Hanns-G HX192D power LED flashes

[jsog]

A Hanns-G HX192D monitor shows nothing, but the green power LED flashes quickly when power is connected. I've seen the same problem reported elsewhere on the web, but no solution.

There's a quiet high-pitched tick that sounds like the inverter is starting and resetting repeatedly.

The inverter board is an FSP043-2PI01H, visually identical to the one in this thread.

Replacing all the caps except the large 100uf, 400V one didn't change the symptoms. My homemade ESR meter shows that large cap as somewhat questionable, but not necessarily bad. Don't have a spare that size on-hand, but I'll get one.

Resoldering the transformer connections didn't help. The fuses near the header are good.

The digital board has a couple of questionable 4.7 uf and 10 uf caps I'll replace next. Any other suggestions?

[PlainBill]

Re: Hanns-G HX192D power LED flashes

A Hanns-G HX192D monitor shows nothing, but the green power LED flashes quickly when power is connected. I've seen the same problem reported elsewhere on the web, but no solution.

There's a quiet high-pitched tick that sounds like the inverter is starting and resetting repeatedly.

The inverter board is an FSP043-2PI01H, visually identical to the one in this thread.

Replacing all the caps except the large 100uf, 400V one didn't change the symptoms. My homemade ESR meter shows that large cap as somewhat questionable, but not necessarily bad. Don't have a spare that size on-hand, but I'll get one.

Resoldering the transformer connections didn't help. The fuses near the header are good.

The digital board has a couple of questionable 4.7 uf and 10 uf caps I'll replace next. Any other suggestions?

1. Post pictures (top and bottom) of your board. The guy in the other thread didn't have your problem, why would we expect to find the answer to your problem in his pictures?

2. What caps (brand and series) did you use?

3. Did you replace the small electrolytic caps near the SMPS controller?

4. Did you check the output voltages of the power supply without the signal card connected? With it connected?

5. Have you checked the inverter for shorted transistors?

PlainBill

[jsog]

Re: Hanns-G HX192D power LED flashes



Only C21, top middle, had leaked. The black around the others is RTV. The three 470uf 25v replacements are Panasonic FC, the other four are Nichicon, not sure about the series. Except for the 100uf, 400v, these are all the electrolytics I see. U101 is a DM0565, and the 10 uf, 50V cap near it was replaced (one of the Nichicons). The double diodes on the top are an MBR10100CT and LT6233. Diode test says they are okay.

The big chip on the bottom is an MP1038EY.

Outputs on T1 are both about 1K, and the reddish fuse on the left is good.

Haven't checked the voltages yet, or for shorted transistors.

Thanks!

[jetadm123]

Re: Hanns-G HX192D power LED flashes

Have you tried checking the two fuses directly behind the 8-pin connector? Also what are the part numbers of U2 and U3 (8 pin mosfets on bottom of board) ? Check U2 and U3 for shorts.

[Rtech]

Re: Hanns-G HX192D power LED flashes

RTV ??????? Rumanian Television

[jsog]

Re: Hanns-G HX192D power LED flashes

I did check the two black fuses (FB260, can't see the other label); they're good. U2 and U3 are SP8K3 635. Pins 7 and 8 are tied together on the board on both, datasheet says they're connected internally. Both show a short to pin 3, which seems bad; but both? U2 pin 3 goes to pin 25 of U1, the MP1038EY. U3 pin 3 goes to pin 18 of U1.

[jsog]

Re: Hanns-G HX192D power LED flashes

RTV ??????? Rumanian Television

"Room Temperature Vulcanizing". Silicone.

[jetadm123]

Re: Hanns-G HX192D power LED flashes

Since each SP8K has 2 mosfets, try measuring for shorts on an individual basis. Measure :


using pins 1,2 and 8:
D1-S1
S1-G1
D1-G1

using pins 3,4 and 6
D2-S2
S2-G2
D2-G2

Not sure how each pin is connected externally, which could cause unusual readings.

[PlainBill]

Re: Hanns-G HX192D power LED flashes

Here's a quick 'divide and conquer' test. JP4 and JP5 appear to carry respectively +12V and Gnd to the inverter circuit and the bypass cap for the inverter. Lift JP4. That will take the inverter out of the circuit. If the power supply now comes up, the problem is in the inverter, probably U2 or U3. Conversely, if the power supply does not come up, the inverter is not the cause of the problem.

PlainBill

[jsog]

Re: Hanns-G HX192D power LED flashes

For both U2 and U3, no shorts or connections at all between pins 1, 2, and 8 or pins 3, 4, and 6.

Disconnected JP4, but the LED flashing has not changed, and the high-frequency tick is still audible. Confirmed that JP4 and JP5 are connected to +12V and ground at connector CN101 at the bottom of the board. The 12V line measures 13.02V, and 5V measures 5.22V.

For fun, after that I replaced three small caps on the digital board, 4.7 uf and 10 uf (both replaced with 10 uf, since I don't have any 4.7 uf, 25V, 105C) and now I see that another I took out by mistake was replaced with 10 uf instead of 100uf. I'll fix that tomorrow, but it's probably not the problem.

This is from before I replaced the caps (C22, C85, C60):

[PlainBill]

Re: Hanns-G HX192D power LED flashes

For both U2 and U3, no shorts or connections at all between pins 1, 2, and 8 or pins 3, 4, and 6.

Disconnected JP4, but the LED flashing has not changed, and the high-frequency tick is still audible. Confirmed that JP4 and JP5 are connected to +12V and ground at connector CN101 at the bottom of the board. The 12V line measures 13.02V, and 5V measures 5.22V.

For fun, after that I replaced three small caps on the digital board, 4.7 uf and 10 uf (both replaced with 10 uf, since I don't have any 4.7 uf, 25V, 105C) and now I see that another I took out by mistake was replaced with 10 uf instead of 100uf. I'll fix that tomorrow, but it's probably not the problem.

This is from before I replaced the caps (C22, C85, C60):

Good pictures. I wish more people would do as well.

A couple of questions: 1. Were the voltages measured with the signal card connected or disconnected? 2. Are the voltages steady? 3. Using H1 as the ground point, what are the voltages at the pins of U2 and U3 (the tab is tied to the middle pin).

PlainBill

[jsog]

Re: Hanns-G HX192D power LED flashes

Sorry, I forgot to mention that I checked, and the voltages seemed steady as far as my Fluke 79's analog bar could show. These were measured with the digital board connected; I considered testing without it but wasn't sure that was a good idea.

Should also add that surface-mount "FB"s are peppered around that board, but all I've tested are still conducting.

[PlainBill]

Re: Hanns-G HX192D power LED flashes

Sorry, I forgot to mention that I checked, and the voltages seemed steady as far as my Fluke 79's analog bar could show. These were measured with the digital board connected; I considered testing without it but wasn't sure that was a good idea.

Should also add that surface-mount "FB"s are peppered around that board, but all I've tested are still conducting.

Postings crossing in the night.

FB represents 'ferrite bead'. Unlikely (but not impossible) that they would go open.

Check the voltage on the regulators on the signal card. It is possible that the ticking sound is from the power supply in low demand mode - normal.

The evidence is that this is NOT a power supply issue, but a signal card issue. CN5 is the connector to the front panel of the monitor. Do any of the pins on that connector change voltage when the power button is pressed?

PlainBill

[jsog]

Re: Hanns-G HX192D power LED flashes

Left to right, with the tab up:

U2: 0, 1.79V, 3.3V
U3: 0, 3.3V, 5.18V

All steady.

[jsog]

Re: Hanns-G HX192D power LED flashes

Pin 5 on CN5 (well, fifth from the CN5 on the silkscreen) is at 2.2V, drops to zero when the power button is pressed. That leads to a cap (C95), then a 93.3 ohm resistor (R99) right next to the + on the silkscreen for the big cap, a 470 uf, 16V. Then it dives through a via and comes up on a pin on U7 (TSUM056J-LF), near the "E", the eleventh pin from the bottom on the right side.

(Had thought "FB" was fusible or fuse block, never mind.)

[alexanna]

Re: Hanns-G HX192D power LED flashes

This is at best a long shot, because of the steady voltages you're seeing at the logic card.
Take something else out of the equation, See what happens without the LCD cable hooked up.

[PlainBill]

Re: Hanns-G HX192D power LED flashes

Readings at both of the regulators are reasonable - 3.3 and 1.8V out. The power button signal is making it's way to the processor.

Looking at the picture of the back of the Inverter / power supply (IPS), the bottom two pins of the 8 pin connector are Backlight On/Off and brightness. Any changes on those?

PlainBill

[jetadm123]

Re: Hanns-G HX192D power LED flashes

How about using your esr meter to check the caps on the logic board?

[jsog]

Re: Hanns-G HX192D power LED flashes

Looking at the picture of the back of the Inverter / power supply (IPS), the bottom two pins of the 8 pin connector are Backlight On/Off and brightness. Any changes on those?

There's a silkscreen label under the connector that says (from top to bottom) +12V, GND, +5V, ADJUST. The top three pairs of pins are connected in parallel, but the Adjust pins are separate. One stays at .062V, the other stays at 4.94V. Pressing the power button does not change these. With the LCD panel disconnected, those both stay at zero.

Oh, and I have tested all of the caps on the digital board with the ESR meter. Only two were questionable (analog meter, mostly a go/no-go), and I replaced those. One of those still shows as questionable, but they're small-capacitance and I suspect there's some circuitry nearby that's affecting it.

I replaced most of the rest of the electrolytics on the digital board, but no change.

Is it right to think that the flashing power LED indicates that the microcontroller is at least partly alive?

[alexanna]

Re: Hanns-G HX192D power LED flashes

The 2 voltages you describe are interesting.
You mention .062v and 4.94v what does the silkscreen indicate these should be, is one dim and the other on? And I am also wondering why they change to 0v with the ribbon to the LCD disconnected.