Planar PE1700-BK monitor

[Tinbendr]

Re: Planar PE1700-BK monitor

Now place 1 probe firmly on each end of F1. What reading do you get?

.6Ω

Now place 1 probe firmly on each end of F2. What reading do you get?

.6Ω

Now switch the DMM to the 20VDC range. Plug in the monitor and have it hooked to a computer displaying a desktop or something similar. Hold one probe on pins 3 or 4, and the other probe on ...

pin 5 - 1.75v
pin 6 - 4.75v
pin 7 - 4.75v

All displayed this for approx 5 secs.

Also, do you get a flash of the display every time you push the power button and the power led comes on?

Yes

[PlainBill]

Re: Planar PE1700-BK monitor

.6Ω
.6Ω



pin 5 - 1.75v
pin 6 - 4.75v
pin 7 - 4.75v

All displayed this for approx 5 secs.
Yes

I'm trying to make sure we are communicating properly here. To me 'flash' implies something lasting under a second. 5 seconds would be much longer. Is that accurate? (5 seconds sounds like a 'no signal' timeout.)

PlainBill

[Tinbendr]

Re: Planar PE1700-BK monitor

It's definitely longer than 1/2 second. At least 3 sec for sure.

[alexanna]

Re: Planar PE1700-BK monitor

In your very first post you indicated the PLED was yellow all the time, But that was without a signal going to the monitor.
Now that you have a signal going to the monitor dose the PLED change colors?

[Tinbendr]

Re: Planar PE1700-BK monitor

Bill, my apologies. I reread your 'back-to-basics' and realized I didn't have a source hooked up.

Pin 7 - 4.75v - steady
Pin 6 - Nothing
Pin 5 - 1.75 steady.

AlexAnna, the LED appears yellow (maybe green) to me. (See video)

Monitor turn on

[alexanna]

Re: Planar PE1700-BK monitor

The signal important
So we lost pin six 4.75v altogether or just when the display turned off?

[PlainBill]

Re: Planar PE1700-BK monitor

Bill, my apologies. I reread your 'back-to-basics' and realized I didn't have a source hooked up.

Pin 7 - 4.75v - steady
Pin 6 - Nothing
Pin 5 - 1.75 steady.

AlexAnna, the LED appears yellow (maybe green) to me. (See video)

Pin 5 is probably brightness, pin 7 On/Off. I'm trying to establish if any of these change when the backlights turn off. This definitely appears to be an almost classic 'two seconds to black'. The 'on' time is less than a second, judging from the video.

Here's the next test: Unplug one set of backlights. Turn the monitor on. Do you still get the flash? Reconnect those and disconnect the other set. Turn the monitor on again. Do you still get the flash?

PlainBill

[Tinbendr]

Re: Planar PE1700-BK monitor

So we lost pin six 4.75v altogether or just when the display turned off?

With source connected, no reading from pin 6 at rest or when monitor is started.

Here's the next test: Unplug one set of backlights. Turn the monitor on. Do you still get the flash? Reconnect those and disconnect the other set. Turn the monitor on again. Do you still get the flash?

No change when I unplug either backlight. (I'm assuming the backlights are the two white plugs in picture 1?) I still get the flash as illustrated in the video.

David

[PlainBill]

Re: Planar PE1700-BK monitor

I'm just about out of ideas on this. Before I have you take apart the LCD panel to examine the CCFLs, there are a couple of points I want investigated.

Referring to the picture of the inverter, I believe the pin in the upper left corner of the transformer is one end of the secondary, of course the one in the lower left corner is the other end of the secondary. Measure the resistance of the secondary on each transformer. If it reads greater than 10K, check the resistance from each pin at the upper end of the transformer to the pin on the lower left corner of the transformer. Compare the resistances; they should match to within 3%.

I am also suspicious of the surface mount electrolytic capacitors.

PlainBill

[Tinbendr]

Re: Planar PE1700-BK monitor

Pin T2 T1
1-11 - 337Ω 337Ω
1-3 - 1270Ω 1279Ω
1-4 1266Ω 1274Ω
1-5 1266Ω 1272Ω
1-6 1265Ω 1270Ω

All other combination's were 0.

[PlainBill]

Re: Planar PE1700-BK monitor

The transformers appear to be good.

Argh!!! I forgot to ask - what is the part number of the 16 pin IC on the inverter?

PlainBill

[Tinbendr]

Re: Planar PE1700-BK monitor

1250et

[PlainBill]

Re: Planar PE1700-BK monitor

1250et

Aww, crud!!! No datasheets found.

PlainBill

[alexanna]

Re: Planar PE1700-BK monitor

Open up one of you other monitors,See if the problems are the same.If there different you can try substitution.

[Tinbendr]

Re: Planar PE1700-BK monitor

Open up one of you other monitors,See if the problems are the same.If there different you can try substitution.

Yeah, I thought of that today. Definitely will be a weekend project.

Later,
David

[Tinbendr]

Re: Planar PE1700-BK monitor

Well its what we call 2 seconds to black.

OK, I had a little time to work on the monitor. I decided to back up and reread the thread and some of the other sticky's on the board. I got a stronger, wider beam light source, a small flood light, to check the monitor. Much to my surprise (and embarrassment), the monitor actually IS displaying the image from the source.

But, knowing this, does this change the tests we've been conducting?

[PlainBill]

Re: Planar PE1700-BK monitor

OK, I had a little time to work on the monitor. I decided to back up and reread the thread and some of the other sticky's on the board. I got a stronger, wider beam light source, a small flood light, to check the monitor. Much to my surprise (and embarrassment), the monitor actually IS displaying the image from the source.

But, knowing this, does this change the tests we've been conducting?

No; I'd pretty much concluded the problem was in the backlight circuit.

PlainBill

[alexanna]

Re: Planar PE1700-BK monitor

On one of the first monitors I worked on PlainBill helped me, And we identified the backlight on signal and traced it down to the backlight controller, the signal was OK.But at least we knew the logic board was asking for the backlights to be on. There are some monitors that even if there is an image on the dark screen it can be almost impossible to see even with a bright light. If there is a backlight on signal that is making its way down to the backlight controller we know to look to the inverter section for problems.
On a few occasions I have had a good backlight on signal at the connector to the logic board, but there was a weak spot in the circuit going to the backlight controller. This would result in a momentary flash of the backlamps, as the weak spot totally opened up.

[Tinbendr]

Re: Planar PE1700-BK monitor

I am also suspicious of the surface mount electrolytic capacitors.
PlainBill

OK, finally got back to this project.

I dug out my Supco MFD10 Cap.Tester. I usually use this for my laundromat equipment, but it tests down to .01. All caps report within their range except C14, C15 and C23, C24. These do not give any reading. I removed C24 from the board and it still nothing. (I've realized as I write this that the tester might not read low enough, but it reads all others on the board and they are much smaller.)

Would it be possible that just these four on the transformer are bad? It would seem strange to me that ALL would go bad. But, educate me. (Oh and can you tell me what capacity these are?)

[PlainBill]

Re: Planar PE1700-BK monitor

OK, finally got back to this project.

I dug out my Supco MFD10 Cap.Tester. I usually use this for my laundromat equipment, but it tests down to .01. All caps report within their range except C14, C15 and C23, C24. These do not give any reading. I removed C24 from the board and it still nothing. (I've realized as I write this that the tester might not read low enough, but it reads all others on the board and they are much smaller.)

Would it be possible that just these four on the transformer are bad? It would seem strange to me that ALL would go bad. But, educate me. (Oh and can you tell me what capacity these are?)

Those are typically in the 10 - 30 pico farad range. And if they fail, it's obvious from the charred cap.

PlainBill