What might of caused these main caps to bulge so badly?

[Dang]

As you can see from the photo they are much domed and as I result I believe this is why I have no VE, I've noticed by CN8002 that Diode D8044 has a resistance reading of about 3 ohms in both directions, I don't believe this to be normal as surely it should go off the scale one way and give a reading somewhere near 400 or so the other?

[tom66]

Re: What might of caused these main caps to bulge so badly?

Can you push the plastic dome down?

[Dang]

Re: What might of caused these main caps to bulge so badly?

Hi Tom66, yes, there's certainly air space there and I've looked on Ebay for a reference as to how they should look, all were flat as you would expect.

[tom66]

Re: What might of caused these main caps to bulge so badly?

Try cutting the disc or pulling it off and seeing if the actual capacitor is bulged underneath. It is sometimes common for the disc to bulge upwards as a result of heat build up in these TVs. Doesn't mean it's bad.

[Dang]

Re: What might of caused these main caps to bulge so badly?

Hi again, removed the domed plastic caps and indeed you are right, the cap heads are perfectly flat so I guess these are fine, which still leaves the question, why no VE? is that diode faulty?

I should explain that when the Tv is first turned on 3 green LEDs on the PSU light up after both relays have clicked on, there is also a green light that comes on on the logic board, within about 5 seconds these relays click off with 2 of the 3 greens lights going out and the logic board light turning red, I believe this gives an error code but not sure what it is, this is to come next...

[selldoor]

Re: What might of caused these main caps to bulge so badly?

Make and model might help?

[Dang]

Re: What might of caused these main caps to bulge so badly?

It's a no brand plasma with Samsung parts, a Firstline FS4211HI, quite old I think, only paid a fiver for it so thought it worth a shot.

Seems this is by Hisense which I believe is a name started by Ebuyer.

[tom66]

Re: What might of caused these main caps to bulge so badly?

Loss of Ve would not cause no image. It would cause pink/maldischarged/grey image. Is that what you see?
Some of these power boards have Ve pin, but it's not electrically connected.
Could also be shorted Ve on X-main.

[Dang]

Re: What might of caused these main caps to bulge so badly?

Loss of Ve would not cause no image. It would cause pink/maldischarged/grey image. Is that what you see?
Some of these power boards have Ve pin, but it's not electrically connected.
Could also be shorted Ve on X-main.

OK, I've tried tracing VE from the connector back to it's roots, as far as I can tell it disappears under the two main caps described above, where it goes from there I don't know. I don't see any picture but a momentary select flash of sparkles when it decides to turn off, I can see other flashes from time to time but it doesn't last long, just a few seconds.

I have disconnected all the obvious boards, one at a time, so the X-sus, the Y-sus and also the Z-sus, I've even had both the Y-sus and X-sus off at the same time, the power supply acted the same way with LED8001/LED8002 (LED8003 always stays on) extinguishing and LED8004 turning on red so I don't think any of these boards are at fault.

Can I go back to this diode, can I assume by a lack of response to this idea that all is perfectly normal?

[tom66]

Re: What might of caused these main caps to bulge so badly?

The diode might be bad. May be worth removing it from circuit and testing it out of the board.

[Agent24]

Re: What might of caused these main caps to bulge so badly?

I see that diode looks a bit browned... could just be dirt on it though.

[Dang]

Re: What might of caused these main caps to bulge so badly?

Hi again, OK, so after some research it seems the VE area of the board(pictured) is at fault, firstly the diode looks like it's blown short, the main capacitors are also suspect with one most definitely short across both it's terminals in either direction(C8071), it's the one right besides the aforementioned diode. Now all three of these I shall be replacing but not too sure what rating diode to use as a replacement and will two 250v, 150uf caps be OK to the replace the 250v, 100uf caps already present?

Thanks.

Just to add: It would seem a possibility that this shorted cap might be responsible for the two main caps bulging as it seems that VE originates from there, any ideas?

[tom66]

Re: What might of caused these main caps to bulge so badly?

Again, the bulging of the disc is a normal thing for some capacitors to do - it does not mean the capacitor is bad.

Cannot say for sure if increasing the capacitance will upset the circuit, best to use the correct values.

Please verify if you get Ve fault symptoms (dim/pink image) or something else?

[Dang]

Re: What might of caused these main caps to bulge so badly?

Basically this is how it reacts, I took this information from a Polish website:

1) disconnect SSB; * in addition to which the tape drive. + 5V ssb goes for the control and returns to the power supply,

2) turn on the jumper J8003, J8004, BJ8902,

3) turn on the plasma should light 8001, 8002, BJ8902; * if you do not light the UPS entirely to exchange,

4) for a few sec drive should appear in August, given above,

5) then leds 8001, 8002 extinguish,

6) LED should blink.

1x - V_A OVP, UVP
2x- 12V OVP, UVP
3x - V_SCAN OVP, UVP
4x - D3V3 OVP, UVP
5x - V_S OVP, UVP
6x - V_G OVP, UVP
7x - V_SET OVP, UVP
8x - V_E OVP, UVP
9x - Over-temperature (> 105 ° C)
10x - PFC_OK UVP (> 330 V)
11x - 5V2 OVP or Active DC_PROT
13 x- D5VL OVP, UVP

A little sketchy I know, I haven't done the jumper thing but mine turns on as soon as the plug is attached, I don't see any [main] power switch.

The Tv never properly turns on or holds stable, it just cycles the same way every time it try's to. I've tested most if not all other voltages while it's starting and all seem to reach their stated values, so Vscan, VA, VS etc just no VE. As stated above there's a definite short in the VE area and the cap and diode seem to be the problem, I can't find any other problematic components so these will have to be my first port of call.

[Dang]

Re: What might of caused these main caps to bulge so badly?

So I've removed both caps and the diode, not really that surprised to see both caps measuring seemingly OK(DMM goes of the scale in diode mode), the diode on the other hand still measures bad, it's this one here: http://www.datasheetcatalog.com/data...BYV26EGP.shtml.

[Dang]

Re: What might of caused these main caps to bulge so badly?

I also have this one, are they interchangeable?

https://cdn.badcaps-static.com/pdfs/...d9225d077f.pdf

[tom66]

Re: What might of caused these main caps to bulge so badly?

If yours is RGP15M type yes.

[selldoor]

Re: What might of caused these main caps to bulge so badly?

I am just answering this in case you are tempted to try it before Tom gets back:
Iwouldnt have thought so if you have the 15A version looks to be only 50v where the one you need looks to be 800-1000v peak reverse.

EDIT
Too little too late

[Dang]

Re: What might of caused these main caps to bulge so badly?

Thank you, yes, it's the RGP15M. OK, so here goes, be back soon and fingers crossed.

[Dang]

Re: What might of caused these main caps to bulge so badly?

Success, a simple change of the diode and all is working, for now, it's been about 20 minutes so early days but looks good, stable picture too.