Hanns-G HH251 no power

[maudam]

Re: Hanns-G HH251 no power

Connected PS_ON with 5.2v a 1k resistor with no result.
Same thing with INV_ON
Selldoor, did you mean connect 5v to BRT too ?

In attach there are pictures of the mobo.

[budm]

Re: Hanns-G HH251 no power

"Selldoor, did you mean connect 5v to BRT too" Do that also with the resistor, some inverter does need Dimming control voltage.
BTW "Connected PS_ON with 5.2v a 1k resistor with no result.Same thing with INV_ON." You do not have the cable to the main board connected, right? It must not be connected while force on test is made.

[Davi.p]

Re: Hanns-G HH251 no power

IN the mobo the chip labeled 84-33 the center pin must read ~3,3v, can you tell me the markings on the 3 near 3-leg chips on same heatsink in psu? It's strange a reading of 20v all.

[budm]

Re: Hanns-G HH251 no power

Can I get the straight shot pictures of the bottom side of the power supply board? It looks like the the 12V is used for the audio amplifiers.

[maudam]

Re: Hanns-G HH251 no power

@Selldoor and @Budm: just tested

PS_ON <----1kohm <---5.2v
BRT <--- 1kohm <---5.2v

PS_ON <----1kohm <---5.2v
INV_ON <----1kohm <---5.2v

BRT <----1kohm <---5.2v
INV_ON <----1kohm <---5.2v

Display never lamp.
All test made with mobo cable disconnected

[maudam]

Re: Hanns-G HH251 no power

@davi.p

on mobo chip 84-33
picture attached

[maudam]

Re: Hanns-G HH251 no power

@budm
pictures of bottom side of psu

[maudam]

Re: Hanns-G HH251 no power

@davi.p
i made again the measures on transistors with mobo attached to the psu.
In attach there are the readings.

[Davi.p]

Re: Hanns-G HH251 no power

i know that you've made many photos already but is difficult for me to see well, in particular the part of the secondary of psu is difficult to see traces.. if you can make better one; now measurements has more sense, anyway i don't find how the 23v output serves to.. in the photo where you put measurements the 3-leg chip where you measured 23,9v can you measure all 3 pins and tell me its part number? Bye

[budm]

Re: Hanns-G HH251 no power

You need to use 3 resistors on
PS_ON, INV_ON, BRT. If that does not work then I will need to trace out the circuit of the inverter section, you have to do the resistors connection without having the logic board connected.
BTW, that red wire on that connector looks dangerous, it looks like it is touching the pins next to it.
You also need to verify the 24v and the 30vdc readings, what do you use for the ground ref point for the secondary circuit?
The board has 3 power supplies as shown in my redlined picture.

[maudam]

Re: Hanns-G HH251 no power

@davi
The reading on that transistor with mobo disconnected is 15.5v
With mobo connected voltage range is from 21v to 29v in different times.
Hi res photo of transistor in attach

[maudam]

Re: Hanns-G HH251 no power

@budm
very beautiful schema!
i have tried to connect 5.2v to those 3 pins but the tft won't switch on.
I have changed the red wire with something more useful just to be sure
The grounf ref point is the monitor chassis connected to the boards with crocodiles and to the multimeter with another one.

Soon i'll post the readings for all transistor with the 3 pins disconnected and then connected.

[selldoor]

Re: Hanns-G HH251 no power

Is that an H on the end - perhaps this is datasheet

http://html.alldatasheet.com/html-pd...AP40T03GH.html

[maudam]

Re: Hanns-G HH251 no power

@budm
All measures with mobo disconnected:

Pins connected: (PS_ON, BTR, INV_ON)

T1 12.5
T2 17.6
T3 5.2
T4 17.6
T5 17.6
T6 0.20~0.40

Pins disconnected (after some minutes 'cause voltages on T1 T2 T4 and T5 slowly vary after disconnection of pins):

T1 increase up to 24v than decrease and stabilize to 18.8
T2 25.7
T3 5.2
T4 25.8
T5 25.8
T6 0.3

[selldoor]

Re: Hanns-G HH251 no power

Whoopee ! Think I have spotted another fuse F200 Between T4 and T5

[budm]

Re: Hanns-G HH251 no power

@selldoor, good eyes! I did not even see that. The Voltages are about right. No need to do T6 reading since it is on the primary side which you cannot use the chassis ground (cold side ground) as the ground ref. for the meter.
So check the F200.

[maudam]

Re: Hanns-G HH251 no power

F200 is ok

[budm]

Re: Hanns-G HH251 no power

OK, since the two MOSFETs T4, T5 which drives both inverter transformers in half-bridge setup and they are getting voltage, it means that the PWM IC (to the left of the T4) may not be driving the Gate of the MOSFETs. There is a SMD 18 or 20pins IC which is the PWM IC. Can you read the P/N as printed on the top?
BTW, What dc voltage do you get at both ends of the F200 fuse with ref to chassis ground?

[maudam]

Re: Hanns-G HH251 no power

Tomorrow i'll make all measurement.
This is the IC you asked for.
There is also the picture of the other chip smd located down to the big cap.

[budm]

Re: Hanns-G HH251 no power

BIT3501 is the one we need to look for the spec sheet.