Acer Ferrari F-20" monitor display interference and replacement capacitor selection

[ADV]

Good day everybody

I hope I'm posting in the right section - I am new to this awesome forum.

I have received an ACER Ferrari F-20" LCD Monitor to repair.

It produces interference lines on the image displayed and slowly rotates across the whole screen, with respect to the center of the screen. One rotation takes about 4 minutes and the cycle repeats over and over.
For some reason the On Screen Display Menu is not affected when switched on with the Menu button.

I opened the external 18V power supply and see no bulged capacitors or anything suspicious. It uses Rubycon branded caps.
The output voltage measures 18.35V when the monitor is switched on and displaying an image while connected to the VGA port of my laptop.

When I opened the monitor, I immediately noticed that the 3 leaded electrolytic capacitors (C1,C2 and C3) on the top side of the inverter pcb were bulged. The values are 180uF 35V each. Their ESR was high (10R to 20R) and the capacitance not measurable. They are connected directly to the power coming in through connector CN1 at the top of the pcb.

My questions:
1. Is it possible that the faulty capacitors can cause the interference described above?

2. The original capacitors used on the pcb has got the following specs, as found on the datasheet:

Brand: CapXon
Series: GF Series - Low Impedance
Case size: 8mm Diameter X 16mm Length
Impedance: 0.098R @ 100KHz & 20 deg C
Ripple Current: 810mA RMS @ 100KHz & 105 deg C
Dissipation Factor: 0.09 @120Hz
Endurance: 3000 Hours
Temperature Range: -55 to 105 deg C


When searching DigiKey for replacements, the following options are available, limited by the maximum height:

Brand: Wurth
Series: WCAP-ATLI
Part Number: 860080574010
Case size: 8mm Diameter X 16mm Length
Impedance: 0.098R @ 100KHz & 20 deg C
Ripple Current: 810mA RMS @ 100KHz & 105 deg C
Dissipation Factor: 0.09 @120Hz
Endurance: 3000 Hours
Temperature Range: -55 to 105 deg C


Brand: Panasonic
Series: FR-A - Low ESR (Same as FM Series)
Part Number: EEU-FR1V181
Case size: 8mm Diameter X 11.5mm Length
Impedance: 0.056R @ 100KHz & 20 deg C
Ripple Current: 950mA RMS @ 100KHz & 105 deg C
Dissipation Factor: 0.12 @120Hz & 20 deg C
Endurance: 6000 Hours
Temperature Range: -40 to 105 deg C


Brand: United Chemi-Con
Series: KYB - Low impedance, high ripple and long life from KYA series
Part Number: EKYB350ELL181MHB5D
Case size: 8mm Diameter X 11.5mm Length
Impedance: 0.087R @ 100KHz & 20 deg C
Ripple Current: 840mA RMS @ 100KHz & 105 deg C
Dissipation Factor: 0.12 @120Hz & 20 deg C
Endurance: 7000 Hours
Temperature Range: -40 to 105 deg C

The Wurth capacitor is basically a perfect match, compared to the CapXon.
I don't know if Wurth is a good brand; I have never used them. I have read the discussion on this forum about different cap brands - the good and bad ones.

Should I select the Wurth as the exact match, or should I rather choose the Panasonic or United Chemi-con? Their endurance is higher and the impedance/ripple current specs are better.

3. If you do advise me to use one of the latter two, is the fact that their height is much shorter a problem? I have never really understood for example if two caps are identical, but one is half the other one's height, if they are still seen as identical.

I would really appreciate your advice and input.

Thank you very much.

[Per Hansson]

Re: Acer Ferrari F-20" monitor display interference and replacement capacitor selecti

I would use the Wurth capacitor in this case, they do have a good price/performance ratio and I have not read anything bad about them yet...

That said if price is no concern then the United Chemi-Con KYB is a better choice.

[ADV]

Re: Acer Ferrari F-20" monitor display interference and replacement capacitor selecti

Hi Per Hansson

Thank you very much for your input and advice.

[ADV]

Re: Acer Ferrari F-20" monitor display interference and replacement capacitor selecti

Good day everybody

I really need your advice please.
I didn't get any replies the first time regarding this problem; so I am trying again.

I have received an ACER Ferrari F-20" LCD Monitor to repair.

It produces interference lines on the image displayed and slowly rotates across the whole screen, with respect to the center of the screen. One rotation takes about 4 minutes and the cycle repeats over and over.
For some reason the On Screen Display Menu is not affected when switched on with the Menu button. Please see attached RAR file for a short video, showing the problem.

I opened the external 18V power supply and see no bulged capacitors or anything suspicious. It uses Rubycon branded caps.
The output voltage measures 18.35V when the monitor is switched on and displaying an image while connected to the VGA port of my laptop.

When I opened the monitor, I immediately noticed that the 3 leaded electrolytic capacitors (C1,C2 and C3) on the top side of the inverter pcb were bulged. The values are 180uF 35V each. Their ESR was high (10R to 20R) and the capacitance not measurable. I replaced them with new ones but the interference is still there.

Using the ACER AL2032W service manual schematics, I measured the voltages of all the dc-dc converters and linear regulators on the main board. They are all stable and read a bit over. Please see attached photo of the main board. I also attached a thermal image of it while it has been running for a couple of minutes. All the capacitors seem to run quite cool.

Does anyone have any advice on what could cause this interference and where to look for the fault?

I would sincerely appreciate your input.

Thank you very much.

[ADV]

Re: Acer Ferrari F-20" monitor display interference and replacement capacitor selecti

Thanks everyone. I will continue to try and find the fault

[ADV]

Re: Acer Ferrari F-20" monitor display interference and replacement capacitor selecti

Good day friends

I have replaced the 3 bulged electrolytic capacitors on the inverter pcb and the interference is still there.

So I decided to have a look at the main pcb. I attached the schematics - 'ACER AL2032W Main PCB Schematics.pdf'. It is not that great, especially the last page on the power supply section. Actually disappointing quality for a service manual.
All the electrolytic caps look in good condition - none are bulged.
The brand is Teapo and they are all SS series, 105 deg C and 1000 hours. I have attached a datasheet - 'Teapo SS Series Caps.pdf'.
They only use 3 values on the board: 22uF 25V 5x7mm (quantity:20), 100uF 25V 6x7mm(quantity: 9), 330uF 16V 8x9mm(quantity:5).

I measured all the electrolytic caps' ESR/Capacitance in-circuit with my Peak Atlas ESR70 meter. For the capacitance values, all the capacitors showed 'In-circuit/Leaky'. For the ESR values, I measured 0.06R to much higher.

Normally the meter gives a capacitance value when measuring in-circuit; so I was sceptical. I decided to remove C9(330uF 16V). With the big ground planes, it was quite difficult to do. I measured it again with the meter and for the capacitance value it still showed 'In-ciruit/Leaky' and for the ESR value it showed 28.8R. I measured the capacitance with my Fluke 87V multimeter and it showed 'OL'.
When I measured the pads on the pcb where the part was soldered, it showed an ESR value of 0.06R. So my conclusion is that measuring ESR values in-circuit can't be trusted.

As none of the caps in-circuit showed a capacitance value with the meter, I wonder if all of them might be faulty and if the best option would be to replace all of them. They are all the same series, age and in the same environment. Hopefully it will solve the display interference problem. The customer said that the monitor would also switch off at random times when used. Hopefully it will solve this problem as well.

Using DigiKey and RS Components, I tried to find replacement caps. The absolute maximum seated height must be 10mm or less, limited by the metal cover over the pcb. I could only find the 22uF in the correct Size. Please see attached 'DigiKey 22uF 25V Dia 5mm.jpg' for the 3 options. The highest value for 100uF I could find was 47uF and for 330uF the highest was 220uF.
I don't know for the 100uF and 330uF, If I should consider buying bigger/taller ones and lying them on their sides? Please see attached 'Example some caps lying on their side.jpg'.

The Teapo SS series looks to me like general purpose caps. They use them with the 3 low dropout regulators and other places. They even use them on the 2 dc-dc converter outputs, which I think runs close to 100kHz, based on the 120pF timing capacitor used. I would have thought that low ESR caps would have been the correct choice.

Please see attached semiconductor datasheets: 'AIC1563_AnalogIntergrationsCorporation.pdf', 'AIC1084.pdf' and 'AIC1117.pdf'.


I want to ask the following advice please, as I don't feel that comfortable with selecting capacitors for replacement - I need more experience:
1. For the 22uF, do you think that one of the 3 options in the attachment will be suitable?
2. For the 100uF and 330uF, what would you suggest with regards to the selection/soldering/placement/gluing down?
3. What specific DigiKey capacitor part numbers would you suggest for the dc-dc converters' input and output capacitors?
4. What specific DigiKey capacitor part numbers would you suggest for the 2 low dropout regulators' input and output capacitors? I understand that they can be sensitive to ESR values.

I would sincerely appreciate your input and I am always eager to learn.

Thank you very much.

[ADV]

Re: Acer Ferrari F-20" monitor display interference and replacement capacitor selecti

Any advice, anyone?