Sony SDM-HS73 Turns on for a few seconds then black screen

[Welchs101]

Hi,

I have a Sony Monitor that a friend brought me. Is a sony SDM-HS73. It turns on for a few seconds then turns off.

I checked the bulbs and they seem fine.

So looking at other things i found these transistors (i think they are transistors.....see enclosed pic). I ohmed out the components but without a datasheet i am not sure if the readings i get are correct or not. Can someone find a data sheet for this part? I have enclosed a picture of the part in question.

[Mikeley]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

Its a 2SD1691 NPN Power transistor.

Google it... Emitter, Collector, Base as your look at the shot.

[retiredcaps]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

Check inverter transformers. I circled the pins again. Measure both and report both. They should be within 3% of each other.

[Welchs101]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

I checked transformer:
Red measurement: 0.2ohms
Yellow measurement: 0.2ohms


I also measured the SD1691 transistors: But i think they are ok.......arent they?

Q209:
Red-multimeter wire/Black-multimeter wire:
Emitter-Collector: 6.34K
Emitter-base: 6.76K
Collector-base: 0.5K

Black-multimeter wire/Red-multimeter wire:
Emitter-Collector: 267K
Emitter-base: 265K
Collector-base: 0.5K

Diode-check:
Red lead on Base, Black on collector and then emitter.
Base-collector: 0.346V
Base-emitter: 0.485V


Q210:
Red-multimeter wire/Black-multimeter wire:
Emitter-Collector: 6.33K
Emitter-base: 6.85K
Collector-base: 0.5K

Black-multimeter wire/Red-multimeter wire:
Emitter-Collector: 272K
Emitter-base: 272K
Collector-base: 0.5K

Diode-check:
Red lead on Base, Black on collector and then emitter.
Base-collector: 0.344V
Base-emitter: 0.485V



Q211:
Red-multimeter wire/Black-multimeter wire:
Emitter-Collector: 5.76K
Emitter-base: 6.24K
Collector-base: 0.498K

Black-multimeter wire/Red-multimeter wire:
Emitter-Collector: 203K
Emitter-base: 202K
Collector-base: 0.498K

Diode-check:
Red lead on Base, Black on collector and then emitter.
Base-collector: 0.342V
Base-emitter: 0.486V


Q212:
Red-multimeter wire/Black-multimeter wire:
Emitter-Collector: 5.9K
Emitter-base: 6.35K
Collector-base: 0.498K

Black-multimeter wire/Red-multimeter wire:
Emitter-Collector: 200K
Emitter-base: 194K
Collector-base: 0.498K

Diode-check:
Red lead on Base, Black on collector and then emitter.
Base-collector: 0.342V
Base-emitter: 0.488V



I think these measurements are ok..........arent they?

Any other thoughts?

[retiredcaps]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

I checked transformer:
Red measurement: 0.2ohms
Yellow measurement: 0.2ohms

Hmm, I must of identified the secondaries wrong. Let me look again.

The Q measurements look fine to me.

edit: Are you measuring the inverter transformer solder joints that are marked 8 and 9?

[Welchs101]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

retiredcaps,

Not sure what your asking here

"Are you measuring the inverter transformer solder joints that are marked 8 and 9?"

[retiredcaps]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

The transformer pins on the back are numbered 1 through 9. I believe the secondaries are pins 8 and 9 (which I circled). I expected those ohms measurements to be way way higher than 0.2 ohms.

[Rtech]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

Looks like 8 & 9 are commoned,which occurs on some boards.You need to measure the resistance from any contact on the red,to the two outside pins on the other side of the transformer,One of those readings will probably give you the secondary resistance.do the same from the yellow.

[retiredcaps]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

You need to measure the resistance from any contact on the red,to the two outside pins on the other side of the transformer.

I was going to suggest the same. Try pins 1-8 or 7-8.

[Welchs101]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

ok..... here are the measurements i made.

For the transformer you circled in red:
Pin8(red multimeter lead) to Pin 1(black multimeter lead): 6.67kilo-ohm
Pin8(black multimeter lead) to Pin 1(red multimeter lead): 236.3kilo-ohm
Pin8(red multimeter lead) to Pin 7(black multimeter lead): 263.2ohm
Pin8(black multimeter lead) to Pin 7(red multimeter lead): 236.2ohm



For the transformer you circled in yellow:
Pin8(red multimeter lead) to Pin 1(black multimeter lead): 7.36kilo-ohm
Pin8(black multimeter lead) to Pin 1(red multimeter lead): 288.8kilo-ohm
Pin8(red multimeter lead) to Pin 7(black multimeter lead): 260.3ohm
Pin8(black multimeter lead) to Pin 7(red multimeter lead): 260.3ohm


How did you know to measure on the outside pins? Just curious?

Do the measurements look ok to you? Kinda interesting that it matters what lead goes where.

[Rtech]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

Presume you mean..Pin8(black multimeter lead)to pin 7 (red multimeter lead)263.2ohms and not 236.2 as you have annotated ?????

[Welchs101]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

Yes, your correct. Just remeasured to be sure .........yes.....it should be 263.2ohms.

[Rtech]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

AS your are SURE the lamps are good ??...AND the transformers and transistors look good,I would heat up the soldering iron and go over everything from the inverter transformers to the lamp sockets,and see if that makes a difference.If it does not then..things get tough....I hate Sony.. when things go wrong,as usually its not straight forward...which is probably why I will not buy faulty ones to repair and resell.

[retiredcaps]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

Kinda interesting that it matters what lead goes where.

What multimeter brand and model do you have? If you touch the two probes together, what do you get for an ohms reading?

I took a random board and measured the secondary inverter transformer pins and got almost the exact same ohms measurement with red on one side and then switching to the other side.

[Welchs101]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

I have a fluke 79III True RMS Multimeter. Meter reads 0.2ohms when i touch the two probes together.

They way i tested the lamps is i used a 19" monitor to power up the lamps of the monitor in question. But it should be noted that the monitor in question has 4 lamps and for example..........the two top lamps has only one "return" but two hot leads. When i tested the lamps of the "monitor in question" my 19" tester did not "shut off".....ie...i guess it did not detect any issues.

[retiredcaps]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

I have a fluke 79III True RMS Multimeter.

Nice Fluke. No question those readings are accurate and 260 and 263 ohms are within 3% of each other.

[alexanna]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

I have a fluke 79III True RMS Multimeter. Meter reads 0.2ohms when i touch the two probes together.

They way i tested the lamps is i used a 19" monitor to power up the lamps of the monitor in question. But it should be noted that the monitor in question has 4 lamps and for example..........the two top lamps has only one "return" but two hot leads. When i tested the lamps of the "monitor in question" my 19" tester did not "shut off".....ie...i guess it did not detect any issues.

I have had better luck troubleshooting a 2 second to black problem by using known good ccfls on the suspect monitors inverter. It helps if you can have at least one bulb out of the LCD where you can see it.
There is the possibility you might notice something specific to one inverter transformer or on one side of the inverter. The easiest example I can think of is a bulb a little dimmer.
Al

[Rtech]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

The way you tested the ccfls ,meant that you had an inverter capable of driving 19" lamps, driving 17" lamps, so should be able to do that, with no problem.BUT what you really need to do is test 'like for like',so you really need to use the Sony Inverter etc to try and drive KNOWN good 17" lamps,and that would confirm for certain in what area the fault lies,and as 'alexanna' says its always better to use 'loose' test lamps,then you can see brightness,and in some cases,you can get an immediate idea of whether the fault is top or bottom.

[Welchs101]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

ok. First let me say thanks to those helping out on this.

Second, let me say...........opps! Monitor actually works.......well it stays on at least. The color is kinda off but monitor works. Apparently you need to have a computer hooked up to this monitor otherwise lamps shutoff. Now i know what your thinking.......lamps will always shut off if you dont have video connected........and this is true.......but with this monitor it happened quicker than i had seen before and so i thought it was "shutting off" as i could still see a faint image on the screen once lamps shutoff with no video connected.

Anyway, monitor works in the sense that it does come one and stay on.

But i would not have figured this out had I not been trying to do something to satisfy one of the posts. So thanks guys!

If feel a little stupid...........

[Rtech]

Re: Sony SDM-HS73 Turns on for a few seconds then black screen

Ugh......