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Hyundai HPT-4240 - Dodgy looking caps a cause for concern?

 
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g0rak



Joined: 19 Mar 2008
Posts: 6
Location: Brighton, England

PostPosted: Thu Mar 20, 2008 1:37 am    Post subject: Hyundai HPT-4240 - Dodgy looking caps a cause for concern? Reply with quote

Hi everyone,

I think I know the answer to this, and it’s an easy one, so here goes.

I acquired a Hyundai HPT-4240 Plasma TV from an insurance write-off when the classic black strips occurred, and I fixed these previously with no problems. However, I now have the other popular problem with this set, bad 1uF caps on the PSU (DGK-420w) causing it to fail. I should be obtaining replacement caps for the PSU and will replace these tomorrow.

However - in the process of inspecting the TV for problems I noticed some large capacitors had swelled up on another circuit board to the left of the PSU board. I believe this board powers the plasma rather than being part of the PSU itself, as it has ribbon cables running directly into the panel.

The caps that have failed don’t like the usual low-ESR caps that normally go – but are large power caps. They are noticeable in particular as there are a pair of identical caps on a sub-board of this one that are not swelled at all.

Should I replace these caps as well?? I’m wondering that a fault with the caps on this board may have stressed the PSU and caused the initial components to fail. Ive included photos of the good caps and the bad below – any comments much appreciated… Thanks!

FYI the details of these power caps: Samwha 250wv / 680uF HK 105°C (M)
Plasma power board (with the swelling caps): 42V5_YSUS
Plasma power sub-board (with the good caps): 42V5_Z

(P.S. for info on the PSU problem please see the forum page http://forum.eserviceinfo.com/viewtopic.php?t=22005&highlight=dgk420w )

Bad caps pic 1


Bad caps pic 2 (side view)

larger image

The good caps (for comparison)


[/img][/b]
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Thu Mar 20, 2008 4:34 am    Post subject: Reply with quote

Good observation but more than likely those caps are ok:

While there can certainly be the top body bulging, Those are actually round plastic covers that tend to bow out & give the appearance of a bulged cap. To be 100% sure, try pushing down on center & you'll notice it is not that actual case---just a plastic cover that has bowed
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g0rak



Joined: 19 Mar 2008
Posts: 6
Location: Brighton, England

PostPosted: Thu Mar 20, 2008 7:55 pm    Post subject: Reply with quote

Thanks for your reply vtech.

I have to say you have to press relatively hard on the top of the capacitor for the plastic to push inwards, but this could be thick plastic. The other cap with the rippled top moves even less, if at all when pushed.

Both of the caps in question are directly above a large heat sink and the area is relatively enclosed. This could be from heat as they are pretty near to the heat sink compared to other capacitors of their design. There is no sign of burning thankfully.

I think I'll carry on with these as they are for now. I'll replace the PSU caps that are definitely damaged and see how it goes. After all it was a free plasma so I can't complain if it dies!

FYI: To compare, there is another larger power cap on a different board that is a little bulged, and I can press the top of this one with much greater ease so know this one is definitely fine. It is the same brand, but a bit smaller so its top may be made of a thinner plastic top and thus easier to press.

Any more comments welcome! ......
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Fri Mar 21, 2008 7:19 pm    Post subject: Reply with quote

Ok, if you want to be absolutely sure of the condition, you can go ahead and remove the plastic caps as it will not cause any problem whatsoever.

They are nothing but a thin round plastic cap that is tucked under the black plastic cover. Get a razor blade & cut a small slit on the top lip & you can easily remove them & examine the exposed metal body if in doubt?

As a matter of fact I have seen some that literally pop out & fall in the set after a while.
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g0rak



Joined: 19 Mar 2008
Posts: 6
Location: Brighton, England

PostPosted: Sun Mar 23, 2008 1:47 am    Post subject: Reply with quote

To be honest you've put my mind at rest; I'll leave them for now!

Thanks very much for the info.

Si
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PostPosted: Wed Nov 11, 2009 8:15 pm    Post subject: Reply with quote

can the dlp psu be used on this model?
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