Bush (samsung) - Plasma Sound but no picture, click click

[Vipermarty]

Hi There,

Ref: Bush (Samsung parts) 42" Plasma, sound - no picture

Firstly I would like to say I have found badcaps a excellent site, first one I have found of great ideas and very happy to be a new member. This is something new to me, a computer tech by trade but thought I would have a go repairing a TV for a family member. To the point...

A Bush PAL TV by brand but parts are totally Samsung. Turn it on, click click power on (we have good VA & VS) click click power loss. So from there i've removed power from Y & X board and ribbon cables to the logic board. VA & VS are now holding after the initial boot click.

The PSU supplies the Y board and the Y board then feeds the X board so it is not possible to try the X board on its own. If I disconnect the X board and leave the Y board connected to PSU voltage holds. The moment I connect the Y ribbon cable, voltage drops with the click click off.
I suspect a fault with the Y board and would like to repair it. I can not find any fuses on the Y board. The only fuses I am familiar with is glass or ceramic but I believe there is other types that looks like resistors? I need help with that part.

I have also tried the test in the below thread, the outcome was no screen (I believe I done it right) https://www.badcaps.net/forum/showpo...61&postcount=2

I have included some picture. There is a close up of the y board, maybe you can see a fuse? Any tests you can think of, i'll be happy to do.

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

The only thing Bush about this is the case, stand and main board. The plasma panel is Samsung, but it would be wrong to say this is a Samsung TV. It's 95% Samsung. :P It's basically a Samsung PS42B450, and those sets are plagued with X-main board failures, so you likely have an X-main board fault, if the set stays on with the power connected.

You should get a faint image after some time without the X-main. Also, try in a dark room -- see if you can see faint screen glow.

Also show us the control board so we can see if the test mode is correctly set up.

There are no fuses at all on these boards.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Hi Tom,

Thank you for your assistance. When i connect the ribbon for the y main board to the logical board the tv clicks into standby mode. Are you asking me to leave the power only connected to the y-main?

Also I don't see the control board under the main board? Unless it is part of the main or hiding behind e/f buffers?

Thank you very much.

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

On this set your control board is smack in the middle. Same on recent Samsungs and pretty much on all newer TVs, input board on the side. Easier to access ports, and cheaper to make I guess.

You need to have everything except the X-main board connected, to clarify the X-main is the plasma driver board which is on the right of the back of the plasma panel.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Hi Tom,

Once again thank you for you valued support.

HDD jumper test: LVDS cable removed from logical board (presume another name for control board?) and HDD set to pin 3&4. TV powers on, has VS & VA for a second or two, TV click click, VS/VA power loss, TV now in standby mode. Pic included of logical board/control board so you can see HDD jumper and LVDS cable removed.

Testing with out X-Main: Able to switch TV on but no voltage readings. I did remember to remove the jumper from the logical board and reconnect the LVDS. The X-main was removed from the ribbons connecting to the screen, logical board and power cables, infact I completely removed it, see pics. It was left for 30 minutes, came back and the TV was in standby mode.

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Did you try with X-main removed and the control board jumpered?

On these sets a bad X-main can damage the Y-main so you may be looking at replacing both. Shame I sold both of my boards for PS42B450 but they're available cheap elsewhere.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Each test was done differently. The jumper test, everything was connected other than the LVDS cable to main board(board with inputs).

I then reconnected the LVDS cable and removed the jumper, removed the x-main and done a new test.

I may do the test again to be sure but I am believing both boards are knackard too. One test I done was. Power on TV with both boards unplugged (power and ribbon cables removed), TV holds VA/VS. Connect a power cable to Y board it is still ok but connect anything more (either the ribbon from Y to control board or the power cable from Y to X), VA/VS volts gone and click click, tv is now in stand by.

From the information I have gave you, what is your thoughts? And if you can send me in the direction of a good price for the parts pretty please.

I have to say, you are very dedicated to what you are good at and your response time is out of this world. Fair play to you, give yourself abit of credit! I am sure you here that allot.

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

X-main:
http://www.ebay.co.uk/sch/i.html?_fr...05780A&_sop=15

Y-main:
http://www.ebay.co.uk/sch/i.html?_fr...01737B&_sop=15

You can test the boards; show me pictures of the top and bottom and I will show you how.

As far as free time... I got a lot. I've finished my exams, so am currently sitting at home enjoying pizza.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

mmm, num num, pizza, nice! I want some

I like your thinking, testing boards Added some pics that was in my phone, if they are not enough (2 sections taken of each board, close up) I will take new ones tomorrow when I am there.

Fingers crossed for your exam results

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

I'll need one of the bottom of the board, too.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

I will get you exactly what you need tomorrow matey

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Hi Tom,

Took many pictures this morning, i'll leave you to decide which is the best ones. I hope I took them right

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

I'll require ones of the bottom of the boards; the green side.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Hi Tom,

Got it right this time, I hope. If the front pictures are not good enough, please let me know. I'll take some more.

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Can you remove the grey thermal pads? Keep them to the side though; they're necessary to reinstall the board again.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Done

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

I've highlighted devices on the Y-main for your testing.

To test the three legged FETs/IGBTs: Put your meter on diode mode, and test all six combinations (red-black) (1-2, 2-1, 1-3, 3-1, 2-3, 3-2) Report readings and part# for each.

To test the two legged diodes: Put your meter on diode mode, and test both combinations (red-black) (1-2, 2-1). Report readings and part# for each.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Hi Tom,

Thank you very much for teaching me how to test the transistors. Some of the reading give the beeping short sound. The results are as follows:

Diode Test
A: 280 457
B: .016 .016 .017 .017 .002 .002
C: .051 .052 .052 .052 .01 .01
D: .466 .482
E: 1.635 1.100 1.866 1.505 .375 .460
F: .001 .001 .001 .001 .001 .001
G: .448 .278
H: 1.424 .783 1.646 1(no reading) .492 1(no reading)

Part numbers (wasn't sure which was part numbers so I took them all down, very small and hard to read so best to my eye sight) Particularly hard to identify if O or 0 in part numbers So a best guess.
A: AUK, 91517, SF10A400H
B: RJP30E2, 515113
C: RJP30E2, 515113
D: STTHL2R06FP, GKO8D, VU, CHNLL9
E: G, RJP63F3, 1302
F: RJP30E2, 515113
G: AUK, 71518, SF10A400H
H: K10A60D

I done a quick test using the same theory on the X-main, similar results.

Thanks Tom Your a legend!

[tom66]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Yep, that's a dead-un. Several dead shorted FETs on there.

[Vipermarty]

Re: Bush (samsung) - Plasma Sound but no picture, click click

Replacing FET an option? I have the equipment to do it.