HP Touchsmart 310 backlight driver fail

[inflex]

Have a HP Toucsmart 310 (AIO machine), no backlight, system works fine. Doesn't seem to be a 2-seconds-to-black failure, just never seems to come on at all (I could be wrong but it's a little harder to test on an AIO because you can't get signal prior to powering up for obvious reasons).

I've tested the actual CCFL tubes, they seem to be running (though dimly with the generic tester).

It's a dual-output inverter. I've tested the following;

* input; no short to ground. Zener is good at 5.6V, fuse is good
* transformers; 614R on secondary, ~0R1 on primary

Beyond those quick checks I'm not sure what to check for next or if there's any "good known" failure points.

[budm]

Re: HP Touchsmart 310 backlight driver fail

I cannot see any labels for the pins of the inverter to see if it is getting the BL-ON command and the DIM command from the main board or not.
The board is made by SUMIDA, can you read the P/N? IV????????

[inflex]

Re: HP Touchsmart 310 backlight driver fail

i cannot see any labels for the pins of the inverter to see if it is getting the bl-on command and the dim command from the main board or not.
The board is made by sumida, can you read the p/n? Iv????????

iv18182/t-hf

[budm]

Re: HP Touchsmart 310 backlight driver fail

I see people selling them but I did find any pinout info.
Can you read the P/N of that 16-PIN SMD PWM IC? If you can find the IC spec sheet then you can find out if it is getting the BL-ON signal or not.

[inflex]

Re: HP Touchsmart 310 backlight driver fail

I see people selling them but I did find any pinout info.
Can you read the P/N of that 16-PIN SMD PWM IC? If you can find the IC spec sheet then you can find out if it is getting the BL-ON signal or not.

Managed to find the part# It's an OZ9933, not a lot of info on it but enough to at least determine if it's being told to turn on etc.

I've also since found that the IV18180T is supposedly a substitute for the module, seems to sell at about half the price too, though I'd be preferring to repair this one if possible since the machine overall isn't worth spending even $50 hard cash on ( most likely the CCFLs will be nearing end of life or knowing my luck ).

[inflex]

Re: HP Touchsmart 310 backlight driver fail

UPDATE: It's getting 3.3V on both EN and PWM at the moment. I'm going to check all pin voltages and report back.

[inflex]

Re: HP Touchsmart 310 backlight driver fail

UPDATE 2:

I realised I could pull out the cable driving the backlight while the machine was running; and on doing that and placing it back in, it flashed for about a quarter of a second or less and went black again - so that's some good news I suppose (though it could be implying that the tubes are too old)

Voltages;
1(VSEN) 0.00
2(SSTCMP) 0.00
3(CT) 4.95V
4(RT1) 4.82V
5(GNDA) 0.00V
6(PDR2) 0.00V
7(GNDP) 0.00V
8(NDR2) 0.00V

9(NDR1) 0.00V
10(PDR1) 0.00V
11(VDDA) 4.95V
12(TIMER) 0.01V
13(PWM) 3.30V
14(ISEN) 0.00V
15(OVPT) 2.25V
16(EN) 3.30V

[inflex]

Re: HP Touchsmart 310 backlight driver fail

This morning I tried running just one lamp instead of both, and it stayed on for at least 2~3x longer than with both (regardless of which of the two outlets I used), so it's making me think that perhaps there's an issue with the over-current sensing (or still that the tubes might be too old).

[inflex]

Re: HP Touchsmart 310 backlight driver fail

I'm really starting to think this is old tubes.

It managed to fire up and stay fired up but one segment (tube) is flickering slightly. When I measure the peak on VSEN pin it gets up to 2.29V which is over the OVPT setting but when it runs properly it's about 1.88V.

[budm]

Re: HP Touchsmart 310 backlight driver fail

Do you have another similar size LCD panel that you can use as test lamps?

[inflex]

Re: HP Touchsmart 310 backlight driver fail

Do you have another similar size LCD panel that you can use as test lamps?

Not any more. I even went looking for some 12~14W CFL twisted-tubes to check with but lo behold I've already replaced the whole house with LED units.

For now I'm writing this job off, back to the back of the workshop. The screen (when lit) also has that classic orange-brown old CCFL hue.