Sony SMD-HS73

[torin3]

Re: Sony SMD-HS73

Ok, I tried 4 known good CCFLs all at the same time.

Same flashing behavior.

Caps should arrive tomorrow.

[torin3]

Re: Sony SMD-HS73

Ok, I tried with 2 known good CCFL lamps at a time, and got the same behavior.

I can't try 4 at a time just yet because the only monitor I have available for this has all 4 plugs close together and this monitor has them on opposite sides of the inverter board.

I'll order the rest of the caps to make sure they are all replaced. Should get them in by Wednesday or Thursday.

I'll be happy to try any other tests.

[torin3]

Re: Sony SMD-HS73

Of course, I didn't do the math the other way.

There is a possibility that the 470uF cap is still bad. Right now, I'm out of ideas and have to head out soon.

Wel, with the 470uF cap back in, it is working the way it was before.

I'm going to try 2 lamps at a time from another monitor, but I don't think I can get all 4 to reach.

I'll be putting together an order for all the other caps that haven't been replaced and see if that helps.

Have a good evening.

[retiredcaps]

Re: Sony SMD-HS73

Well, with the 680uf cap in, it doesn't light up at all. Power light is green, but the screen stays black. Putting the 470uf cap back in now.

Of course, I didn't do the math the other way.

There is a possibility that the 470uF cap is still bad. Right now, I'm out of ideas and have to head out soon.

[torin3]

Re: Sony SMD-HS73

For test only purposes, I would substitute the 680uF in. This reasoning could be totally WRONG, but

470uF * 1.20 (+/-20%) = 564uF

680uF * 0.8 (+/-20%) = 544uF

Well, with the 680uf cap in, it doesn't light up at all. Power light is green, but the screen stays black. Putting the 470uf cap back in now.

[torin3]

Re: Sony SMD-HS73

What points on T1 and T2 did you check when you first took these readings?

The points Retiredcaps circled. I realize they weren't exactly the same, but they were less than 30 ohms apart at about 1000 ohms.

Edit: I'm also currently letting it warm up to see if I can adjust the brightness control.. Currently it isn't staying on long enough to access the menu.

[alexanna]

Re: Sony SMD-HS73

Don't forget
it is entirely possible to have more than one bad ccfl, to rule that out you could hook up all the ccfls from your good monitor, The ribbon cable does not need to be hooked up just make sure it's well insulated, A video source is required
Al.

[retiredcaps]

Re: Sony SMD-HS73

That would be normal. Usually the 5V output is regulated, the 12V output floats depending on the load on the 5V supply. I'd expect the 12V output to be very close to 12V if the inverter was on, higher otherwise.

PlainBill

That makes sense. Arrgh, missed this reply earlier. Darn, 9 inch netbook.

[retiredcaps]

Re: Sony SMD-HS73

Edit: Crud, I'm out of 470uf 25V caps. I have 680uf 25V caps. Too much of step up in capacitance?

For test only purposes, I would substitute the 680uF in. This reasoning could be totally WRONG, but

470uF * 1.20 (+/-20%) = 564uF

680uF * 0.8 (+/-20%) = 544uF

[jetadm123]

Re: Sony SMD-HS73

I tried checking T1 and T2. I think they are ok. Secondaries are about 1K ohm. And I get identical restances for the two units.

I also tried 1 lamp from another montior, in each of the sockets.

Still no change in behavior.

What points on T1 and T2 did you check when you first took these readings?

[torin3]

Re: Sony SMD-HS73

Has this one been replaced as well?

Not yet. I'll do it now.

Edit: Crud, I'm out of 470uf 25V caps. I have 680uf 25V caps. Too much of step up in capacitance?

[torin3]

Re: Sony SMD-HS73

May I suggest you try turning down the brightness to see if that affects the flickering at all.

I'll give that a try.

Take your soldering iron and touch up the solder joints for the inverter transformer pins.

Did that before my first post about this monitor.

Try measuring the secondaries. I believe what I circled in red and blue are the secondaries.

Put your mulitmeter on 2000 ohms. You should have one reading for red and one for blue. Report both.

Red 974
Blue 1003

[retiredcaps]

Re: Sony SMD-HS73

Also there is a 470uf 25V cap on the logic board I can replace as well.

Has this one been replaced as well?

[retiredcaps]

Re: Sony SMD-HS73

R22 -470 - 47 ohms
R23 - 195 - 560 ohms
R24 - 202 - 664 ohms
R25 - 1095 - 933 ohms
R26 - 222 - 935 ohms
R27 - 470 - 23.5 ohms
R28 - 470 - 23.5 ohms
R42 - 3907 (3902?) - 1265 ohms
R44 - 272 - 2680 ohms

R22 and R44 are definitely correct. The others readings are affected by other components in circuit. For now, let's assume they are all okay.

D1 is 5.05V
D12 is 13.81V

Hmm, I'm still confused with the 13.81V and the 12V DC connector reading, but let's assume that is correct and move on. I thought it would be closer to 12V DC at the connector area. At the diode area, I can see it being 13.81V DC.

Try measuring the secondaries. I believe what I circled in red and blue are the secondaries.

Put your mulitmeter on 2000 ohms. You should have one reading for red and one for blue. Report both.

[jetadm123]

Re: Sony SMD-HS73

Looks like you have good output voltages from both your power board and logic board regs.

May I suggest you try turning down the brightness to see if that affects the flickering at all.

Take your soldering iron and touch up the solder joints for the inverter transformer pins.

I see your logic about replacing the smd caps on the logic board. If others have had problems with those caps, then it might be a good idea to replace them.

[torin3]

Re: Sony SMD-HS73

Everyone has different troubleshooting techniques, but this is what I would do.

1) Have the upper 4 capacitors in your picture been replaced? I know you replaced some, but I can't tell from the picture if those 4 have been replaced?

Yes, all 4 have been replaced. But after that photo was taken.

2) In that same area, there are 2 inductors (marked with L on the PCB). They are covered in glue. You can remove the glue. With power off and LCD unplugged, the inductors should measure less than 1.0 ohms on your multimeter.

Yes, both of them are less than 1.0 ohms.

3) On the backside, there are 9 SMD resistors by the connector area. With power off and LCD unplugged, measure the resistance of each one. List the values and their measurements.

I'm not quite sure about the values, some of them were hard to read. However, I do see that not all the ones marked 470 read the same. Also, I attached a closeup photo of that area.

R22 -470 - 47 ohms
R23 - 195 - 560 ohms
R24 - 202 - 664 ohms
R25 - 1095 - 933 ohms
R26 - 222 - 935 ohms
R27 - 470 - 23.5 ohms
R28 - 470 - 23.5 ohms
R42 - 3907 (3902?) - 1265 ohms
R44 - 272 - 2680 ohms

4) There are two, I believe, Schottky diodes mounted on the heat sink. With power on, put your black probe on a ground screw and red probe on the middle pin. Report both readings.

D1 is 5.05V
D12 is 13.81V

And thank you again for helping walk me through troubleshooting this.

[PlainBill]

Re: Sony SMD-HS73

The legend on CN1 in the photo is a bit obscured, but if it says 12V, then 13.82V is pretty high? Was this measured with all the boards (logic and ccfl) hooked up?

I believe the 12V DC is for the inverter section.

That would be normal. Usually the 5V output is regulated, the 12V output floats depending on the load on the 5V supply. I'd expect the 12V output to be very close to 12V if the inverter was on, higher otherwise.

PlainBill

[retiredcaps]

Re: Sony SMD-HS73

And yes, almost 14V out of a 12V line seems like it would be out of spec to me too.

Everyone has different troubleshooting techniques, but this is what I would do.

1) Have the upper 4 capacitors in your picture been replaced? I know you replaced some, but I can't tell from the picture if those 4 have been replaced?

2) In that same area, there are 2 inductors (marked with L on the PCB). They are covered in glue. You can remove the glue. With power off and LCD unplugged, the inductors should measure less than 1.0 ohms on your multimeter.

3) On the backside, there are 9 SMD resistors by the connector area. With power off and LCD unplugged, measure the resistance of each one. List the values and their measurements.

4) There are two, I believe, Schottky diodes mounted on the heat sink. With power on, put your black probe on a ground screw and red probe on the middle pin. Report both readings.

[torin3]

Re: Sony SMD-HS73

The legend on CN1 in the photo is a bit obscured, but if it says 12V, then 13.82V is pretty high? Was this measured with all the boards (logic and ccfl) hooked up?

I believe the 12V DC is for the inverter section.

CN1 legend:
+12V
+12V
GND
GND
+5V
+5V
GND
N/C
ON/OFF
Dimming
N/C

And yes, almost 14V out of a 12V line seems like it would be out of spec to me too. But I'm not sure where to look for what might be affecting it.

Yes, all boards and lights hooked up. VGA cable not plugged in though. I don't know if that will make a difference.

[retiredcaps]

Re: Sony SMD-HS73

12V = 13.82V
5V = 5.05V

The legend on CN1 in the photo is a bit obscured, but if it says 12V, then 13.82V is pretty high? Was this measured with all the boards (logic and ccfl) hooked up?

I believe the 12V DC is for the inverter section.