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Samsung TXJ2879 - No Sound, No Picture    
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Georgie



Joined: 24 May 2015
Posts: 3
Location: Massachusetts

PostPosted: Sun May 24, 2015 8:46 am    Post subject: Samsung TXJ2879 - No Sound, No Picture Reply with quote

Samsung TV Model TXJ2879, Model Code TXJ2879EX/XAA.
No sound, no picture. Here is what I have done:
1. Unplug from a.c. outlet. Then plug in after several minutes. Monitor power consumption with "Kill A Watt P3" meter.
2. Power consumption starts at 12 watts and quickly goes down to 6 watts.
3. Press power button on TV. Power consumption goes up to 90 watts (sometimes higher). I think meter is not fast enough to record peak power. Click from relay inside TV. Green LED next to power button comes on and then flashes a total of 9 times. After two or three flashes, another click. Then TV draws 6 watts.
4. Press power button again, green LED comes on then blinks nine times. Power consumption goes up to 12 watts, then back to 6 watts. No relay click. This repeats each time power button is pressed so long as TV is plugged into a.c. outlet.
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JTS1957



Joined: 21 Jan 2009
Posts: 2328
Location: Far, Far Away

PostPosted: Sun May 24, 2015 10:58 am    Post subject: Reply with quote

Relay is for degaussing coil, Unplug or leave set off for 15 - 30 MINUTES to allow posistor to cool.

Measure the B+ Voltage at the Cathode of D812 (D811).
Georgie



Joined: 24 May 2015
Posts: 3
Location: Massachusetts

PostPosted: Wed May 27, 2015 3:46 pm    Post subject: Reply with quote

Hello again,

Thank you for your help so far.

I have been diligently studying the service manual for the Samsung TXJ2879.
I have not yet opened up the TV itself.
Here are some important questions that I have. They are indicated by A, B, etc.
After those, I have listed my notes; I'd appreciate any comments on the notes.

A. Since I have determined (see notes) that 5V and 12.5V power is on, does this mean that the entire SPS is working properly?

B. Should I be able to open up the TV when it sits on a table it its normal position? Or will I have position the CRT face down?

C. Assuming that I figure out which component(s) I need to replace, how difficult will it be for me to do that?
Is there just one, big PCB inside this TV? Will I need to remove that PCB?

**********
NOTES:

1. 12.5V to the degaussing control relay is turned on and off by the microprocessor (IC901 - apparently a Zilog Z9036512PSC) --> IC901 pin 17 through transistor Q951.

2. IC901 requires 5V and the degaussing control relay (RL801) requires 12.5V, so both of those voltages must be present. This means that the switching power supply (SPS) must be supplying these.

3. Also, since the green LED on the front (I think it is LD901) flashes, I again think that the 5V is working.

4. Signal from IR (infrared) remote goes into pin 36 of IC901, apparently after being processed by RM901. Note that the complete part number for RM901 is ORC-50VF,38KH. I think the 38KH means 38 kHz, which is the typical "modulation" freq for TV remotes.

4. IC902 is an EEPROM that communicates with IC901 on the I2C buss.

5. Voltages lower than 12.5V are (apparently) derived from the 12.5V by IC802.

6. I have no idea what is going on with the components (e.g. DZ810, D804, DZ805 and DZ806) that seem to be related to the SYNC pin (pin 5) of IC801 (the SPS PWMCONTROLLER;3S1265R).
JTS1957



Joined: 21 Jan 2009
Posts: 2328
Location: Far, Far Away

PostPosted: Wed May 27, 2015 6:34 pm    Post subject: Re: Samsung TXJ2879 No Sound, No Picture Reply with quote

Georgie wrote:
Samsung TV Model TXJ2879, Model Code TXJ2879EX/XAA.
No sound, no picture. ************** I skipped ahead to Troubleshooting - No Raster No Sound. I'm assuming here that you actually have 'No Raster'. 'You can have a RASTER with NO picture - But, with eyes only, you cannot TELL IF you have a picture without a raster.'
Here is what I have done:
1. Unplug from a.c. outlet. Then plug in after several minutes. Monitor power consumption with "Kill A Watt P3" meter.
2. Power consumption starts at 12 watts and quickly goes down to 6 watts.
3. Press power button on TV. Power consumption goes up to 90 watts (sometimes higher). I think meter is not fast enough to record peak power. Click from relay inside TV. Green LED next to power button comes on and then flashes a total of 9 times. After two or three flashes, another click. Then TV draws 6 watts.
4. Press power button again, green LED comes on then blinks nine times. Power consumption goes up to 12 watts, then back to 6 watts. No relay click. This repeats each time power button is pressed so long as TV is plugged into a.c. outlet.

Based on the relay click & power button/LED indicator, I also presume that that secondary is OK. But there are two other secondaries (that may or may not be working). One for (primarily) Audio and the other for (primarily) Horizontal Output. IF you report even a single secondary present, the primary IS working. (I have yet to see what I requested from last post, which IF approximately 130 Volts, would prove another secondary is OK.)
Since you are NOT reporting any high voltage crackling or hair lifting on the back of your hand as the set is cycling On-Off and since the HO circuit is one of the highest power drawing and failure prone areas, I skipped ahead.
You have a SM too. Mine does not show disassembly, but does show exploded views (I have a SM based on chassis K51A - NOT exact to your MODEL, but should be close enough. I ain't payin' for one or searching for more than a few minutes for a free one).
However you can SAFELY reach components - setting the set on one of its sides or loosening or removing connectors/wires (as needed) to pull board partially or completely are popular. You will need to desolder and solder.
Georgie



Joined: 24 May 2015
Posts: 3
Location: Massachusetts

PostPosted: Thu May 28, 2015 6:06 am    Post subject: Reply with quote

OK. Thank you, again.
Keep in mind that I have not yet opened the box.
Is there any way I can check for 130V without doing that?
This is a very large and heavy TV.
I plan to open it up this weekend. I already borrowed an isolation transformer. I have a DMM, and I plan to borrow an o'scope on Friday.
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JTS1957



Joined: 21 Jan 2009
Posts: 2328
Location: Far, Far Away

PostPosted: Thu May 28, 2015 11:19 am    Post subject: Reply with quote

Georgie wrote:
OK. Thank you, again.
Keep in mind that I have not yet opened the box.
Is there any way I can check for 130V without doing that? NO
This is a very large and heavy TV. You want large & HEAVY ... Try a 36" Sony
I plan to open it up this weekend. I already borrowed an isolation transformer. I have a DMM, and I plan to borrow an o'scope on Friday.
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