Iiyama E511S blown SMT caps on PSU board

[fergal]

Hi

I have a Iiyama E511S which switches on for a fraction of a second and during that time the picture looks ok. All the electrolytics on the PSU board look ok, but on the underside there are a couple of blown SMT caps (see picture). These caps are so burnt so I can't see what value they were.

Any ideas of what value these are likely to be? If it helps, the 8 pin chip next to the caps is an APM9435 P-Channel Enhancement Mode MOSFET. I've looked for a reference circuit which uses this chip but had no luck so far.

Thanks

Fergal

[fergal]

Re: Iiyama E511S blown SMT caps on PSU board

As I don't know much about SMT, I've been reading up and here's a bit more info.

It looks like the caps are in a 1206 package and one side is connected to ground so maybe they're doing some decoupling? Would 0.1uF or 1uF be a reasonable value to try as a replacement?

Thanks

Fergal

[gonzo0815]

Re: Iiyama E511S blown SMT caps on PSU board

Yup, 0,1Uf -1uf should be sufficient, depending on the purpose the capacitor was placed there.
But probably there is more bad then simply the MLCC`s.

[Krankshaft]

Re: Iiyama E511S blown SMT caps on PSU board

Are you sure that they are caps?

They could be protection diodes for the FETs.

One of my monitors with those SMT switching FETs had diodes in close proximity like that too.

[fergal]

Re: Iiyama E511S blown SMT caps on PSU board

Yes, they're definitely caps. They're still recognisable as such plus they have C7 and C28 printed next to them on the PCB.

I realise there might be other problems, but as I got this monitor for free I thought it's worth a try.

Thanks

Fergal

[tjmatt]

Re: Iiyama E511S blown SMT caps on PSU board

Hi,

I have a monitor with exactly the same problem. Where you able to solve it by replacing just the cap? Mine has only blown C28 but has also broken the track where it blew.

Cheers,

Matt

[Wizard]

Re: Iiyama E511S blown SMT caps on PSU board

When this happens, this means your other capacitors (electrolytics) are going too, putting too much noise into power plane, eventually that 2 high capacity ceramic caps fry.

Cheers, Wizard

[JEWilson]

Re: Iiyama E511S blown SMT caps on PSU board

I repaired one of these today. Different sympton
The display was rendering artefacts such as shadowing and random lines.

I opened the VDU up and found the PSU board to be in good condition
Notwithstanding the UCC KY O/P filter caps, the remainder were all
Elite, various series and values.

The ESR was good on all of these caps but I have noticed this
VDU gets hot. Puts out more heat than my HP1130 CRT!

Anyway, I replaced these with Pana FCs and found furthermore, one
of the caps on the logic pcb beginning to dome. There were two others,
three in total 16V 470uF - Elite GPs 85 deg C right beside the power
stage on the logic pcb. Why oh Why? These are getting fried (possibly).

Suffice to say, these were summarily replaced with Pana FMs and I
further replaced the remaining two lytics worth a mention on the logic pcb.

These again were Elites, 16V 330uF - again replaced with Pana FMs.

The remainder of the lytics are all 25V 47uF bypass caps for the
ICs and such like.
Guess I was lucky and got to this VDU prior to major issues.

Anyway, I'm using it presently and no problems thus far.

[WojtasJD]

Re: Iiyama E511S blown SMT caps on PSU board

Hello,
the blown decoupling caps near APM9435 are 1uF, maybe 50V MLCC with Y5V dielectric (I'm not sure). You may put here 1206 1uF 50V X7R

Does anybody know what two THT caps are on the other side of the pcb near two small fuses ?
I think they are 220uF / 35V - is that correct ?

[FIXITNOW]

Re: Iiyama E511S blown SMT caps on PSU board

had one of these
These caps were so burnt C7 and C28 0.1uF 50v 1206 sm check case broken the track . plus replace all electrolitics in psu if ESR measures 16V 470uF etc

[wreeve]

Re: Iiyama E511S blown SMT caps on PSU board

I have two E511S monitors side by side! One was showing the switch on problem (back-light not working) the other the artefacts / noise on the screen. Fixed one by replacing the two SMT capacitors on the PSU board (they looked OK but now replaced monitor works fine). Fixed the noise on the other monitor by replacing all the caps around the PSU area on the micro-board, again they looked OK but replacing them fixed the problem! Thanks guys.

[Greeno]

Re: Iiyama E511S blown SMT caps on PSU board

I also have a faulty E511S - it has the same obviously overheated surface-mount capacitors on the underside of the board and I found a faulty transistor beside them. Capacitors seemed to be OK so I only replaced the transistors.

It worked for a minute then failed again - pulsing on and off. The replaced transistors appear to be OK so I fear I may have pushed the fault elsewhere.

There are two suggestions above for the value of the capacitors: WojtasJD says 1uF, FIXITNOW says 0.1uF.

Can anyone say definitively which it should be?

Thanks.

[bouncingboffin]

Re: Iiyama E511S blown SMT caps on PSU board

I have just encountered the same problem on the exhibit I run at a computer museum. I couldn't find instructions on how to disassemble the monitor, so after a bit of head scratching I worked it out.

I took the monitor apart, usual screws on the back and unclip the case, run a blunt knife, from the centre of each side back and forth and the two halves split, then remove the RF conductive tape, remove the bottom screw and then remove the outer shielding box.

This monitor has burnt up its SMD MLCC and taken a chunk of PCB with it (some more adventurous rework needed!) The problem seems to lie with the ESR of the capacitors increasing as their capacitance is decreasing (age/heat/electrolyte related). I pulled every electrolytic capacitor from the board and measured its ESR and capacitance, just to be 100% sure to avoid parallel capacitance. It seems the small value capacitors (Elite branded) suffered the most in this respect. Their ESR went from 0.05R to as much as 6R with a loss of capacitance of around 20-30%

This photo shows the caps that I am going to replace

This photo shows how only half of this board failed, the ESR value of the 47uF electrolytic was about 1/3 of the failed side.

This is a close-up of the burnt C29 MLCC - it shows typical overheat and arcing damage. Probably worth replacing its counterpart...

Of course, I don't know if this is all that is damaged, I am awaiting components to do this fix. This is the list of capacitances and ESR of the electrolytics on the board, might be of help to someone.

Name	uF	V	uF read	ESR 	Replace?
C134	10	50	8.36	2.62	YES
C133	10	50	8.46	2.44	YES
C4	10	50	8.71	1.47	YES
C35	47	25	41.42	2.92	YES
C34	47	25	32.44	6.28	YES
C27	220	35	237.48	0.05	NO
C2	220	35	241.31	0.04	NO
C144	10	50	11.42	0.62	NO *on daughterboard, may replace
C126	680	35	693.78	0.03	NO
C127	680	35	694.54	0.02	NO
C130	220	35	242.36	0.06	NO
C132	680	16	705.14	0.02	NO
C141	680	16	710.46	0.04	NO
C129	2200	10	2392.33	0.02	NO
C131	330	25	323.19	0.06	NO
C121	10	50	9.24	1.52	YES
C154	100	25	88.82	0.75	YES
C106	47	450	45.54	0.55	NO

[Stefan Payne]

Re: Iiyama E511S blown SMT caps on PSU board

Remove the MLCC Cap and check the traces for resistance...

Sometimes when those things go, they make everything close to it conductive...

[printerman]

Re: Iiyama E511S blown SMT caps on PSU board

Hi

I also have an E511S I think the problem started with one of the 3 high voltages caps at the end of the inverter arcing through the insulation under the board also 2 of the 2sc5103 transistors failed. and 1 of the 3A fuses had failed.

I have changed all 3 of the high voltage caps, the 2 2sc5103 but still have no inverter, what seems to be missing is the high voltage driving the transistors, not sure what value this should be as I do not have a manual so I do not even know where the voltage comes from.

Would anyone have a circuit diagram of the PSU showing the area in question and saying what the voltage should be.

I have also carried the suggested repair the the wiring of the caps by bending over of the wires to these caps and then resoldering.

Any suggestions would be appreciated