LCD Monitor problem

The display generated internally is just fine. Only the externally input display tears. So it can't be "every single cap." I imagine it is something in the sync input. I'll be checking it out. And like I said, it is a "saved" monitor. If a quick fix won't do it, back to the dump.

Al

Al

Sure it could, may only be one or two that are bad enough to cause a malfunction, but it's worth checking the rest. Usually when one of these surface mount capacitors is bad, the rest are nearly shot too. I usually replace them all, then the thing is good for years. In a pinch, one can check the ESR of all of them and replace those that check bad. There's usually only a dozen or so.

Agreed, but be aware that the ESR values of surface mount electros tends to be somewhat higher than those of a similar value in 'conventional' leaded format, so a cap that you are expecting to read say 1 ohm, may correctly read several ohms in surface mount.

Arfa

I'd be interested to know what makes you so sure that the caps you bought for replacement are of superior longevity compared to those the manufacturer did put in :-).

Regards, H.

Well, I guess by now that is over, but in the past, the market was flooded with bad electrolytes. Some manufacturer copied a formula from another manufacturer, but it contained a deliberate mistake to foul anyone who might want to steal it. The result was that a lot of electronic equipment contained these bad caps. Mainboard from around 2000 are very suspect for example. The most likely cause form any mainboard from that period which has become unstable, is the caps.

But the problem wasn't limited to computers. Even airplane electronics contained them...

It's not unusual for bad caps to only affect the video from the computer, leaving the OSD looking fine. Andy Cuffe

snipped-for-privacy@gmail.com

Well for starters they don't have several years of use on them. All else being equal, they're probably not. I hate surface mount lytics.

I replace them with regular through hole caps. It usually works without any problems. Just bend over the leads and solder them to the lands on the board. The biggest reason I do this is I can`t get smd stuff locally but can get almost any value through hole cap.

Mike

That's interesting. On some Sony servo boards fitted to many of their CD players a few years back, there were three sm electros along one edge of the board, which used to go faulty, and occasionally leak. This gave the symptom of either totally refusing to play, or very poor playability. If you tried to sub regular electros for them, the board would never work again, even if it worked, allbeit poorly, before. However, fit the correct sm types, and it would immediately work again to full original spec.

Arfa

Sony has a history of building things which are very particular about the components used. I've had issues with some of the TVs not working with subs that were fine in everything else.

Well I haven`t worked on nearly as much equipment as you have so, I`m sure that there are plenty of things that you know that I dont. ;-) I am just a novice and just mess around with stuff of mine that breaks or stuff I get for free.

Mike

Well, if ever you get one of those Sony players - and there was lots of 'em that used variations of the same board, mounted directly to the underside of the deck - if it 'feels' like you've got a bad laser, look to see if it's got those three caps along the edge of the board. If it has, you better start looking for a supplier ... !! I never have figured out why 'standard' electros won't work in that position. Like you, I have subbed leaded for sm's in other places, without problem. About the only difference that I've found is that the leaded types tend to have a lower ESR than the sm's, which under normal circumstances, you'd say was a good thing.

Arfa

Doesn't it have to do with higher stray inductance (more inductance, less high-frequency shunt capability)? SMD parts are usually the only usable kind of part in sensitive equipment, like PWM amplifiers.

That's certainly a possibility. The servo data strippers and loops, are quite sensitive bits of circuitry in CD players, and these caps are glued straight on the end of pins on the servo processor chip, so they may well be decouplers or timing caps.

Arfa

I would hope that all timing is done with a clock pulse, based on a crystal. Caps used for timings yield very unstable circuits, at least where high frequencies are concerned, such as FM transmitters.

Yes, but this is not an FM transmitter ... The servo processor chips used in CD players are a hybrid mix of digital and analogue circuitry. There are analogue servo loops to control focus, tracking, disc rotational speed and laser output power, as well as accurately defined reference voltages for such things as the data slicer, and temperature tracking and compensation. In common with most hybrid loops, although they may be controlled digitally, with a clock derived from a crystal source as you surmise (and hope!), they will still have analogue filtering in the loop feedback, formed from C and R. If the time constant of these is not correct within a relatively small range - as may be the case if the filter capacitor is no longer to spec - then failure of the servo loop to lock reliably, is the likely outcome.

Arfa