Bush BPDP42HD2 Ysus kills Xsus

[satinser]

Original fault was 3 clicks on start up and back to standby. Found that one of ics on y buffer board had gone short circuit on 3 pins but no physical damage. Also xsus had blown 2 fets. Replaced the 2fets and tried again without buffer board which is on order and fets blew again. Now tried anaother xsus board which I had available and the 2 fets have now blown on that one too.
Tested the ve voltage from ysus and found voltage is not stable and goes as high as 100v when it should be 55v so thats the cause of killing of xsus.
Anybody any experience of this fault. Perhaps CRT MAN?

[flocko]

Re: Bush BPDP42HD2 Ysus kills Xsus

Sorry to say but all three X sus,Ysus Y buffer to be safe need to be changed as a set you will go round in circles otherwise, look up posts for BPDP42HD3 and PS42C450 same sets Flocko

[tom66]

Re: Bush BPDP42HD2 Ysus kills Xsus

Ve is supposed to be about 100V you are probably confusing it with Va.

[satinser]

Re: Bush BPDP42HD2 Ysus kills Xsus

Thanks for both your replies. Have read your previous post (Flocko) regarding problems that you had with HD3 version of above TV. It would seem that the Ysus board is also faulty(even though fets test as ok)I originally believed it to be just the buffer and xsus. From similarity s with problems you experienced with your HD3 repair I will source a ysus board and once again replace the failed fets on xsus board. Will let you know how I get on. I just hope I dont have problems trying to source boards that dont themselves have faults. I have found great difficulty lately to get used buffer boards that dont have ics shorted even though there listed as ok!

[flocko]

Re: Bush BPDP42HD2 Ysus kills Xsus

I have not seen or heard that anyone has had any luck repairing these boards, but please let us all know how it goes,on the Y buffers if fitted(there are two types) with the blue caps in the center and check the glue as this sometimes shorts Flocko

[satinser]

Re: Bush BPDP42HD2 Ysus kills Xsus

Yes will keep you informed. As regards to your comments regarding the repair of these boards are you referring to the xsus board? Received another ybuffer board today from another Ebay seller claiming item tested and working and once again tested shorted on 1 of the ics!
As regards the Ybuffer for this model can anybody confirm that the LJ41-08594a which is fitted to the PS42C450B1W would be compatible. As the one fitted has the is LJ41-09470A but shares the same LJ92 number (01739a).

[tw2005]

Re: Bush BPDP42HD2 Ysus kills Xsus

Yes will keep you informed. As regards to your comments regarding the repair of these boards are you referring to the xsus board? Received another ybuffer board today from another Ebay seller claiming item tested and working and once again tested shorted on 1 of the ics!
As regards the Ybuffer for this model can anybody confirm that the LJ41-08594a which is fitted to the PS42C450B1W would be compatible. As the one fitted has the is LJ41-09470A but shares the same LJ92 number (01739a).

LJ92-01739 Rev A - D will all work (board assembly number)

LJ41-08594A & LJ41-09470A are PCB numbers so in other words the blank board.

If you have a look at each you will notice the subtle differences e.g. the 2 large polyester caps now used in place of the SMD caps. The PCB has been modified for the through hole fitment hence the different number.

[Alastair E]

Re: Bush BPDP42HD2 Ysus kills Xsus

A faulty buffer-board with the 42C450 can damage a Y-SUS on these sets, they say a faulty Z-SUS will also....
They recommend that all three are replaced--as a kit, problem for us lot is finding three known working boards--from different sources/sets!

I have a number of boards from these sets, only one 'kit' that I know is good out of say, 4 sets of boards, that I'm hanging on to....

[flocko]

Re: Bush BPDP42HD2 Ysus kills Xsus

As i have said before if you want to be safe change all three boards as a set, the part number that you need to match are the LJ92-xxxx on all boards, these are also fitted in the PS42Cxxx,Bush BPDP42HD2 and 3 and some philips sets, i cannot work out why there are so many bad boards out there, all the cracked screen PS42C i have parted out have all ways had good boards or have i just been lucky Flocko

[crt man]

Re: Bush BPDP42HD2 Ysus kills Xsus

Original fault was 3 clicks on start up and back to standby. Found that one of ics on y buffer board had gone short circuit on 3 pins but no physical damage. Also xsus had blown 2 fets. Replaced the 2fets and tried again without buffer board which is on order and fets blew again. Now tried anaother xsus board which I had available and the 2 fets have now blown on that one too.
Tested the ve voltage from ysus and found voltage is not stable and goes as high as 100v when it should be 55v so thats the cause of killing of xsus.
Anybody any experience of this fault. Perhaps CRT MAN?

Hi,
Of the six I have done I have found no fault on the Ysus, only Ybuffer
which has shorted the Xsus FETS.
Personally I would not recommend running the set with any boards disconnected
I did it with one, and shorted the LVDS board I have found if the buffer
has one short then that only will be faulty, but it has three or more then it is likely to short the FETS on the Xsus

HTH
Alan.

[satinser]

Re: Bush BPDP42HD2 Ysus kills Xsus

Appreciate your comments Allan but could you explain why running the ysus without buffer board attached still blew the fets on xsus board?

[crt man]

Re: Bush BPDP42HD2 Ysus kills Xsus

Hi

I think it is overloading the Xsus board, with one side of the screen connected and the other not.

If I pluck up the courage in the next couple of days then
I will disconnect the Y buffer from my test set,
and see if the the two FETS short on my board.

Alan.

[satinser]

Re: Bush BPDP42HD2 Ysus kills Xsus

Thank you for that Alan! It would inspire me with more confidence to try the Xsus board that I have again replaced the 2 fets on when I finally manage to obtain an ybuffer board that hasnt got shorted ics!!
I once again received a ybuffer yesterday which again I was assured by the seller that all boards are tested prior dispatch which had 1 shorted ic.
I have ordered another such board today, trouble is my confidence levels of receiving a good board are at an all time low. Consequently, when it takes so long to obtain parts protracting the repair time you begin to lose face with the customer.
As a matter of interest have you ever had to replace any other components on blown xsus boards other than the 2 fets?

[tom66]

Re: Bush BPDP42HD2 Ysus kills Xsus

If you find IGBTs to be blowing constantly, I would replace the driver IC which drives them.

The fact that a Y-buffer can kill the X-main or vice versa is very odd, and hard to believe; there is no electrical connection between them inside the panel.

Something else might be going wrong like a faulty control board or maybe it doesn't handle bad X-main properly.

[tw2005]

Re: Bush BPDP42HD2 Ysus kills Xsus

Thank you for that Alan! It would inspire me with more confidence to try the Xsus board that I have again replaced the 2 fets on when I finally manage to obtain an ybuffer board that hasnt got shorted ics!!
I once again received a ybuffer yesterday which again I was assured by the seller that all boards are tested prior dispatch which had 1 shorted ic.
I have ordered another such board today, trouble is my confidence levels of receiving a good board are at an all time low. Consequently, when it takes so long to obtain parts protracting the repair time you begin to lose face with the customer.
As a matter of interest have you ever had to replace any other components on blown xsus boards other than the 2 fets?

I tried this on a C450 and replacing just the 2 IGBTs that blew did not work. They blew again and then I also killed my Y

[satinser]

Re: Bush BPDP42HD2 Ysus kills Xsus

In a previous post from crtman it was mentioned that in 3 of the 6 that he had repaired the fets on xsus board had blown. It was also mentioned that the 2 fets were replaced. I would be interested to know whether in those cases replacement of the fets was all that was required to repair those xsus boards. It would appear that with this particular Samsung model the only way to repair it is by using 3 good boards Ysus,Xsus and Ybuffer or you run the risk of blowing the xsus fets again. Diagnostic checks without Ybuffer also apparently runs the risk of blowing fets on xsus as in my case.

[crt man]

Re: Bush BPDP42HD2 Ysus kills Xsus

In a previous post from crtman it was mentioned that in 3 of the 6 that he had repaired the fets on xsus board had blown. It was also mentioned that the 2 fets were replaced. I would be interested to know whether in those cases replacement of the fets was all that was required to repair those xsus boards. It would appear that with this particular Samsung model the only way to repair it is by using 3 good boards Ysus,Xsus and Ybuffer or you run the risk of blowing the xsus fets again. Diagnostic checks without Ybuffer also apparently runs the risk of blowing fets on xsus as in my case.

Hi
In the cases of the blown FETS all I did was replace them,and the board
worked perfectly. The only thing I found was that if the Y buffer had one
short on a IC then only the Y buffer needed replacing, but if there were
more than one short on the IC then the FETS would short.

Alan.

PS I am still working up the courage to disconnect the Y buffer on my test set and see what happens with the FETS.

[satinser]

Re: Bush BPDP42HD2 Ysus kills Xsus

Go on go for it!!

[crt man]

Re: Bush BPDP42HD2 Ysus kills Xsus

Go on go for it!!

Well I did, and the worst thing is I knew what was going to
happen. Disconnecting the Y buffer on the set shorts the
FETS on the Xsus.

So now that is another board to repair

Alan.

[tom66]

Re: Bush BPDP42HD2 Ysus kills Xsus

Wow, that is a surprise. I am guessing that is bad firmware design rather than an electronic problem with the TV. Sorry to hear about your board though!