Bush PDP42TV006 Problem No Picture

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

Tom

I've run into a problem. The power lead is chased into the wall and the only other one I have powers the PC.

I'll have to grab one from work tomorrow.

I assume you mean the left most connection marked Vs and I stick the probe down into the connector where the wire connects - I can just see the end of the exposed internals of the connector

Many thanks

Fritz

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

Hi Tom

Well I'm not sure I'm doing this right but when I put the probe in either of the pins marked Vs I'm getting a reading of 20 v which gradually drops off to zero over about a minute. I can hear some clicking and various lights come on then some go off again. There's also a crackling sound when I push the probe in but guess that could be as the probe connects. It's just once, then it goes.

Attached is a photo of how I'm testing; how the meter is set; and also a couple of photos of the sticker on the back of the panel that I think is telling me what voltages I should get.

Many thanks

fritz

[tom66]

Re: Bush PDP42TV006 Problem No Picture

Is the red probe in the VOLT jack, black probe in COM?

The PSU looks likely to be the fault, but there are some other tests that can be done.

That connector goes to a board on one side of the plasma panel.

There will be a board on the other side too.

You need to unplug both big thick power connections to these boards then measure Vs.

If it rises to 175V, you should then get sound (though this depends on if the set is switched to a source with sound and if all is connected right.)

This will mean one of these boards is defective. Through process of elimination you can locate which one is defective. (Note, only change the connectors after switching off the set by unplugging it, and leaving it alone for 5 minutes, or damage/arcing may occur when reconnecting.)

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

Hi Tom

Yes probes are connected correctly.

I unplugged both connectors and re-tested all Vs pins and still get voltage dropping although it now peaks at about 50 v as the set is switched on but drops off much faster.

Fritz

[tom66]

Re: Bush PDP42TV006 Problem No Picture

It would seem the fault is definitely with the power supply. It may have something to do with that bulged capacitor, so I would consider that first. What is the part # on power board (usually LJ44- or BN44-)? In many cases a new power board is cheaper than replacing parts, especially considering the time taken to diagnose and repair.

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

Hi Tom

The board number is LJ44-00068A. I can pick one up for about 50 pounds. I picked up a capacitor earlier for about two pounds. Do you think it's worth trying changing that to see what happens?

Fritz

[newtothis]

Re: Bush PDP42TV006 Problem No Picture

I would certainly change the CAP before replacing the board at that cost

Can you tell me what CAP you bought? Manufacturer... Will be written on the side.

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

Yep

Got it from RS

nichicon
33mF 450 v
CA(M)
105 C H1142

RS part no. is 7394589

I e-mailed them with the details off the blown one and that's what I got.

Many thanks

Fritz

[newtothis]

Re: Bush PDP42TV006 Problem No Picture

Yep

Got it from RS

nichicon
33mF 450 v
CA(M)
105 C H1142

RS part no. is 7394589

I e-mailed them with the details off the blown one and that's what I got.

Many thanks

Fritz

Get that cap changed and see how you go.

I would suggest changing all caps on the board at some point though, generally if one has failed the others will follow suit shortly and its hassle and time wasting to keep opening the set up and ordering parts.. IMO anyway.

Good luck and keep us updated

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

Ok so I out the new cap in and still no picture. Basically the same symptoms BUT I now get 6 flashing LED instead of 7! If only I could reduce it to none I'd be laughing.

But seriously, I'm still getting the same voltage from Vs. 20 max and slowly dropping. with both VS plugs disconnected 50 V and reducing much faster.

Fritz

EDIT: Hold that thought, it's still 7 flashes. Is there a way I can check my soldering is good? Grasping at straws really though

EDIT 2: As it warms up I get 3 green LED very close to the power in connection and then when it trips 2 of those go out and I get a red LED on the other side of the board

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

Another update......

Couldn't sleep last night so I took the power board out and started testing components.

There is another cap that I'm getting no reading for . It's in the VE section of the board.

There might also be some blown resistors there and in the PFC section (where I changed the capacitor before) as well but I'm getting some really odd readings as in I check it once and get a reading, check it again a few minutes later and get no reading so I can't be sure which are blown and which are not. There's about 10 resistors like this.

Components cost I guess is about 12 pounds if I replaced everything that gives me no reading; second hand board 50 pounds; new set 300 pounds.

Not really sure which way to jump

Fritz

[newtothis]

Re: Bush PDP42TV006 Problem No Picture

On my phone at the moment, will get back to you once I'm at my pc

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

Ok I found a used board for 42 pounds. The same model number but the Rev number is different.

Does that matter? If not I'm going to give the replacement board a run.

Fritz

[FritzCT]

Re: Bush PDP42TV006 Problem No Picture

So fitted the new psu and all seems ok.

Thanks for the help, much appreciated
Fritz

[tom66]

Re: Bush PDP42TV006 Problem No Picture

Glad to hear, enjoy your TV.