help id'ing a diode from a Toshiba laptop (see pic)

Picture here:

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I burned this one up by supplying it -19V (mistakening reversed the polarity when fixing/resoldering a break in the power cord connector

-doh!)

Perusing the digikey catalog, I assumed it was a toshiba semiconductor schottkey diode CMS01.

It had an S1 inscribed on it. Even though the dimensions were'nt quite the same, I gave it a shot.

I've since shorted the 2 CMS01's, so that tisn't it. The CMS01 worked fine until the laptop drew more current on AC power; it worked fine allowing the battery to be charged; and on low power app's.

Can anyone help id'ing this component?

Its in parallel with (2) k-ohm resistors on a 19V P15 toshiba notebook. You can see a good shot of it in the pic.

Advice much appreciated,

Carl snipped-for-privacy@gmail.com

Reply to
Carl
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On 15 Dec 2006 13:48:12 -0800, "Carl" put finger to keyboard and composed:

Do you mean PC1 and PC2? If so, I'm guessing they are capacitors, one electrolytic, one ceramic. The diode looks like it might just be an ordinary rectifier. It's job would be to short circuit the input in the event of a polarity error. However, AFAICS this should take out the fuse (?) at PF1 (Littelfuse 12Amp?).

- Franc Zabkar

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Reply to
Franc Zabkar

Franc,

Thanks for the reply. The 12Amp fuse did survive ok.

What happened on the polarity error was that this diode literally fried/smoked (I'm glad I had a pic saved of the board). I plucked it out in little broken pieces.

Can you help with best make/model/specs for a good replacement of this type rectifier?

The power supply specs are 19V ~ 6.3A

Thanks again for your time, Carl snipped-for-privacy@gmail.com

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Franc Zabkar wrote:

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Carl

On 16 Dec 2006 12:18:40 -0800, "Carl" put finger to keyboard and composed:

The fuse rating seems odd, so I can't suggest a suitable diode. In any case you need to find out why your Schottky rectifiers are failing. Assuming you've corrected your polarity error, then the PIV rating (30V) of the CMS01 should be more than enough for this circuit, unless I've misunderstood the workings. Is D1 connected between 19V and ground?

Then maybe I'm wrong about the 12A fuse. Also, PC3 appears to be the main bypass cap, not PC1 or PC2. The latter probably provide HF bypassing.

- Franc Zabkar

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Reply to
Franc Zabkar

PC1, PC2, and the diode all are between +19V and ground.

I am also curious about the purpose of this diode, and if I can power the laptop safely without it. This would be my assumption if its just for reverse current protection.

The Schottky's may be failing because of the current? They are rated at 3A (max).

They may be failing due to heat? Rated at 100deg C. (125 max)

In any case, I am up for a best educated guess on replacement specs. You mentioned an ordinary rectifier.

Also note the situation in which the Schottkys failed... they worked fine on powering the battery, and if the notebook was idle, but when running some intensive apps, pop- it shorted.

Thanks, this is a bit of a puzzle,

Carl snipped-for-privacy@gmail.com

Reply to
Carl

On 17 Dec 2006 14:19:29 -0800, "Carl" put finger to keyboard and composed:

The diode is reverse biased. In this state it should draw no current. That's the puzzle. You need to sort this out before you can safely leave it out.

I have no relevant experience with laptops, but in automotive equipment I have often seen a reverse biased 1A 1N4001 rectifier across the supply. Such equipment is usually protected by an external

2A fuse or thereabouts. The purpose of the diode is to sacrificially protect the device in the event of a battery polarity reversal.

- Franc Zabkar

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Franc Zabkar

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