Bad caps infestation in 21 trinitron monitor

[laser]

Hi masters

I have a pair of 21 'trinitrons based monitors (sun GDM-5410)

1 of them works fine however it have the classic brightness problem which affects all trinitrons monitors, even in this case color restoration do not works, if I do it the monitor turns off

some ppl says is aging tube problem but I know is a capacitor issue

ok I dismantled one of them and I have not see any damaged or bulged cap, all the caps are chemicon and rubycons , excepting for the power supply big cap 450v 330mf which is a nichicon

The G board (easy to dismantle )contains power supply big cap and some other caps I think related to horizontal or vertical etc

The D board contains the flyback and lot of caps, this board is very hard to dismantle due tons of connectors and soldered cables of the flyback

the other boards do not contains electrolytic caps

so my question is:

which caps on this monitor do you think are bad and generating excessive brightness ?

thx

[stj]

Re: Bad caps infestation in 21 trinitron monitor

all RGB drive is usually on the neckboard.

[laser]

Re: Bad caps infestation in 21 trinitron monitor

all RGB drive is usually on the neckboard.

I don't understand what you are saying, if you can explain better

[stj]

Re: Bad caps infestation in 21 trinitron monitor

the board that plugs onto the back of the tube normally has all the colour-drive circuits on it.

[laser]

Re: Bad caps infestation in 21 trinitron monitor

the board that plugs onto the back of the tube normally has all the colour-drive circuits on it.

perhaps you are right, but that's the N board and haven't electrolytic caps
the only boards which have electrolytic caps are G and D

so which ones I must first starting to check/replace?

[stj]

Re: Bad caps infestation in 21 trinitron monitor

you need to slow down.

first, it may not be caps.
it could be low emision from the tube.
and it could be failing brightness control on the line-output transformer.

you need a schematic.
they exist for sony monitors - so go find one.

and just hope you dont need a high-voltage probe.

[momaka]

Re: Bad caps infestation in 21 trinitron monitor

I doubt it's a caps issue.
Most likely, too high G2 voltage in combination with the drift-correction circuitry. It's a common problem with the 21" Sony Trinitron monitors. The G2 is controlled by an MCU (i.e. micro-controller). The fix is to disable the drift-correction circuit (pretty easy) and flash the MCU with WinDAS to adjust the G2 to a proper level.

See the thread below and read it carefully. You'll probably need a Serial to TTL adapter and a PC with a serial port.
https://www.badcaps.net/forum/showth...ighlight=p1110

WinDAS software:
https://www.badcaps.net/forum/showpo...8&postcount=24

And these posts detail what the drift-correction circuit does and how to disable it:
https://www.badcaps.net/forum/showpo...7&postcount=25
https://www.badcaps.net/forum/showpo...7&postcount=46
If your G2 has gone significantly higher, it's possible that you don't have to re-adjust it after disabling the drift-correction circuit.

[laser]

Re: Bad caps infestation in 21 trinitron monitor

I doubt it's a caps issue.
Most likely, too high G2 voltage in combination with the drift-correction circuitry. It's a common problem with the 21" Sony Trinitron monitors. The G2 is controlled by an MCU (i.e. micro-controller). The fix is to disable the drift-correction circuit (pretty easy) and flash the MCU with WinDAS to adjust the G2 to a proper level.

See the thread below and read it carefully. You'll probably need a Serial to TTL adapter and a PC with a serial port.
https://www.badcaps.net/forum/showth...ighlight=p1110

WinDAS software:
https://www.badcaps.net/forum/showpo...8&postcount=24

And these posts detail what the drift-correction circuit does and how to disable it:
https://www.badcaps.net/forum/showpo...7&postcount=25
https://www.badcaps.net/forum/showpo...7&postcount=46
If your G2 has gone significantly higher, it's possible that you don't have to re-adjust it after disabling the drift-correction circuit.

thanks master for the reply and for all the links
I know about windas software etc even there is a resistor hack to cure partially brightness issue (resistor 459)

but I'm sure brightness problems is related to some caps losing capacitance over the time,
I'm sure replacing wasted caps the brightness will return to normality or near normality and there is no need to use windas software or the resistor hack

also I have a 21' samsung syncmaster monitor 1100mb,( no sony tube)
such monitor started to became shiny like trinitrons monitos, I dismantled it and I found 4 bulged caps over the board, replaced such caps and solved the birghtness problem

in the case of this sony based monitor there is no bulged caps, all caps looks fine ie all are japanese rubycon and chemicon except the big power supply cap 450v 330mf is nichicon

[momaka]

Re: Bad caps infestation in 21 trinitron monitor

High-end Trinitron monitors like these are well designed and don't run hot enough to cook caps. And as you noted, all of the caps are Japanese. I would be absolutely surprised if you find any bad caps. On the Samsung SyncMaster monitor, though, I can absolutely believe you that you found bad caps in there. I have a SyncMaster 955 myself, and it runs HOT. I haven't opened it, but I'm sure it's full of SamWha or Sam Young caps, which are known to be not very reliable. Also, it's a completely different animal from the Trinitrons, which have NO G2 OUTPUT FROM FLYBACK.

The brightness problem in the Trinitron monitors is a combination of the drift-correction circuit interacting with the aging of the tube and the color-restoration feature. Also, the firmware on some Trinitrons tends to go corrupt over time and also automatically ups the G2 level (hence why WinDAS is sometimes unavoidable).

That resistor hack with R459 is different from disabling the drift-correction. I don't think anything has even been written online about the drift-correction circuit in these monitors. I've read plenty of Trinitron threads myself, and I think Th3_uN1Qu3 was the first to find out about the drift-correction circuit and disable it.

[laser]

Re: Bad caps infestation in 21 trinitron monitor

High-end Trinitron monitors like these are well designed and don't run hot enough to cook caps. And as you noted, all of the caps are Japanese. I would be absolutely surprised if you find any bad caps. On the Samsung SyncMaster monitor, though, I can absolutely believe you that you found bad caps in there. I have a SyncMaster 955 myself, and it runs HOT. I haven't opened it, but I'm sure it's full of SamWha or Sam Young caps, which are known to be not very reliable. Also, it's a completely different animal from the Trinitrons, which have NO G2 OUTPUT FROM FLYBACK.

The brightness problem in the Trinitron monitors is a combination of the drift-correction circuit interacting with the aging of the tube and the color-restoration feature. Also, the firmware on some Trinitrons tends to go corrupt over time and also automatically ups the G2 level (hence why WinDAS is sometimes unavoidable).

That resistor hack with R459 is different from disabling the drift-correction. I don't think anything has even been written online about the drift-correction circuit in these monitors. I've read plenty of Trinitron threads myself, and I think Th3_uN1Qu3 was the first to find out about the drift-correction circuit and disable it.

in my samsung syncmaster there a a few chemicon caps but most of them are capxon caps which are total crap and were the ones which were bulged
I bet if you open your monitor which is from the same series than mine you will found those capxons

btw, I don't think that brightness problem is a combination of the drift-correction circuit interacting with the aging of the tube and the color-restoration feature....
I think is a myth, specially the myth of the firmware going corrupt ( it can't be)

I bet that G2 level varies according to lost of capacitance, but then the lost of capacitance is so important that such automatic correction not works

for my point of view is a capacitor issue, in the case of this monitor is so shinny that color restoration not works, the monitor turns off itself


japanese capacitors rarely bulge but lost capacitance over the time , you read datasheet of those japanese capacitors you will find they have life expectance, generally 5000 hs or so

this monitor was manufactured in 2001 so note it than in 1 year there are 8760 hours

******
what I will do and I will report here later what happened


1 replacing the chemicon caps which I calculate are weaker than the rubycon ones and I think they are the ones causing brightness problem, they are located in board D and G

2 if replacing caps not works I will do the resistor hack

3 if resistor hack not works fine I will build a serial TTL board and I will try windas software


btw2 ,also I read in a thread that replacing caps near the flyback will cure brightness problem, but near the flyback I just checked...there are no caps

[momaka]

Re: Bad caps infestation in 21 trinitron monitor

I bet if you open your monitor which is from the same series than mine you will found those capxons

CapXon? Ugh . I really expected better from Samsung.

btw, I don't think that brightness problem is a combination of the drift-correction circuit interacting with the aging of the tube and the color-restoration feature....
I think is a myth, specially the myth of the firmware going corrupt ( it can't be)

The firmware going corrupt - I am a bit weary of that too. But the drift-correction circuit is not a myth, sorry. Slightly older Sony monitors don't have this circuit and they don't have this issue either. If you actually read all of Th3_uN1Qu3's threads on these monitors (there's a particular one that I'm not sure I posted), he found that if you disable the drift-correction circuit and adjust G2 with WinDAS so that brightness is normal, you will find that the G2 voltage will be exactly the same as on a Sony monitor without this drift-correction circuit. So clearly, the drift-correction circuit is a big part of the problem.
I myself have several even older Sony monitors that not only lack this circuit but also use discrete transistors for the cut-off amps. Neither has brightness issues.

for my point of view is a capacitor issue, in the case of this monitor is so shinny that color restoration not works, the monitor turns off itself

Color restoration does NOT turn the G2 down. It usually only turns it up and up, making the problem worse.

japanese capacitors rarely bulge but lost capacitance over the time , you read datasheet of those japanese capacitors you will find they have life expectance, generally 5000 hs or so

this monitor was manufactured in 2001 so note it than in 1 year there are 8760 hours

You are mistaken here.

The datasheets don't mention life expectancy. They mention endurance time - that is, the amount of time the capacitors can be subjected to maximum stress - i.e. maximum ripple current, at their maximum rated voltage, and maximum temperature. Within this time, the capacitors are guaranteed to meet datasheet specifications. After this period, the capacitors may still be okay and meet the specifications, but are no longer guaranteed.

Also, what's NOT mentioned in the datasheets, but is known as a general rule, is that for every 10C reduction in temperature, the expected lifetime of the capacitors double.

So if you have a capacitor rated for 5000 hours at 85C (typical for a CRT), that cap will run fine for 5000 hours at 85C, maximum rated voltage, and maximum ripple current. If you lower the temperature to 75C, the lifetime will become 10000 hours. And yet if you lower the temperature by another 10C down to 65C, the lifetime will double again to 20000.
Sony monitors usually run much cooler than that - probably not higher than 55C on the inside, if even that much. So that gives you 40000 hours, or roughly 4.5 years of ON time.

And of course, if the maximum voltage and ripple current on the capacitors are lower than the allowable in the datasheet, then the lifetime increases even further.

That said, feel free to change all of the capacitors to prove me wrong.
I've tested a few from my dead GDM-FW900 board, and all were in spec - both ESR and capacitance -wise.