Sony SDM-HS73 on for 2 seconds then off

[jetadm123]

Re: Sony SDM-HS73 on for 2 seconds then off

I did want to make one final post on this monitor. I never did fix this monitor, instead I decided to use the monitor as a learning experience. I completely disassembled the panel. I was curious to see the make up of the inside of the panel. That way, if in the future I have a monitor that needs CCFL replacing I know what to expect. All and all this was a fun project, I'm just a little bummed I wasn't able to fix it.

Even though I wasn't able to fix it, I *believe* I found the problem. The upper inverter would briefly produce an electric noise almost like it was arcing. Also, I was getting some very inconsistent resistance readings from the inverter. So I suspect this inverter went bad.

While working on this monitor there were a few things which struck me.

1. The build quality on this monitor was higher than that of many other monitors. The frame contained more metal and less plastic than you would typically find. Probably my favorite feature was the fact the monitor was assembled using screws instead of plastic tabs - this made it easy to disassemble.

2. The internal components were nicer than I was expecting. I recently got an ESR meter and I went back and retested all the caps in this monitor. They all tested good. I also noticed the caps were high quality caps to begin with. After working on so many cheap monitors like Samsung and ViewSonic it's nice to see one with decent components for once.

I guess both of these are to be expected when you spend a little more for a nicer brand like Sony versus the el-cheapo brands.

Yes, it is too bad that you couldn't repair it. I've seen several sony monitors on this site with problems similar to yours that also went unfixed. Hopefully, someone will find some common part that has failed on these models. Although, it would seem that you've come close with a possible failed inverter transformer. Hopefully, you can find a replacement transformer to prove your theory.

[Freezer]

Re: Sony SDM-HS73 on for 2 seconds then off

I did want to make one final post on this monitor. I never did fix this monitor, instead I decided to use the monitor as a learning experience. I completely disassembled the panel. I was curious to see the make up of the inside of the panel. That way, if in the future I have a monitor that needs CCFL replacing I know what to expect. All and all this was a fun project, I'm just a little bummed I wasn't able to fix it.

Even though I wasn't able to fix it, I *believe* I found the problem. The upper inverter would briefly produce an electric noise almost like it was arcing. Also, I was getting some very inconsistent resistance readings from the inverter. So I suspect this inverter went bad.

While working on this monitor there were a few things which struck me.

1. The build quality on this monitor was higher than that of many other monitors. The frame contained more metal and less plastic than you would typically find. Probably my favorite feature was the fact the monitor was assembled using screws instead of plastic tabs - this made it easy to disassemble.

2. The internal components were nicer than I was expecting. I recently got an ESR meter and I went back and retested all the caps in this monitor. They all tested good. I also noticed the caps were high quality caps to begin with. After working on so many cheap monitors like Samsung and ViewSonic it's nice to see one with decent components for once.

I guess both of these are to be expected when you spend a little more for a nicer brand like Sony versus the el-cheapo brands.

[Freezer]

Re: Sony SDM-HS73 on for 2 seconds then off

I replaced the 4 27K3KV ceramic disc capacitors but that didn't fix the problem. I am beginning to suspect one of the inverters is bad. Between several of the pins the resistance starts at 6+ mohm and then after about 1 second it drops to several hundred kohms. This only happens on one transformer, but consistently happens between a certain group of pins. So I'm thinking either the transformer is bad, but I guess it's possible a short in the board is causing this as well. My plan is to try and desolder the transformers and test them out of circuit. Should be interesting, I've never tried to desolder something with so many pins.

[retiredcaps]

Re: Sony SDM-HS73 on for 2 seconds then off

I'm not sure since the Sony is a 17" and the Viewsonic is a 19"

Members report that a couple of inches difference doesn't make matter for this test. If the difference was more like 4 or 5 inches, it may make a difference.

[PlainBill]

Re: Sony SDM-HS73 on for 2 seconds then off

Using the schematic in this thread I tested the 4 mosfets as suggested. All 4 check out okay. None of them indicate a short, and all 4 have very similar readings. I'm in the process of more thoroughly testing the inverters, I'll report back with those number soon.

I just acquired a broken Viewsonic Q191wb (19" widescreen) off craigslist. Can I use this monitor to test the CCFLs in the Sony and vise versa? I'm not sure since the Sony is a 17" and the Viewsonic is a 19". Also, I'm not sure if the different makes would cause a problem.

So in addition to my posts on the Sony SDM-HS73, I'll be posting soon in the existing thread for Q191wb.

You can try using the CCFLs in one to test the other. Of course, if the CCFLs in both are bad....

PlainBill

[Freezer]

Re: Sony SDM-HS73 on for 2 seconds then off

Using the schematic in this thread I tested the 4 mosfets as suggested. All 4 check out okay. None of them indicate a short, and all 4 have very similar readings. I'm in the process of more thoroughly testing the inverters, I'll report back with those number soon.

I just acquired a broken Viewsonic Q191wb (19" widescreen) off craigslist. Can I use this monitor to test the CCFLs in the Sony and vise versa? I'm not sure since the Sony is a 17" and the Viewsonic is a 19". Also, I'm not sure if the different makes would cause a problem.

So in addition to my posts on the Sony SDM-HS73, I'll be posting soon in the existing thread for Q191wb.

[retiredcaps]

Re: Sony SDM-HS73 on for 2 seconds then off

This will be the 3rd monitor I've worked on, so I have some experience.

[*]If all else fails I may consider CCFL replacement.

If you already have 2 working monitors, you can stretch the ccfl cable from the Sony to one of the working ones as a test.

[retiredcaps]

Re: Sony SDM-HS73 on for 2 seconds then off

I set my multimeter to diode and tested these four chips. All four chips test exactly the same. So my guess is the mostfets are fine.

1) I usually check mosfets for shorts by doing the following

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.

Any reading under 30 ohms suggests a short.

2) Did you check the inverter transformers to see if your secondaries are around 597 ohms?

[Freezer]

Re: Sony SDM-HS73 on for 2 seconds then off

I finally got a chance to snap some pictures of the power/inverter board. Although I'm not pleased with the quality, I may take them again. In the meantime, here's the front and back of the board, plus a zoom in of the inverter section.

I have already cleaned up the solder around the inverter transformers. It didn't fix the problem, but it looks much better than it did.

In between the two inverters are 4 mosfets (datasheet is located earlier in this thread). I'm by no means an expert when it comes to testing components like this. I set my multimeter to diode and tested these four chips. All four chips test exactly the same. So my guess is the mostfets are fine. I may go so far as to probe the "gate" lead during power on to see if I have a signal.

[Freezer]

Re: Sony SDM-HS73 on for 2 seconds then off

I bought the BK Precision 2709B after watching the EEVBlog's $100 shootout. Me personally, I love the episode where it blows up meters using a high-voltage generator.

Anyway... I'll get some pictures up as soon as I can. It will be a couple of days however. My wife is out of town right now and she has the nice DSLR camera.

[Welchs101]

Re: Sony SDM-HS73 on for 2 seconds then off

freezer,

usually when i have a ccfl that is bad what happens is when i turn on the monitor it comes on for a "brief" period of time usually 2sec and then shuts off.

What i do then to "verify" its the bulb is this. You normally have 4 bulbs in the monitor. Each bulb has its own "wire" and connector-plug lets say you have connectors c1, c2,c3 and c4 in your monitor. With c1,c2,c3 connected to your monitor connect c4 to another monitor that you know has a good working bulb............turn on monitor and see if it stays on. If it does not stay on then reconnect c4 and try again. This time......with c1,c2,c4 connected to your monitor connect c3 to another monitor and then turn it on..........if it still does not stay on then proceed again. this time ......with c1,c3,c4 connected to your monitor connect c2 to another.............you get the idea.

Now this method works if only "ONE" bulb is out.........if you have more than one bulb out you will need to swap more than the one bulb as i mentioned above................hope this helps.

[retiredcaps]

Re: Sony SDM-HS73 on for 2 seconds then off

destroying a DMM other ppl can't even afford just to get hits on his video. how lame.

I don't want to take this thread off track, but he doesn't destroy stuff just to "destroy stuff" like a banned member here. Since the Fluke 28 II is advertised as the "most rugged Fluke multimeter", he went to extremes to test it. I'm sure Fluke themselves test their own products to an extreme and so don't live.

If, however, you are referring to epidsode 100 where he did smash multimeters at the end, they were all POS meters (in his opinion and not worthy of life).

[Scenic]

Re: Sony SDM-HS73 on for 2 seconds then off

destroying a DMM other ppl can't even afford just to get hits on his video. how lame.
even if his videos are sometimes kinda helpful, his voice makes my ears bleed..

[retiredcaps]

Re: Sony SDM-HS73 on for 2 seconds then off

Isn't he that crazy Aussie who does videos of doing really nasty things to a Fluke?

Yes. I love the death and destruction of the Fluke 28 II multimeter video. Dropping it from 100 feet, throwing it out of a car doing 60km/h, etc.

http://www.eevblog.com/2010/03/07/ee...ke-multimeter/

[smason]

Re: Sony SDM-HS73 on for 2 seconds then off

2) Nice meter. It won the Dave Jones eevblog $100 multimeter shootout.

Isn't he that crazy Aussie who does videos of doing really nasty things to a Fluke?

[retiredcaps]

Re: Sony SDM-HS73 on for 2 seconds then off

It's only a fraction of a second - not the 2 seconds previously reported.

I also have a fairly decent multimeter to work with, a BK Precision 2709B

1) Fraction of a second might suggest a shorted component somewhere (like mosfet/transistor in the inverter section)? Pics of your board will help because manufacturers do make revisions to their boards.

2) Nice meter. It won the Dave Jones eevblog $100 multimeter shootout.

[Freezer]

Re: Sony SDM-HS73 on for 2 seconds then off

Thanks for the reply, I'll go ahead and order that part from digikey.

My monitor has a slightly different symptom than yours did. When I turn the monitor on, the CCFLs light up for a split second. It's only a fraction of a second - not the 2 seconds previously reported. The power switch LED stays illuminated green (or amber when the monitor eventually goes into standby).

I am by no means an expert here. I enjoy trying to fix things as a hobby. This will be the 3rd monitor I've worked on, so I have some experience. I also have a fairly decent multimeter to work with, a BK Precision 2709B (http://www.bkprecision.com/products/...ultimeter.html).

What I've done up to now:

• I checked both the power/inverter board and the video processing board for the following; cracked boards, cold or bad solder joints, burned components, bulging or leaking caps, etc. I found no issues.
• I replaced all the electrolytic caps with brand new ones. None of the caps looked bad, and indeed after removing them they all tested fine. But I replaced them nonetheless.

My plan of attack is as follows:

• Check the the two CCFL inverters. I don't have a Q/ring tester so I can only check resistance. If the readings are similar between the two then they are probably good, if they disagree one or both is probably bad.
• Cleanup the solder joints around the CCFL inverters. There is a lot of excess solder on these joints.
• Replace those 4 ceramic caps that were obviously bad on your monitor.
• If all else fails I may consider CCFL replacement. I've never done this and I'm not sure it's worth the time or money.

Any other ideas or suggestions. I'll see if I can't post pictures soon, although mine looks the same as yours on the inside.

[Welchs101]

Re: Sony SDM-HS73 on for 2 seconds then off

+/- 5% is actually better than +/-10%........in that you are going to have a part that is within 5% of the expected value of 27pf/3000V. The 10% part means that you could have a part that is 10% from 27pf.

What are the symptoms of your monitor not working?

[Freezer]

Re: Sony SDM-HS73 on for 2 seconds then off

No, I haven't tested the existing CCFLs, but then I don't have a way to test them.

I have used a cap checker to verify all the electrolytic caps are good. I'm thinking about replacing the 4 ceramic caps which were bad on your monitor. They show no signs of failure on mine, but a visual inspection tells you nothing. I'm also planning on cleaning up the solder around the inverter transformers, there is a lot of excess solder.

As for ordering replacement caps, the originals are 27pf 3000V +/-10%. I've looked everywhere online for these and can't find them. The closest part I've found is the following which is 27pf 3000V +/-5% (http://search.digikey.com/scripts/Dk...&name=P9647-ND). Is the change in tolerance going to be a problem.

[Welchs101]

Re: Sony SDM-HS73 on for 2 seconds then off

I usually order ccfl bulbs from

http://www.ccflwarehouse.com/


I really like these guys...........

Its was not too hard to replace........but its all relative. I hate replacing bulbs! It takes me a long time to do........i move slow so i dont break the bulb and so that i can put it all back together the same way it came apart.

I am sure i probably move slower than the average person but i dont do this for a living.........just a hobby of sorts.

Have you verified it is indeed the ccfls?

HOpe this helps.