2 minute video question

[ln76d]

Great job, now wee see something

Both resistors (yes they looks like 27ohm) from psu on negative and positive rails replace with jumpers on each channel.
Do you have spare ne5532? If so, replace it on channel 2. If not, don't connect channel  2  to tests.

 

[ReRibbon]

Thanks

Let me make sure Im understanding this next process.Am I to remove the burnt resistor  (and every other resistor in that position on each channel ) and replace them with a jumper?
Both resistors?  This confuses me. I dont understand.

Would it be bestter to just replace the burnt resistor and that 5532?

 

[ln76d]

Look at the top of your PCB where the burnt resistor is.  This resitor is in the PSU -V path. Under it (placed in parallel) is the same value resistor in the +V PSU path. You need to remove both and replace with jumpers - on every channel.
Those resistors are probably your issue. After removing it and replacing with jumpers your VU meters should work properly, if there's no other faults.
If you have spare NE5532, replace it on channel 2, if not don't connect this channel right now for tests.

 

[ReRibbon]

Ok.

Out of curiosity,  why notvjyst replace that resistor andvop amp?

 

[ln76d]

Look for updated previous post. Those resistors can't be there if you want to use NE5532 instead LM833N

 

[ReRibbon]

Also wondering please, what is it that made the op amp hot? Why inky that one and not the rest?

Additionally,  is there enough of a tonal improvement  by replacement of the 833n by the 5532  that would warrant me going through the trouble of installing jumpers rather than just pooping the 833's back into the sockets?

 

[ln76d]

Also wondering please, what is it that made the op amp hot? Why inky that one and not the rest?

With such marginal  informations i can't say why. Maybe it's damaged? Usual all should similar hot, due too current limiters in the path. Maybe in this channel is something different and because of that it suck more current. It's like you will drive the car with parking brake.

Additionally,  is there enough of a tonal improvement  by replacement of the 833n by the 5532  that would warrant me going through the trouble of installing jumpers rather than just pooping the 833's back into the sockets?

No.
Yes.
I don't know. 
No warranty included.
It was your idea.
I can say that i hear the difference and nine persons could admit that.
Another ten would say that there's no difference.
Another ten - that it's only auto - suggestion.
In different circuits you can hear more difference and sometimes completely no difference.
It depends on the rest of the circuit too, not only one opamp.
Finally. How long time ago did you do hearing test? Did you ever done?

Logical would be to make one channel with NE5532 (without resistors) and the other leave with LM833N to make comparision...

 

[ReRibbon]

Just finished putting jumpers in and replaced the op amp on 2. Fired it up to check voltage. Pin 4 and ground read -16.76 and pin 8 reads +17.43.
THEN, tge 5532 on channel 6 starts to smoke. I turned off the board immediately. I wasn't even working on channel 6.

VU meters still stay spiked and still no audio. Am at a total loss.

 

[synthiaks]

You should start checking the power. The VUs spike and burnt resistors on the power traces sound like power failure to me. Put the original ICs back, Be 100% sure they sit the way they should. Go back and check ALL the caps you put in there are they the right way? Is the PSU giving the right Voltage. Try this without any Strips in the board. Be sure the Caps are the right value and voltage. If not have they shorted to ground? Check for any other possible short. Beep your way around the PCBs first to see if you can find something that seem strange.

keep away from powering the mixer up before the problem is found.  And do NOT change burnt resistors to jumpers without knowing what you are doing and why.

And find the schematic

 

[ln76d]

Just finished putting jumpers in and replaced the op amp on 2. Fired it up to check voltage. Pin 4 and ground read -16.76 and pin 8 reads +17.43.
THEN, tge 5532 on channel 6 starts to smoke. I turned off the board immediately. I wasn't even working on channel 6.

VU meters still stay spiked and still no audio. Am at a total loss.

Ehh...

Maybe i wasn't clear previous, i don't know...
Again...
If you want  to test any channel with ne 5532, you need to replace resistors with jumpers...
If you replaced it only on one channel, disconnect all other channels from power supply for tests...
This doesn't change anything when you put jumpers only on one channel, when on the rest not.
Even one channel with ne5532 and these resistors is stressing for the whole power supply.
Make one channel with ne5532 with jumpers and other with lm833N and resistors and connect only those two channels to power supply! Then make tests!

 

[ln76d]

You should start checking the power. The VUs spike and burnt resistors on the power traces sound like power failure to me. Put the original ICs back, Be 100% sure they sit the way they should. Go back and check ALL the caps you put in there are they the right way? Is the PSU giving the right Voltage. Try this without any Strips in the board. Be sure the Caps are the right value and voltage. If not have they shorted to ground? Check for any other possible short. Beep your way around the PCBs first to see if you can find something that seem strange.

keep away from powering the mixer up before the problem is found.  And do NOT change burnt resistors to jumpers without knowing what you are doing and why.

And find the schematic

There is marginal possibility that reversed electrolytic capacitor will not explode or wouldn't be visible bulging.
I've posted twice, that he should measure whole PSU secondary side...
If he want to use or even check any of the channel with  ne5532, those resistors must be jumpered.
There's no way to find schematic.

Resistors for sure are current limiters.
Example:
Two channel mike preamp - 4 opamps changed from TL072 (max 5mA) to OPA2134 (max 10mA), there is a lot of other opamps in the circuit, led vu meters,  current limiting resistors. After replacing only four opamps - PSU transformer buzzing/vibrating, VU meters were indicating up to the middle of the scales even when gain/out potentiometers were set to "zero" and no signal, all OPA2134 where hot as hell. There was a sound but little bit distorted. After jumpering current limiter resistors everything works as it should be.
These affect each opamp, even those in meter drivers, that's why VU are going crazy.

 

[ReRibbon]

The jumpers were installed on every channel.
It had been asked that I measure the secondary of the power supply. I am not sure where is being talked abiut to be honest. Is it in reference to the actual secondary of the PT or to the place at the end of the power supply  (the part that connects to the mixer itself).

Unloaded voltage? I did a google search for that and found no instructions. I have a fluke 77 that im working with. No Oscope.
guess I'll just make a pot of coffee and take it from the top.

 

[ln76d]

The jumpers were installed on every channel.
It had been asked that I measure the secondary of the power supply. I am not sure where is being talked abiut to be honest. Is it in reference to the actual secondary of the PT or to the place at the end of the power supply  (the part that connects to the mixer itself).

Unloaded voltage? I did a google search for that and found no instructions. I have a fluke 77 that im working with. No Oscope.
guess I'll just make a pot of coffee and take it from the top.

Sorry but my english sucks
You need to disconect whole PSU secondary side, this side where cables are going to the modules.
So, disconnect the cables and measure DC voltage (20V or 200V range)  on each pin - refered to ground.

Back to the previous tests, the best option is starting testing with only one or max. two channels connected to the power supply.
After you changed opamps to the ne5532, you could damaged something else...
So best option is  - measure PSU, connect one channel and check only that one channel for different issues...
If you will be checking PSU, with the beeper for example, don't touch any electrolytic capacitor leads/soldering points with the fingers!

 

[ReRibbon]

Back to the beginning. 

On one channel,  i put the resistors back as well as the original op amp. It is the only channel hooked up. Power on, VU meters spike. Ok. Its got to be in the power section. ...

On the PSU, the DC from ground to the outside +V pin reads +.323. Ground to the -V reads 0 (but reads). +V pin to    -V pin  also reads +.323.

Issue must be somewhere in the PS...

****....
Coffee and cigarettes for me please.

 

[ReRibbon]

PSU reads .294 and .312 ground to each V.
Am moving on to the module...

 

[ln76d]

What you measured? 
On the opamp you get circa 17V on 4pin and 8 pin.
So what is  .294 and .312? How it is possible?

 

[ReRibbon]

That is the unloaded DC voltage measurement of the PSU at the last point on the PSU (where the power c able leaves the PSU after being filtered through the PSU caps etc., and goes to the board).

 

[mjrippe]

That is the unloaded DC voltage measurement of the PSU at the last point on the PSU (where the power c able leaves the PSU after being filtered through the PSU caps etc., and goes to the board).

Your unloaded DC measurement will be AT LEAST as high as what you measured at the opamp pins, likely higher, unless the power supply needs a minimum load on it to regulate properly. 

 

[ReRibbon]

Hmmmmmm. Did i measure at the right place? If so, should i remeasure with the PSU plugged in to the wall?

 

[synthiaks]

Oh yes, but be VERY careful. You can die from that stuff.

There is marginal possibility that reversed electrolytic capacitor will not explode or wouldn't be visible bulging.
I've posted twice, that he should measure whole PSU secondary side...
If he want to use or even check any of the channel with  ne5532, those resistors must be jumpered.
There's no way to find schematic.

Resistors for sure are current limiters.
Example:
Two channel mike preamp - 4 opamps changed from TL072 (max 5mA) to OPA2134 (max 10mA), there is a lot of other opamps in the circuit, led vu meters,  current limiting resistors. After replacing only four opamps - PSU transformer buzzing/vibrating, VU meters were indicating up to the middle of the scales even when gain/out potentiometers were set to "zero" and no signal, all OPA2134 where hot as hell. There was a sound but little bit distorted. After jumpering current limiter resistors everything works as it should be.
These affect each opamp, even those in meter drivers, that's why VU are going crazy.

This is good information and i will remember this if i would ever change ICs in a mixer.

What i wanted to suggest though was that he should go as far back as he can to the original to narrow things down. Putting jumpers where burnt resistors was isnt a safe way to check a faulty circuit. It is MUCH better to put the original ICs back ( the right way around..) and check if the strip works like that. If so, well we have found the problem, if not Well the Jumpers wont help much

I still suspect something went wrong in the recapping process,