VOGONS


Reply 20 of 36, by Thermalwrong

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There is a height limitation for the capacitors because it's inside the screen housing. Max height is 5mm and that means you'd have to carefully arrange any electrolytic capacitor on its side like silvestron did in his video.

Personally I'd go with MLCC capacitors because they're tiny and they're non polarised so they can't be installed backwards. They also won't leak (like electrolytic caps), explode (yellow tantalums) or be too expensive (polymer tantalums).

Here are my recommendations for surface mount capacitors which are less work to arrange in the casing:
C6 - search on ebay for "High Quality 1206 SMD/SMT Capacitors. ALL VALUES. 25pc. UK Seller. Fast Dispatch" they have an option for "4.7uF / 50V / X5R". That should work and fit nicely in the C6 footprint

C5 - ebay "10pcs 6.3V to 5KV 1812 SMD/SMT Capacitors Range 100PF 680PF 1NF 68NF to 100uF" value: "25V 33UF +-10% X7R"

C1 - ebay same as C5 but value "35V 10UF +-10% X7R"

Reply 21 of 36, by boby

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Thermalwrong wrote on 2024-02-28, 14:25:
There is a height limitation for the capacitors because it's inside the screen housing. Max height is 5mm and that means you'd h […]
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There is a height limitation for the capacitors because it's inside the screen housing. Max height is 5mm and that means you'd have to carefully arrange any electrolytic capacitor on its side like silvestron did in his video.

Personally I'd go with MLCC capacitors because they're tiny and they're non polarised so they can't be installed backwards. They also won't leak (like electrolytic caps), explode (yellow tantalums) or be too expensive (polymer tantalums).

Here are my recommendations for surface mount capacitors which are less work to arrange in the casing:
C6 - search on ebay for "High Quality 1206 SMD/SMT Capacitors. ALL VALUES. 25pc. UK Seller. Fast Dispatch" they have an option for "4.7uF / 50V / X5R". That should work and fit nicely in the C6 footprint

C5 - ebay "10pcs 6.3V to 5KV 1812 SMD/SMT Capacitors Range 100PF 680PF 1NF 68NF to 100uF" value: "25V 33UF +-10% X7R"

C1 - ebay same as C5 but value "35V 10UF +-10% X7R"

There is a store which sells electronic stuff here in Vienna, so I will try there first for SMD caps, if not then I can order online. So voltage can be higher, but capacity must match?

Reply 22 of 36, by boby

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I only found these bellow, they are higher voltage but correct capacity. Guy didn't have SMD version. Will this work?

33 uF 35V (original is 25V)
4.7 uF, 63V (original is 35V)
10uF, 63V (original is 35V)

Reply 23 of 36, by boby

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I managed to tear one trace while removing old caps but it is ground contact and I managed to solder new caps. Checked all connections and all seams fine. Also I find the polarity of the new caps using multimeter.
However my screen is white again! 🙁
What is wrong now? Poor quality caps?

Reply 24 of 36, by nuno14272

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Not great .. usually the legs have the same distance. but will do the work.

UPS. isn't C5 soldered the wrong polarity ? be carefull...

1| 386DX40
2| P200mmx, Voodoo 1
3| PIII-450, Voodoo 3 3000

Reply 25 of 36, by boby

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nuno14272 wrote on 2024-02-29, 10:18:

Not great .. usually the legs have the same distance. but will do the work.

UPS. isn't C5 soldered the wrong polarity ? be carefull...

Far from great. Too much solder and I needed to twist the legs so the cap can be on the PCB not touching other components.
But I can fix that, that is fine. But why it is not working. I tried soldering twice, the only thing that I could think of is faulty caps. I pay around $3 for 30 pieces.
Higher voltage than original caps is not the issue?
Regarding polarization, I put the red probe on multimeter on one leg, and the black one on the other. It shows a little voltage. If there is a minus prefix it means that Red probe (+) goes to other leg.
Am I right?
This is what I have:

Reply 27 of 36, by boby

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Ok, so last update, I make it to work, but I am not very happy with how I solder it. For now, I will leave it as is.

Thx all for the help!

Reply 28 of 36, by boby

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So back to the beginning. After some time of not using this laptop, I started to get white screen again. I replaced the 3rd cap (which I didn't first time), but the result is the same. Same happens as on the beginning, screen is white and ext screen is working. Is it the caps again? Could it be that they failed already?

Reply 29 of 36, by boby

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boby wrote on 2024-06-14, 10:01:

So back to the beginning. After some time of not using this laptop, I started to get white screen again. I replaced the 3rd cap (which I didn't first time), but the result is the same. Same happens as on the beginning, screen is white and ext screen is working. Is it the caps again? Could it be that they failed already?

Solved, broken trace was the issue.

Reply 30 of 36, by Thermalwrong

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boby wrote on 2024-07-03, 08:51:
boby wrote on 2024-06-14, 10:01:

So back to the beginning. After some time of not using this laptop, I started to get white screen again. I replaced the 3rd cap (which I didn't first time), but the result is the same. Same happens as on the beginning, screen is white and ext screen is working. Is it the caps again? Could it be that they failed already?

Solved, broken trace was the issue.

Nicely done, I got hold of a T2450CT since and have discovered its LCD panel is very special - the signalling for hsync / vsync is all transmitted in the display-enable signal which means regular modern TFTs can't be put in its place.
I wish mine was so simple to fix, the replacement I got so far has a damaged column driver, the original LCD both polarisers have broken down and the capacitors damaged a bunch of traces so all I can get it to show is a white screen.

Reply 31 of 36, by boby

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Thermalwrong wrote on 2024-07-03, 14:07:
boby wrote on 2024-07-03, 08:51:
boby wrote on 2024-06-14, 10:01:

So back to the beginning. After some time of not using this laptop, I started to get white screen again. I replaced the 3rd cap (which I didn't first time), but the result is the same. Same happens as on the beginning, screen is white and ext screen is working. Is it the caps again? Could it be that they failed already?

Solved, broken trace was the issue.

Nicely done, I got hold of a T2450CT since and have discovered its LCD panel is very special - the signalling for hsync / vsync is all transmitted in the display-enable signal which means regular modern TFTs can't be put in its place.
I wish mine was so simple to fix, the replacement I got so far has a damaged column driver, the original LCD both polarisers have broken down and the capacitors damaged a bunch of traces so all I can get it to show is a white screen.

Maybe you can replace entire PCB. I think I saw for mine somwhere for 30$

Reply 32 of 36, by kolian86

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boby wrote on 2024-07-03, 08:51:
boby wrote on 2024-06-14, 10:01:

So back to the beginning. After some time of not using this laptop, I started to get white screen again. I replaced the 3rd cap (which I didn't first time), but the result is the same. Same happens as on the beginning, screen is white and ext screen is working. Is it the caps again? Could it be that they failed already?

Solved, broken trace was the issue.

Hi, Could you tell witch one?
Have absolutelly same problem with t4700ct

Reply 33 of 36, by boby

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kolian86 wrote on 2025-12-28, 19:25:
boby wrote on 2024-07-03, 08:51:
boby wrote on 2024-06-14, 10:01:

So back to the beginning. After some time of not using this laptop, I started to get white screen again. I replaced the 3rd cap (which I didn't first time), but the result is the same. Same happens as on the beginning, screen is white and ext screen is working. Is it the caps again? Could it be that they failed already?

Solved, broken trace was the issue.

Hi, Could you tell witch one?
Have absolutelly same problem with t4700ct

Was this one for me. Check with multimeter where the connection is lost.

Reply 34 of 36, by pentiumspeed

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This above picture shows one capacitor on right is reversed polarity. Note the positive marking on the PCB.

Cheers,

Great Northern aka Canada.

Reply 35 of 36, by kolian86

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boby wrote on 2025-12-30, 12:54:
kolian86 wrote on 2025-12-28, 19:25:
boby wrote on 2024-07-03, 08:51:

Solved, broken trace was the issue.

Hi, Could you tell witch one?
Have absolutelly same problem with t4700ct

Was this one for me. Check with multimeter where the connection is lost.

Thanks, but it's not my situation. My laptop sometimes working properly (1:50 times, 49:50, that only white screen appears). I checked resistance between all this capacitors, and found, that only one (like on your photo with broken contact) has infinity resistance when it soldered on pcb), others capacitors shows kilo, or mega ohms. Is it similar in your pcb? Many thanks.

Reply 36 of 36, by kolian86

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Hello again! I think solution has found. This defect depends not only LCD controller capacitors leaks. PSB board need to be rebuild too. In my case i changed 25v 1000, 6.3v 3300, 6.3v 1000, 16v 56*2, 25v 33mkf capacitors in internal power supply. After that I have seen white screen only once. So, now situation chanded from chance 1:50 to 50:1 if it will work normally.