Onkyo TX-NR616 won't stay powered on

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

When measuring voltage on transistor Bases in an output stage, its useful to measure the difference voltage and the Common Mode voltage wrt Ground.
The difference voltage has a large affect on the idle current through the final transistors.
The common mode voltage affects the output DC which we want to be within 50mv of zero volts.

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

The measurements you took last week indicated that the amp was balanced. It seems to be unbalanced now. Did you leave the link from C5446- to NFSBR9 ?

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

I have to measure from the ground to each base? The voltage rises slowly.

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

I didnt expect the Common Mode voltage at the Bases to rise that much. Take readings at +BSBR23 and -BSBR22 also.

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

Between bases at the bad channel, I'm getting 2.4V
The good channel, I have to measure tomorrow.

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

So not from the ground to the bases. Between bases right?
From ground I'm getting ~23V and ~24V slowly rising to these voltages.
The amplifier stays on.
There is no room to measure, I'm soldering wires those the points that I have to measure.
"you can carefully measure this voltage in the good channel", if I understand correctly, I have to measure between bases on a good working channel, for comparison right?

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

So at the bases of those two transistors should be 2V?

The voltage measured between the Bases should be about 2v. If the amplifier stays on, you can carefully measure this voltage in the good channel.

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

So at the bases of those two transistors should be 2V?

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

Check the bias circuit next by removing the short across Q5416.
The bias circuit is supposed to control the voltage difference between the bases of Q5436 and Q5446 to some precise voltage of around 2v.
Its when this voltage goes too high that all the transistors turn on heavily and cause damage.
Put a 5.6v zenner doide or a 1K resistor from C to E on Q5416 and take some voltage measurements.
The finals must not be fitted yet.

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

What would be the next step?
My next receiver will be a Yamaha HTR-4065. There is only a blinking power LED when turned on.

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

Yeah, it's around there. Slowly it's creeping up though.
Tomorrow I will continue.
Thank you very much for today. I appreciate it a lot.

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

yes

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

I just have to place both meter leads across each resistor?

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

So, I did those connections and nothing blew up.
Where should I measure the output, at +BSBR23 AND +BSBR22?
If yes, then at those points I'm measuring -.001V/-.003V.

They are the correct places to measure for zero volts balance.
Next, I would like to see what the voltage amp stage's bias current is. Can you measure the voltage drop across R5166 and R5226?
Should be about 0.8v if my did my sums right.

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

So, I did those connections and nothing blew up.
Where should I measure the output, at +BSBR23 AND +BSBR22?
If yes, then at those points I'm measuring -.001V/-.003V.

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

All the burned components are already replaced. I will have to remove the finals then.
What we are trying to accomplish with these modifications?

First we want to see that the output will balance to zero volts.
If all looks ok without the same resistors burning out again, we can then have a closer look at the bias circuit for problems.
The short between C and E on Q5416 makes the bias circuit safe for now.
The idea is to be certain that all is ok including the bias circuit before the finals are connected.

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

All the burned components are already replaced. I will have to remove the finals then.
What we are trying to accomplish with these modifications?

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

Connect NFSBR 9 to the - of C5446.
Short C to E of Q5416.
Replace the burnt resistors you noticed earlier and check all 4 driver transistors for shorts.

[rievax_60]

Re: Onkyo TX-NR616 won't stay powered on

Yes, remove or disconnect the output transistors first.
We also need to close the feedback loop to enable the amp to balance itself. I need to think about this a bit more,

[tibimakai]

Re: Onkyo TX-NR616 won't stay powered on

I haven't installed back the pre-amp board. I'm afraid that I will blow it up if I would install it and turn it on.
Should I remove the the final transistors and then turn it on?