Soundstream XXX6500

[mike49504]

PIN8:-120.2

PIN9:-120.1

PIN14:-120.1

 

[Perry Babin]

What is the DC voltage on each side of R18?

 

[mike49504]

1 side:-120.2

Other side:-93.1

Can i use the MJE171 or 181 as a sub for the MJE172 thats defective just to trouble shoot the amp?

 

[Perry Babin]

If R18 isn't so hot it's melting the solder on its leads, it's likely open. Is ZD1 shorted?

 

[mike49504]

ZD1 is shorted.

 

[mike49504]

If i replace that diode am i gonna have problems since that 1 driver is shorted?

 

[Perry Babin]

Yes. The amp is likely to draw excessive current and possibly blow the outputs if you power up the amp with the PNP driver out of the circuit. It probably hasn't done it yet because the driver circuit hasn't had the proper supply voltages.

 

[mike49504]

Can i sub the MJE172 with a MJE171 or 181 for now to trouble shoot?

 

[Perry Babin]

I think the 171 should be OK.

 

[mike49504]

Do you know what part number ZD1 is?

I pulled a 1n4746A from its location but im not sure if that is the correct part number since someone had already messed with it and installed it backwards.

 

[Perry Babin]

That's the right part (18v Zener). The striped end should connect to the 330 ohm resistor.

Was the 330 ohm resistor open?

 

[mike49504]

It measures 328.1 out of circuit

I have to wait til monday to get a diode since i dont have one right now all i have is 4753's 4744's 4742'2 4755's And not sure of any of thoose will work

 

[Perry Babin]

I don't know how it's being used so I don't know if any of these will work. If I had to choose, I'd say use the 4744.

 

[mike49504]

Ok back to this amp.

I went and got a new diode today and replaced the defective one.

The drivers i pulled out for the outputs are MJE172 and MJE182

I just want to confirm if theese are defective or not.

MJE172
1-2:OL
1-3:OL
2-3:0.023

Probes reversed
1-2:OL
1-3:OL
2-3:0.021

MJE182
1-2:0.476
1-3:OL
2-3:OL

Probes reversed
1-2:0.476
1-3:OL
2-3:OL

 

[Perry Babin]

They both appear to be defective.

 

[mike49504]

so for testing only can i use the MJE181 in place of the 182 for now?

Im gonna use the 171 inplace of the 172 for testing more

 

[Perry Babin]

That should be OK.

 

[mike49504]

Ok replaced the diode and drivers heres what i have on pins9,14 now

PIN9:-116.8

PIN14:-115.8

R118

1side:-117.8

other side:-93.8

 

[Perry Babin]

What's the DC voltage on pin 8?

 

[mike49504]

PIN8:-119.1