Replaced NEC/Tokin capacitors now screen blank help please

[globalmark]

Hi

I have just replaced the NEC/Tokin capacitor in a Toshiba A300 as per instructions on this site and Internet and YouTube etc with the 4 replacement 330's (or whichever was correct)
I am a beginner when comes to laptop repair done light stuff before and I am ok at soldering .
All seems to have gone well no problems removed easily and soldered replacements on fine .no problems that I can think of .
I just put the laptop back together and turned it on. The fan spins and sounds like turned on lights all on etc however now the screen is completely black (blank) - nothing , no flickers , no bios screen just black .

I took apart again to see if left cable disconnected or didn't seat graphics card properly but all seems fine .

Would this be caused by the capacitors ? Or is it lightly to be something else ?
Any suggestions would be appriciated .
Thanks Mark

[raajkumar]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Can you put a Clear image of that capacitor installation. and check the voltage at that capacitor.

[globalmark]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi

Thanks for reply
Photo taken of new capacitors . Have attached image .hopefully shows up .
How would I test that voltage , I have a basic multimeter but where and how should I test ?
As mentioned Laptop seems to power on ok just blank screen ? Would that be the capacitors or something else ?
Thanks Mark

[smali]

Re: Replaced NEC/Tokin capacitors now screen blank help please

check the voltage on the capacitors how many voltage you have receiving? it should be roundabout 1 volts...if not receiving then check the capacitors on ohms range how many ohms showing? it should be above the 5 ohms if you are checking in circuit.. if showing 0 ohms may be one capacitor is short or soldering made a short circuit..

[globalmark]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi

Just check across the terminals on capacitors and get .999v and .998-.999 on each side so basically 1 volt (checking on + and - strips under two of the capacitors and same other two .

[smali]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi

Just check across the terminals on capacitors and get .999v and .998-.999 on each side so basically 1 volt (checking on + and - strips under two of the capacitors and same other two .

its OK...have check on another processor or RAM etc?

[globalmark]

Re: Replaced NEC/Tokin capacitors now screen blank help please

I used this video to remove and replace
https://m.youtube.com/watch?v=4W2AljjOUYQ

And removed all chips/ things he suggested on video to stop damage to them the replaced - think main processor and graphics chip etc (not 100%) sure what they were but removed and replaced ok .
I also replaced with all new heat sink compound - removed old with alcohol cleaned and dried then some new if that makes a difference .

Could I have damaged graphics card (I was really gentle and careful) or incorrectly connected monitor again ?
Is it lightly to be capacitors?

[smali]

Re: Replaced NEC/Tokin capacitors now screen blank help please

and also check voltage on al l( PL) coils with ground on multi meter specially near with RAM which must be 1.5 volts...

[raajkumar]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Did you checked with external monitor, RAM and RTC Battery also. If it is not power off itself with Adaptor and battery, the problem not in that nec/Tokin cap. If everything ok, you try to flash correct bios.

[globalmark]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi guys

Thanks for help so far - how and where exactly do I check other voltage on PL coils (what is PL coil and where is it and how to check ) and ram (have removed and replaced several times in different slot) but only have one ram chip ..

What and how to check RTC battery ?

How to flash bios when cannot see screen - no external monitor (only computer in house)

Laptop was working before changed capacitors just restarting itself if plugged into mains power on battery was fine .

Thanks guys appriciate the help just I have no idea what doing and girlfriends laptop so she not happy even though trying to fix for her ..


Mark

[jiroy]

Re: Replaced NEC/Tokin capacitors now screen blank help please

One good step right now , is to recheck on all the connectors for loose or bent connections , and it isn't bad to re-seat the CPU if you removed it , while checking for any bent pins by mistake .

Remain to ask , Are The 4 capacitors you used brand new or used ?

[petehall347]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi

Thanks for reply
Photo taken of new capacitors . Have attached image .hopefully shows up .
How would I test that voltage , I have a basic multimeter but where and how should I test ?
As mentioned Laptop seems to power on ok just blank screen ? Would that be the capacitors or something else ?
Thanks Mark

those capacitors dont look correct to me . are they correct size ?

[smali]

Re: Replaced NEC/Tokin capacitors now screen blank help please

also clean that area near with capacitor area with a spear toothbrush and alcohol or thinner etc as circul in image and also check PCB line near nec/tokin may be damage some one during nec/tokin remove..

[globalmark]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi guys

Capacitors are brand new came in sealed plastic - from eBay from Portugal reputable seller . For that correct purpose so as far as I know correct size.

I have remover CPU (if that's square thing many pins on it) twice now but will try again , has no bent pins but very loose fit , when took out was very easy and to replace basically dropped in then twisted plastic screw half turn to lock in.

just cleaned area - where is PCB line to check ? - I removed old capacitor as per YouTube video and was very gentle and careful don't think I damaged surrounding area - soldering was fairly quick so don't think got to hot or anything , but don't know .
Closer photo attached .
Thanks again for help Mark

[lefos]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hello,

Try to unsolder the small battery (pink color-this is the RTC battery mentioned above),
leave the board ~1 minute without voltage and try again. Also measure its voltage please when you have it out.

[globalmark]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi all

Ok just taken apart again - reseated everything making sure clean removed and replaced CPU no pins bent .. No change

Lefos - battery removed is 3.19v out of computer -
Do you mean try to start laptop without RTC battery or just leave out one minute , solder back the battery and retry ?

Thanks Mark

[globalmark]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Ok tried to restart without battery
Also resolder back in after couple mins and no change .
Thanks for suggestions ?

Can the replacement capacitors cause this ?

Am I lightly to have left something disconnected ?

Looks like nothing happening with monitor at all ?

[jiroy]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Mark ; Did you try to use an external monitor ? , if not , try it .
And seeing the circumstances , try pressing fn+f5 repeatedly with like 5 seconds intervals ..

[globalmark]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi Jiroy

Don't have external monitor - have LCD TVs , so tried s-video out of laptop (but think need do some settings in system to make work don't I ?) also tried the HDMI out to TV but nothing there ,
TV does have a PC in VGA socket but I don't have a cable - is it worth buying a cheap cable to try it ? VGA to VGA laptop to TV would this show as external monitor ? .?

Do I not have to change settings in operating system to make external display work ? Which cannot do when cannot see ?

Tried the FN F5 key many times no change ..

Thanks for help guys

[raajkumar]

Re: Replaced NEC/Tokin capacitors now screen blank help please

Hi Jiroy

Don't have external monitor - have LCD TVs , so tried s-video out of laptop (but think need do some settings in system to make work don't I ?) also tried the HDMI out to TV but nothing there ,
TV does have a PC in VGA socket but I don't have a cable - is it worth buying a cheap cable to try it ? VGA to VGA laptop to TV would this show as external monitor ? .?

Do I not have to change settings in operating system to make external display work ? Which cannot do when cannot see ?

Tried the FN F5 key many times no change ..

Thanks for help guys

Hi this VGA to VGA cable will cost below 5AU$. If you don't know how to view in external display you just remove the lcd cable from the mainboard. and use VGA to VGA cable to Laptop and the LCD TV. and the same time you have to change tv source mode to VGA or PC.