Dynex DX-32L150A11 Standby Blink

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

134 ohms is low, but not what I would consider dead shorted, because of that, I would be looking for a short "hiding" behind a device, for example, a diode in series with a short after a diode.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

This almost seems impossible to trace without a schematic. It looks like the 5v line goes through some smt capacitors and an aluminum electrolytic cap before a 1.8v regulator. The voltage at the input of that regulator fluctuates the same as when measured at the 5v pin

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

You might be able to use a ~4.5V battery (or 5V from computer PSU) and a 4.7~5.1 ohm resistor (rated minimum 10W) to do the freeze spray test.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

You freeze spray parts of a board whilst passing a small current (around 1 amp) through it. The parts that melt the freeze spray likely have the short.

To try this could I use an old pc psu using the 5v rail and a resistor to limit the current to 1amp?

So using ohms law, the resistor to use: R=5/1 = 5ohms?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

You might be able to use a ~4.5V battery (or 5V from computer PSU) and a 4.7~5.1 ohm resistor (rated minimum 10W) to do the freeze spray test.

Ha nice. We posted at same time. I don't think I have any resisters rated at 10w though. Do they even make that value resistor with that much wattage?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Is there any load I could use instead of a resistor to limit current?

And how long do you keep it running to determine the fault/part that gets hot

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Yes you can buy resistors like that, they are very large with a big heatsink.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Wait can't I just use an iPhone wall charger? They're rated at 5v 1a output

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

And many more amps short circuit. Not unless you want to incinerate what is causing the short.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

And many more amps short circuit. Not unless you want to incinerate what is causing the short.

Thought you said to use minimum 1amp supply? I have some other phone chargers rated at 5v out with lower amps ratings than the iPhone one. What's ideal amps output to use?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I have another charger with output of 5v 0.7a. Would that be safer?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

I assume you are thinking about directly connecting omitting the resistor? That is what I am saying is bad, on its own a power supply with the resistor should be OK.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I assume you are thinking about directly connecting omitting the resistor? That is what I am saying is bad, on its own a power supply with the resistor should be OK.

The resistor was for using a cpu psu but now I'm talking about a small phone charger that outputs 5v 0.7a, I'd still need a resistor for that?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Yes, you do still need one. Such a charger is capable of well in excess of its rated output when driving a short circuit.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

oh ok, would I still need the same type of resistor mentioned before or?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

You need a resistor and a power supply capable of supplying at least 1 amp.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

You need a resistor and a power supply capable of supplying at least 1 amp.

What value resistor if I use the iphone charger thats rated at 5v 1amp out?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

The same for any charger >=1A. Approx 5.1 ohms.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Does the resistor's wattage still have to be high with a power supply only rated at 1A?

Also, do I connect the resistor in parallel or series?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Yes, it does. The resistor is in series at all times.