I now replaced all the parts removed with new ones, got resistors from the local shop.

So i have 0.6W resistors in R330 and R332, and a 0.125W resistor in R324 .. i might replace that one later with a higher wattage, (0.25W) ...but i guess the ones with 0.6W resistors are fine...

Power ON!

Stable, no smoke or draw, measured 0 Volt at both R330 and R332

All LED's in the front panel lit up and some small relays are clicking, it went in to balance input so the signal disappeared, then i put that little button on and switched to unbalanced, then i got 1khz signal i can adjust up and down with the volume knob on both R330 and R332.

 

That's good news. What you will do next is rejoin jumper J224 (R-CH).
Test the voltage at R450 and R452.
Expected voltage is 0V.
Again, we are looking for clean sine waves centered on 0V.

 

I rejoined J224

Power ON.

Measured voltage at R450 and R452, 0 Volt

Tested signal, looks good, see attached video. Same on both resistors.

 

Great! You are making good progress.
I am assuming that all the components in the RIGHT channel x4 section are installed including IC402.

Go ahead and install all components in LEFT channel x4 section.
Reconnect jumper J222.
Do the same test on the LEFT channel and measure the voltage at R449, R451.
Expected voltage is 0V.
-------------------------
After you have checked both channels x4 section, it is time to test the x5 sections.
On RIGHT channel, are all components installed?
Q508/Q510 is a push-pull pair.
Q516/Q518 is another pair.

If all four transistors are already in place, leave them in.
If not in place, install one pair only.

Perform the voltage test and sine wave test as you have been doing.
Test voltage at
TP502 +
TP502 -

Expected voltage is 0V.

 

Great! You are making good progress.
I am assuming that all the components in the RIGHT channel x4 section are installed including IC402.
-------------------------
On RIGHT channel, are all components installed?
Q508/Q510 is a push-pull pair.
Q516/Q518 is another pair.

I’ll go ahead and install X4 LEFT!

All components in X4 circuit RIGHT channel are in, except C425...

In the X5 RIGHT section all the power transistors are out at the moment.

 

Just a question before proceeding. After i complete X4 circuit LEFT, should i reconnect J121 and J219 before turning power on?

i might also check if that section is stable at first, without the front pcb, just to be sure?

 

Yes. Connect J121 and J219.
I would go ahead and test both LEFT and RIGHT channels x4 section with the front pcb plugged in.

 

So i reconnected jumper, J222,J121 and J219

Completed X4 LEFT circuit.
Plugged in front PCB

Power ON.

No power draw, or smoke

Measured:
R449, R451: 0 VOLT
TP502+: 0 VOLT
TP502-: 0 VOLT

Connected 1khz sine wave, tested at R449 and R451, and i got signal at both !


Just added a picture of the X4 complete

 

OK.
Which transistors are installed in RIGHT channel x5 section?
Q508/Q510 pair?
Q516/Q518 pair.?

Now do the same for LEFT channel x5 section.
Q507/Q509 pair
Q515/Q517 pair
Measure voltage at
TP501 +
TP501 -
Expected voltage is 0V.

You are at the final testing stage.
Do you have an old 8Ωspeaker that can be used for testing?

(Just remember that we still have to do some bias adjustments.)

 

I have enough of old speakers so that's not a problem.
None of the X5 power transistors are in.... LEFT or RIGHT.
But before putting in any of these, i remember i found numerous resistors being open, shouldn't i examine that first?
Also at LEFT side, Q505 and Q503 are out...

 

We are out of sync. Maybe I am going too fast.
You said in post #628 that the voltages at TP502 are 0V. This has no meaning if the x5 section is not active.
I had assumed that you had installed the components in the RIGHT channel x5 section as per my post #624.
Perhaps I need to slow down.

You are doing very well and you are on to the final stages.
Let us check components on both LEFT and RIGHT channels.
Did you purchase replacements for the white power resistors 0.22Ω 2W?

You can check all of these resistors in-circuit while some of the transistors are out.
(Just remember that numbers ending in odd number are in LEFT channel, even numbers in RIGHT channel.)
R509 680Ω
R510 680Ω
R511 680Ω
R512 680Ω

R513 330Ω
R514 330Ω

All 2.2Ω
R515
R516
R517
R518
R565
R566
R567
R568

All 0.22Ω 2W
R547
R548
R549
R550
R569
R570
R571
R572

Install
Q503
Q505
Q507
Q509

Power on and test voltages at TP501
TP501 +
TP501 -

 

We are out of sync. Maybe I am going too fast.
You said in post #628 that the voltages at TP502 are 0V. This has no meaning if the x5 section is not active.
I had assumed that you had installed the components in the RIGHT channel x5 section as per my post #624.
Perhaps I need to slow down.

You are doing very well and you are on to the final stages.
Let us check components on both LEFT and RIGHT channels.
Did you purchase replacements for the white power resistors 0.22Ω 2W?

yees, might to fast right now..

I believe we sat the X5 section aside earlier when the smoking of components in X4 LEFT channel appeared.
But yes, RIGHT X5 was merely complete earlier, but i removed the power transistors.. because of some measurement we did....

And about the voltages at TP502, i measured from GND to TP502+ and TP502- , i got 0 volt when power was applied.
Inconsistency ? I have to check again...

No i haven't ordered the ceramic resistors yet, plan was to find "all i would need" before i placed an order, so it's been a little delayed

I will need to check the resistors you listed and get back

 

And about the voltages at TP502, i measured from GND to TP502+ and TP502- , i got 0 volt when power was applied.
Inconsistency ? I have to check again...

No need to check. I do not see an inconsistency.
We check TP501 and TP502 once you have at least one push-pull pair of transistors installed at the output stage.
We will wait for the power resistors to arrive.

 

Okey.
Measured the resistors you listed, most of them measured ok in circuit.
R547,R548,R569,R570 are open, so i need four of the ceramic 0.22 ohm resistors.
Seems like it's the only component i'm missing at the moment to complete the circuit.

Also, R515,R517,R567, are open circuit, but i have new ones in stock.

Could you help me finding suitable replacements at digikey ?

 

Lots to choose from but not in the same package as the original resistors.

https://www.digikey.com/product-det...onents/AC03000002207JAC00/BC3426CT-ND/7350856

 

Ordered the 3 watts in your link, also new thermal pads for the to-3p transistors, because i'm missing some.

 

I was about to mention that when you install the power transistors make sure that they are not grounding out to the metal plate. The thermal pads are also electrical insulating pads.
Spread a thin film of heat sink compound on both the back of the transistor and the metal plate.
Use the ohmmeter to check that the transistor is isolated from the metal plate if the transistor tab is exposed metal.
Usually the tab is also the collector.

 

Yes, i have never mounted the power transistors without the pad.
Got parts from digi-key today, their shipping is really fast.

The thermal pads i ordered were really thick... made of ceramic... not bad i guess..... but not as i thought they were.

Soo plan is now to replace all the open resistors i found... and also replace R505/R506 with resistors?
Or still keep the 21W bulbs?

 

We are still in the testing stage. Leave all three bulbs installed for now.

 

Ready to power on.
Has replaced all open resistors i earlier found, mentioned in #634, and installed new Q503 and Q505,
Also installed Q507 and Q509..... but Q501 is still out, should this be installed before power on ?