syncmaster 913n flickering led

[onejay09]

I got given this monitor by my brother who got given it from someone else, so im not sure how the monitor failed, ive replaced all the medium and large caps with new ones low esr, i matched the voltage and fareds too, ive resoldered all the pins on the board too, ive checked the diodes with my dmm also.
but its led is still flashing rapidly,
theres no heat from any components when power is in no funny noises or smell or smoke whitch is good but means i havnt found whats wrong
Any advice would be appreceated.
im new here from uk

[jetadm123]

Re: syncmaster 913n flickering led

I got given this monitor by my brother who got given it from someone else, so im not sure how the monitor failed, ive replaced all the medium and large caps with new ones low esr, i matched the voltage and fareds too, ive resoldered all the pins on the board too, ive checked the diodes with my dmm also.
but its led is still flashing rapidly,
theres no heat from any components when power is in no funny noises or smell or smoke whitch is good but means i havnt found whats wrong
Any advice would be appreceated.
im new here from uk

Welcome to the forum! Just a few words of advice:

1) Picture are ALWAYS welcome, but they need to be in focus and it's better if you take a overhead photo of the top and bottom of the board as members cannot see through components of photos taken at an angle.

2) It's good that you replaced caps, but you should have also replaced the small ones. I see at least one capxon cap that's pure junk and should have been replaced. One small cap is generally used in the power supply startup process. If you had replaced all the caps, then we would have had a good starting point.....

[onejay09]

Re: syncmaster 913n flickering led

Thanks, and sorry about the pictures, i did take one of top and bottom and made sure they were clear i must have uploaded the wrong ones, its my fault i posted them via android mobile. I am planning to replace all of the caps i just thought id wait and see whether the new caps would solve it first, the caps are on there way so hope they get here soon. Yes i read somewhere that one small one is the startup cap but i was also told the big caps rarely fail,

So do you think it is the other caps that need changing too?
thanks
Jamie

[onejay09]

Re: syncmaster 913n flickering led

Heres the other pic it wouldnt upload before

[jetadm123]

Re: syncmaster 913n flickering led

Thanks, and sorry about the pictures, i did take one of top and bottom and made sure they were clear i must have uploaded the wrong ones, its my fault i posted them via android mobile. I am planning to replace all of the caps i just thought id wait and see whether the new caps would solve it first, the caps are on there way so hope they get here soon. Yes i read somewhere that one small one is the startup cap but i was also told the big caps rarely fail,

So do you think it is the other caps that need changing too?
thanks
Jamie

You can generally leave the 450V cap alone as that rarely fails. All other caps (including the small ones) should be replaced with low-esr caps.

[retiredcaps]

Re: syncmaster 913n flickering led

1) On connector CN201, there is a legend. List each pin and its legend.

2) With a multimeter, measure each pin on CN201 with respect to ground. List the DC voltage readings along with the expected value.

3) We also need a clear focused picture of the main/logic board.

[onejay09]

Re: syncmaster 913n flickering led

Sorry im still learning all this, i understood what u meant about cn201 but what legend? Do u mean measure voltage on each pin on the ribbon going to the other board?

[retiredcaps]

Re: syncmaster 913n flickering led

Sorry im still learning all this, i understood what u meant about cn201 but what legend?

Legend. See

https://www.badcaps.net/forum/attach...3&d=1303127782

[retiredcaps]

Re: syncmaster 913n flickering led

Do u mean measure voltage on each pin on the ribbon going to the other board?

Yes. Put your multimeter on 20V DC (if manual ranging). Put your black probe on a ground screw closest to the connector. Put your red probe on each pin and report it like

Pin # - Legend - Reading
Pin 1 - 5V - 4.98
Pin 2 - GND - 0.0V

[onejay09]

Re: syncmaster 913n flickering led

Right i thought so thanks

Pin 1 red- 10.0v +13v
Pin 2 blk- 10.2v
pin 3 blk- gnd
Pin 4 blk- gnd
Pin 5 blk- gnd
Pin 6 blk- 1.6,1.7v +5v
pin 7 blk- 1.6v
pin 8 blk- 1.5v
pin 9 blk- 0.7,0.6v on/off

These were with the other board plugged in hope thats right

[retiredcaps]

Re: syncmaster 913n flickering led

Pin 1 red- 10.0v +13v
Pin 2 blk- 10.2v
pin 3 blk- gnd
Pin 4 blk- gnd
Pin 5 blk- gnd
Pin 6 blk- 1.6,1.7v +5v
pin 7 blk- 1.6v
pin 8 blk- 1.5v
pin 9 blk- 0.7,0.6v on/off

1) Hmm, all those readings are way off to what is the legend states (if that is the last column).

10V is way off from 13V. 1.6V is way off from 5V.

2) Let's rule out the multimeter first as being possibly bad. A weak battery or poor test leads will lead to inaccurate readings.

a) Take a fresh akaline battery (say AA) and measure it. For a fresh battery, I think you should get 1.6V DC.

b) Put your multimeter on 200 Ohm scale. Touch the 2 probes together. What do you get?

3) A picture of your multimeter will also help.

[onejay09]

Re: syncmaster 913n flickering led

I get a reading of 0.01 to 0.02 ?
i get 1.5 vdc from battery
the dmm is about 2 weeks old, i havnt got it to hand right now for a photo sorry

[retiredcaps]

Re: syncmaster 913n flickering led

I get a reading of 0.01 to 0.02 ?
i get 1.5 vdc from battery

Your multimeter appears to be working correctly given the above readings.

Let's try this. Disconnect the logic/main board. Leave the ccfls plugged in. Re-measure all those connector pins and report the readings.

[retiredcaps]

Re: syncmaster 913n flickering led

ive replaced all the medium and large caps with new ones low esr,

The small caps that you didn't replace all play an important part of the entire SMPS application. Depending on your voltage readings with the main board disconnected, you may be asked to get replacements for them especially if the caps are Capxon brand.

[onejay09]

Re: syncmaster 913n flickering led

Hi just measured voltages without the video board plugged in
1 13.14v
2 13.14v
3 0v
4 0v
5 0v
6 5v
7 5v
8 0v
9 0v
so does that mean a short on the other board ?

[PlainBill]

Re: syncmaster 913n flickering led

Hi just measured voltages without the video board plugged in
1 13.14v
2 13.14v
3 0v
4 0v
5 0v
6 5v
7 5v
8 0v
9 0v
so does that mean a short on the other board ?

Maybe, but there is another possibility. There are 5 small caps - C103 C105, C204, C33, and another net to R101 whose component number is obscured (C104?) Were those replaced?

PlainBill

[onejay09]

Re: syncmaster 913n flickering led

No i havent replaced them yet the parts are on their way, should be here in a few days. So would they cause an issue with the voltage drop?
also should the voltage from big cap be steady or fluctuating?
Should it be changed also?

[onejay09]

Re: syncmaster 913n flickering led

Those caps are
50v 47 uf
35v 47uf
50v 22uf
50v 4.7uf
Ill post the results when i replace them
thanks

[PlainBill]

Re: syncmaster 913n flickering led

No i havent replaced them yet the parts are on their way, should be here in a few days. So would they cause an issue with the voltage drop?
also should the voltage from big cap be steady or fluctuating?
Should it be changed also?

The voltage on the big cap should be steady.

The short story is I spent hours troubleshooting a Samsung TV/monitor that would try to start up, and fail. It didn't have a power led, but the speakers would click every second or so. After a LOT of troubleshooting I discovered that the startup cap in the external power supply was bad. The funny thing was I had tested the supply at about 2 1/4 amps load. The supply was rated at 4 Amps, the TV/monitor drew about 3.

PlainBill

[onejay09]

Re: syncmaster 913n flickering led

It seems that my thoughts turned out to be right in the big cap fluctuating ! :-) I replaced it and it started right up ! Whoo, only to find that when me and the ex fell out the other day shed taken her anger out in the LCD panel ! She did a his job in it too :-(. So now am selling the power board and video board anybody in Lancashire UK area is welcome to PM me