Hisense HLUD65XT880 wont start.

**Mr 672A** · 09-12-17, 10:11 AM

Hisense HLUD65XT880 4K telle

Last night I turned this tv on and ir started for 30 seconds and when I turned my back to it I heard a High frequency pitch for 2 seconds and it Died. I reset it on the Power Point and turned the power back on and notice the Front HISENSE name was lit but it does not look to be the full brightness. (I could be wrong here for not being bright as I think when the TV fire up the HISENSE Dims a little).
What do you think could be the Cause? Could it be the SMPS ( the high pitch sound) or could it be something else that has unloaded the SMPS and make it squeel and possible killed it. (Haven taken the back off yet)
Thanks

**Skepticist** · 09-12-17, 11:04 AM

The 'squeal' is probably the power supply detecting an overload and shutting down/restarting until it became a hard short circuit
That fault could even be in the supply itself but it does sound like the standby supply is still working. The TV needs exploratory surgery and perhaps it will be something visually obvious like a swollen capacitor (if you're lucky)

**Mr 672A** · 09-12-17, 04:38 PM

I still have no time to look at it as I'm busy ATM. Maybe 2morrow I will look at it.

**Mr 672A** · 10-12-17, 01:21 PM

I suspect the LARGE HDMI board killed the TV. Firstly one HDMI died for no reason then another died with the Skybox after one storm (the first flash of lightning) and now my daughter whilst was watcing the TV said to me that the TV went to a BLUE screen than to FTA TV back to Blu screen than to a Analogue screen (HASH) then had the high pitch sound then it died. I would say it it was the HDMI board and that also could have taken the large SMPower supply

**Skepticist** · 10-12-17, 02:00 PM

So many possibilities and it will need sectionalising to narrow down where the actual fault is.
First thing I'd check is the power supply board for a blown fuse then (if the fuse is ok) try to start the main supply without any load connected to it. That can be tricky as you'd need to jumper the standby supply to mimic the 'on' button of the TV being pressed.
Lots of ways you can liven yourself up while doing this so a lot of experience and care required to do it safely.

**Reschs** · 10-12-17, 07:22 PM

How old is it ?
They have a 3 Year Warranty.
I would talk to them before opening it.

**Mr 672A** · 16-12-17, 08:55 AM

Originally Posted by Reschs

How old is it ?
They have a 3 Year Warranty.
I would talk to them before opening it.

Yes the TV is 3 years and 3 months old. I'm 3 months out. Well I can but another superseded 65 inch Hisense for $1250 which is better than the original one aas the wife wants Freeview TV.

**Mr 672A** · 16-12-17, 09:03 AM

Originally Posted by Skepticist

So many possibilities and it will need sectionalising to narrow down where the actual fault is.
First thing I'd check is the power supply board for a blown fuse then (if the fuse is ok) try to start the main supply without any load connected to it. That can be tricky as you'd need to jumper the standby supply to mimic the 'on' button of the TV being pressed.
Lots of ways you can liven yourself up while doing this so a lot of experience and care required to do it safely.

I cannot believe it as the TV does not have a conventional fuse that I know, I have disconnected all the three secondary outpus of the Large SMPS about 300X250 MM and turned it on and most of the Voltages are correct as they are marked on the board. The other are hard to test as you will short it. No visible problems on the TV. Also I tested the bridge rectifier and I found on the AC side 240V (you would expect this) and 280V DC on the output of it. How can be this the case than having a higher output than the input.

**Skepticist** · 16-12-17, 03:50 PM

I'd definitely be checking out the caps in the power supply with an ESR meter.
That voltage discrepancy could be due to high ripple on the rectified output (or your voltmeter)
Then check that those output voltages hold up with the boards connected (individually if possible to locate where the overload is and if there is an actual overload pulling the voltage down)

The investigation gets messy after that if the supply is in good condition

**Reschs** · 16-12-17, 09:37 PM

With only 280V on the output of the rectifier (should be 340V) , I would definitely check the main filter cap and the bridge rectifier itself.

**Mr 672A** · 16-12-17, 10:23 PM

Originally Posted by Reschs

With only 280V on the output of the rectifier (should be 340V) , I would definitely check the main filter cap and the bridge rectifier itself.

Shi.t You put in 242 Volts A C from the mains and should have 340 V DC on the output of the bridge Recifier. Is this Normal on many TV today? If I only have 280V DC something must be pulling the Voltage down (no swollen caps). Also If I remember correctly I had the Three 20 0dd pin sockets disconnected where I found the 280 V DC on the ouput. Also the voltage could be the same with connected sockets (should have wrote it down)

**Reschs** · 16-12-17, 10:39 PM

The bridge rectifier converts the AC to DC and this AC x 1.414 = DC for full wave.
The main cap ensures this voltage by removing the ripple and holding the peak value. If the cap is no go the waveform will still have a lot of AC present hence the lower reading.
If one of the diodes in the bridge is open circuit you can get the same problem.

The main cap only runs at 100Hz and bulging rarely occurs.

**Skepticist** · 16-12-17, 10:44 PM

Yes 340V is the peak of the rectified waveform and the large capacitor should smooth the voltage to that peak value with no load. With no smoothing (eg cap open circuit) your meter would read the average value of the rectified half-waves which would be considerably lower. The actual reading would depend on whether the voltmeter is a 'true RMS', or simply an averaging, type.

If there's something funny about the power supply voltages with no load then that's very likely where the problem is - maybe first remove that mains cap and measure its capacitance & ESR out of circuit (if you have the test gear at hand) Discharge it first for safety purposes O_O

**loopyloo** · 17-12-17, 03:49 PM

Measured with reference to the negative lead of the rectifier/s ?

**Mr 672A** · 17-12-17, 04:23 PM

Originally Posted by Skepticist

I'd definitely be checking out the caps in the power supply with an ESR meter.
That voltage discrepancy could be due to high ripple on the rectified output (or your voltmeter)
Then check that those output voltages hold up with the boards connected (individually if possible to locate where the overload is and if there is an actual overload pulling the voltage down)

The investigation gets messy after that if the supply is in good condition

Sorry to forget your Post. Yes I had a good ESR meter but I forgot who I lent it to . You can buy cheapees on ebay or at a price at Jayca. The funny is I cannot see a fuse. I might have to take a Phot and let see if you can find me.
My Stroke Fu.ck me as I was reasonable good of doing a lot of Electronic work. The only thing I have fixed since the strok was the Induction cook top that a Cockroach Fried I blew the Tranny and a Bridge rectified on one cooker like what the TV has. It looks very similar.
I do know that 2 out of the 4 HDMI's are no good to start with and this is the reason why i'm 50% of getting a new Tell. for the eat room. On the main TV room we have a Sony KD X9400E, The best LCD on this planet with its Yank, an POM model being the same

**Mr 672A** · 17-12-17, 04:34 PM

Originally Posted by loopyloo

Measured with reference to the negative lead of the rectifier/s ?

Measure across the terminals of the rectifier itself (+ and (-)

**Mr 672A** · 17-12-17, 04:41 PM

Originally Posted by Skepticist

The actual reading would depend on whether the voltmeter is a 'true RMS', or simply an averaging, type.

If there's something funny about the power supply voltages with no load then that's very likely where the problem is - maybe first remove that mains cap and measure its capacitance & ESR out of circuit (if you have the test gear at hand) Discharge it first for safety purposes O_O

I have just about everything I need in my house workshop but the trouble is after the Stroke I had to re teach myself everything again. I have two Multi Meters But don't think they measure RMS. One is a Dick Smith one (one of there expensive ones and the other is a badged Cable Accessory one.

**Mr 672A** · 17-12-17, 05:23 PM

Photo below is the TV itself. SMPS is on the Left, on the right is the Tuner / HDMI board.

The Photo below is the SMPS

the Photo below is the Bottom of the SMPS (where is the Fuse, cant see it)

The Photo below is the mid of the SMPS

The Photo below is the top of the SMPS

The Photo below is my repair room

**Skepticist** · 17-12-17, 09:51 PM

Those varistors like RV801 (near bottom right side) would be doing the job of overload protection on the mains input (a guess). The fact that the supply actually runs suggests the varistors are ok so checking the bridge rectifier would be the next step to take followed by those 3 HV electrolytics (450V 82uF) which I expect are in parallel.

A schematic would be nice

**Reschs** · 17-12-17, 10:28 PM

The small round component, black capacitor like, right next to the mains input is the fuse.
The fact that you have 240V on the input to the bridge rectifier eliminates the fuse.
Again check the bridge rectifier for open circuit diode. Short circuit would blow fuse.
Just bridge a 450V any reasonable size electro across the existing and see if the DC Volts rise.