HP no backlight

[jvelez]

Re: HP no backlight

I'm really happy that I found this forum: I have an HP VS19e that stopped working, and the power supply board is exactly the same as posted in this thread.
After inspecting the circuit, I found a few electrolytic caps clearly blown up, and after replacing the complete set I got power again, but the CCFLs are still dead.
I turned my attention to the inverter part of the module, and found that the chip that generates the pulses to the lamp system is not showing the right voltages.
More specifically, I101 (OZ9930) shows 0.6 volt in the PSEN instead of > 3.1volt, and therefore I have no pulses in DRV1 and DRV2.
Following the indications in the service Manual, I switched Q106 and Q107 but nothing changed. I believe that I101 is faulty (I'm waiting for a replacement), I may be completely wrong. I will post the final outcome here, good or bad...

[budm]

Re: HP no backlight

Great, thanks for posting the repair feedback, thanks to lestr for giving us those resistance readings.
Not sure if he got his monitor fixed or not though.

[davg]

Re: HP no backlight

You will get high resistance reading because there is a resistor (1Mega Ohms, you are reading 956K Ohms) in parallel with the cap. So you are now getting the same reading as lestr.
I would replace the IC at this point.

Thanks again budm finally got the replacement IC off Ebay all the way from China and I chose the pink lol. You were right the I101 was the problem. This HP is now a working unit

[davg]

Re: HP no backlight

gotya (over my head)

[selldoor]

Re: HP no backlight

Thanks guys I knew I would have to go to China lol. butterfly hip flask - filled???

Scroll down the ebay link

[davg]

Re: HP no backlight

Thanks guys I knew I would have to go to China lol. butterfly hip flask - filled???

[budm]

Re: HP no backlight

Pink is not my color, I would go for black though.

[selldoor]

Re: HP no backlight

Id go for the butterfly hip flask - filled!!

[budm]

Re: HP no backlight

http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40

[davg]

Re: HP no backlight

Thanks budm a google search did not produce any results for OZ9930 or the OZ9RRAG which I read is the same. any idea where to purchase?

[budm]

Re: HP no backlight

You will get high resistance reading because there is a resistor (1Mega Ohms, you are reading 956K Ohms) in parallel with the cap. So you are now getting the same reading as lestr.
I would replace the IC at this point.

[davg]

Re: HP no backlight

Ok with pin 7 de-soldered the readings are as follows
black on GRN red on soldering pad where pin was soldered .956m
red on de-soldered pin 7 123ohm not touching trace.I just removed all solder around pin 7 I did not lift it. It is free in the hole.
C110 is still removed. Should I be able to get a reading across C110 when removed?

[selldoor]

Re: HP no backlight

Not sure how you are going to do that as this is a through the hole fitting
not surface mounted?

[budm]

Re: HP no backlight

Yes.

[davg]

Re: HP no backlight

Thanks budm with C110 removed pin 7 is still reading 123.9 ohms so should I try lifting pin 7?

[budm]

Re: HP no backlight

There is something at pin 7 to make it show real low resistance (123 Ohms) at that pin, you can remove the cap C110 or lift pin 7 off the trace and measure the pin7 solder pad to see if you still get low resistance reading. We are trying to find out what is causing this low resistance reading since there is no component with that low value resistance connected to that pin7.

[davg]

Re: HP no backlight

Thanks Selldoor that is pin 6 & 7 it was some flux and I cleaned it up still no difference

[selldoor]

Re: HP no backlight

Cant second guess that but have been looking at the pics. I am not sure
which is pin 7 but if you start at bottom left or bottom right in the attached as pin1then can you check that pin6 and pin7 are not conducting at the solder joints.
Clean the flux off if it is only flux.

[davg]

Re: HP no backlight

Thanks budm I am not sure I understand your request with respect to C110? C110 is not surface mounted and if I remove it do I try the board without it in place??

[budm]

Re: HP no backlight

Pin 7 is the big suspect right now since there is no any low resistance circuit connected to this pin at all (lestr was getting about 900K Ohms).
It can be c110 (.01uf) may be bad or internal IC at pin 7 is bad. Try removing C110 first, see if it is surface mounted or not? You can try lifting pin7 but that may be difficult to do.