Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Could I possibly break the circuit at an easier location? I don't entirely understand how that circuit works. Are there any other (possibly larger) components/issues I could test for first? I'm not even sure I'll be able to get R2204 off by itself, let alone put one back on, haha.

Thanks heaps

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Have you tried unplugging the speaker connector? I have seen problems like this caused by a piinched speaker wire.

I've tried with the speakers entirely disconnected and reconnected, I also tested the speakers which are functioning correctly. Any other ideas?

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Are there any obvious traces/lines running off the resistor? Maybe you could cut one.

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Am I correct in thinking it's the black resistor with the question mark next to it in the attached photo? If so, it's only half a mm in size .

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Am I correct in thinking it's the black resistor with the question mark next to it in the attached photo? If so, it's only half a mm in size .

That looks like it. I know, they are tiny. 0402 size (0.04" x 0.02" / 1mm x 0.5mm.)

First, can you test the diode "9-1"? On diode test it should measure 400 to 700mV one way, and infinite the other way.

You can try cutting the trace I have highlighted. Use a small scalpel to cut through the solder mask (green). You should see brown copper. Then, cut this. Leave a bit of copper on both sides. When you need to reattach it, you can simply run a bead of solder along it. Be careful not to scratch the other trace, although it would be repairable. Ohm out (measure resistance of) your trace to make sure it is definitely open.

BTW - Very nice, clear photos. How did you get such a clear shot of these components?

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Just realised I'm being silly. THIS is the trace you should cut. All other instructions/notes/warnings apply. It should actually be easier to cut this trace.

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Could you please clarify which diode I should test? Also, cheers about the photos, I'm just using an old $100 Canon Ixus, all it takes is a little bit of time and manual settings, haha.

Edit: Oh, sorry, I see the diode now!

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Pardon my ignorance, but how exactly should I be testing the diode? I only get a very brief drop in resistance (when first connecting/reconnecting my probes) in the correct direction of current flow, but then it goes to infinite. However, it always blocks current in the reverse direction, as it should.

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Pardon my ignorance, but how exactly should I be testing the diode? I only get a very brief drop in resistance (when first connecting/reconnecting my probes) in the correct direction of current flow, but then it goes to infinite. However, it always blocks current in the reverse direction, as it should.

So, it shows infinite in both directions?

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

It gives a momentary drop in resistance in one direction (when first connected), only long enough for my multimeter to register one reading, and then it jumps back to infinite. Almost like a small capacitor.

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

It gives a momentary drop in resistance in one direction (when first connected), only long enough for my multimeter to register one reading, and then it jumps back to infinite. Almost like a small capacitor.

It should definitely read something in one direction; are you using diode test or resistance? Post a picture of your meter if unsure...

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Ok, sorry, it seems I was mistaken. It's reading 750 in the correct direction, and in the opposite direction it quickly jumps to a very brief reading each time I connect it. Is it at all normal to get any reading in the reverse direction? I can record a video later, if it would help. Also, yes multimeter is on diode mode, but I also tried measuring ohms.

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Ok, sorry, it seems I was mistaken. It's reading 750 in the correct direction, and in the opposite direction it quickly jumps to a very brief reading each time I connect it. Is it at all normal to get any reading in the reverse direction? I can record a video later, if it would help. Also, yes multimeter is on diode mode, but I also tried measuring ohms.

It's probably fine, the diode has some capacitance which in effect must charge up causing low readings briefly; but if it goes infinite quickly then it's fine.

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

I know we probably don't really need it any more, but I just got the original PDF of the service manual if you'd like to add it to your database:

You should be able to just right click > save as.

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

I know we probably don't really need it any more, but I just got the original PDF of the service manual if you'd like to add it to your database:

You should be able to just right click > save as.

Thanks. I will upload it when I get home tonight. It may help others fix their TV.

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Damn, I cut that trace, and accidentally knocked Q2017 off the board in the process. I tested the cut trace, no connection left at all. Put the board back in the TV, and still exactly the same behaviour. Any thoughts? Did removing that transistor void our test? I wonder if there's any way we could just bypass the entire audio section? If something like that worked, it'd be okay because I use an external amp/speakers/tuner anyway.

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Can you post a picture of the damage? What did you use to cut the trace? I'm surprised this did not work. Then again I have not worked on any Sony TVs yet.

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

It's pretty embarrassing, it looks like I've totally massacred the board in the photo. I had two attempts to cut the trace, and neither broke the circuit, so I realised I needed to use a lot more force than I was, it was on that third cut that I slipped and hit the transistor. The transistor survived pretty well and can be seen in the photo (below and to the right of where it should be), but I don't think I'll be able to solder something so small with my iron anyway. I did the damage with a less than ideal box cutter, I should have waited and purchased a smaller blade.

[tom66]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Okay, in the worst case, all you have done is disabled the protection features of the TV. No big deal.

Can you test the resistance across that trace, to make certain it is definitely cut?

[386]

Re: Sony Bravia KDL-40D3100 - Doesn't Turn On - Standby Light Blinks 8 Times

Yup, tested and retested with my meter, no signs of any current flow.