LG bh9530tw home theater no power

[DjKrish]

Hi folks, im in need of service manual for this model. Any kind soul able to upload the service manual for me? The model is LG bh9530tw

Few of the smd components burned at the bottom

[DjKrish]

Re: LG home theater no power



SMPS model is EAX63689124

Can anyone pleaseeeeeeeee help me get the service manual for this model?

[DjKrish]

Re: LG home theater no power

Like it stated in the smps, the same power supply is used in various models such as BH7xxx, BH8xxx, BH9xxx and DH7xxx. Does anyone has any service manuals for any of the said models?

[Khron]

Re: LG home theater no power

I can't be 100% sure from the first photo, but it kinda looks like most of the components between the PWM chip and the MOSFET gate are toast.

http://omapalvelin.homedns.org/tesla...fets-large.gif

T2 = Q912
T3 = Q913
D2 = D913, with R948 added in series with it
R17 = R907, in parallel with the series'd D913/R948

ZD905 added to limit the max voltage going to the MOSFET gate; FB903 in series with the gate, to prevent high-frequency interference from affecting the gate.

Odds are good the PWM chip is gone as well. Can you still read the markings on it?

[DjKrish]

Re: LG home theater no power

I can't be 100% sure from the first photo, but it kinda looks like most of the components between the PWM chip and the MOSFET gate are toast.

http://omapalvelin.homedns.org/tesla...fets-large.gif

T2 = Q912
T3 = Q913
D2 = D913, with R948 added in series with it
R17 = R907, in parallel with the series'd D913/R948

ZD905 added to limit the max voltage going to the MOSFET gate; FB903 in series with the gate, to prevent high-frequency interference from affecting the gate.

Odds are good the PWM chip is gone as well. Can you still read the markings on it?

Didnt realise that LG service manuals are really hard to find. Sighs. Thank god manage to get the manual for DH series that uses the same smps. Now i have identified all the components

[DjKrish]

Re: LG home theater no power

Ok time for updates. Have changed all the faulty components. Power is up. Theres standby light on the home theater BUT i measured the voltages on the power board, the voltages on all the pins seems higher than rated as i checked using MM on DC mode. Now thats weird. Check screenshot

Upon measuring using MM on DC mode, these are the voltages im getting

3.8VA im getting 9.3VA
6VA im getting 13.7VA
14VA im getting 31.8VA

[budm]

Re: LG home theater no power

I did not look at the schematics yet but I wonder if those Voltages may not be ref. to the circuit common GND.

[DjKrish]

Re: LG home theater no power

I did not look at the schematics yet but I wonder if those Voltages may not be ref. to the circuit common GND.

Hi budm, heres the service manual that has the exact same smps. Pls check and tell me what u think.

[mmartell]

Re: LG home theater no power

Some of the joints on T901 look suspect at least from the photo you provided.

[DjKrish]

Re: LG home theater no power

Some of the joints on T901 look suspect at least from the photo you provided.

That was when i first took it out. Its all soldered already. Now the board is all good. Just wanted to verify the mismatch of voltages. Dont wanna end up blosing things again. Thats why i dont dare operate the unit yet. For now, i know the power light is there. So there is standby present.

[redwire]

Re: LG home theater no power

Optocoupler PC903 (transistor) may be open circuit, it connected to the blown parts and controls voltage regulation.

[DjKrish]

Re: LG home theater no power

Optocoupler PC903 (transistor) may be open circuit, it connected to the blown parts and controls voltage regulation.

All 3 Optocouplers has been replaced

[DjKrish]

Re: LG home theater no power

I did not look at the schematics yet but I wonder if those Voltages may not be ref. to the circuit common GND.

Im sorry i dont get u budm.

[Sparkey55]

Re: LG home theater no power

Like it stated in the smps, the same power supply is used in various models such as BH7xxx, BH8xxx, BH9xxx and DH7xxx. Does anyone has any service manuals for any of the said models?

Remove as much of that yellow glue as possible because it becomes conductive when aged.

[DjKrish]

Re: LG home theater no power

Remove as much of that yellow glue as possible because it becomes conductive when aged.

All removed. I couldn't turn on the unit. Its stuck at standby. Then later on after a few minutes upon checking all voltages, the standby light vanished as well. Checked for voltages again, noticed all voltages from the psu is reducing drastically with load. If i power on without load, the voltages are stable.

[Rain0989]

Re: LG home theater no power

Hey

I have the same sound system with same problem --> NO POWER

Can you tell me what you have replaced?

Perefctly with the voltages and Amperes from the SMDs that you have changed.

best regards

[Rain0989]

Re: LG home theater no power

Push

[Rain0989]

Re: LG home theater no power

Push

[DjKrish]

Re: LG home theater no power

Nope still no luck as i couldn't fix the power.

[R_J]

Re: LG home theater no power

Maybe if you posted the service manual with smps schematic (post#8) others could help.