Samsung SyncMaster 914v

[spaceman]

Next up is a SyncMaster 914v that has something going on with the inverter board. At first I thought it would be a quick cap replacement once I saw a few bulging a little, but even after that, I still have an increasing buzz power-up until it discharges, powering everything down until the cycle picks back up again.

I'm not able to get pictures today, but will update later. I was just curious if there were any usual suspects in cases like this.

As always, thanks.

[ipman]

Re: Samsung SyncMaster 914v

Usually that is a sign that the power supply enters in protection mode.
You should try to check the rectifiers.

[spaceman]

Re: Samsung SyncMaster 914v

Hmm, rectifiers brings up a few different images. Some look like diodes and some look like voltage regulators. Both of which are in the area that produces the sound. If you don't mind, could you mark it on this picture please?

Thank you
Brad

[ipman]

Re: Samsung SyncMaster 914v

You should track the circuit. Or identify the parts based on the datasheets.
Anyway, the two on the right seem to be rectifiers anyway, don't know about the TO220 capsule mounted on heatsink.

[spaceman]

Re: Samsung SyncMaster 914v

Thanks. I had a feeling you might be refering to them, but I really wasn't positive. Although the plan is to desolder them to get a better look, any idea what sort of specs they typically are?

EDIT: It looks like they might be Schottky SR506's. At least according to Allinbox.com. As long as no one has any complaints about these, I'll get a few more and swap them out.

And here's the list they refer to just in case the link ever goes dead.

Bill of Material

Usado our aparelhos: SAMSUNG 740N, 940N

BN44-00124A (IP-35135B) - BZ-17 REV0.4

IC101 = FSDM0565R (DM0565R)

IC102 = KIA431A

C107 = 47uF x 50V

C109 / C110 = 1000uF 10V x ==> 1000uFx16V

C301 / C111 / C112 = 820 uF 25V x ==> 1000uFx25V

C113 = 330UF 10V x ==> 1000uFx10V

C123 = 10uF x 50V

D102 = BYV38V - Fast Avalanche 1000V - 2A

= D103 = UF4002 UF101D - Ultra Fast 100V - 1A

D105 = MBRF20100CT - Schottky 100V - 20A

D106 / D107 = SR506 - Schottky 60V - 5A

F301 = 3.15A (em baixo da cola silicone)

PC101 (opto) = 817B

Q101 = KTC3205

R102 = 36K - 2W

R105 = 6R8 - 1W

R117 = 180R - 3W

T301 / T302 (Transformer Driver) = TM1222

U201 = BIT3195G

U202, U203 = = AF4502C AM4502C

U301 = KIA431A

ZD101 / ZD102 = 1N4756

ZD201 7V5 =

DC Output:
B-DIM (CN2-1)
13 V dc 0.4A (CN2-2)
GND (CN2-3/4/5)
+5.1 Vdc 1.5A (CN2-6 / 7)
A-Sun (CN2-8)
ON / OFF (CN2-9)

[spaceman]

Re: Samsung SyncMaster 914v

I don't know what the odds are, but I'm about 85-90% certain that it's the transformer. At that point, I gave up and got a $14 board from ebay. Works like a charm, but without the satisfaction.

Thanks for the help though.

[acinfo64]

Re: Samsung SyncMaster 914v

I tried all the caps but now it seems that the inverter transformer is broken. One has an infinity ohms at the secondary side.

Does someone know where can I buy one (TM1222)?

[retiredcaps]

Re: Samsung SyncMaster 914v

Does someone know where can I buy one (TM1222)?

Normally ebay has plenty of low cost replacements + free shipping, but I can't find one this time.

[acinfo64]

Re: Samsung SyncMaster 914v

Thanks for your reaction. That's indeed my problem. I found a lot of transformers nowhere this one.

[selldoor]

Re: Samsung SyncMaster 914v

Hmm, can you measure the primary and secondary on the good transformer and
ask lcdparts.net or someone like that if they have a transformer with those resistances
and the same physical size?

Can you update your profile with at least the country where you live