Dynex DX-32L150A11 Standby Blink

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

The connector on my mainboard with the 5v is at connector x601 but I don't see it anywhere in the manual? Just x501

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Other possibles
C529, C538, C528, C531, C533, C520.
You can lift: L505, L624, L504, L502 to isolate these rails and capacitors, may be easier.
If short disappears on one, then you know where to look.

Predominately a short to ground that low is almost always a capacitor or FET, and I can only see capacitors on that line.

Could be hard to read 5/6 on board?? Do check common components to see if general layout is close.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Here's a close up pic of the area I removed the regulator and where x601 connector is on left

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I only have R603 on the adjustable leg of that regulator, it's supposed to be 510ohms but it measures 313ohms, that's in circuit. Does it need to be out for accurate reading? Would the low ohms create the problem?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

The schematic may be slightly different then, but if the general blocks are there, should be fine, is that reading with or without reg in place? Sure you did not accidentally pull off it while removing reg?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Reading is without regulator, and I'm sure there's not even any pads for another resistor there. Also I found one small smd capacitor near processor CS38 that measures 0 ohms as well as two others in the area but none of which are on the 3.3v circuit shown in the schematic that also measure 0 ohms.

There are lots of caps, inductors shown in schematic that I can't find on the board

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Looks to be different variant then, is that possibly wrong main board for this set?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Hmm so I continuity tested both ends of that CS38 cap with the output pad of the regulator I removed and meter beeped both times, will try to remove it and see what happens after I place regulator back in.

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Just remember a cap will show short if other things are in parallel, but from that schematic if it's at least close there isn't -much- on that rail. Maybe 10~15 caps tops.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Removed cap, back to same problem with regulator in circuit.

I can't find the corresponding caps next to it as shown in the schematic.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Found the short! It was the tiniest smd cap CS27 figured closest to CS28 on the schematic since I could not find that one. I did some continuity measurements and there were three caps all linked together including that one, it was second I removed and boom got my standby light.

With it removed though pressing power button doesn't do anything.

How can I substitute another? These things are so small with no markings. Could I just use any off a junk board?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Measure one near it, will likely be same value. Typically 100nF. Yes you can use one off a board if it is same value. Do you get 3.3V or 1.8V or whatever at that regulator now?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Oddly the output voltage of that regulator is now only reading 0.6v. What's up with that? Did it go bad after finding the short?

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Also I'm confused. I looked up that regulator and it says it needs two resistors to work but there's only one connected to it on the board. I've looked and looked, only one. Even found same mainboard on ebay and the picture up only has one resistor.

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Such a regulator when using only one resistor has an output of 1.2V.

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Since the regulator is not outputting I wonder if I even found the short.

I have some fixed value 3.3v regulators, could I use one to replace it and just put a jumper where the resistor is?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

I think it's probably not a 3.3V regulator, doing that could cause damage, you need to replace it with the exact type (1117 ADJ.)

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

I think it's probably not a 3.3V regulator, doing that could cause damage, you need to replace it with the exact type (1117 ADJ.)

Know where I get a couple?

[tom66]

Re: Dynex DX-32L150A11 Standby Blink

Digikey, eBay... a few bucks and a few days wait (the hardest part about any repair project!)

[ohmmy]

Re: Dynex DX-32L150A11 Standby Blink

Ha yeah. I feel like the short is still there. Wonder if it's even worth the hassle