Alpine PDX1.1000 powers on, no audio (IR2010s HELP)

[mild2wild]

Yes. Nothing but DC on the collectors.

 

[Perry Babin]

Q310

 

[mild2wild]

Yes, that is what I tested. Results are in post #59.

 

[Perry Babin]

Did you pull Q303/304 to see if they had open junctions?

 

[mild2wild]

Q303/304 did not survive removal as the emitter legs of both detached. I don't have 2n5400 so I replaced them with 2n5401. The scope readings are exactly the same.

 

[mild2wild]

What next?

 

[Perry Babin]

Lift terminal 1 of IC304/306. Does that allow you to see a signal on the collectors of Q303/304?

 

[mild2wild]

With pin 1 of both IC304/306 lifted, there is no change, still DC on the collectors of Q303/304.

Is the signal supposed to be getting through D361/362? I see audio on the collectors (terminal 3? The side with the single tab?) but nowhere downstream in the circuit. It may be nothing but I don't even know what kind of smd diode it is... The side with the two tabs have them joined together. The diode has a K on it.

What next?

 

[mild2wild]

With pin 1 of both IC304/306 lifted, there is no change, still DC on the collectors of Q303/304.

Is the signal supposed to be getting through D361/362? I see audio on the collectors (terminal 3? The side with the single tab?) but nowhere downstream in the circuit. It may be nothing but I don't even know what kind of smd diode it is... The side with the two tabs have them joined together. The diode has a K on it.

What next?

Below is a pic of the diodes.

 

[Perry Babin]

I don't see those diodes.

What is the negative rail voltage in the amp?

Are either D 305 or D306 shorted?

 

[mild2wild]

Negative rail voltage is-56.4. Positive is 59.8. I wish I knew why they were uneven....

Neither D305 or D306 are shorted.

Better pics of the diodes are posted.

 

[Perry Babin]

Was D361/362 a typo?

 

[mild2wild]

Is that D301/302? The writing looked a bit unclear so I was thinking it was D361/362...

Another funny thing is that while testing those diodes, most of the time the signal does not pass through and the scope shot looks like pic1, but a few times when I touch to the side with two tabs, I saw a waveform, like pic2

 

[Perry Babin]

I think you're losing your ground and are seeing 60Hz mains noise.

 

[mild2wild]

That would make sense since I am having an issue right now where I am seeing a waveform, even without RCAS plugged bin, or no signal. I will recheck my ground.

What to do next?

 

[mild2wild]

Ground is fixed, ready to proceed.

 

[Perry Babin]

What is the DC voltage on the collector of Q303/304 with the black meter probe on the negative rail?

Also post the negative rail voltage to verify that it has not changed.

Where are you placing the black probe when measuring rail voltage?

 

[mild2wild]

With black probe on negative rail:
Q303 collector 4.8v
Q304 collector 5.9v

With black probe on amp ground terminal:
Negative rail -56.53

Where should I put the black probe to measure rail voltage?

 

[Perry Babin]

I have to think about this. It looks like (with the meter) that you're getting drive on the collector but there's nothing there with the scope.

The probe placement shouldn't matter on this amp but you could try using both the primary ground (ground terminal) and the secondary ground to see if there's a difference.

 

[mild2wild]

The drive on the collector is supposed to do what exactly?

The emitter and base both have a square wave on them. Is that not supposed to be there?