Sony SMD-HS73

[torin3]

Re: Sony SMD-HS73

This is a low probability, but just for my own curiousity, can you carefully measure the voltage across the main filter capacitor (the big one) and see if you get steady DC voltage?

You are looking for a steady voltage while the screen is flickering. You can use the original ccfls for this test.

For this test, I like to use aligator clips with my multimeter so I can do this measurement without using my hands. It is high voltage that you will be measuring (about 165V DC).

When the lamps are off, it read 153.6 to 154.6 VDC. When the lamp flicks on, it drops down to roughly 150 VDC. The lamp doesn't usually stay on long enough to get a very precise reading with my DMM.

Did you ever verify that you can see an image if you shine a flashlight on the screen? The logic board is getting 5V and the voltage regs are working, therefore, you should at least get an image.

Sorry if I wasn't clearer before. When it goes dark, there is no picture visible on the screen with a bright light. I might not have a bright enough light, but given that it changes resolution occasionally, I'm pretty sure there is no picture when the lamps are off.

I did try again with the spare good CCFLs. I couldn't tell any color/brightness differences per plug for sure. I'm going to try and readjust the wiring so I can have a lamp on each side at the same time to have them next to each other to compare, just to be sure.

[retiredcaps]

Re: Sony SMD-HS73

U2 = 4542 / (logo)AD(Delta smbol) / W37A
U3 = same as U2

Datasheet for 4542 is at

http://pdf1.alldatasheet.com/datashe.../KI4542DY.html

Let's see if U2 and U3 are good?

If any ohm reading is less than 30 ohm you might have shorted mosfet. Remove from circuit and repeat the tests to verify.

Some mosfets are more than 3 pins. To test those, identify the part number and search for its datasheet. Once you find the datasheet, the pins will be designated source (S), gate (G), and drain (D). It will probably be documented as S1, S2, G1, G2, D1, D2.

Simply test

a) black on pin S1- red on pin G1 - record ohms
b) black on pin S1- red on pin D1 - record ohms
c) black on pin G1- red on pin D1 - record ohms

Repeat for the "2" pins. That is S2-G2, S2-D2, G2-D2.

edit: Just thinking out aloud, what if just one of them is bad? Would that explain the backlight off/on?

[alexanna]

Re: Sony SMD-HS73

Did you ever verify that you can see an image if you shine a flashlight on the screen? The logic board is getting 5V and the voltage regs are working, therefore, you should at least get an image.

I have noticed what is being displayed on the screen, May be hard to see even with a flash light. If you could display a web page with several different colors, writing pictures ect.it May it be easier for you to see?

[torin3]

Re: Sony SMD-HS73

Datasheet for 4542 is at

http://pdf1.alldatasheet.com/datashe.../KI4542DY.html

Let's see if U2 and U3 are good?

If any ohm reading is less than 30 ohm you might have shorted mosfet. Remove from circuit and repeat the tests to verify.

Would I need to test out of the circuit if all are over 30 ohm?

-------U2----U3
S1-G1 100K 100K
S1-D1 OOR  OOR
G1-D1 OOR  OOR

s2-G2 736  737
S2-D2 460  460
G2-D2 72K  72K

OOR = Out Of Range on the 2000K selection

[retiredcaps]

Re: Sony SMD-HS73

Would I need to test out of the circuit if all are over 30 ohm?

U2 and U3 test/look fine. You would need to test out of circuit if the readings are less than 30 ohms.

[torin3]

Re: Sony SMD-HS73

U2 and U3 test/look fine. You would need to test out of circuit if the readings are less than 30 ohms.

That is what I thought, but I wanted to make sure. Just got back home and I'm a little tired.

[retiredcaps]

Re: Sony SMD-HS73

CN1 legend:
ON/OFF

I haven't done this test myself, but plug in the lcd into the wall outlet/power bar with power off. Measure the DC voltage at the ON/OFF on CN1.

Now turn on the power LED, what is the voltage? When the backlights go off, what is the voltage?

So you should have 3 readings.

Also, try alexanna's suggestion in post #43.

[torin3]

Re: Sony SMD-HS73

I haven't done this test myself, but plug in the lcd into the wall outlet/power bar with power off. Measure the DC voltage at the ON/OFF on CN1.

Now turn on the power LED, what is the voltage? When the backlights go off, what is the voltage?

So you should have 3 readings.

Also, try alexanna's suggestion in post #43.

Off = .12V
On = .14V
Light on, hard to tell with my slow meter, but it looks like close to 5V.

[torin3]

Re: Sony SMD-HS73

I have noticed what is being displayed on the screen, May be hard to see even with a flash light. If you could display a web page with several different colors, writing pictures ect.it May it be easier for you to see?

Nearly white web page window, moving it around on the monitor with a dark green background. When the lamps are off, I can't see anything.

Also, sometimes when the lamps are on, there is no picture on the display.

When the lamps are on, screen is sometimes 'rolled' (top half of image is on the bottom half of the screen, and bottom half of the image is on the top half of the screen. Orientation correct, but like the vertical hold is off.)

[jetadm123]

Re: Sony SMD-HS73

May I suggest that you take some voltage measurements off of the OZ960 (U1). Pins 2 (OVP), 5 (VDD), 10 (CMP). Use Pin 6 for ground.


With power off and monitor unplugged, try checking/measuring the capacitance of the cap off of pin 4 (SST) of the OZ960.

[torin3]

Re: Sony SMD-HS73

May I suggest that you take some voltage measurements off of the OZ960 (U1). Pins 2 (OVP), 5 (VDD), 10 (CMP). Use Pin 6 for ground.


With power off and monitor unplugged, try checking/measuring the capacitance of the cap off of pin 4 (SST) of the OZ960.

I'll get the voltage readings in just a bit. I had to jury-rig some leads for the capacitance reading. My meter than has capacitance (only up to the 20uf range) has just the 4 holes for sticking in cap leads. I tested the leads I made against a 1uf cap I'd tested the normal way and the readings were the same. So I think I'm ok with this method.

C9 = .82uf
C10 = .17uf
C18 - .84uf

(C locations from the photo, not a data sheet)

Edit: Pin 2 mostly at 0VDC, but bounces up to .74VDC
Pin 5 seems to mostly stay around 1.17VDC, but bounces from nearly 0 to up to around 5-6VDC
Pin 10 seems to stay mostly at .47VDC with drops down to about .05VDC and up to about 1.2VDC

[jetadm123]

Re: Sony SMD-HS73

Pin5 (VDD) is the voltage supply pin required by the chip to operate. The specs call for a voltage between 4.7-5.5V and is generally supplied by the 5V output of the power supply. If it's bouncing around, then I suggest you check the components connected to that pin to see if anything is open or shorted.

Also, make sure you're still getting a steady 5V and 12V output from the power supply.

[torin3]

Re: Sony SMD-HS73

Pin5 (VDD) is the voltage supply pin required by the chip to operate. The specs call for a voltage between 4.7-5.5V and is generally supplied by the 5V output of the power supply. If it's bouncing around, then I suggest you check the components connected to that pin to see if anything is open or shorted.

Also, make sure you're still getting a steady 5V and 12V output from the power supply.

If I'm understanding the path from pin 5, it is going through C9 and then to J7 where it jumps directly to ground. Other than going through C9, it appears to follow the same path to ground as pin 6.

[jetadm123]

Re: Sony SMD-HS73

Check out Figure 1 on the spec sheet. It's really simplified, but should give you a better idea how this chip works. From Fig 1, the cap connected to pin5 has one end at ground and the other end to 5V. The question is: what other components are between that cap and the 5V that causing the low VDD?

[torin3]

Re: Sony SMD-HS73

Check out Figure 1 on the spec sheet. It's really simplified, but should give you a better idea how this chip works. From Fig 1, the cap connected to pin5 has one end at ground and the other end to 5V. The question is: what other components are between that cap and the 5V that causing the low VDD?

Ok, I'm lost here. Looking at the schematic, I see there should be an R1 at 33 ohms in between pin5 and 5VDC. I found a location marked R1 on the bord, but there is no component there, just 2 solder balls. Just for the heck of it I check the resistance, and between each side, it was 102ohms.

Also, the pins aren't matching up in the schematic to what is on the board. Pin 4 on the schematic goes to C9, but on my board it goes to C10. Pin 5 in the schematic goes to C2, but on my board it goes to C9. C2 is on the other side of the board and it is marked E 222M 3KV. If I understand the datasheet it is 2200pF ceramic cap.

Anyway, I don't seem to be able to trace where the circuit goes, as I don't have a schematic for it, and visually following the traces isn't working. The component numbers aren't matching up for the datasheet schematic you attached. I really don't know what to do.

Help?

[alexanna]

Re: Sony SMD-HS73

What are 5volts pins doing on CN1, steady or coming and going?
Al.

[jetadm123]

Re: Sony SMD-HS73

Ok, I'm lost here. Looking at the schematic, I see there should be an R1 at 33 ohms in between pin5 and 5VDC. I found a location marked R1 on the bord, but there is no component there, just 2 solder balls. Just for the heck of it I check the resistance, and between each side, it was 102ohms.

Also, the pins aren't matching up in the schematic to what is on the board. Pin 4 on the schematic goes to C9, but on my board it goes to C10. Pin 5 in the schematic goes to C2, but on my board it goes to C9. C2 is on the other side of the board and it is marked E 222M 3KV. If I understand the datasheet it is 2200pF ceramic cap.

Anyway, I don't seem to be able to trace where the circuit goes, as I don't have a schematic for it, and visually following the traces isn't working. The component numbers aren't matching up for the datasheet schematic you attached. I really don't know what to do.

Help?

Let me explain. What's supplied by the manufacturer of the chip is meant as a guide to help the designer understand how the chip works. It is in NO WAY meant to correspond to the configuration of your board. It's up to the designer to determine how much of the chip manufacturer's design they want to use. It could be some of it, or none of it. Since I don't have a schematic and only photos to work from, I have to use something besides words to get the point across. At this point, it's going to be rough if you can't trace the voltage feeding the OZ960.

[torin3]

Re: Sony SMD-HS73

What are 5volts pins doing on CN1, steady or coming and going?
Al.

Ok, trying to get these readings I managed to bump a heatsink to touch a part of frame that wasn't covered in insulation. So, F1 reads no continuity. 2.5A 250V slow blow ceramic fuse.

Heading over to Radio Shanty to get a replacement.

[torin3]

Re: Sony SMD-HS73

Let me explain. What's supplied by the manufacturer of the chip is meant as a guide to help the designer understand how the chip works. It is in NO WAY meant to correspond to the configuration of your board. It's up to the designer to determine how much of the chip manufacturer's design they want to use. It could be some of it, or none of it. Since I don't have a schematic and only photos to work from, I have to use something besides words to get the point across. At this point, it's going to be rough if you can't trace the voltage feeding the OZ960.

I didn't think there was an exact correlation, but I was grasping at straws here. I'll post a real closeup if I can of the area, but I really don't see where it is getting the 5VDC from. Unless there is another layer to the board with hidden traces. But it doesn't look like a multi-layer board as far as I can tell.

Ok, trying to get these readings I managed to bump a heatsink to touch a part of frame that wasn't covered in insulation. So, F1 reads no continuity. 2.5A 250V slow blow ceramic fuse.

Heading over to Radio Shanty to get a replacement.

They didn't have ceramic slow blows in the size and amperage I needed. I got a glass slow-blow with the same amperage and voltage ratings, and a fuse holder to wire it in.

Any issues with this? I'll be ordering a ceramic with pigtail connectors with my next order from digikey, so this will only be used while troubleshooting.

[torin3]

Re: Sony SMD-HS73

What are 5volts pins doing on CN1, steady or coming and going?
Al.

4.88VDC when the lamps are off.

Up to 5.11VDC when the lamps flash on.