Also note, the same 10R0 resistor that failed before, has failed again.
I checked with the ohm meter and it reads in the 200's. All other re-installed resistors (the 100s, and the other 10R0) were checked for resistance and short, and are ok.

 

Ok, thanks.
That looks like a 100nF decoupling capacitor.
Unsolder the capacitor and try again.

 

Photos of IC removal and resistor that failed again. The one with burn marks I shared above still has resistance as other similar types of decoupling capacitors on board.

 

Ok, thanks.
That looks like a 100nF decoupling capacitor.
Unsolder the capacitor and try again.

I will do so on my break at noon.
I need advice. My concern is risking a short to the motherboard.

What should I do to avoid damaging the motherboard?

 

I believe I have a multi-voltage AC to DC adapter that fits in the wall socket. Can I use that as a source of 12 volt to check the Audio IO instead of plugging it into the motherboard?

 

From where does the Analog Input Output board get its power? Is it from the Motherboard?

I cannot give you any assurances from where I am sitting. However, I am confident that we are looking at a power supply problem on the Analog board that is unlikely to feedback to the Motherboard.

 

From where does the Analog Input Output board get its power? Is it from the Motherboard?

I cannot give you any assurances from where I am sitting. However, I am confident that we are looking at a power supply problem on the Analog board that is unlikely to feedback to the Motherboard.

The Analog IO get power from the motherboard. There are pins that plug into the IO coming from the motherboard.

 

In parallel to here, I have sent a request to an audio store and here are their notes. I am not sure where on the board are they referring to, can you understand their notes?


Below are notes from our technician,

"Alright, from what I see, the resistors at R34 & R35 have the +/-15v audio rails for the ADC. They are isolated from ground via the resistors that seat directly behind them at C46 & C47. I surmise that the caps have failed and are shorting the voltage rails to ground."


Res. AH-AC6599 10ohm
Caps. AH-AF5235 10uf 16v
ADC: AH-AE7184

 

He is not stating anything new that we do not already know.

There is a short across the -12V (or -15V) supply lines.
Check it with an ohmmeter to confirm. Don't bother to check all the capacitors because they are all connected in parallel across the rails.

Find and remove the faulty capacitor and hopefully your problem is fixed.

Did your remove the chip capacitor and test again?
Or did you check across the chip capacitor after removing it, both the chip itself and across the capacitor pads?
I have never seen a chip capacitor go bad but anything is possible in electronics.

I will be away for awhile.

 

Ok. Can you please help where on the board to check for this short? I couldn't follow the numbers they stated in bold below.


" R34 & R35 have the +/-15v audio rails for the ADC. They are isolated from the ground via the resistors that seat directly behind them at C46 & C47. I surmise that the caps have failed and are shorting the voltage rails to the ground.

Also where are these?
Res. AH-AC6599 10ohm
Caps. AH-AF5235 10uf 16v
ADC: AH-AE7184


I have not done this yet.
"
Did your remove the chip capacitor and test again?
Or did you check across the chip capacitor after removing it, both the chip itself and across the capacitor pads?
I have never seen a chip capacitor go bad but anything is possible in electronics. "

 

These are Allen Heath specific designations...nvm
Res. AH-AC6599 10ohm
Caps. AH-AF5235 10uf 16v
ADC: AH-AE7184

 

The component ID numbers R34, R35 and C46, C47 are the same components with which you have been struggling, the two 10R0 resistors and the capacitors beside them.

Measure the resistance across the two capacitors, reversing the meter leads a second time.
This test does not identify any single bad capacitor because you are measuring across about a dozen other components.

 

I'm resuming work on this now.
I just want to clear one check. With the LOGIC IC removed and everything else ok, the shorts found earlier should not happen, is that correct? I want to rule out that removing the IC did not contribute to the short.

 

I took these caps out and measured capacitance. Do these value tell you anything?

 

The purpose of removing the CS5368 is so that it does not interfere with our next tests.
If the next tests fail we know for certain that the CS5368 is not the cause of the failure of the tests simply because it is not present in the circuit.

It does not tell us if the CS5368 is the cause of the failure in the first place. We have to wait until all the evidence is in before we can cast a verdict.

 

I took these caps out and measured capacitance. Do these value tell you anything?

No. I did not ask you to remove those capacitors.
I asked you to remove the suspect chip capacitor and to measure the resistance across the chip capacitor and the resistance across the vacant pads from where the capacitor came.

At this point we are not interested in capacitance values. We are interested in resistance values across the capacitors.

 

No. I did not ask you to remove those capacitors.
I asked you to remove the suspect chip capacitor and to measure the resistance across the chip capacitor and the resistance across the vacant pads from where the capacitor came.

At this point we are not interested in capacitance values. We are interested in resistance values across the capacitors.

Ok.
I removed the decoupling capacitor from this spot and tested for continuity. It beeps when continuity.
Or has zero Ohm reading stating OL.

 

Ok.
I removed the decoupling capacitor from this spot and tested for continuity. It beeps when continuity.
Or has zero Ohm reading stating OL.

OK. This capacitor is shorted. Keep it off the board.

Install the two 10R0 resistors.
Apply power and check for smoke and hot spots.

 

resistance across the vacant pads from where the capacitor came.

The measurement across the vacant pads where that cap came from is 8.9 Mohm and 19Mohm when switched the probes.

 

We did not have a chance to discuss solder and soldering techniques.
It would help me if I saw a photo of your soldering iron station or at least the make and model.

You need some solder wick and a flux dispenser.
You should use both to clean up any pads before reinstalling any component. Also do this to make sure that there are no solder bridges.

You should avoid using lead-free solder. Use 63/37 Sn/Pb solder with a rosin core.

If you have questions about soldering technique, don't be afraid to ask.