LG 60PB5600 - No picture

[mtb604]

Reading through the forums, I have so far done the following.

- Confirmed both fuses on the power board are intact

- Measured Va voltage on the power board at VA TP initially at ~380V and then drops

- Measured Vs voltage on the power board at VS TP at 0.0V

- Searched for replacement Y-Sus boards but everyone is sold out of this board.

Is there a way to identify which components are bad and replace them on the board?

[Hamie]

Re: LG 60PB5600 - No picture

Va should be around 60v
Are you sure your DMM is working?

[mtb604]

Re: LG 60PB5600 - No picture

Yes, I just tested it with known voltages.

[Hamie]

Re: LG 60PB5600 - No picture

So you're getting 380 dc on the va test point?
And 0 on the vs test point?

So if you connect rl-on to 5v stby what do you get?

[dick_barton]

Re: LG 60PB5600 - No picture

Shopjimmy do a complete repair kit.

[mtb604]

Re: LG 60PB5600 - No picture

when I first turn it on, I get 380 vdc at TA TP but then it drops down to 0.7 mv.

I can find the RL-ON pin, but I don't see the 5V STBY.

I have
5.2 V- 17V_DET
5.2 V- VS_DET

[cliff_hootarski]

Re: LG 60PB5600 - No picture

Could you please show us where the TA test point is an how you are trying to measure with your meter. VA voltage is usually on the average of 60Vdc. 380Vdc would burn up every board in the set!

[mtb604]

Re: LG 60PB5600 - No picture

Sorry- 380 mv and then drops to 0.1 mv

I'm measuring it at the TA TP just above the connector on the lower left of the picture

[dick_barton]

Re: LG 60PB5600 - No picture

Have you checked the fuses on the power supply board. You have 17V, 5.2V, 17V_Det.
What voltage do you have for RL_ON, M_ON , VS_ON and VS_Det

[mtb604]

Re: LG 60PB5600 - No picture

RL_On: 3V and then a breaker clicks and it goes to 40mv
M_On: Same as RL_On
VS_On: 0V
VS_DET: 5.2 V

[mtb604]

Re: LG 60PB5600 - No picture

I only see two fuses on the power supply board and both of them are intact.

[Hamie]

Re: LG 60PB5600 - No picture

So with the z and y-sustains disconnected from the power supply what voltages do you get at vs and va?

[mtb604]

Re: LG 60PB5600 - No picture

with both disconnected:

VS: 205.5V
VA: 54.7V

With just the z-sus connected:

VS: 205.4
VA: 54.7

Y-sus is connected to the Z-sus, not directly to the power panel

[mtb604]

Re: LG 60PB5600 - No picture

So it seems like it is the Y-Sus that trips the breaker.
Is there any way to identify which components on the board have failed or do I just replace everything that comes with the shopjimmy repair kit?

[ReeceyBurger123]

Re: LG 60PB5600 - No picture

Probably the 30F or 30J type fets are shorted. Disconnect the buffer from the Ydrive and test again.

[mtb604]

Re: LG 60PB5600 - No picture

Seems like I will have to remove the Y-sus board to disconnect it from the buffer. I'm having trouble releasing the connectors from the Y-sus board to the buffer. How are they released?

[mtb604]

Re: LG 60PB5600 - No picture

Never mind. I got it out.

[mtb604]

Re: LG 60PB5600 - No picture

No voltage measured at VA or VS with Y-Sus connected and buffer disconnected.
I suspect that since nobody has the Y-sus boards in stock that this is a common failure.

[Hamie]

Re: LG 60PB5600 - No picture

Take photo of the underside of the y-sus.
I've repaired this model a few times and it tends to fail the same way.

[mtb604]

Re: LG 60PB5600 - No picture

Here is the underside of the y-sus board