No Standby voltage 26" Sabre LCT260BKA

[jetadm123]

Re: No Standby voltage 26" Sabre LCT260BKA

Are you taking the measurement across the leads of the cap? If yes, I'm beginning to think there is something wrong with the DC portion of your meter.

[aris21067]

Re: No Standby voltage 26" Sabre LCT260BKA



Yes I tested from the 2 leads on the board (in the red circled area). I also marked the +/- orientation of the cap.


ETA: ive connected the tester via gator clips to a new 9v battery to test for faults.

[selldoor]

Re: No Standby voltage 26" Sabre LCT260BKA

@jetadm123 I wondered that but he has tested a few things with ok results.
I am going to suggest testing for some secondary voltages just to see what results there are and if they are steady of fluctuate - can you tell if this has PFC? if the controller for that was dodgy would it account for the odd results?

[jetadm123]

Re: No Standby voltage 26" Sabre LCT260BKA

@jetadm123 I wondered that but he has tested a few things with ok results.
I am going to suggest testing for some secondary voltages just to see what results there are and if they are steady of fluctuate - can you tell if this has PFC? if the controller for that was dodgy would it account for the odd results?

Yes, good point. Yes, it looks to have PFC and the fluctuating high voltage we're seeing might be the PFC stage trying to start up. Maybe a startup cap?

[selldoor]

Re: No Standby voltage 26" Sabre LCT260BKA

I think we will pass on that for now though you could measure the voltages at the bridge rectifier - near the top of the board there is a 16 leg Ic - IC2 (can you read the part number on that - may need it later) and near that attached to the heatsink is a wide component with a slope on one end board mark may be BD1 . It has 4 legs the inner ones should be AC and may be similar to mains
the outer legs are DC and should be similar to the Big Cap but it may be too difficult for you to get in to measure.

I suggest you try some of the secondary voltages on the connectors.
I cant see any legend on the board as to what you are expecting but will attach a link to a wiring schematic which might have them on
It is for A M666B so may be different?

Meter on DC200 black pin on a ground screw probe each pin and record voltage

https://www.badcaps.net/forum/attach...0&d=1348049359

[aris21067]

Re: No Standby voltage 26" Sabre LCT260BKA

Yes, good point. Yes, it looks to have PFC and the fluctuating high voltage we're seeing might be the PFC stage trying to start up. Maybe a startup cap?

the only cap I havent replaced was the 50v/10uF located just to the left of the line in connector. So far Ive had the tester connected to the 9v battery for 10 mins. and it hasn't budged, so it seems like the tester is working fine.

let me know which cap you want me to replace and I will.

[jetadm123]

Re: No Standby voltage 26" Sabre LCT260BKA

Suggest you follow selldoor's idea and measure the voltages at the connectors.

[aris21067]

Re: No Standby voltage 26" Sabre LCT260BKA

Suggest you follow selldoor's idea and measure the voltages at the connectors.

you mean the ribbon connectors on the right side of the board?

[jetadm123]

Re: No Standby voltage 26" Sabre LCT260BKA

Yes.

[selldoor]

Re: No Standby voltage 26" Sabre LCT260BKA

If you only have one cap that you have not replaced then I would replace it.
Are you using good quality caps panasonic , nichicon, rubycon etc? - They get cooked in these boards so need to be good and 105 degree ones.
That IC is a MC0628R cant find a data sheet it may be a proprietory item

[aris21067]

Re: No Standby voltage 26" Sabre LCT260BKA

I tested all the pins and the results are in the pic attached. All Pins were fluctuating except 1.

[aris21067]

Re: No Standby voltage 26" Sabre LCT260BKA

If you only have one cap that you have not replaced then I would replace it.
Are you using good quality caps panasonic , nichicon, rubycon etc? - They get cooked in these boards so need to be good and 105 degree ones.
That IC is a MC0628R cant find a data sheet it may be a proprietory item

All the caps I used are 105C but there is a mixture of caps, some are also pulls.
Here are the Ebay links to the new caps I used:
http://www.ebay.com/itm/271114835322...84.m1439.l2649

http://www.ebay.com/itm/320878792258...84.m1439.l2649
(I hope these link right)

[jetadm123]

Re: No Standby voltage 26" Sabre LCT260BKA

If you press the on/off button, does that have any affect on the voltages at the connectors?

[aris21067]

Re: No Standby voltage 26" Sabre LCT260BKA

Ill test that now

ETA: the pin that seems effected by hooking up the ribbon cables and power on is the pin that had the steady 4v reading. It now fluctuates between 1v to 2v. Also the 4 pins on the top connector now shows 13-20 volts with the ribbons wires connected.

[selldoor]

Re: No Standby voltage 26" Sabre LCT260BKA

All the caps I used are 105C but there is a mixture of caps, some are also pulls.
Here are the Ebay links to the new caps I used:
http://www.ebay.com/itm/271114835322...84.m1439.l2649

http://www.ebay.com/itm/320878792258...84.m1439.l2649
(I hope these link right)

I suspect you have wasted your money on these neither are named manufacturers please tell me the first lot are not Chang caps.

This is some advice from retiredcaps regarding caps
We only rarely advise buying caps on ebay there are many fakes and half truths. There are one or two exceptions and generally only advised when no other sources are available in the members country.

https://www.badcaps.net/forum/showpo...84&postcount=3

[aris21067]

Re: No Standby voltage 26" Sabre LCT260BKA

I suspect you have wasted your money on these neither are named manufacturers please tell me the first lot are not Chang caps.

This is some advice from retiredcaps regarding caps
We only rarely advise buying caps on ebay there are many fakes and half truths. There are one or two exceptions and generally only advised when no other sources are available in the members country.

https://www.badcaps.net/forum/showpo...84&postcount=3

Thank you for the information and links. yes the caps in the first link are Cheng brand, I take it that they are garbage then and maybe my whole problem could be the new caps i got from ebay?

[jetadm123]

Re: No Standby voltage 26" Sabre LCT260BKA

The fact that you're using the wrong type caps and pulls off another board only adds another layer to the list of potential problems. It also wouldn't hurt to check for solder bridges and for caps installed backwards.

What I was looking for earlier was the 5V Standby voltage, which I'm guessing is the 4V you're seeing.

[aris21067]

Re: No Standby voltage 26" Sabre LCT260BKA

kk I used a strong magnifying glass to check all solder points for gaps and bridges, all good there. When I installed the caps, i made note of the orientation of the negative side stripe for the caps.
Anyone have any suggestions on a good place to get caps thats very easy on the wallet? The reason I ask is because atm im unemployed so money is very hard to come by, hence why buying caps from ebay and using pulled caps. Any advice is more than welcome.
Thank you guys again so much for the education and help youve given so far.

[tom66]

Re: No Standby voltage 26" Sabre LCT260BKA

Digikey is a good source. $3 shipping, 30-80 cent each cap, Panasonic FC/FM/FR excellent caps.

[ben7]

Re: No Standby voltage 26" Sabre LCT260BKA

You know, there is no point in fixing this, since you cut apart/destroyed the heatsinks!