FSU05A40, 400Volt 5 Amp diode. This is not my permanent fix BUT ONLY for TESTING! I ordered an STTH10R04G-TR from DigiKey as the permanent fix.

Bottom line IT WORKS !! to summarize the fix: Q5017 (IGBT FGD4536) was shorted and D5014 (F10A400HD) was shorted. A couple of $2.00 parts max and I'm up and running. Thanks to all that helped me track down the diode that was not bad, but eventually led me to the answer.

Gonna have to rename you Smartarse. Can't think of many, if anyone who's replaced 2 parts and come up trumps on a samsung xmain

Nice work

[smartjohn]

Re: Samsung 42 inch Plasma - Sound chimes no video

HaHA! Thanks! Yeah, I can be bull headed but I love the adventure of finding the root cause..

[NIGHTWHISPER68]

Re: Samsung 42 inch Plasma - Sound chimes no video

Please help!I need to now what numbers are on the resistor R5052 and R5053. I am working on a faulty board LJ41-10136A and those resistors are burned and I need the value to change them. I bought the other components but I don't know the value of this two resistors, are they 101?They are in the proximity of MOSFET Q5024 and Q5025.They have connections with OP 5007 wich is also defective and I must replace him.Thanks in advance for who want to help me.

[tw2005]

Re: Samsung 42 inch Plasma - Sound chimes no video

Please help!I need to now what numbers are on the resistor R5052 and R5053. I am working on a faulty board LJ41-10136A and those resistors are burned and I need the value to change them. I bought the other components but I don't know the value of this two resistors, are they 101?They are in the proximity of MOSFET Q5024 and Q5025.They have connections with OP 5007 wich is also defective and I must replace him.Thanks in advance for who want to help me.

Not great but maybe you can just see, I don't think it looks like 101, looks like it could start with a 2, 27?

Dunno, good luck

[NIGHTWHISPER68]

Re: Samsung 42 inch Plasma - Sound chimes no video

Thanks, man!I'll keep looking ...

[NIGHTWHISPER68]

Re: Samsung 42 inch Plasma - Sound chimes no video

Hello .The resistors where 222. I finished adjusting the board .Everything is working!I changed: two MOSFET 5N50, one IRG7R313U, one optocoupler P155E, two resistors 105, and two resistors 222, one capacitor 105 -1kv and the tv is back to life!To forum member tw2005 again many thanks!

[RickyZA]

Re: Samsung 42 inch Plasma - Sound chimes no video

Again, a little more investigation revealed another fault. Q5016, another IGBT (IRG7R313) appears to be shorted. But looking a little further, I see it is also parallel with a larger diode pack D5014 (F10A400HD) a 10 amp, 400Volt TO-252 device (see Image). So not to be fooled again, I un-soldered only the the collector tab of Q5016, and it tested OK. So this time IT WAS THE DIODE !! HA!! D5014 tested 300 ohms in one direction, and about 600 ohms the other. I did not have another F10A400HD laying around, but I did find a suitable diode for just for testing, an FSU05A40, 400Volt 5 Amp diode. This is not my permanent fix BUT ONLY for TESTING! I ordered an STTH10R04G-TR from DigiKey as the permanent fix.

Bottom line IT WORKS !! to summarize the fix: Q5017 (IGBT FGD4536) was shorted and D5014 (F10A400HD) was shorted. A couple of $2.00 parts max and I'm up and running. Thanks to all that helped me track down the diode that was not bad, but eventually led me to the answer.

Your a life saver ! I have the exact same set which is giving the same issue from what ive tested, D5014 ( F10A400HD ) & Q5017 ( IGBT FGD4536 ) are both shorted out on my YSUS board # LJ41-10136A. Struggling to find stock of the IGBT FGD4536 though , if anybody knows of any site i can use to find substitutes it will be utterly appreciated. Thanks !