Samsung 591S Clolor Problem

[joe6210]

Hi all, first, sorry for poor english.
I have samsung 591s color problem. when i turn ON ( VGA cable disconnected ) it show Self test mode and the color is ok. VGA card is OK, VGA cable is OK, i check all component in the RGB ( expect IC because i not know how ) and found nothing problem.

Some illustration : turn on my computer and :
1) I unplug the RGB cable from the RGB board and it's show black screen.
2) Plug the red cable to RGB board and it show picture clearly with red color dominan
3) Unplug red cable, and Plug green cable to RGB board, it show picture clearly with green color dominan
4) Unplug red cable, and plug the blue cable to RGB board, it show BLUE SCREEN and i cannot see the picture, it's just BLUE SCREEN.

Please anybody kindly help me.

[Nama]

Re: Samsung 591S Clolor Problem

Welcome to Badcaps Joe. From reading this forum I have found most people suggest us amateurs taking a CRT to a professional for repair. Many risks are involved when opening a CRT. As much as I like the idea of playing with a electron gun. I would not risk my life. Unless you are 100% comfortable playing with Hi-Voltage. I would look for a new monitor, Good luck, Jacob

I am not a PRO so make sure you check back and see if anyone else has a better suggestion!.

[EGuevarae]

Re: Samsung 591S Clolor Problem

most people suggest us amateurs taking a CRT to a professional for repair.

I agree. LCDs are one thing, but CRTs are a different kind of beasts. Maybe Toasty, PlainBill or one of our other seniors could help you, but you must know how to handle things inside a CRT (specially around the flyback) for your own safety. And for a final word: 15" CRT that probably would give you just 14" visually usable is not worth your life (not mine, at least).

[PlainBill]

Re: Samsung 591S Clolor Problem

Hi all, first, sorry for poor english.
I have samsung 591s color problem. when i turn ON ( VGA cable disconnected ) it show Self test mode and the color is ok. VGA card is OK, VGA cable is OK, i check all component in the RGB ( expect IC because i not know how ) and found nothing problem.

Some illustration : turn on my computer and :
1) I unplug the RGB cable from the RGB board and it's show black screen.
2) Plug the red cable to RGB board and it show picture clearly with red color dominan
3) Unplug red cable, and Plug green cable to RGB board, it show picture clearly with green color dominan
4) Unplug red cable, and plug the blue cable to RGB board, it show BLUE SCREEN and i cannot see the picture, it's just BLUE SCREEN.

Please anybody kindly help me.

There are three possible causes of this problem.

1. The monitor is defective
2. The VGA card (RGB board) is defective
3. The cable is defective

I don't know what kind of signal source you are using, and I can't find much information on the monitor. Most video cards for a PC use a HD-15 connector. Some monitors have 4 or 5 BNC connectors. When used with a PC a HD15 to BNC cable is used. I have also seen video sources with 4 or 5 bnc connectors.

You have already done a very good job of troubleshooting. Your tests show that the CRT itself is working properly, and that the red and green signals are getting through.

Test 1: Hook the blue input of the monitor to the red signal source. If you get a picture with blue dominant the problem is in the blue signal from the RGB board (or the cable supplying the signal) . If you get a blue screen with no picture the problem is in the monitor (or the cable carrying the signal).

Test 2. Try a different cable, monitor, or video source.

PlainBill

[Krankshaft]

Re: Samsung 591S Clolor Problem

So you're using BNC connectors?

In other words Red, Green, and Blue, connectors and a sync connector?

[Krankshaft]

Re: Samsung 591S Clolor Problem

Follow Bill's suggestion if the problem isn't in the cable then it's in the blue signal path.

A service manual will be a must here to trace the faulty component out. It's probably in the signal processing section.

If the blue wasn't normal during the self test I'd say Heater to Cathode short but since it's normal during the self test that's out the window.

[joe6210]

Re: Samsung 591S Clolor Problem

Thanks for all. I'm use D-SUB 15 pin VGA connector, but not BNC connector to the RGB. I have plug the Blue Cable to the red or green pin and get picture clearly. Plug the green or red cable to the BLUE pin and the result is BLUE SCREEN. The VGA cable is good, i have checked it.

[joe6210]

Re: Samsung 591S Clolor Problem

Thanks for all. I'm use D-SUB 15 pin VGA connector, but not BNC connector to the RGB, it's 6 pin in 1 socket to RGB( i don't know what type of this connector ). This monitor use LB15V MAIN and RGB Board, i have the Schematic Diagram. Like Mr Plainbill suggestion, i plug the Blue Cable to the red or green pin and get picture clearly. Plug the green or red cable to the blue pin and the result is BLUE SCREEN. The VGA cable is good, i have checked it. The CRT is good because when entering Setting Menu from monitor, the color is perfect.

[PlainBill]

Re: Samsung 591S Clolor Problem

Thanks for all. I'm use D-SUB 15 pin VGA connector, but not BNC connector to the RGB, it's 6 pin in 1 socket to RGB( i don't know what type of this connector ). This monitor use LB15V MAIN and RGB Board, i have the Schematic Diagram. Like Mr Plainbill suggestion, i plug the Blue Cable to the red or green pin and get picture clearly. Plug the green or red cable to the blue pin and the result is BLUE SCREEN. The VGA cable is good, i have checked it. The CRT is good because when entering Setting Menu from monitor, the color is perfect.

Your explanation makes it clearer. If it isn't the monitor or the cable, the problem is the video card.

PlainBill

[joe6210]

Re: Samsung 591S Clolor Problem

Sori, maybe we have some misconception, i mean that i'm plug the Blue Cable to the red or green pin ( at RGB Board ) and get picture clearly. Plug the green or red cable to the blue pin at RGB board and the result is BLUE SCREEN. I have been try this monitor with others computer and the result is same. So my prediction that the problem is at RGB board, please you all professional can tell me how repair the RGB board, what should i replace? Thanks...

[EGuevarae]

Re: Samsung 591S Clolor Problem

Sori, maybe we have some misconception, i mean that i'm plug the Blue Cable to the red or green pin ( at RGB Board ) and get picture clearly. Plug the green or red cable to the blue pin at RGB board and the result is BLUE SCREEN. I have been try this monitor with others computer and the result is same. So my prediction that the problem is at RGB board, please you all professional can tell me how repair the RGB board, what should i replace? Thanks...

If you insist, post a pic to get the help you want. As I've told you, one of our senior members would jump in with some good idea after seeing a pic.
Good luck

[joe6210]

Re: Samsung 591S Clolor Problem

Screen shot :

[kc8adu]

Re: Samsung 591S Clolor Problem

did this happen suddenly?
the windows screen looks almost normal but it might be the pic.
if the self test looks good and shows all 3 colors and makes good white the issue is before the main video amps.
bad solder joints and dried out caps are high on the list of suspects.
if this has a blue label samsung crt just toss it now and save your time and parts.
between the bad crt's and the unobtanium calogic video amps these things were turds.

[dmbj]

Re: Samsung 591S Clolor Problem

+1

did this happen suddenly?
bad solder joints and dried out caps are high on the list of suspects.

also you could have a shorted yoke.

[Wizard]

Re: Samsung 591S Clolor Problem

Wow, you did a troubleshooting method, by swapping signals! That's awesome, we'd hire you on the spot.

Now, That TELLS us the blue section lost control most of voltage (full railed to 90V or so) on CRT board (particularly 90V supply for this to amp IC but anywhere in the blue circuit paths). Go there and check resistors and transistors. Also change capacitors if this is older design. Newer monitors use two ICs design (one to inject OSD and pass through signal to the main amp IC) to drive all 3 guns. But the usual process of checking resistance, transistor and measuring voltage applies with DMM.

Note the newer monitors microcontroller now talk to the IC and IC itself on the CRT generate the details to make OSD and pass to the amp IC is recent design in last 8 years. Not the older LM1203 style. It's found in junky monitors.

Cheers, Wizard

[PlainBill]

Re: Samsung 591S Clolor Problem

Wow, you did a troubleshooting method, by swapping signals! That's awesome, we'd hire you on the spot.

Now, That TELLS us the blue section lost control most of voltage (full railed to 90V or so) on CRT board (particularly 90V supply for this to amp IC but anywhere in the blue circuit paths). Go there and check resistors and transistors. Also change capacitors if this is older design. Newer monitors use two ICs design (one to inject OSD and pass through signal to the main amp IC) to drive all 3 guns. But the usual process of checking resistance, transistor and measuring voltage applies with DMM.

Note the newer monitors microcontroller now talk to the IC and IC itself on the CRT generate the details to make OSD and pass to the amp IC is recent design in last 8 years. Not the older LM1203 style. It's found in junky monitors.

Cheers, Wizard

Wizard, note this:

I have samsung 591s color problem. when i turn ON ( VGA cable disconnected ) it show Self test mode and the color is ok. VGA card is OK, VGA cable is OK, i check all component in the RGB ( expect IC because i not know how ) and found nothing problem.

NOW I understand the 'RGB board' is the board on the monitor. And yes, I concur, very good job of troubleshooting.

Joe, what is the part number of the IC on the RGB board?

PlainBill

[joe6210]

Re: Samsung 591S Clolor Problem

there are 3 ic in the RGB board:
1. LM1236 (RGB Preamplifier)
2. LM2470 (Monolithic Triple 7.0 ns CRT Driver)
3. LM2480 (80V Triple Bias Clamp)

[kc8adu]

Re: Samsung 591S Clolor Problem

+1



also you could have a shorted yoke.

also you are dead wrong.yoke has nothing to do with a missing color.
looks to me that the bias(dc level) is correct but the ac(video) is missing.
since osd is fine its not the output stage.poking around with a scope i would find this fault in 30 seconds.