Samsung LN52A550 - clicking. Eeprom or something else?

[nomoresonys]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Your link is not correct. Use the one Budm specified.
http://www.samsung.com/us/support/ow...ct/LN52A550P3F

I upgraded my firmware but the problem still exists. I've ordered 2 new switchmode regulators and the caps. Hopefully they will solve the problem.

Thank you Budm for all of your help!!

Bob

no, I used budm's link, its just not there.

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

You did not try paralleling the caps? I am trying to collect the info to see if that method can be used to verify if the cap will fix the problem, so far it is three out of three for me.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

If you scroll about 1/2 way down the screen you should see
"Manuals and Downloads". Under that and to the right it should say "Downloads".
Under that is a link to a pdf and a "See More +" link.

Do not have that on your screen?

[nomoresonys]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

thanks for trying, but they have none for my model on their site, but I will find it somehow.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Hi Budm,
I did try paralleling both caps with 68uF/10v and it made no difference.
I used some tantalum caps that I had around, but they probably aren't low ESR. I don't have any 100uf/10v low esr here.

I should have my parts from Mouser in a few days.

[nomoresonys]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

You did not try paralleling the caps? I am trying to collect the info to see if that method can be used to verify if the cap will fix the problem, so far it is three out of three for me.

not sure I trust my soldering enough, do you have a pic. of how you did it?, apologies if you already posted one, I'm all over the place trying to fix and help.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

I did some poking around with my scope on the 2 regulators on the main board (IC101 and IC102) both with the relay cycling and with the TV working. In both states, both of these regulators appear to be working. I see a chopped output on pin 3 at about the same duty cycle whether the set is working or cycling.
The input voltage on both of them remains steady around 5VDC in both good and bad conditions, so I'm starting to think the problem with my board is not around these regulators. That would explain why adding capacitance made no difference in my case.
So here's what I've done so far, with no change in the problem:
Changed PS caps
Reprogrammed firmware
Added capacitance across switch mode regulator input caps

This set still cycles for a while then comes on and works.

Still stumped.

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

That is the good info to have.
Does it come on every time pre heat the main baord with hair dryer first before applying the power?

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

That's a good test. I tried freeze spray with no luck.

One thing to add to my list:
Checked all PS voltages at 24 pin connector.

I'll try the heat gun in a while and report back.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Heat definitely helps the issue. When I heat the top left over the switching regulators, the set powers on every time.

[CapLeaker]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

did you check these smd caps there? maybe its time to grab the oscope.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

I think I've narrowed the problem are down to the section around Q500 and R572. When this area is cold, the relay just cycles. When I heat up this area, the TV works. This is very repeatable with freeze spray just on this area and a soldering iron on the PCB in that area.
Q500 appears to control the WP on the NVM 24C256. If I watch the input to Q500, under good conditions it transitions low to high 4 seconds after POR then cycles a few times. When the set fails (is cold), the input just stays low. I'm not sure what the caps do in that are next to Q500.

Does anyone have the schematic for this board (BN41-00975B)? I would like to know the values of the caps in that area (C518, C517, C516) as well as Q500.

Thank you.
Bob

[CapLeaker]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Q500 I has markings I read as ALY? If I done my homework, that is a NPN transistor KTC3875. Maybe check it out too. Maybe there is a bad solder joint some where, maybe a cap goes bezerk when hot or cold... Check that resistor too...

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Hmm that is what happened with 46", I can heat up that are with just small amount of heat in those areas of the two switching regulator and caps the TV will turn on and stays on every time, so I solder in the 100uF in parallel with C102 then it also starts up every time without heating that area.
So if you can when you get the caps and the ICs, can you please try replacing just C102 first to see what happen?

[aaronwt6]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Bud,

Just thought I'd let you know that I got those caps from mouser yesterday. I repaired the PN50A550 plasma as well as a LN40A630 & LN46A630 main board. The plasma had the screeching / green issue after being on for 10-30 seconds. Both of the A630 LCDs would just show a flashing red light indefinitely when the power button was pressed but no chime or backlight. All three were repaired with just replacing C102 but I did do C131 on the top of the boards as well just to be safe.

[fireman_bob]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Capleaker I don't think it's Q500 or the resistor since the input signal is missing when the set won't start. Q500 is on the output side that connects to the NVM. That's just the area of interest. There's also the 4 caps right above those parts that may be bad, but I don't have the values for them and I don't know where they go. The input to these caps comes from a via from internal traces. The input voltage looks solid at 3.3vdc whether the set starts or not. The backside of this area has a part that looks like a DPRAM chip. I resoldered all the pins but no luck.

Budm - I should have my parts today and will try your test.

[nomoresonys]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Bud,

Just thought I'd let you know that I got those caps from mouser yesterday. I repaired the PN50A550 plasma as well as a LN40A630 & LN46A630 main board. The plasma had the screeching / green issue after being on for 10-30 seconds. Both of the A630 LCDs would just show a flashing red light indefinitely when the power button was pressed but no chime or backlight. All three were repaired with just replacing C102 but I did do C131 on the top of the boards as well just to be safe.

Nice fix, can anyone tell me what c102 and c131 do?, having a hard time locating them on shop jimmy images, thanks.

[CapLeaker]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

O.k. I must have read something not correctly, as I thought heating and cooling Q500 is the problem. Maybe I should go to bed earlier. lol.
I guess you have to figure out what the heck feeds that thing. It sounds like either something has a cold solder, or some cap that is bad. Problem is that even some expensive DMM's don't show capacitance correctly. Got fooled with that a few times now. My LCR meter never lies. I wonder what you see with an oscilloscope around the area in question?

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

C102 and C131 connected the Vin pin 2 of the switching regulator IC MP2623.
Look at the requirement of the input cap, it has to have high current ripple capacity.
https://www.badcaps.net/forum/showpo...&postcount=129

[budm]

Re: Samsung LN52A550 - clicking. Eeprom or something else?

Bud,

Just thought I'd let you know that I got those caps from mouser yesterday. I repaired the PN50A550 plasma as well as a LN40A630 & LN46A630 main board. The plasma had the screeching / green issue after being on for 10-30 seconds. Both of the A630 LCDs would just show a flashing red light indefinitely when the power button was pressed but no chime or backlight. All three were repaired with just replacing C102 but I did do C131 on the top of the boards as well just to be safe.

Thanks for the repair feedback, I am trying to keep track as to how many fixes are done with replacing the caps (47uf 10V POLYMER TANTALUM) C102, C131.
https://www.badcaps.net/forum/showpo...&postcount=129