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Old 04-14-2008, 12:52 AM   #1
Bstock72
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Default Sceptre X9G-Komodo II* blinking power light

Any help on where to start on this monitor. No visual signs of leaking or bulged caps. Power led flashes green and screen faintly flickers with it. I've attached some photos of the board where the power comes in if needed i can try and get some better ones and pics of the other boards if needed. Thanks
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Old 04-14-2008, 06:55 AM   #2
kc8adu
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Default Re: Sceptre X9G-Komodo II* blinking power light

looks like a common board with samxon gl on it.
replace any samxon caps then try it.gl is a known bad series which does not bulge when bad.they just go high esr.
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Old 04-14-2008, 09:47 PM   #3
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Default Re: Sceptre X9G-Komodo II* blinking power light

caps in it are Elite (which are prolly junk too) was wondering if it would would make a difference if I replaced them all with hi temp caps?

Thanks for the help.
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Old 05-02-2008, 11:30 PM   #4
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Default Re: Sceptre X9G-Komodo II* blinking power light

Have a Gateway 19" LCD TFT. Turn on and screen would flash and go off. power light would stay on. Removed inverter board and replaced all caps. (two had tiny bulges-had to use magnifier to see.) Put back together-same problem. After much research found out because of the high temperature generated the solder joints around the invertors had dried out. Re-soldered and now the sucker works perfect. By the way. The monitor was given to me cause it would not work....Researching a problem can be invaluable..
Good luck...
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Old 06-18-2008, 01:09 AM   #5
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Post Re: Sceptre X9G-Komodo II* blinking power light

I just opened today a Sceptre X9G-KomodoIV that does not power up. It has two boards: a main processing board and a LM004 board for both power supply and backlight inverters. Two caps were slightly bulged, but replacing these [see two brown caps on photo] did not solve the problem. I will have to investigate further.
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Old 06-18-2008, 06:33 AM   #6
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Default Re: Sceptre X9G-Komodo II* blinking power light

replace all the caps.thats what i see wrong in every one of the x9's
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Old 06-19-2008, 08:03 PM   #7
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Default Re: Sceptre X9G-Komodo II* blinking power light

Thanks kc8adu: I replaced all caps, but without success. The power light continues to flash 5 seconds ON, 2 seconds OFF. Probing the board shows that both +12VDC and +5VDC go though the same 7 seconds cycle: full voltage for 4 seconds, then going to 0VDC during the next 3 seconds. Power is steady though high [5.5VDC and 13VDC] when the power board is unplugged from the processing board, so I guess that the problem might be coming from that processing board: I will have to reconstruct the pinout of the connector between the boards.
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Old 04-11-2009, 05:59 PM   #8
Bobdee
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Default Re: Sceptre X9G-Komodo II* blinking power light

For cross refference purposes,
The Gericom Model S1902D-
P/N T920
Has the same PSU/Inverter, LM004
Of German Manufacturer
as used inThread title
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Old 09-23-2009, 02:08 PM   #9
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Default Re: Sceptre X9G-Komodo II* blinking power light

I have a Sceptre X9G-Komodo VII A monitor with similar symptoms. It has Elite caps, but no signs of bulging. Testing with an ESR meter showed all caps appeared to be good. Power supply output voltages were stable.

Examining the board carefully I found a bad solder joint on C21 in the inverter area. (C21 is not an electrolytic). Resoldering did not fix the problem. Eventually I started looking at the overall inverter circuit and realized it is similar to the design of the Dell E172FPb / E173FPb. And that lead me to Q11 and Q12, which appear to be shorted. Comparing them to Q6 and Q7 confirms this.

The transistor is in a SOT-223 package, and has the letters DK and QH. There is a - or _ above the H and what appears to be a tiny Xb in a circle in the center of the package.

The only cross reference I can find to the letters DK is a Siemens BCX42, but that is the wrong package. QH doesn't even come up in the cross references I have found. Any suggestions?

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Old 10-21-2009, 06:14 PM   #10
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Default Re: Sceptre X9G-Komodo II* blinking power light

It was a tangled trail, but I have identified the transistors. They are Rohm 2SC4672. The Q indicates hfe in the 120-270 range.

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Old 12-04-2009, 09:07 AM   #11
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Default Re: Sceptre X9G-Komodo II* blinking power light

Hi Plain Bill,

Did you ever get the SCEPTRE monitor working? Also, did you ever find the transistor you were looking for? I have a SCEPTRE that i am trying to fix for a neighbor and i think it might also have a transistor issue.

Dave
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Old 12-04-2009, 11:07 AM   #12
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Default Re: Sceptre X9G-Komodo II* blinking power light

Quote:
Originally Posted by Welchs101
Hi Plain Bill,

Did you ever get the SCEPTRE monitor working? Also, did you ever find the transistor you were looking for? I have a SCEPTRE that i am trying to fix for a neighbor and i think it might also have a transistor issue.

Dave
The transistors are available from Digikey. Also make sure you resolder the pins on the transformer, and replace the poly caps if they appear to be damaged.

PlainBill
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Old 08-08-2010, 10:20 PM   #13
alexanna
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Default Re: Sceptre X9G-Komodo II* blinking power light

This monitor Gives a very brief flash of the back lamps on power up.the desktop is there after back lamps go out.
Q6 and 7 showed a short between pins.These have been replaced,
With a single ccfl hooked up one at a time there is a normal 2sec bright flash of the lamps on the two ccfl connectors at the bottom of the board near the A.C. plug.On the top of the board the conector near the edge of the board there is a very brief dim flash. And at that point q6 and 7 show shorted again
On my initial visual inspection of the board the area of C10, the grey polycap and L1 had bad solder joints,I have removed measured these, along with the T1 coil,And comparied the readings to the out of circuit readings of T2 L2 and C21 These readings are almost exactly the same.These have been resolderd back into the board.
I have replaced the two caps for the inverter section. c2 was replaced with a panisonic fm series.Due to a mix up [capacitors packaged wrong ]I had to use a nichion audio grade cap for testing proposes for c4.The correct part is on the way.
I need to have some help figuring out why Q6anQ7 are faling?
Al.
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Old 08-08-2010, 10:49 PM   #14
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Default Re: Sceptre X9G-Komodo II* blinking power light

Quote:
Originally Posted by alexanna View Post
I need to have some help figuring out why Q6anQ7 are faling?
What are the part numbers for Q6 and Q7? I assume Q11 and Q12 are the same?

This may not be correct, but the Q6/Q7 and Q11/Q12 look symmetrical to me. Can you test D1, R8, R7, ZD1, C7, R35, R31, R5, R6, Q(the 8 leg FET) above C7? Record all values and compare them with the Q11/Q11 counterparts?

You already did something like this for the transformers and caps.
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Old 08-08-2010, 11:24 PM   #15
alexanna
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Default Re: Sceptre X9G-Komodo II* blinking power light

Q6thruQ12 are Rohm 2SC4672 as identified by plainbill in post # 10
Something dose not look right on the 8 leg fets apm9435 on one, legs 5-6-7 are soldred together and on the other 1-2-3 are together. This may be normal but I am unsure.
Al.
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Old 08-09-2010, 10:43 AM   #16
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Default Re: Sceptre X9G-Komodo II* blinking power light

Quote:
Originally Posted by alexanna View Post
This monitor Gives a very brief flash of the back lamps on power up.the desktop is there after back lamps go out.
Q6 and 7 showed a short between pins.These have been replaced,
With a single ccfl hooked up one at a time there is a normal 2sec bright flash of the lamps on the two ccfl connectors at the bottom of the board near the A.C. plug.On the top of the board the conector near the edge of the board there is a very brief dim flash. And at that point q6 and 7 show shorted again
On my initial visual inspection of the board the area of C10, the grey polycap and L1 had bad solder joints,I have removed measured these, along with the T1 coil,And comparied the readings to the out of circuit readings of T2 L2 and C21 These readings are almost exactly the same.These have been resolderd back into the board.
I have replaced the two caps for the inverter section. c2 was replaced with a panisonic fm series.Due to a mix up [capacitors packaged wrong ]I had to use a nichion audio grade cap for testing proposes for c4.The correct part is on the way.
I need to have some help figuring out why Q6anQ7 are faling?
Al.

Hello! Can you please provide the capacitance value and voltage of the grey polycap. And can you verify if this polycap is across the collector leads of Q6 and Q7. Thanks!
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Old 08-09-2010, 04:09 PM   #17
alexanna
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Default Re: Sceptre X9G-Komodo II* blinking power light

Quote:
Originally Posted by jetadm123 View Post
Hello! Can you please provide the capacitance value and voltage of the grey polycap. And can you verify if this polycap is across the collector leads of Q6 and Q7. Thanks!
The grey poly cap has markings on it
.1 and 250
and it is conected to the center thrminals of 2sc4672, Q6 and Q7
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Old 08-09-2010, 05:57 PM   #18
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Default Re: Sceptre X9G-Komodo II* blinking power light

Quote:
Originally Posted by alexanna View Post
The grey poly cap has markings on it
.1 and 250
and it is conected to the center thrminals of 2sc4672, Q6 and Q7



Okay, from the 2SC4672 spec sheet, it looks like the center lead is for the collector terminal. The center lead of Q6 and Q7 should each also be connected to a leg of the inverter transformer (please verify this). If correct, this inverter circuit is somewhat similar to some viewsonics and dells (as PlainBill mentioned in POST #9). Now, since the poly cap is connected across both collectors and rated at 250 volts, I'm thinking it might be used for voltage transient/noise suppression from the transformer. If this cap has failed, then it might be allowing excess voltage to reach Q6 and Q7 (2SC4672 is rated @ 50V), thus shorting them out. Make sense? Anyone else feel free to chime in.
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Old 08-09-2010, 06:18 PM   #19
alexanna
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Default Re: Sceptre X9G-Komodo II* blinking power light

jetadm 123 Thanks for the reply.
the poly cap is measuring 101nf ,Can a poly cap fail and still be within spec?
also in some of my testing I have damaged D1 markings on it are s4 3b any ideas on a replacement for it?
Al.

Last edited by alexanna; 08-09-2010 at 06:24 PM.. Reason: typo on cap reading
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Old 08-09-2010, 06:50 PM   #20
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Default Re: Sceptre X9G-Komodo II* blinking power light

Sure, it's a possibility that the cap is still bad. The only way to find out is to replace it. Others may have a different approach to this problem and may be able to provide additional testing/insight that I may have overlooked.

As for D1, I suggest you contact Bstock72, since he is the originator of this thread and has a board identical to yours and can provide more accurate info on D1.
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