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Old 08-12-2021, 11:20 PM   #1
MrCreosote
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Default HiSense 55HtB power supply bench test: weird voltages

There was a power surge at home from "direct" (no sound delay !!!) lightning strike. Popped a 15 amp breaker for ceiling lights (old knob and tube wiring - perfect antenna?) "Fried" garage door opener buttons and remote, KVM switch, Magic Jack, and a ceiling fan motor.

And my 55" 6 year old Hisense Black Friday Walmart TV.

There is no Red standby LED.

I was wondering how to "jumper" the board on to test voltages thinking the STB pin would be one of the pins.

However, I decided to measure voltages at all 10 pins just so see there was something there to power the standby switch. What I found was something I cannot explain: Voltages with no power connection to board. Now I was working under 4 compact fluorescent light bulbs but that is a reach.

Maybe this is telling me the board is fried?

I have the board pinouts and the voltages are (line cord unplugged) / (line cord plugged to outlet) which is beyond my pay grade. Tried 2 different multi meters.

1 gnd
2 gnd
3 pwm -0.2v / -2v
4 sw
5 12v
6 12v
7 stb
8 gnd
9 18v 22v / 24v
10 18v 22v / 24v
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Old 08-13-2021, 09:07 AM   #2
MrCreosote
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Default Re: HiSense 55HtB power supply bench test: weird voltages

OK found the following definition of the unrecognized pinouts. Also appears this board does not have a 5v standby. Here is a copy from another thread:

Where is the 5V pin on this board? I do not see one.
http://www.badcaps.net/forum/attachm...3&d=1472170236

STB = PS-ON
SW = BL-ON
PWM = PWM dimming

RE: Measured Voltages: the 24v is troublesome: much higher than the 18v spec'd.

Also, the voltage measured with no power to board could be caps still charged up? But I repeated measurements w/ and w/o power and the values alternated between 22 and 24. If charged caps, I would expect 24 and 24 or the 22 would would change with time while discharging. Could get a VOM to put a little load on it.
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Old 08-13-2021, 10:58 AM   #3
lotas
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Default Re: HiSense 55HtB power supply bench test: weird voltages

STB is the standby power supply (voltage DC5V).

STB can be 3 - 6v DC

Last edited by lotas; 08-13-2021 at 11:14 AM..
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Old 08-13-2021, 11:06 AM   #4
lotas
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Default Re: HiSense 55HtB power supply bench test: weird voltages

PWM - backlight level
SW - switching on the main power supply 12V and 24v.
no load and will jump power to 24v.
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Old 08-23-2021, 12:49 PM   #5
MrCreosote
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Default Re: HiSense 55HtB power supply bench test: weird voltages

Both STB and SW are 0v.

So I've go NO standby power supply and the 18v pins are running 24v.

RIP power supply board.
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Old 08-23-2021, 12:55 PM   #6
Th3_uN1Qu3
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Default Re: HiSense 55HtB power supply bench test: weird voltages

I would not worry about 18V being 24V for now. The standby section should be fixable, it should be nothing more than replacing the switching IC, startup resistor and associated capacitors and maybe the optoisolator.
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A working TV? How boring!
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Old 08-23-2021, 05:05 PM   #7
R_J
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Default Re: HiSense 55HtB power supply bench test: weird voltages

Quote:
Originally Posted by MrCreosote View Post
Both STB and SW are 0v.

So I've go NO standby power supply and the 18v pins are running 24v.

RIP power supply board.
I answered this in your other thread, The power supply board is working fine, it does NOT supply a separate standby 5 volts
STB is an input which requires a high (+3~5v) to fully turn on the main power supply and pfc circuit. SW pin also requires a high signal to turn on the 12V_VCC for the backlight circuit
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