Samsung LE32R88BD LCD TV – No picture or sound

[GeoW]

Re: Samsung LE32R88BD LCD TV – No picture or sound

I would think you have a backlight problem. You indicate that you have all the supplies 5V, 12V & SB
Can you check you have 24V at both side of the white ceramic fuse on the inverter board just above where it says 125V/7A

I have 24V at both ends of that fuse marked F1 on the inverter board.

I've attached another image of the inverter - the camera on my phone isn't very good, so that's about the best I can get.

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

What voltages do you have on pins 1 -> 14. Cannot read the printed legend.

[vinceroger69]

Re: Samsung LE32R88BD LCD TV – No picture or sound

in a very dark room when you first power on the tv do you get a brief flash of light on the screen (1 second to black fault)

[GeoW]

Re: Samsung LE32R88BD LCD TV – No picture or sound

Vince, I did get that brief flash of light on the screen when first switched on.

Dick, I assume you mean the markings on the inverter board connector to the power board.
1-5 VCC
6-10 GND
11 Error Out
12 ENA
13 DIM
14 EX-DIM

[vinceroger69]

Re: Samsung LE32R88BD LCD TV – No picture or sound

a brief flash usually points to a bad inverter transformer or a bad cclf lamp or wiring

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

You said you had tested the power supply by substitution and there was no change so I suspect an inverter board fault.

Yes, if you could give the voltage readings of VCC, Error_Out, ENA etc.

As Vicerogers69 has said check all the solder joints on the inverter board and redo the transformer pin solder joints.

If you could also check the resistances of the transformers windings and tell us what they are could be useful. Set off, meter set to ohms or Kohms.

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

Check resistance between
1,2 &1,3 &1,4, 2&3, 2&4, 3&4
5&6, 5&7, 5&8, 6&7, 6&8, 7&8

and repeat for the small transformer
Check 1&2 then 3&4
compare readings with similar transformers

Finally check any small bue capacitors close to the transformers are not cracked or have any burn marks.

[GeoW]

Re: Samsung LE32R88BD LCD TV – No picture or sound

I have attached the resistance readings of the transformers on the inverter and also the power readings on the inverter board. I took the inverter power readings while the power plug between the power board and the main TV board were reattached (i.e. no resistor connections). The power readings were very erratic, with 1-5 VCC readings starting from about 9 then dropping to 1, then doing it again. Similar with the readings for 12-14, starting from about 2.34 and dropping to 0.01, then rising and falling again.

I have checked the capacitors on the inverter and can see no burn marks or cracks. I have not re-soldered at this stage as I have also tried a 2nd inverter which I have from a previous repair about 3 years ago (which was not the fault at that time, it was the T-Con board), and that gives the same results.

[vinceroger69]

Re: Samsung LE32R88BD LCD TV – No picture or sound

number 2 transformer is diffrent 1.18 compared to 1.192 on the other 2 can you measure the other inverter board to see what the readings are (just the large transformers) it maybe ok but if ones .18 and ones .192 thats a big diffrence

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

Inverter power reading is given as 1V in your pdf. What happened to the 24V you had earlier?

[vinceroger69]

Re: Samsung LE32R88BD LCD TV – No picture or sound

Inverter power reading is given as 1V in your pdf. What happened to the 24V you had earlier?

whats your thought on that inverter readings .18 compared to .192? or is it .19.2?

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

If my memory serves me right your looking for a difference of 3% or greater to establish if the inverter transformer requires replacing.


I think at this point as the last thing I can think of at the moment would be to lift the BL wire from CNM802 going to the inverter and jump 5V standby to it using the 1K resistor, power up and if no backlights then I would say faulty inverter board.

The power readings given in an earlier post showed all the secondary voltages were there but not BL voltage.

[vinceroger69]

Re: Samsung LE32R88BD LCD TV – No picture or sound

yes thats probably the best idea too be honest but as hes tried two invertor boards not sure but both could be faulty i guess.

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

yes thats probably the best idea too be honest but as hes tried two invertor boards not sure but both could be faulty i guess.

Thanks, I missed the comment saying that a second inverter board had been tried.
Maybe the above test will give some results, otherwise I must admit I'm at a loss other than knowing from the voltage readings given earlier that there was no backlight voltage.

[vinceroger69]

Re: Samsung LE32R88BD LCD TV – No picture or sound

ive just reread the whole thread even when psu was forced on bk light voltage was 1.72v (post 18 ) is that enough to turn the bk lights on could this low voltage be why theres only just a quick flash of light?

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

Budm did say that there are two pins. BL & BLU and which one(s) is required for the backlight I don't know. However from the voltage readings given they were both at 0.04V so I wonder if they were common and fed into and out of the power supply board from the mainboard.

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

Just had a look at the circuit diagram for the power supply and BL & BLU are connected together on the power supply = Backlight On/Off

[vinceroger69]

Re: Samsung LE32R88BD LCD TV – No picture or sound

so forcing them on like you have said should rule out the inveters/ccfls? im still learning too so bear with me

[dick_barton]

Re: Samsung LE32R88BD LCD TV – No picture or sound

That's the idea. With all the other voltages reporting to be correct then disconnecting the backlight on/off wire from the connector which runs up to the inverter board and connecting the lead to 5V using the 1K should bring the backlights on. If it does then it would be a mainboard fault. Failing that then I have no further idea.

[GeoW]

Re: Samsung LE32R88BD LCD TV – No picture or sound

If my memory serves me right your looking for a difference of 3% or greater to establish if the inverter transformer requires replacing.


I think at this point as the last thing I can think of at the moment would be to lift the BL wire from CNM802 going to the inverter and jump 5V standby to it using the 1K resistor, power up and if no backlights then I would say faulty inverter board.

The power readings given in an earlier post showed all the secondary voltages were there but not BL voltage.

I just tried this and the backlights came on. Suppose that means I need to change the mainboard then?