baird 42 flickering strobing wont start up

[notallbad]

Re: baird 42 flickering strobing wont start up

I had a PS b/d MLT668 rev1.5 with same symptoms, strobing backlight, replaced 5 caps and worked fine. The 5v stby, 12v and 24v rail voltages were unstable so may be a different fault causing the same symptom.

I remember a couple of them being under a cage heatsink and the board looked very similar to yours. Used tweezers to hold cap in place through the cage, i.e did not remove cage heatsink, maybe I was just lucky to have easier access.

[wreksta]

Re: baird 42 flickering strobing wont start up

replaced all visual and one in left heatsink theres about 13-14 caps under right side heatsink

I still haven't tested after replacing the 10uf 50v under left heatsink doing some more checks toms helping me

[wreksta]

Re: baird 42 flickering strobing wont start up

The 5v stby, 12v and 24v rail voltages were unstable so may be a different fault causing the same symptom.

how to check this mate?

[tom66]

Re: baird 42 flickering strobing wont start up

OK, that is PFC IC (http://www.ti.com/product/ucc28060). I would replace the cap near it. You can measure the resistance across the positive and negative of the cap -- power must be off while doing this.

[notallbad]

Re: baird 42 flickering strobing wont start up

The caps I replaced, may differ on yours, were

1000uF 10V
470uf 25V (x2)
470uF 35V (x2)

If memory serves me well they were all located either near or under the cage next to the output connectors.

[wreksta]

Re: baird 42 flickering strobing wont start up

OK, that is PFC IC (http://www.ti.com/product/ucc28060). I would replace the cap near it. You can measure the resistance across the positive and negative of the cap -- power must be off while doing this.

tom that's the one I replaced mate so wht do yu think resolder heatsing back on screw mosfets back and test?????????

[wreksta]

Re: baird 42 flickering strobing wont start up

notallbad if what we doing fails il take a look and let you know what I got under that cage

[notallbad]

Re: baird 42 flickering strobing wont start up

Have you checked for any obviously bloated caps under the right heatsink?
A couple I replaced were bloated but a couple were not!

[tom66]

Re: baird 42 flickering strobing wont start up

tom that's the one I replaced mate so wht do yu think resolder heatsing back on screw mosfets back and test?????????

Yep, I'd try it.

[wreksta]

Re: baird 42 flickering strobing wont start up

Have you checked for any obviously bloated caps under the right heatsink?
A couple I replaced were bloated but a couple were not!

nothing visual mate had a good look to lol
tom ttesting now will report back

[wreksta]

Re: baird 42 flickering strobing wont start up

exactly the same tom any ideas

now if I remove the main av board power from the psu I don't get the clicking not sure hhow that works this connector is located on the right of the psu next to that on the left is all those caps under heatsink
this connector



anything else to check for

[notallbad]

Re: baird 42 flickering strobing wont start up

With the Main a/v board disconnected the PS board is not fully running only provides 5v stby, 5v stby goes to main a/v, main a/v then sends on signal to PS b/d when remote control or power on button is pressed (not rocker on/off switch), the PS b/d then provides 12v to Main b/d and fully powers up.

So PS b/d switched on but disconnected from Main b/d will not be conclusive.

You could with a 1kOHM resistor jump the PS ON pin (not to be confused with the BL On pin) and 5v stby pin, with main A/V b/d connector disconnected.

[notallbad]

Re: baird 42 flickering strobing wont start up

Do you have a DMM?

Measure voltages on the connector pins and note them here, remembering to number them and note the connector label.

Looks like the PS board connectors to the right of photo are from top to bottom

Main board
Audio (possibly) 4-pin (2 gnd and 2 might be 12,24 or 33v)
Inverter 10-pin (most likely 5 are gnd and 5 are 24v)

Refer to this thread for another Baird 42" (as suggested above):
https://www.badcaps.net/forum/showth...light=baird+42

Bump

The 4-pin connector could go to the inverter b/d and not be audio!

[wreksta]

Re: baird 42 flickering strobing wont start up

hi mate

how to measure that what should multi meter be set to and what pin where is this with all connectors disconnected except 2 pin power in and powered

[wreksta]

Re: baird 42 flickering strobing wont start up

Bump

The 4-pin connector could go to the inverter b/d and not be audio!

]

4 pin is audio connector mate

could be those caps couldn't it under right heatsink

[notallbad]

Re: baird 42 flickering strobing wont start up

To check voltages leave all the connectors in place.

The black lead, Com, connected to the chassis, usually the screw holding the Ps b/d to the frame is fine.
The red lead, Volt/Ohm, this probe connects to each pin, one at a time, be careful not to touch anything else with it whilst connected to the pin being measured.
Set DMM to V DC 20, if it displays OL or 1. it means the voltage is greater than the DMM setting is set to so move it up to 200 in the same range i.e V DC.

Never hesitate to ask if your unsure before doing something.

[notallbad]

Re: baird 42 flickering strobing wont start up

]

4 pin is audio connector mate

could be those caps couldn't it under right heatsink

OK just wanted to be sure as can't see where it goes from the picture.

[notallbad]

Re: baird 42 flickering strobing wont start up

I'm not trying to hijack this thread and by no means trying to suggest the problem is the same as I have experienced, just trying to help out and perhaps free a bit of Toms time by helping where I can.

Tom is the best person for advise. I 'm always happy to help when and wherever poss.

[wreksta]

Re: baird 42 flickering strobing wont start up

To check voltages leave all the connectors in place.

The black lead, Com, connected to the chassis, usually the screw holding the Ps b/d to the frame is fine.
The red lead, Volt/Ohm, this probe connects to each pin, one at a time, be careful not to touch anything else with it whilst connected to the pin being measured.
Set DMM to V DC 20, if it displays OL or 1. it means the voltage is greater than the DMM setting is set to so move it up to 200 in the same range i.e V DC.

Never hesitate to ask if your unsure before doing something.

mate I set my meter to 600vdc is this fine its only one of these
http://www.petervis.com/electronics%...esistance.html

[notallbad]

Re: baird 42 flickering strobing wont start up

600vdc will be too high and not give accurate enough readings, 20 will be fine, to the left of the OFF.

Once you get a reading, say 4.6v for example, set the meter to the 600v setting and then see what reading you get then on your DMM. You will then see what I mean. The reading will probably say 3.8v or something lower than your original reading so less precise and be misleading when diagnosing.