Dynex DX-32L150A11 Standby Blink

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I found a junk board with a 1117a regulator. Not sure if it'd work?

The one that needs replacement is only labeled 1117

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Would these work?

http://www.ebay.com/itm/US-Seller-10...-/281040404035

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Think I'm chalking this one up as a bad processor.

Found a regulator to use in a junk board, same problem came back.

I traced numerous smd caps that were fed by output of the regulator and all linked to a smd inductor. So I removed it to essentially remove that entire network of caps, problem still existed.

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

It's really rare to get a dead short across a low power processor like one in this TV, maybe a few ohms but not 0.2 ohms.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I don't know where else to look. Any suggestions?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

You're not going to believe this, all those components in the schematics I couldn't find on board... Are on the bottom!

Even found that second resistor for the regulator so it is a 3.3v output.

Here's what's weird though, in board both those resistors (510 and 820 ohms) measure 313 ohms. Is that because they're on board?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Yeah probably. I thought you had looked on the bottom.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Yeah probably. I thought you had looked on the bottom.

Haha didn't even cross my mind because everything on top was so overwhelming

Two smd caps on bottom measure short circuit, it's tough trying to use an ohm meter to try seeing if they're bad. Is my only option to remove them one by on and power on?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Have to remove and see, sorry!

[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

[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

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

What value resistor?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

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

[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?

[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

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

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

So what do you suggest like a 2 ohm resistor?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

What value resistor?

390 ohms

[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.