Directed 650 5 channel amp

[mike49504]

I got this amp in for repair. The problem im having is the Output thats outlined has 22 volts on the first leg and 22 volts on the second leg and 0 volts on the 3rd leg . The driver thats circled has 26 volts on all 3 legs And the resistor that connects to the driver gets so hot it desolders itself from the board.

Any ideas on where to begin looking?

 

[Perry Babin]

Photo?

 

[mike49504]

sorry thoght i put one in there

 

[Perry Babin]

Can you post a photo of the bottom of the board covering the same section of the board?

 

[mike49504]

Heres a pic of that section of board. I removed the output (tip 36) and the arrow points to the driver of that output

 

[Perry Babin]

I'd suspect that Q209 or Q211 is leaking or shorted.

 

[mike49504]

Replaced Q209 same thing . I dont see a Q11

 

[Perry Babin]

Q211.

 

[mike49504]

sorry meant Q211 i dont see it

 

[Perry Babin]

It may not be reading it correctly. It's next to Q207.

Left to right, what are each of the output transistors (TIP35/36)?

 

[mike49504]

From left to right.

TIP36,35,36,36,36,36,36

Other side of amp
Tip36,35,36,35,35,35,35

 

[Perry Babin]

Are you sure that the fourth one on the top row shouldn't be a TIP35?

 

[mike49504]

If i put a tip 35 in the fourth spot the amp will draw excessive current.

How do i tell on which output goes where?

 

[Perry Babin]

The collectors of all of the 35s should be connected together. The collectors of all of the 36s should be connected together.

 

[mike49504]

ok in the fourth spot it has positive voltage on middle pad and thats connected to the middle pad on the other tip35 so im guessing the 4th one is suppose to be a tip 35.

Theres no Q207 in this amp either.

 

[Perry Babin]

I can't read these clearly. What are they?

 

[mike49504]

Q211 And Q207

Q207:C3200

Q211:TIP36

 

[Perry Babin]

Now you're back to checking the driver transistors in that channel. Also check the bias transistor (Q207).

 

[mike49504]

Bias transistor (C3200)

1-2:OL
1-3:OL
2-3:32.41K

Probes reversed

1-2:OL
1-3:0.620 and meter goes crazy up and down with readings
2-3:23.90K

Does this apper to be defective?

 

[Perry Babin]

It doesn't look normal. Either pull another one and compare or post the same thing on diode check.