Diagnosing what's wrong with an old Soyo Topaz

[Yuriman]

I inherited a Soyo Topaz a while back which was shutting off or turning yellow intermittently, and fixed it by taking it apart, inspecting everything and not being able to see any visible problems (swollen caps, burnt spots on PCB) and putting it back together. Somehow this revived it and it worked for several months without issue. Perhaps that was just a loose connection.

Recently it has developed a new problem. Immediately after turning on the screen it looks normal, but over the course of 5-10 minutes it brightens up to the point where it's difficult to look at and colors are washed out. I have compensated by lowering the contrast down to 25% and the individual color brightnesses to 0% and it looks almost like a normal screen again, but there is also a pixel shimmering on moving objects, like it might be out of phase or something. It seems to have nothing to do with overheating as I've placed a large fan behind the screen with the back panel off and it doesn't behave any differently.

So, I have the screen open on my desk, and there seem to be several distinct components, which I have diagrammed below:

So, I know that these monitors are notorious for their power supplies going out, but I wanted an opinion - does this sound characteristic of the PSU going out? I'm suspecting the "LCD control board" right now. What might I look for?

 

[SOFTengCOMPelec]

Starting point ONLY, please feel free to find your own, potentially better websites

I don't know about your particular monitor, but let me give you some general advice, which is available on many websites.

By and large, the capacitors (Electrolytic ones) tend to deteriorate with age and usage. Although looking at them can often show signs of imminent failure, as you mentioned, bulging packages etc, they can also deteriorate with NO external visible signs.
An electronics engineer or competent hobbyist could check their individual values, but it is usually not worth it, and difficult to do in-circuit, because the surrounding circuitry would mess up most attempts at checking their values.
So, if you are determined to fix it, and with absolutely NO guarantee of success!, you could replace ALL the electrolytic capacitors. By reading their values (usually printed on the capacitors), you can order new ones from suppliers such as digi-key, and it should not cost a huge amount, as they are fairly cheap, but it may not be economically viable, depending on how many there are. Some types are rather expensive. The voltage rating needs to be AT LEAST what the original one is marked as. They are polarized, so you MUST connect the negative and positive terminals the right way round.

The reason for the above advice, is because, (super VERY approximately) 30 .. 50% (estimates vary WIDELY) of older electronic equipment will be rejuvenated by doing this.

If you asked me for advice, I would say that modern LCD monitors are of high quality nowadays, and apparently very good value for money. So, I would recommend getting a new one.

The electrolytic capacitors tend to lose value (capacitance) and go (electrically) leaky as they age. This can eventually get to the point, that they no longer perform their function correctly, which could easily explain your symptoms.

DISCLAIMER: I offer absolutely no guarantee, and there COULD EASILY be something else wrong.

If you are really going to do this, please refer to a good website which explains how to change all the electrolytic capacitors.

The following link is NOT specifically about monitors (it's about motherboards), but will give you some background, if you need it.
More Information about THIS

You would probably be throwing time, sweet and money at a dead horse, so I would seriously recommend a replacement monitor. You might even be able to get a monitor for free from some of the list(s) which advertise such stuff in your local area, because they got a new computer, and no longer need the old one. etc.

There is probably better advice than I have given, on the net, which may well narrow down which electrolytic capacitors to change, rather than all of them.

For anyone, terminally curious, this page gives some interesting background


Anyway, good luck, maybe you find someone who can diagnose the exact component to replace (but I'm not holding my breath on that happening).

 

[Yuriman]

Thanks! Very solid, albeit pragmatic advice. I'm mostly interested in attempting to fix this screen out of curiosity - I've already replaced it. The information pertaining to capacitors is very helpful and I think I'll make inventory of all the caps inside and price-check them to see if it's worthwhile to try this. I'm pretty handy with an iron.

 

[SOFTengCOMPelec]

Thanks! Very solid, albeit pragmatic advice. I'm mostly interested in attempting to fix this screen out of curiosity - I've already replaced it. The information pertaining to capacitors is very helpful and I think I'll make inventory of all the caps inside and price-check them to see if it's worthwhile to try this. I'm pretty handy with an iron.

Good luck!.

One of my monitors, which I have grown to really like, seems to be suffering from "bad capacitor" syndrome. It is still usable at the moment (but faulty for about a minute, after initial switch on), but I am tempted to at least consider repairing it (even though I could easily replace it).
Fortunately, it seems to be with the CCF/Backlight, which is a common problem, and so narrows down which capacitors to swap, quite nicely.
I think over time, one gets use to the equipment, and sometimes it can be sad to see something go.

Another link

 

[Matt1970]

If the problem shows up after 10-15 minutes you need some cold spray. That will cool the parts back to their startup temperatures and may help you determine which one is at fault. You can spray it right on the caps.

The "LCD control board" is called a T-con board.
The "CFL Control Board" is call an Inverter board.

 

[uclabachelor]

I inherited a Soyo Topaz a while back which was shutting off or turning yellow intermittently, and fixed it by taking it apart, inspecting everything and not being able to see any visible problems (swollen caps, burnt spots on PCB) and putting it back together. Somehow this revived it and it worked for several months without issue. Perhaps that was just a loose connection.

Recently it has developed a new problem. Immediately after turning on the screen it looks normal, but over the course of 5-10 minutes it brightens up to the point where it's difficult to look at and colors are washed out. I have compensated by lowering the contrast down to 25% and the individual color brightnesses to 0% and it looks almost like a normal screen again, but there is also a pixel shimmering on moving objects, like it might be out of phase or something. It seems to have nothing to do with overheating as I've placed a large fan behind the screen with the back panel off and it doesn't behave any differently.

So, I have the screen open on my desk, and there seem to be several distinct components, which I have diagrammed below:

So, I know that these monitors are notorious for their power supplies going out, but I wanted an opinion - does this sound characteristic of the PSU going out? I'm suspecting the "LCD control board" right now. What might I look for?

I had a similar issue and it turns out my issue had to do with the white ribbon cable (that goes in between the input and output board in your image) or a cold solder joint on those connectors. I resoldered the joints and reseated the ribbon cable and all my image issues were resolved.

 

[yhelothar]

I have that monitor with the PSU that went out. I didn't have the issues you had. Mine would flash when I powered it on and flash back off.

Swapping out the PSU fixed it.
There's a cap kit for this monitor on ebay, but it looks like it's for the PSU.