I have the same problem with my monitor as you described - the transistors q6 and q7 and the inverter board are blown. However, the codes I see on the transistors are different from what you described - mine are DK QP, with the DK on top. I am having trouble figure out what they are and I'm wondering if you were ever able to fix your monitor. I am sure if I could get replacements it would fix the problem. If any of this rings a bell (or possibly is helpful, as far as identifying the busted components) please let me know!
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Re: ViewSonic VX924 transistor
Besides those transistors, you may also fine the large capacitor
adjacent to the transformer gone too, Possibly the transformer may be
bad too ?
Also the 924s used at least two style boards.
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Hello Edwin Ortiz---My tv had the red blinking light on the power board and i found a tiny 3amp subminiture fuse listed as F2 on the printed board. It fooled me because it did not look like any fuse i've ever seen. Anyhow the fuse was open and the problem was the two transistor listed as Q6 and Q7 on the power board.The transistors are a brand from fairchild with a part # FQPF9N50CF . They cost $1.60 each and i got them from Mouser Electronics out of texas (www.mouser.com )
On power board check F2 minifuse and transistors Q6 and Q7---make sure that you use so heat sink compound on the new transistors or they wont last long. You can reach me at firstname.lastname@example.org for more detail on how to fix. good luck--jim--
When the DC filter caps no longer filter out high frequency AC, that AC will be fed through out the circuits and cause damages such as the inverter frequency will be running at the wrong frequency and caused overheating.
The service manual does not show the sch of the power supply/inverter board because it is not designed by Viewsonic. http://s807.photobucket.com/albums/yy352/budm/Viewsonic%20VX924/
In the Polaroid FLH-3701, the fuse is located on the power supply board, next to the AC power connector. It is a small black cylinder. It is labelled F1. Value is 5 amp, 250 volts.
A fuse does not blow for no reason. Most commonly a fuse will fail because of a short someplace on the board. I have this same TV. The fuse blew. The reason was transistor Q6 had shorted. There are two identical paired transistors on the output side. Q6 and Q7. They are both Infineon 11N60C3 MOSFET transistors. Check those for a short. There may be a burnt smell.
More commonly, this TV will fail because of bad capacitors on the power supply board.
The Q7 has a tendency to burn up transistors and a high voltage capacitor on the one half of the inverter board which is part of the power board. I have repaired 1/2 dozen of these with that problem. Only way to tell for sure would be to open it up and look at it. If you can do that and send me a picture to email@example.com, I may be able to confirm this. The other possible problem could be a bad bulb, but since it is fairly new ? that is probably not the issue. Fran
This is a generic symptom that could happen to any LCD
The following is a generic answer applicable to most.
The most possible causes are bad capacitors or a bad
Open the unit and check to see if any of the capacitors in the power supply or
other boards look domed or vented on the top.
Replace any capacitors accordingly. Use the same value capacitors. Most often,
1000uF 16V or 25V, 470uF at 16 or 25V, 220uF at 16V or 25V.
If this doesn’t solve the problem, try checking the surface-mount transistors
on the inverter board that run the lights. Some times these transistors go bad
and can cause the power to cycle up and down. Check the area for any cracked or
overheated ceramic or mylar capacitors.
Don’t forget to check for caps on the main board. Some times these boards are
overly simple and only have a couple of caps, but other times they are teaming
One and a half year later I know the solution :-). It is 2SC4672... sure!. DKQ* is in my Jaeger SMD-Decoder book (10.000 SMD - Demiconductor - Codes)
Common problem with inverter PCB. Caused by the damaged or loose 100nF (or some same value)
Succes. For me it is working.