Dynex DX-32L150A11 Standby Blink

[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

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

[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

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

[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

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?

[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

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

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

From the 5v terminal to ground I get a reading of 134ohms. I found the same exact measurement on a smt cap on both ends. It's a shade of grey. No clue what the rating would be. Could this mean it's shorted?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

What resistance did you measure at the 5V terminal directly on the main board, compared to those at the caps/Vreg?

So I'm looking for the same reading I get from the 5v terminal to ground when checking others components to ground?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Low resistance: generally less than 10 ohms is a concern.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I'll have to retest and get back to you. Just left my house. What should I be looking for exactly?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

What resistance did you measure at the 5V terminal directly on the main board, compared to those at the caps/Vreg?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

It would be on that 5V line.

I traced it to a couple smt capacitors and a couple voltage regulators. Do I need to check them off board for shorts? They don't test low ohms as of now, neither do the caps

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

It would be on that 5V line.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Would the short be on that 5v line or anywhere? I could try tracing it on the mainboard

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Shorts are traced by testing resistance along the board, looking for low readings, it can be very difficult on a meter with only one decimal point which is why I suggest the current method, but that requires a constant-current constant-voltage lab power supply.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

PC fan ~100mA is fine for a standby type load, yes it indicates a short on the main board.

What you need to do is either try tracing for shorts using an ohmmeter, or try my favourite method which involves freeze spray. 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.

How would I trace for shorts using an ohmmeter?

When I have mainboard plugged in, every component seems cold to the touch, in the past I'd at least notice some warmth on a faulty component.

Wouldn't know how to exactly only pass 1amp to the entire board while freeze spraying

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

PC fan ~100mA is fine for a standby type load, yes it indicates a short on the main board.

What you need to do is either try tracing for shorts using an ohmmeter, or try my favourite method which involves freeze spray. 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.