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DVD/ STEREO SYSTEM: bridge rectifier question

I've just 'fixed' a dvd/amp/stereo all in one made by the world famous Sunstech :-p ( model hf-dv55m ; manual and details here

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Unit was dead, on power up some garbled text appeared in the display. measuring o/p voltages on the psu pcb, I saw the display lines were ok but the 5v line was dead. Probing further, I found an o/c cct protector or fusible resistor (marked '3000') in the DC output of one of the bridge rectifiers.

I eventually traced the cause to a partially shorted spindle motor. Changed that and the beast works, but I am concerned that the bridge rectifier (marked GW RS202; appearance-wise, its like number 2 in this pic

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) gets extremely hot in operation (you can't keep a finger on it at all). Not sure if that is normal; the pcb looks slightly scorched near there, so could have always been this way for all I know. The other identical bridge is pretty much cool in use.

So, question is, is this likely to be leaky? I've only ever had one case of a similar leaky rectifier, in a VCR a few years ago. In my experience they normally just short out. Maybe fit a beefier one?

Any thoughts welcome.

-B

Reply to
b
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you should check the bridge, you could have one diode in there that is leaking and check the filter cap that is attached to that with a voltage supply that has a amp meter on it, out of circuit.

Reply to
Jamie

On Sun, 13 Dec 2009 17:55:45 -0800 (PST), b put finger to keyboard and composed:

I've seen several instances of leaky rectifiers in linear supplies. The ripple on the output was very obvious in my case, though.

An RS202 crosses to an NTE166 (100V, 2A):

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Here are other datasheets:

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You may want to measure the current drawn by the load.

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar

thanks franc and jamie. I changed the rectifier for a 2KBP02 (2A) I had lying around. Still got hot. Connecting an ammeter in series with the load gave a pretty negligible reading in tuner mode, but an average reading of 1.3A, with occasional peaks of 1.8 or so, when the dvd was in use. Since at no time the reading exceeded the 2A rating of the rectifier, I'm assuming this is just a case of penny pinching in the design, with the component working very close to the limit. I'll keep it in use a while and see, and based on that, may upgrade the rectifier to offset future probs.

-B

Reply to
b

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