[SOLVED]820-3115 Randomly switching between Internal Speakers, Digital Out and Headphones

[bjf]

[SOLVED]820-3115 Randomly switching between Internal Speakers, Digital Out and Headphones

I replaced the headphone jack already and still have the same issue. The computer chimes on startup and then when in the OS it will switch somewhat randomly between Internal Speakers, Digital Out and Headphones whenever you plug in and unplug headphones. Has anyone seen anything like this before? I find the audio switching circuit to be a maze so I'm not sure where this might be failing.

 

[larossmann]

If you remove R6805 does it switch between speakers and headphones or does it consistently work on speakers, and consistently work on headphones?

 

[bjf]

It just stays on Internal Speakers. Unplugging and plugging the headphones in no longer affects anything.

 

[bjf]

Any thoughts about this? I'm trying to follow where you're going, to realize the significance of this result, but I'm not there. I'm assuming this is to isolate whether it's the jack (or damaged jack circuit/area) or the switching circuitry itself, but I'm not sure what this is telling me.

 

[larossmann]

I feel like this is a fucked up jack(the donor board jacks off aliexpress are often shit) or some component that was knocked off during jack replacement. Removing that resistor removes digital output in the switching process but should still switch between headphones and speakers. My guess is on the jack.

 

[bjf]

Ok, got it, thanks, i was very careful but who knows about the condition of the jack. I'll switch it out again. Thanks for the tip.

 

[bjf]

No change with another new jack. If anyone has some basic concepts to share about the headphone circuit I would be greatly appreciative. I'm trying to figure out the paths but it's an absolutely confusing maze. Tips like the one above about removing R6805 to isolate the digital function go a long way to understanding the way this thing works.

 

[dukefawks]

OK, so with nothing plugged in everything works fine? When head phone plugged in it switches between digital and headphone? Need to be absolutely exact here.

 

[bjf]

It was random before. I could have speakers working, plug in headphones, they would work, unplug them, it says Digital Out. So I would lose speakers. But other times I could unplug the headphones and I would get speakers after. I cannot pick up a pattern and don't believe there is one.

Once I removed R6805 it stayed on Internal Speakers. Plugging in headphones changed nothing. I replaced the headphone jack again (from my boards, not purchased boards) and I'm getting the same thing. Let me know if you have any ideas. I just printed up those pages of the schematic and I'm going to try to sit and map this out. I need to understand this circuit.

 

[dukefawks]

Did you put back R6805?

 

[bjf]

No, not yet. According to Louis's post above it should be switching between headphones and speakers with that removed. It's not doing that so apparently we're still having an issue with the switching.

 

[dukefawks]

Voltage on pins 2 and 5 of Q6801 and 6805, voltage on pin 1 of Q6800. Test those with and without a headphone plugged in.

 

[bjf]

Ok, this is with R6805 still removed.
Unplugged:
Q6801 Pin 2: 4.4V
R6805 Pin 2: Slowly rising from around 1.5V
Q6800 Pin1: Slowly rising from around 0.065V

Plugged In:
Q6801 Pin 2: 0V
R6805 Pin 2: Slowly rising from around 5V
Q6800 Pin1: Slowly rising from around 0.048V

 

[dukefawks]

Pin 1 of Q6800 should be high with something plugged in. What are voltages on pin 2 and of Q6804 with phones plugged in?

 

[bjf]

4.5V on pin 2 of Q6804 plugged in (and unplugged also.)

 

[bjf]

You got me there. So appreciative. After seeing that pin 2 of Q6804 was off I went over to pin 5 and saw that it was lingering in a range around 1.7V. Checked R6802 and R6807 and found R6802 was open. Switched it out and we're back in business. Thanks again for working me through this.