Orion 250sx with BJT on power supply

[Perry Babin]

The electrolyte is sometimes difficult to remove.

Check the entire audio section. It only takes a minute or so.

Were there any traces that passed near the terminals of the bad caps?

 

[picco76]

The electrolyte is sometimes difficult to remove.

Check the entire audio section. It only takes a minute or so.

Were there any traces that passed near the terminals of the bad caps?

I use normally diluent to remove electrolyte. Yes, i have found electrolyte on 1000uf bad caps, i will check all audio section

 

[picco76]

No problem around all capacitors..
I have noted one thing, with 2.7 ohm lifted (bad channel), i have on pin7 of the last op-amp -13,15V, is normal or abnormal situation?

 

[Perry Babin]

Did any traces pass between the terminals of the bad capacitors (top or bottom of the board)? The electrolyte can saturate the board and conduct below the surface.

It could be normal. Post the DC voltage on all terminals of the op-amp.


Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:

 

[picco76]

Did any traces pass between the terminals of the bad capacitors (top or bottom of the board)? The electrolyte can saturate the board and conduct below the surface.

It could be normal. Post the DC voltage on all terminals of the op-amp.


Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:

With or without 2.7ohm resistors lifted?

 

[picco76]

I have noted same pop on the other channel, but very very light

 

[picco76]

It could be normal. Post the DC voltage on all terminals of the op-amp.

Pin 1: -0.06V
Pin 2: -0.003V
Pin 3: -0,003V
Pin 4: -14,9V
Pin 5: -0,003V
Pin 6: 0V
Pin 7: +0,07V
Pin 8: 14,80V

If i lift the 2,7ohm resistors, on pin1 have 14V and on pin7 have -13V

 

[Perry Babin]

What happened to the offset that you had on one output channel of the op-amp in post 43?

 

[picco76]

when i power on have -0,35V, but after 2-3 sec goto -0,003V

 

[picco76]

canal with problem is PIN7

 

[picco76]

i could put muting fet on last op-amp output? can work for you?

 

[Perry Babin]

It's already on the input to the last op-amp.

When you shorted the muting transistors, did you short 1-2 of the transistor itself or did you short the square pad to the center pad/terminal?

 

[picco76]

It's already on the input to the last op-amp.

When you shorted the muting transistors, did you short 1-2 of the transistor itself or did you short the square pad to the center pad/terminal?

Pin1-2, drain with source pins.

 

[Perry Babin]

Well, I'm out of suggestions at this point. If I think of something else, I'll post it.

 

[picco76]

I think.. but can be normal this pop? I have 3x orion amplifier, 240gx, 280gx and 250sx all with a pop on power on, this is strange..

 

[Perry Babin]

The newer amps use an NJM4562 as the final op-amp. It may be quieter.

 

[picco76]

Have the same pinout? Can i try to change?

 

[Perry Babin]

Look up the datasheets.

 

[picco76]

I have also op275 op-amp, with the same pinout, It may be quieter of 5532?

 

[Perry Babin]

Install a socket and try any op-amp you'd like.

Don't confuse a low noise figure with low turn-on noise. Better in some regards may not mean better in this application.