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Toshiba Satellite Pro 420CDT high-pitched whining noise - What could it be?

TH2002

TH2002

Experienced Member
Joined
Jan 6, 2020
Messages
393
Location
California, United States
My trusty Toshiba Satellite Pro 420CDT - the first vintage computer I ever purchased over half a decade ago has been running smoothly ever since I got it. However more recently an issue has arised. The computer emits an audible high-pitched whining noise CONSTANTLY and the noise gets annoying very quickly. What could be causing this? I've read that sometimes hard drives that are at the end of their lifespan begin to emit a similar noise, though I've noticed absolutely no symptoms of HDD failure (e.g. long file access times, files disappearing, bad sectors, any other strange noises, etc.) so I'm unsure where the noise is actually coming from. If the hard drive isn't the culprit, what else could be making the noise? Anyone have any ideas??
 
TH2002 said:
My trusty Toshiba Satellite Pro 420CDT - the first vintage computer I ever purchased over half a decade ago has been running smoothly ever since I got it. However more recently an issue has arised. The computer emits an audible high-pitched whining noise CONSTANTLY and the noise gets annoying very quickly. What could be causing this? I've read that sometimes hard drives that are at the end of their lifespan begin to emit a similar noise, though I've noticed absolutely no symptoms of HDD failure (e.g. long file access times, files disappearing, bad sectors, any other strange noises, etc.) so I'm unsure where the noise is actually coming from. If the hard drive isn't the culprit, what else could be making the noise? Anyone have any ideas??
Click to expand...

Maybe the fan? Might need a good cleaning.
 
Sounds like the backlight inverter to me. My Satellite 110CS that I’ve owned for about 11 years started doing that not too long ago, and I replaced the inverter which fixed the issue. Closer inspection of the original revealed leaking capacitors, so replacing those would probably fix it, though I don’t know for sure.
 
Agent Orange said:
Maybe the fan? Might need a good cleaning.
Click to expand...

Tried cleaning the fan, unfortunately no difference.

compaqportableplus said:
Sounds like the backlight inverter to me. My Satellite 110CS that I’ve owned for about 11 years started doing that not too long ago, and I replaced the inverter which fixed the issue. Closer inspection of the original revealed leaking capacitors, so replacing those would probably fix it, though I don’t know for sure.
Click to expand...

How do I get to the backlight inverter and where did you get a replacement? Of course I can just replace the capacitors on the old one if I can't find a replacement.
 
Okay so I finally got around to taking apart the screen assembly on my 420CDT and removed the inverter board. Today actually the high-pitched noise stopped, but right when the noise stopped the backlight shut off. Yep, inverter board is the culprit.

The thing is though, I'm no expert but I can't notice anything wrong with the board. What should I replace?

20210419_192019-640.jpg20210419_192005-640.jpg
 
There are two capacitors on the left side sandwiched between the white connector and the inductors, replace those.
 
I removed the two capacitors, interestingly one of them seems fine and lifted out of the board with no issues (after using some desoldering wick of course) while the other pulled the capacitor straight off the leads. Had to use more desoldering wick to get the leads out but I eventually did and you can see some sort of residue on the board where that capacitor used to be.

Yep, at least one of the capacitors is effed. I'll probably replace both of them though because it's only a matter of time before the other one fails too.
 
OK I have a question about the capacitors? On the first capacitor (the one in worse shape) I can read that the voltage is 35V but absolutely no markings to indicate the capacitance. Does the capacitance even matter or can I use any capacitor as long as it will fit and is rated for 35V?

On the second and larger capacitor (the one in better shape) I can find absolutely no markings to indicate even the voltage it's rated for. Should I just put that one back in or can someone tell me the exact specifications (if necessary) for both capacitors?
 
TH2002 said:
Does the capacitance even matter or can I use any capacitor as long as it will fit and is rated for 35V?
Click to expand...

Yep. Big time. You could use a higher-voltage cap, but you need to stick as close to the capacitance as possible. Any way to get some closer pics on the components in question?
 
Sorry, my camera is too crappy for any closeup pictures (the stupid thing won't focus) so I'll type out the markings I see instead.

First capacitor (smaller one):
35V
10
105°C

Top:
66
b3

Second capacitor (larger one):
33/10
83 105°C
05 CON

No markings on the top.
 
TH2002 said:
Sorry, my camera is too crappy for any closeup pictures (the stupid thing won't focus) so I'll type out the markings I see instead.

First capacitor (smaller one):
35V
10
105°C

Top:
66
b3

Second capacitor (larger one):
33/10
83 105°C
05 CON

No markings on the top.
Click to expand...

The first one would be a 35V 10uf (microfarad).

The second one is likely a 10V 33uf.
 
Thank you for the help! I ordered some capacitors with matching specifications and similar dimensions to the originals and will report back as soon as I receive the replacements.
 
Update: Replaced the capacitors with new ones, made sure the polarity lined up and I had the right capacitors in the right holes, made sure the solder joints were good... No dice.

Did I do something wrong or does this indicate the backlight itself is the problem?
 
There's some "tricks" you can do with trace/pad repair....depends on your level of soldering expertise. Personally I'd give it a go, but I do such every weekday for a living.
 
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