HannsG HH241 problems

[Agent24]

Re: HannsG HH241 problems

Looks like you may well have blown something else then.

I would clean up those 4 joints which were burnt, check they are still intact and the PCB traces are not broken\burnt there.

If they are all OK, I would pull the MOSFET, those diodes D802 and D803 and check them for damage, both visibly and electrically. Replace any which are suspect or you are unable to test.

Pull and test the resistors R808, R810 and R815 to see if they have blown open.

Also worth visually inspecting all the components on the daughter-board at CN852 for damage. It's possible you have blown the PWM controller IC instead\too. If nothing is obvious and replacing\checking the other parts shows no problem, replacing the PWM IC is probably the next step.

[Dougmeister]

Re: HannsG HH241 problems

Agent24, the value across those two points was 0.06.

[Agent24]

Re: HannsG HH241 problems

Fuse status is still unknown, as you have tested the wrong points. You have basically just checked the PCB trace from the fuse output to one leg of the next connected component, C803. The lighter green areas of the board are the tracks\lands where the different parts are soldered onto.

I have marked the image where the fuse leads connect to and where you need to put your meter probes.

[Dougmeister]

Re: HannsG HH241 problems

Agent24, I did as you said and got a reading of 0.03 ohms. See attached.

What else should I check? Or is it probably dead now that we know that the primary fuse is still good?

[Agent24]

Re: HannsG HH241 problems

With luck you may have only blown the fuse, but you could well have blown Q802 and those diodes as well, and maybe other things.

If you want to keep going, clean the soot off the board first as it can be conductive and cause more problems. Check the primary fuse - F801 (black round component near the AC socket).
With the power OFF and unplugged, measure resistance across its pins and you should get close to zero ohms, about the same as what you get if you touch the meter probes together. If you get no reading, it's blown.

[Dougmeister]

Re: HannsG HH241 problems

Oops.

Part of the board touched some metal on the frame and made a loud crackle and spark. Now it won't power on. I think I killed it and put it out of its misery.

[Agent24]

Re: HannsG HH241 problems

So, to clarify:

1) EVERYTHING should be connected for the first set of pin tests

2) What needs to be connected once the monitor shuts off by itself? I have to disconnect the "high Voltage wires" in order to turn the board over to measure the voltage, so I did that (while it is plugged in... sounds like a bad idea?), and left the rest plugged in (ribbon cable, power cord, VGA cable).

Unplugging the lamp high voltage wires after it shuts down would be OK since they'd have no power going to them.

Don't worry about it. I think your test already proved what the problem is: likely something bad on the logic board, turning the inverter off.
I was just confused by the wires you mentioned as I see them as pink\white and blue\black, and the colours you mentioned weren't familiar to me.

I would set it up disassembled and turn it on, then start heating the logic board with the hairdryer like vinceroger69 said. See if by doing that you can make it shut down.

[vinceroger69]

Re: HannsG HH241 problems

As this seems heat related? and goes off quicker when its built up etc, maybe have the monitor on so its showing a picture etc with the back off get a hair dryer and heat diffrent areas of the boards at diffrent times once you find a area where the monitor switches off quickly you can check that area out. DONT over heat the board as if some capacitors get too hot they can explode etc so use caution.

[Dougmeister]

Re: HannsG HH241 problems

So, to clarify:

1) EVERYTHING should be connected for the first set of pin tests

2) What needs to be connected once the monitor shuts off by itself? I have to disconnect the "high Voltage wires" in order to turn the board over to measure the voltage, so I did that (while it is plugged in... sounds like a bad idea?), and left the rest plugged in (ribbon cable, power cord, VGA cable).

[budm]

Re: HannsG HH241 problems

Those are high Voltage wires which go to the CCFL, the panel uses 4 lamps.

[Dougmeister]

Re: HannsG HH241 problems

The wires I spoke of are circled in yellow.

I'll try again this evening, but from memory, when it was all pulled apart, I had the wires mentioned above connected as well as the "ribbon cable".

[Agent24]

Re: HannsG HH241 problems

I am not sure what the red\white and black\blue wires are you speak of - and I can't see them in the pictures. Can you show a photo of them?

Anyway, from your voltage measurements, it seems like the inverter on/off control signal at pin 5 is the major issue here, which would come from the logic board, so the logic board may be the problem. The fact that it happens when assembled is interesting, possibly something overheating. Hard to say at the moment though.

What things did you change between it working OK while disassembled and shutting down when partially assembled? What did you connect or move or screw back together? Can you show photos of both set-ups?

Also what I would like to know is how the shutdown problem manifests - what exactly happens? Does the image or the back lights go out first? Does the power LED go off at the same time or does it stay on and you just lose the picture?

[Dougmeister]

Re: HannsG HH241 problems

Ok. Got it turn off after about a minute by having it partly put together. (Power and VGA still connected; disconnected the red/white and black/blue wires)

1: 5.10
2: 5.10
3: 0
4: 0
5: 3.17 (?)
6: 2.07 (?)
7: 0
8: 0
9: 3.28

Did I do something wrong?

[Dougmeister]

Re: HannsG HH241 problems

OKay. This is unexpected.

While I have it taken apart, it has been powered on and working for 15 minutes straight. It usually lasted less than a few minutes when it was put together...

I will see if it stays on much longer. Could it be something else other than the capacitors? I mean, 15 minutes would imply a different problem now, right?

[Agent24]

Re: HannsG HH241 problems

Sorry, but I didn't know what you meant by this. I powered it off and then all the pins gave "0". I'm almost positive that's not what you wanted me to do.

The fault is that it shuts down by itself, right? Power it up,, leave it running, then wait until it shuts down. (The fault happens again)
At that point, measure all those voltages again.
Like vinceroger69 said, we need to compare the working and fault states to see what, if any of those voltages change.

[vinceroger69]

Re: HannsG HH241 problems

you need too wait for the monitor to power off by it self not you turning it off. when it powers off by its self, post the voltage readings again as we need to see what voltages are dissapering etc.

[Dougmeister]

Re: HannsG HH241 problems

So, get the monitor working and connect your black (negative) meter lead to ground on one of those black wires, and then connect the red (positive) meter lead to each other pin and write down what you measure for each one.

I connected the power (not the VGA input) and got the following results:

1: 5.05
2: 5.00
3: 0
4: 0
5: 0.12
6: 3.04
7: 0
8: 0
9: 3.28

Then, wait until the monitor shuts down by itself, and measure everything again and write it down. Post the results here.

Sorry, but I didn't know what you meant by this. I powered it off and then all the pins gave "0". I'm almost positive that's not what you wanted me to do.

I attached pics of the back of both boards.

[Davi.p]

Re: HannsG HH241 problems

To test the inveter supply you have to put the DMM in volt and red probe to the middle pin of the double diode on heatsink on top of the big transformer in Pic 3, the black probe on chassis. If you want to let your brain relaxed, you can start change the electrolitic caps, exept the bigger one, search online distributors (not ebay) for low esr types, search the forum for the better brands..

[budm]

Re: HannsG HH241 problems

Pin out.

[Agent24]

Re: HannsG HH241 problems

Can someone point me in the right direction as to how to test these voltages?
* 5V for the main board, and
* voltage (14~17V) for the backlights inverter

I don't know where to put the leads of the multimeter. Thanks.

See the connector on the left of the board with the Red, Black, Blue, Yellow and Green wires? Seems to be marked CN8xx but I can't read the whole refdes. That is the connector which brings +5v to the mainboard and also carries control signals from the mainboard to control the inverter etc. Yours won't have the volume\mute signals connected though as your PSU\inverter board doesn't have the onboard audio amplifier.

There is a listing next to that connector showing the pinout for what each pin does. Pins 1 and 2 are 5v, pins 3, 4, and 10 are GND, etc etc.
Most likely there is a 1 and 10 marked on the board at either end of the connector showing which pin is which but I can't see them because the wire is in the way.

Going by the colours though, likely Red will be the +5v rail and Black will be ground.

So, get the monitor working and connect your black (negative) meter lead to ground on one of those black wires, and then connect the red (positive) meter lead to each other pin and write down what you measure for each one.

Then, wait until the monitor shuts down by itself, and measure everything again and write it down. Post the results here.

To find the Inverter power supply (it will run from a different rail than the +5v) we need to trace the PCB so you will need to take the board out of the case and show a good straight-on photo of both the top and bottom sides.