Dynex DX-32L150A11 Standby Blink

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Yeah I'll just shop around for a main board. Thanks for all your help and patience with this one. Even though couldn't directly fix it, it was a fun learning journey.

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Probably not if they have a dedicated program, if not then maybe, swapping a 100+ pin chip may be difficult though.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Is there no cap across AVDD_33 to GND?
AFAIK = As far as I know

No just directly into a pin on the processor and correction LS05 goes into a point on the processor labeled AVDD_DVI

Can't just buy replacement processors for main boards right?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Is there no cap across AVDD_33 to GND?
AFAIK = As far as I know

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

LS04 is connected to a pin on the processor labeled AVDD_33

LS05 is connected to a 390 ohm resistor (which measures fine off board) and that connects to a pin on the processor labeled AVDD_MPLL

Set won't turn on with both them lines disconnected (inductors removed) but I get steady standby light and voltages

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

AFAIK?

Yeah I used freeze spray and only the areas around the processor seemed to evaporate quickest. Lots of smt caps.

However in referring to the schematic I've noticed with LS04 and LS05 removed. Short is gone.

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

3.3 * 1.5 = 5 watts. A lot of heat.
Something should be smoking, I suppose there's a chance it's the processor as that's about the only thing that could get so hot, but they cannot short 0 ohms AFAIK. Did you try freeze spray?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Well I finally got that external power supply in.

Connected it from output of that regulator to ground.

Had to keep raising current before voltage started to rise. Peaked at 3.28A at 1.5V

The only thing that got warm to the touch was the heat sink on the processor. Some smt caps directly underneath were slightly warm too but they were ones I had removed prior to this going by the schematic which didn't cause a change.

What do you think?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

One of the 3.3v outputs goes to pin 27 on the processor called AVDD_DVI, right before the pin there's a resistor. I took it out and the pads when measured without it give a short reading, does that mean the processor is shorted?

I thought you were asking what value resistor this was.

I'm not finding the short, I even tried the 33 ohm with power from CPU psu and ran it for a while as I freeze sprayed. Everything stayed frosty.

The only place it appeared to evaporate quicker was right under the processor as I sprayed some smt caps. Even tried taking them out and still nothing

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Hmm what if I just connect the 33ohms resistor, how many amps does a 3.3v line CPU psu generally deliver? I'm not home to see what mine is rated at

Over 25 amps is possible, and possibly much more when driving a short circuit. 3.3V is not used to power the CPU. Typically it is used to provide chipset, RAM, PCI and general logic power which can draw a ton of power.

Needless to say, 25 amps across a dead short will be extremely destructive.

390 ohms again too much for any significant heating, you need around 3.3 ohms to get 1 amp.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

What value resistor?

390 ohms

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

So what do you suggest like a 2 ohm resistor?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

It can be on, but 100 ohms or 33 ohms really isn't enough current to make anything heat up substantially. On that board in the video, 1 amp only made a slight difference in the melting, I had to go full whack to 3 amps and it became obvious where the fault was.

Hmm what if I just connect the 33ohms resistor, how many amps does a 3.3v line CPU psu generally deliver? I'm not home to see what mine is rated at

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

It can be on, but 100 ohms or 33 ohms really isn't enough current to make anything heat up substantially. On that board in the video, 1 amp only made a slight difference in the melting, I had to go full whack to 3 amps and it became obvious where the fault was.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I found two 5w resistors, 100 and 33 ohms in an old junk board.

If I connect them in series and use 3.3v line from a CPU psu to power that circuit and use freeze spray, do I have to keep turning power off before spraying or can it be on as I spray around?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I forget will check when home. But I'm pretty sure it was under 1k

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

What value resistor?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

One of the 3.3v outputs goes to pin 27 on the processor called AVDD_DVI, right before the pin there's a resistor. I took it out and the pads when measured without it give a short reading, does that mean the processor is shorted?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

This is why I use the constant current & freeze spray method. Narrows it right down to the exact part. Here's how well it can work:
http://www.youtube.com/watch?v=7Xz-iSaEAb8&t=3m13s

That power supply you linked to me in PM would work just fine for this test. Personally I use a surplus old power supply 0-35V/0-3A (CC-CV type) which I got very cheap, it's extremely well built, but there's no reason one of those cheaper ones wouldn't work, provided that you don't allow them to overheat.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Well I checked all those little inductor/capacitor networks coming off the 3.3v line, no change. Guess I need to go even further