Samsung Syncmaster 959 NF

Hi.
Please could anyone help me please?
Horizontal size of picture isn't possible enlarge to the whole screen. A 10 mm
space is at both sides (at 100% hor. size setting). Where could be the problem?

Or have anyone got the service manual or schematic (samsung syncmaster 959 NF)?

Thank You for help.
best regards
michal

hi
can u tell the chassis number or FCC or UL ... ?
search a leaky diode in the E/W circuit
cheers

thank you for reply.....
I attached the label from the monitor (if you mean this codes)

what does it mean E/W circ.?

hello luckym
this pic isn't so helpful to determine the chassis number but i'll try to find out what chassis is this and upload the service manual for u , just if u can help me a little bit by searching the chassis number or FCC ID number on the main board it'll be more helpful finding the equivalent service manual for this model.
well , i mean the east west correction circuit (E/W)
see u later
cheers

It's not easy to make a diagnostic from a distance, but here are a few questions that may help pinpoint the problem.

This sort of problem can have more than one cause:
1. a defect in the pincushion correction (also known as E/W correction)
2. a defective S-correction capacitor
3. a defective MOSFET that switches the S-correction capacitor
4. Insufficient B+ voltage (horizontal scan supply voltage)
Possibly even a few more.

To pinpoint the cause, look for the following:
1. Is the raster distorted (concave, looking like a pincushion) on the left and right side? If so, it could be the pincushion correction circuit.
2. If the image has straight sides: Does the image seem compressed to the left and right of the screen compared to the center of the screen? Move some icons in the center and then to the sides. Do they appear to "shrink" visibly? This would indicate an S-correction capacitor (fairly large 0.1-1.0uF in series with horizontal deflection yoke).
3. Does the phenomenon happen in one mode only? There are generally some MOSFETs that switch in and out of the circuit various S-capacitors. If the problem only happens in one mode only, either that MOSFET or the S-cap is defective (or what drives the MOSFET).
4. If the problem occurs in all modes and the sides of the picture are straignt and there is no significant compression to the sides, then the B+ voltage may be too low.

A schematic would help, but this is what YOU are looking for.
Please post your progress.

hi luckym
try this manual it's close to urs and hope it'll help u solving ur problem
cheers

sawwa thank you..... it will help..... The main board numbers correspond to manual...

To VVV: The whole screen is correct, not distorted, not compressed, in all modes this appears. So according You, B+ voltage too low? Where do I measure it?
Probably without oscilloscope I do nothing. I have to get it......

thanks

Most likely the B+ voltage is the highest voltage on the isolated side of the power supply.
Unfortunately I cannot say what the correct value should be, since I do not have a schematic.
Quite often, lower voltage on the power supply arises from a bad capacitor on the output they use for feeback. When the cap is bad, the increased ripple on that output confuses the error amplifier and you get lower voltages everywhere. So, if you had a scope you could just probe all teh voltages on the power supply and see if one of them has large ripple and then replace that cap.

Not having a scope, you can try to measure the voltages, especially the tube heater. If you find it's not very close to 6.3V, you can be fairly certain the problem is with one of the caps in the power supply. Which one, though, is harder to tell, you would need to find where the sensing is done and then try replacing that cap.

If the manual posted resembles your monitor, then B+ is +210V. I would start by replacing C625. Then, perhaps C646. But my feling is C625.

Now, other things are possible, too. Maybe it's just the horizontal adjust circuit which does not work properly. You can check C464, R465 and C462, R463.

Perhaps someone can post the correct schematic. That would help you with the voltages immediately. I might be able to suggest a few more things, too.

Ok, thank U for suggests
The B+ Votlage is 206V probably ok.....
tube heater 6.26V
C464, R465 and C462, R463 seems to be ok.

but the area under R655 is blacked (due to heat) its value is 290 k
(in Serv.man is 470k) and its code (red violet yellow brown green = 270k? what's the green band?)

This weekend I'm going to measure waveforms by scope..... then I'll know more...hope

hi luckym
i think u have a poor regulation problem , check caps for high ESR .
u have to check the +14V supply reail to be correct, it's part of the regulation circuit reference voltage , check c 625 and c646 and the resistors around for high value or o/c
IC 621 have to get 2 correct voltage, one from the +210v and the other from +14v to get regulation circuit to work properly .
cheers

Hello, after some time......

I changed C625 and C646 but nothing happend. the same problem.
I measured waveforms (3,4,5,7 according to the manual) they seem to be ok.
You can look at them:

http://www.plsanek.szm.sk/3.jpg
http://www.plsanek.szm.sk/4.jpg
http://www.plsanek.szm.sk/5.jpg
http://www.plsanek.szm.sk/7.jpg

Does the voltage +14V have to be exactly 14V? it's 13.6V (the ripple is about 0.2V)
The volatage 210V is about 206V the ripple is small too.
Is It still problem in the reg. circuit?

Thanks for help...
luckym

Hello

Sorry for recovering this old thread but it seems similar to my problem.
# i have not found any other threads like this, neither in german nor english

in the near past my picture gets an east-west cushion.
resolution while working 1440*1080 (4:3) and ingame 1024x786.
the first occurrence was ingame

If i lower the width the picture stays nearly constant (OSD width=80).
if i go further than 90 it starts the cushion.

first i attached a fan outside on the top of case to blow of the upcoming warm air
but that doesnt helped. Then i attached it inside the metallic case - no change.

these minutes the case is open and a fan is blowing on the metallic case a the tube
and i seems to be more stable.

the voltages around T601 with 210/81/14/-14/29 are stable (210 is here 207, same
as the mate before has measured). C's looks good - none inflated or leaking.

i have found the right service manual after a longer search, free download here.
http://elektrotanya.com/samsung_syncmaster_959nf_aq19nscu.tar/download.cgi
(they have many more)

unfortunately i only have a digital multimeter, i dont own a oscilloscope.
but i have some experience with the repair of some older tv.

my thoughts are more that direction that the east-west voltage is somehow injured,
not that high as needed - i need to push it up.

to mention - i already renewed lots of solder on the back side so a cold solder
joint there is not really possible. (but it is possible at the case at the tube.)

hmm, i startet the nokia monitor tester - the right side is a bit condensed.
but only the right half side of the circle...
(you can grab it here, its multi lingual:
http://www.chip.de/downloads/Nokia-Monitor-Test-1.0.0.1_13000336.html
)

same question as before - is 207 also good or has it to be exactly 210?
if i have a look at the other voltages i would say - must be 210!
so the parts around C646 are not in good shape.

i have the schematics printed out here (same for this thread) so its easy to mark
and repair, i also have a second spare monitor (17" only) here.

i have some questions to your answers:

1. a defect in the pincushion correction (also known as E/W correction)
2. a defective S-correction capacitor
3. a defective MOSFET that switches the S-correction capacitor
4. Insufficient B+ voltage (horizontal scan supply voltage)

Click to expand...

1. is that more electronic or more hardware (eg. coil)?
2. where to search?
3. same as 2. where could it be?
4. 207 or 210 volts?

the parts R649/R655 (each 470E, 1/2 W), D650, C649, R656 - which function
parallel to D647?
Same question for C462|R463 and C463, C464-R465 (all page 3 on PDF E.16).
Last results in Q454 which is connected again to +210V.
And thats the point i should have an OSC to measure the diagram [3] there. :/

# my board does not look that dark brown like the picture above

#1
while i write over half an hour the picture is stable with OSD width=80.
wow IC601 on the other side of the T601 supply is really hot (its with the alu cooler),
can only touch it for 1/2 seconds. is that normal?

#2
service manual mirrored here, ~8megs ZIP, contains 10 PDF files
**broken link removed**
schematics only, 1meg ZIP, contains E.16
**broken link removed**
##
is that allowed according rules?

otherwise i move the upload. sorry for inconvenience

#3
i know that TFT is state of the art, but i used to have CRT and play on CRT (unreal).
and i dont own the money for month to buy me one.

any cheaper help is really appreciated before i decide to buy some used CRT again.

Samsung Syncmaster 959 NF

ok, back again - again the case open with some new facts.

i tried some cooling from outside but none really helped.
so i reopened the case last minutes and tried some direct
blowing on several parts. last was the bigger TR at the left
side beside the high voltage transformator (Q402/D403)
(schematics -> 10-1-2 AQ17** & AQ19** Main Part Schematic Diagram)

Possible that one of them is bad - or some of the parts around
like C405/C406/C407/330nF/100V!?

One part has failure when temperature is raising.
Please help.

PS is there any basic adjust for the brightness and contrast?