HP Z24i monitor: caps replaced, monitor still dead

[Delirious]

Hi,


I got an HP Z24i from work some time ago which was completely dead. I decided to replace the caps on the power board/psu and replaced all off them except the one on the primary(?) side. All caps replaced were Panasonic fr or fc. It still will not power on at all it seemed. After it did not work I decided to try and reflow some of the solder joints with mixed results. I also found another large cap from another power supply and replaced the one on this power board.

Unfortunately I have little experience and knowledge about electronic repair so I feel like I have exhausted my options. Is there anything else you would recommend that I try? I added some pictures as well.


I am very happy about the help I got from here last time, I managed to repair my B&W Zeppelin and now its working perfectly. Thank you guys for that

[PeteS in CA]

Re: HP Z24i monitor: caps replaced, monitor still dead

Since that power supply is less that 2 1/2 years old there's a good chance those capacitors were OK. Did you check to see if the fuse is open? In the first picture it's in the bottom right corner, just to the left of that white connector.

Have you tried powering on the power supply with no load, to see if it is OK, and the problem is elsewhere?

If there is no output voltage, do you have voltage (about 300VDC, there in Norway) across that big capacitor you were asking about when you power it on (be very careful, of course)?

Judging by the lack of an output inductor, that is probably a discontinuous flyback design.

What is that 16-pin IC? Are there components on the underside of the PCB?

[Delirious]

Re: HP Z24i monitor: caps replaced, monitor still dead

Thanks for your reply PeteS. Unfortunately I messed up and managed to short the capacitor on the power board (yes the one on the primary side..) The result was a destroyed conductive track,. I can only blame myself for this and had I tried to keep a cleaner work bench this probably would not happen.

I am afraid that the result might be that I will have to bin it. The only way to save the monitor now is to get a new power board, but I am not sure if this is really possible. Only good thing to come of this is that I am learned that I should be a little bit more careful when trying electronics repair..

About the fuse. How would I go about checking if the fuse is open. Using a multimeter and test for continuity?


Thank you for your help.

[PeteS in CA]

Re: HP Z24i monitor: caps replaced, monitor still dead

Re the fuse, yes, though the fact there was voltage on that big cap means it was intact. Since your accident, it's probably blown.

If the fried trace isn't too complicated, and if there's ample space in the monitor between that trace and anything metal, you should be able to replace the trace with AWG #20 wire (or similar metric size). Depending on how many connections were made to that trace, you may be able to use insulated wire. Just cut off the fried trace, clean the PCB, and run the wire along the path of the trace.

[jazzie366]

Re: HP Z24i monitor: caps replaced, monitor still dead

Thanks for your reply PeteS. Unfortunately I messed up and managed to short the capacitor on the power board (yes the one on the primary side..) The result was a destroyed conductive track,. I can only blame myself for this and had I tried to keep a cleaner work bench this probably would not happen.

I am afraid that the result might be that I will have to bin it. The only way to save the monitor now is to get a new power board, but I am not sure if this is really possible. Only good thing to come of this is that I am learned that I should be a little bit more careful when trying electronics repair..

About the fuse. How would I go about checking if the fuse is open. Using a multimeter and test for continuity?


Thank you for your help.

Yes, test with a multimeter.

Also, post a pic of the bottom of the board so we can see the short. If the fuse is small and the short was only split second, you might get away with not having blown the supply.

[kgavionics]

Re: HP Z24i monitor: caps replaced, monitor still dead

Thinking all Tv problems are only due to Electrolytic caps can be deceiving.In my experience i have fixed around 30 Tv, only 2 of them were fixed by replacing bulging caps.
common power supply problem: shorted Mosfets, diodes, resistors, switching IC...
your best friend to fix Tv problems is your multi meter.
an advice to novices: Troubleshooting tv can be too dangerous, you can kill your self.Be careful especially by not using cheap multimters ( 5 $ crap meters).The voltage can be as high as 400V across the leads of big filter caps.