Electronics > Repair

Help repair my Samsung CRT SyncMaster 1100DF, please!

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13hm13:
Not mine, but here's what I have ...


It had less than 100 hrs total ON time (since purchase in early 2004) before it stopped working (after I replaced it with an LCD, in 2005, it was plugged in, but used VERY sparsely ... and then, one day 3 yrs ago, it ran into the issue below)

The bottom line seems to be that either the HV ckt/supply is shot, or it's not getting the signal to turn on -- me thinks the latter  :-\

When I power it ON (via front panel push-button), the green LED on the left of the switch will light after about 1sec. But I get NO display on the CRT. Normally, I used to hear a familar high-voltage THUMP, after a few secs (followed by the usual static pops as the CRT "warms up").

In the past (when this CRT monitor was working normally) and when there  was no signal (PC was off or the VGA cable was unplugged), I'd still get a on-screen message stating "No Signal -- Check Connection" and that front pwr-button LED would blink. Of course, now there is nothing on the screen, and the LED is solid (not blinking -- that is what is/was normal if there was a VGA signal).

I do seem to be getting 5V TTL and IC pwr supply voltage to many of the ICs.

I'm looking for a quick, cheap fix, as this monitor is not that important to me. So ... just a hobby fix ;)

Off the tops of your heads, some of you experienced techs may know of component(s) that often go bad in these monitors. E.g., caps, regulators, etc.  I'm thinking more like Dave Jones' Yamaha receiver fix, that was a bad poly cap (at the mains). I just watched that EEV episode and what Dave ran into reminds me of this monitor's issues.

I do have the schematic, I think, but they are poor/cryptic and seem to be meant for several models in the series ???

Thx!

13hm13:
The electro caps LOOK fine -- no swelling.
Also, no sight/smell of damage (cooking) on any boards.
Methinks it's gotta be something simple ... like Dave's Yamaha receiver cap fix.

Jonny:
As they say, check all voltage rails. If you're lucky what they should be will be printed on the board. If not, follow the diodes that come off the power supply switching transformer see if they go into caps or regulators that will give you some idea of what to expect. If there's no EHT (the pops and crackles) check the line output transistor (usually on a heatsink that is beside, and sometimes large enough to enclose the flyback transformer, the thing with the lead that goes up to the top of the tube). These are well known to short out. If you have lights up and the heaters in the tube are glowing then chances are it's that. Good luck!

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