Viewsonic Optiquest Q19wb

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

Anyone have a lamp source?

[eradz]

Re: Viewsonic Optiquest Q19wb

Anyone have a lamp source?

Have you taken yours apart yet? i couldnt get just the bulbs to come out. Ill have to post a few pics

[lucky13]

Re: Viewsonic Optiquest Q19wb

so it seems to be bad lamps? i took apart the screen and it seems like the lamps arent any like i normally see. Like the ones u can just side out. These seem built into the whole back clear screen once u removed the top darker peice.

They normally use aluminium tape to secure the lamp assy to the top and bottom of the thick plastic backing. I use a knife to cut it.

At this point, I am suggesting lamps. Get yourself one of those CCFL kit for computer mod to test your lamps before you start ripping it all apart (I may be wrong... but I doubt it). It is very easy to damage your actual screen (like put a rip on one of those flat cables).

[dcubed]

Re: Viewsonic Optiquest Q19wb

Hi guys,
I am having the same "2 second to dead" problem with this monitor this is what i have done so far;
Re-cap all of the inverter capacitors with quality units from my local electronics supplier (no evidence of any of them had burst/leaked), no results.
Measuring the voltage of the reference locations from this thread
01 ~250VAC
02 ~250VAC
03 ~250VAC
04 ~170VAC <--- this, to me, would indicate a bad CCFL PlainBill im looking at you

also using the LG repair flow chart i get to "Is there High-Level voltage on pin10 of IC501" would I be expecting 5VDC during the "boot up cycle" ? if so i am only getting a peek of 3.5VDC. then i move over to "Is Ok R526" the reading is within 10% of the value in the service manual, ~3.5Mohm...

im stumped but not going to give this up
please post any suggestions
D

[PlainBill]

Re: Viewsonic Optiquest Q19wb

Hi guys,
I am having the same "2 second to dead" problem with this monitor this is what i have done so far;
Re-cap all of the inverter capacitors with quality units from my local electronics supplier (no evidence of any of them had burst/leaked), no results.
Measuring the voltage of the reference locations from this thread
01 ~250VAC
02 ~250VAC
03 ~250VAC
04 ~170VAC <--- this, to me, would indicate a bad CCFL PlainBill im looking at you

also using the LG repair flow chart i get to "Is there High-Level voltage on pin10 of IC501" would I be expecting 5VDC during the "boot up cycle" ? if so i am only getting a peek of 3.5VDC. then i move over to "Is Ok R526" the reading is within 10% of the value in the service manual, ~3.5Mohm...

im stumped but not going to give this up
please post any suggestions
D

The four output connectors are CN401, CN402, CN403, and CN404. While they aren't labeled, the plugs that connect to them are PL401, PL402, PL403, and PL404, with of course PL401 being connected to CN401, etc.

You will have to move the board around to do this, but hook them up so PL401 is hooked to CN403, PL402 is hooked to CN404, PL403 to CN401, and PL404 to CN402. Then repeat the voltage test. If O4 still reads low, the problem is on the inverter card. If the low voltage is now on O1, the problem is either the CCFL or the wiring to the CCFL.

PlainBill

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

The four output connectors are CN401, CN402, CN403, and CN404. While they aren't labeled, the plugs that connect to them are PL401, PL402, PL403, and PL404, with of course PL401 being connected to CN401, etc.

You will have to move the board around to do this, but hook them up so PL401 is hooked to CN403, PL402 is hooked to CN404, PL403 to CN401, and PL404 to CN402. Then repeat the voltage test. If O4 still reads low, the problem is on the inverter card. If the low voltage is now on O1, the problem is either the CCFL or the wiring to the CCFL.

PlainBill

I bet it is the bulbs. is there another way to test a bulb. I have a Samsung SyncMaster 205BW that is power cycling. I had a pair of pc mod 12V inverters and tested all of the bulbs. I could light them all about 3/4 of the way down the 18'' bulb. Anyhow I pulled the bulbs out and rigged up 4 ccfls and the screen works fine.
I think the bulbs need 13V to fire all the way up possibly. Is there a way to test the bulbs with a meter? I'm trying to find proper replacement bulbs

[scampo77]

Re: Viewsonic Optiquest Q19wb

i came across this thread on a google search and i am very excited to be a part of this forum. i am very new at this but i really want to learn how to fix my problem. i have the same same power supply it is slightly differnt so i included a picture .i have different symptoms, mine is just dead. i seem to have DC voltage for the first bit of the board then when it reaches the blue transformer (P/N SPW-055 Rohs) i have +-160vdc going in and nothing coming out. also next to it there is a cap (JNC JM472M) and a 4 leg zener diode (P/N 817B)all have voltage on one side and not the other.

im not too sure what i should measure next or what to pull out next

any help would greatly be appreciated. please keep in mind im willing to learn but im new to this

[jetadm123]

Re: Viewsonic Optiquest Q19wb

i came across this thread on a google search and i am very excited to be a part of this forum. i am very new at this but i really want to learn how to fix my problem. i have the same same power supply it is slightly differnt so i included a picture .i have different symptoms, mine is just dead. i seem to have DC voltage for the first bit of the board then when it reaches the blue transformer (P/N SPW-055 Rohs) i have +-160vdc going in and nothing coming out. also next to it there is a cap (JNC JM472M) and a 4 leg zener diode (P/N 817B)all have voltage on one side and not the other.

im not too sure what i should measure next or what to pull out next

any help would greatly be appreciated. please keep in mind im willing to learn but im new to this

Welcome to the forum! Good initial try at trying to figure what's going on. Here's what you need to do:

1) post some photos (top and bottom) of the entire power board and logic board (the board you plug your video cable into) per PlainBill's links on post #45

2) I think you're measuring the 160VDC off the bridge rectifier. This should be the same voltage across the 450V main capacitor.

3) looks like you're getting voltage to the PWM controller chip.

4) when you push the power button, does it show any activity?

5) any flash on the screen when you push the power button?

6) any other observations will be helpful.

[Dpacro]

Re: Viewsonic Optiquest Q19wb

Hi guys,

I have 2 of these Screens here,

They at first had no power. After replacing 2 caps both c818 and c815 they came back to life BUT

They show picture for around 2 or 3 seconds then turn off.... ligh goes standby.

Then i press power and the screen goes on for 2 - 3 seconds then goes back off ...

Would it be such as a transistor problem that cut the on/off source from staying ON ?

Im stuck with this repair and i do not know what to test now.

Any idea ?

[retiredcaps]

Re: Viewsonic Optiquest Q19wb

They at first had no power. After replacing 2 caps both c818 and c815 they came back to life BUT

They show picture for around 2 or 3 seconds then turn off.... ligh goes standby.

If 2 caps are bad, most here will recommend replacing them all except for the biggest one which rarely, but not never fails.

Bad caps can be the cause of 2 seconds to black. Other causes might be a bad transformer and/or bad ccfl/wiring. See post #13 section 1, post #14 sections 4, 5, and 6.

https://www.badcaps.net/forum/showthread.php?t=10419

[PlainBill]

Re: Viewsonic Optiquest Q19wb

Hi guys,

I have 2 of these Screens here,

They at first had no power. After replacing 2 caps both c818 and c815 they came back to life BUT

They show picture for around 2 or 3 seconds then turn off.... ligh goes standby.

Then i press power and the screen goes on for 2 - 3 seconds then goes back off ...

Would it be such as a transistor problem that cut the on/off source from staying ON ?

Im stuck with this repair and i do not know what to test now.

Any idea ?

Somewhere some fool came up with only changing a few caps, just enough to get a monitor working. Congratulations, you have just become a victim of his foolishness. Change ALL of the electrolytic caps with the exception of the large (100 uF, 450 Volt) one. Use good quality caps like Panasonic FM of FC series.

PlainBill

[Dpacro]

Re: Viewsonic Optiquest Q19wb

What do you mean by changing them ALL ?

I have taken the cap one by one and tested them with my meterman capacitor tester and i have only replaced the one that had defective reading...

Will you suggest that some of the caps might give good reading but keep failing under stress of work !

[PlainBill]

Re: Viewsonic Optiquest Q19wb

What do you mean by changing them ALL ?

I have taken the cap one by one and tested them with my meterman capacitor tester and i have only replaced the one that had defective reading...

Will you suggest that some of the caps might give good reading but keep failing under stress of work !

Does your Meterman tester check ESR, or does it only check capacitance? A capacitor may pass one test, but fail the other.

The monitor is exhibiting a problem we call 'Two seconds to black'. The most likely causes of this problem are:

1. Bad capacitors.

2. A flaw in the wiring to the CCFLs

3. 'Dying' CCFLs

4. A problem with a transformer

5. A problem with the sense circuitry

PlainBill

[Dpacro]

Re: Viewsonic Optiquest Q19wb

Meterman CR50

Capacitance and resistance tester.

http://www.tequipment.net/WavetekCR50.html

I just bought it cause with my standar multimeter it was a real pain in the xxx to check the capacitors,

[PlainBill]

Re: Viewsonic Optiquest Q19wb

Meterman CR50

Capacitance and resistance tester.

http://www.tequipment.net/WavetekCR50.html

I just bought it cause with my standar multimeter it was a real pain in the xxx to check the capacitors,

Unfortunately, while it is adequate for caps in analog power supplies, it only does half the job for the caps in SMPS supplies. The actual capacitance is important, but the ESR is also vital. Too high and things don't work properly.

One common problem we see is someone deciding to save a few bucks and using a bunch of Xicon caps from Radio Shack. Often they work (at least for a while), but sometimes the result is just what you are seeing - two seconds to black.

PlainBill

[Dpacro]

Re: Viewsonic Optiquest Q19wb

Those that i have bought from here in Montreal from a local electronic supplier call access o tronik inc are capacitors : gemcon and sitecl , not sure, i cant even read the name on the caps...

I also have some rubycon but none that i need.

I do not know any other place other then that place to get good quality electronic parts. So far i always ordered online for other parts but for caps i didnt really pay attention to the quality. I tough caps were just caps.

What do you recommend as a good brand where to buy the caps from ?

[PlainBill]

Re: Viewsonic Optiquest Q19wb

Those that i have bought from here in Montreal from a local electronic supplier call access o tronik inc are capacitors : gemcon and sitecl , not sure, i cant even read the name on the caps...

I also have some rubycon but none that i need.

I do not know any other place other then that place to get good quality electronic parts. So far i always ordered online for other parts but for caps i didnt really pay attention to the quality. I tough caps were just caps.

What do you recommend as a good brand where to buy the caps from ?

If you check the FAQ, there is a thread 'Which caps should I buy', which lists a number of brands and series. Note that contrary to real life, the ones on the right are better.

My personal preference is Panasonic FM or FC series. As you will see in the FAQ there are other brands and series that are also quite good. Don't be afraid to mix brands. My preferred vendor is Digikey, in part because of their low cost shipping option (when you are ordering a dozen caps, saving $3 on shipping seems major). Alas, while they DO ship to Canada, they charge more for shipping.

PlainBill

[Dpacro]

Re: Viewsonic Optiquest Q19wb

Hi , i have done few tests and I replaced all the caps with nichicon products and i found out that the bridge rectifier was defective . I have built a temporary bridge rectifier with 4 diode and the screen was working fine untill shut it off and put back the monitor together and the problem was back. The bridge is defective again.

Is there any special with this bridge FL406 828V ???

Maybe the diodes wasnt strong enough

[PlainBill]

Re: Viewsonic Optiquest Q19wb

Hi , i have done few tests and I replaced all the caps with nichicon products and i found out that the bridge rectifier was defective . I have built a temporary bridge rectifier with 4 diode and the screen was working fine untill shut it off and put back the monitor together and the problem was back. The bridge is defective again.

Is there any special with this bridge FL406 828V ???

Maybe the diodes wasnt strong enough

The FL406 is a 4 Amp 600 Volt bridge rectifier. It has a very high peak current rating - 200 Amp. Substituting 4 - 1N4005 would be marginal in my opinion. The Vishay KBL06-E4/51GI would be an exact replacement.

PlainBill

[Dpacro]

Re: Viewsonic Optiquest Q19wb

I used 1N4007 diode . I know it wasn't very durable. But i least it showed me that the monitor will work with the good bridge rectifier replacement.

Thank you for your help.

This forum is very helpfull and is filled with alot of good trick and tips.