Re: Image problem with Samsung 2243SN display
I see the link to Samsung site in my original posting is dead. [URL="http://support-us.samsung.com/cyber/popup/iframe/pop_troubleshooting_fr.jsp?modelname=S23A350H&from_osc=&idx=135689&modelcode=&"]Here[/URL]'s a working one that shows the Check signal cable message.
Thanks guys, appreciate you looking into this.
Same symptoms.
It is hard to pinpoint the actual location precisely. I rolled a sheet of paper into a "listening cone"...
munuainen
Member
Last Activity: 09-13-2015, 07:15 AM
Joined: 07-13-2010
Location: Finland
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Last edited by munuainen; 01-07-2015, 08:04 AM. -
Re: Image problem with Samsung 2243SN display
Bumping this after a very long period of inactivity. Is there anything to be done about this or should I just recycle the screen?Leave a comment:
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Image problem with Samsung 2243SN display
Hi there.
The background of this 22" unit is as follows. When I got it there was a classic 2 secs to black problem. Screen image was totally fine at this point.
I was able to pinpoint the problem to CCFL inverter which had one of its secondaries messed up and did not turn on one of the backlight tube pairs. Found a replacement at eBay, ordered, replaced and this time both tube pairs worked, but still 2 secs to black. I left the screen alone for quite some time as I was busy with other things. When I got back to business, I had also built four CFL test tubes to... -
Re: Dantax DVB-C 700 digibox chopper controller keeps failing
Sorry it's been a while...been busy with tons of other things.
Snubber seems fine. All components measure correct values off-circuit. Secondary rectifiers are ok too. How would I go about measuring secondary loads?
Well, yeah, I surely would, if I had a way to make sure firing the circuit up wouldn't keep destroying my remaining yet functional TNYs....Leave a comment:
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Dantax DVB-C 700 digibox chopper controller keeps failing
Hi there,
I got this Dantax cable TV digibox for free some time ago...I think it had suffered a mains voltage spike due to a lightning strike. Now trying to get it back working.
Initial inspection revealed that the chopper controller / mosfet chip TNY265PN had exploded. What was left of the mosfet drain pin was still attached to PCB but not to the chip anymore.
HV side of the circuit is constructed pretty much according to TNY datasheet recommended layout on page 12. All components in HV branches measured fine offline.
I had a TNY267PN... -
Re: LG 22W2234S troubleshooting and spare parts
C808 definitely not shorted. I'm getting a reading around 1,5Mohm in-circuit, blown mosfet and large resistor having been removed.Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Line fuse fine.
The thermistor RT801 should be 4.5 ohm according to the data sheet . I'm getting almost 11 ohms off-circuit at room temperature.
Line rectifier. Again, unstable readings. Several hunder Kohms anyway.
Line filter cap charging up.
Mosfet I cannot really check, can I? One is dead, the other I don't want to sacrifice.
Output rectifiers are located further up the pcb. Do they really matter at this point?
By the way, when I checked VCC voltage...Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Just thought this might be worth mentioning if it helps with pinpointing the culprit. I plugged in the power to measure voltages on different spots when another bomb hit, killing the mosfet and the two largest resistors. This time it wasn't due to probe shorting.Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Nope. All three diodes in the proximity give one-way reading only.Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
I also thought the change in voltage must be due to resistors. However, all resistor values in the pcb section related to LD7522 seem fine to me (measured off-circuit). See the attached image for details....Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
1) Yes, its plastic all over.
2) Around 320 V which I assume is a healthy reading.
3) I'm getting a steady 86 V. I suppose that can't be good as the supply voltage should be 30 volts, right?Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Mosfets arrived. Unfortunately the seller had sent AP2761s instead of AP2763s. Upon contacting the seller said the two mosfets should be interchangeable. I'm not quite sure if that's the case. Maybe someone here is competent enough to clarify? I tried installing one and this time nothing blew up but there were no signs of life in the monitor either.
AP2761: [url]http://www.a-power.com.tw/ProductDetails.asp?M_ID=154[/url]
AP2763: [url]http://www.a-power.com.tw/ProductDetails.asp?M_ID=157[/url]Re: LG 22W2234S troubleshooting...Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Thanks for the link. Good news: I found a Chinese eBay seller who had AP2761I-As for sale. I sent him a message about if he could get AP2763s and got a fast response saying he's already got them and that he can list them right away. I already purchased two, just in case. I'll have to get back to this topic once they arrive which is probably going to take another two weeks.
Thanks for all the help I've already received!Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Actually, I found a thread on google. The correct mosfet is [url]http://www.a-power.com.tw/ProductDetails.asp?M_ID=157[/url] . Unfortunately they are pretty hard to find
Re: LG 22W2234S troubleshooting and ...ard to find :(Re: LG 22W2234S troubleshooting and spare parts
Actually, I found a thread on google. The correct mosfet is [url]http://www.a-power.com.tw/ProductDetails.asp?M_ID=157[/url]Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Not counting the thermistor RT801 the first resistors are exactly the ones that blew up.
Ohm readings won't keep steady. I guess I should desolder the component to get reliable readings.
Symptoms pretty much match the description here.
Thanks to both of you for taking the time to assist! I could use some more help identifying the mosfet. Attached is the image. I couldn't find datasheets or anything with the exact code (2763I ?) on the component. Maybe this is the...Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Ok, I'm going to quote Krankshaft's message entry by entry to make sure I'm working on the correct component(s).
This must be the only fuse, F801. It's fine, no resistance whatsoever.
Are these the resistors I replaced? If so, then they are fine.
This is the large rectangular diode D801. This is how I measured it: DMM probes connected to plus and minus (on the back side) pins. One way, I get 1.192, whatever unit it is. The other way the diode shows open.
The big cap. Charges...Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Yes, sir. Can't really argue with that.
Both diodes appear fine. I'm getting one-way reading in DMM diode measurement setting....Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Ok, I got the replacements. Install the IC and resistors. Connect power - BANG! Oops, I mixed resistor places. Replace resistors with correct placing, connect power - BANG! Oops, shorted due to having forgot to trim the legs after soldering. Good job. At least the IC is still intact.
After I finally got everything set up, the red-red-silver-gold resistor keeps still blowing up at the moment power is connected. Something I haven't yet noticed must have also gone wrong when the IC was shorted
The original...Leave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
After further investigation it's not a metal film but a metal oxide film type I need (the original has non-reflective matte surface). Fortunately, there are ones valued pretty close to 0.43 ohm available at ebay [url]http://cgi.ebay.com/20pcs-Metal-Oxide-Film-Resistor-2W-5-Axial-Taiwan-/130333019945[/url]Re: LG 22W2234S troubleshooting and ...re ones valuedLeave a comment:
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Re: LG 22W2234S troubleshooting and spare parts
Wow, I may have found a supplier for LD7522PS in Bulgaria, via google.
[url]http://www.ksp-electronics.com[/url] . I've already registered and placed an order. Apparently they have manual order processing system as I haven't received any email confirmation or payment details. Gotta keep waiting...Re: LG 22W2234S troubleshooting and ...red and placedLeave a comment:
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