Phoenix Gold XS4600 blown trace

[Perry Babin]

Pin 15 is the power supply pin for the logic section of the IC. Pin 13 is only for the output drivers. Without voltage on pin 15 (above about 7 or 8v), the IC won't power up.

 

[jrodajames]

To verify, pin 12 needs to be grounded, correct?

 

[jrodajames]

The only transistors on the board measuring 12v are the drivers. Q2 and q5 at the collector.

 

[Perry Babin]

There may be damage to the board breaking the connection to 12v. You'll have to find the various components in the circuit shown (which may not be exactly like your amp but is VERY common in PG amps).

 

[jrodajames]

I replaced q13 with a new transistor and reinstalled c5.

with no voltage at remote terminal I would get 0v at the base of q13 and pin 15.

When I applied voltage to remote terminal I got negative voltage to the base of q13 and pin 15.

I attempted to double check my numbers and now get no voltage at q13 base or pin 15 with voltage applied to remote terminal.

Is it possible one of the 06 (npn - q1,q6) transistors is supposed to be a 56 (pnp) transistor?

The base of q13 is connected to the emitter of q6

 

[Perry Babin]

Typically, NPN transistors will have + voltage on their collectors and - voltage (ground, anything less than the voltage on their collectors) on their emitters.

PNP are the opposite.

If you any significant negative voltage on pin 15 of the 3525, it will very likely be damaged.

 

[jrodajames]

I don't know who was in the amplifier before I purchased it or what was done. It is obvious someone had attempted to repair it and failed. It's also possible they replaced parts incorrectly. I was getting negative voltage on both q13 and pin 15.

 

[jrodajames]

Is there a chance anyone has a schematic of the power section of the amplifier?

 

[Perry Babin]

Are you using the ground terminal of the amp for the reference (black probe)?

 

[jrodajames]

Yes

 

[Perry Babin]

Do you have the leads in the right jacks in your meter?

 

[jrodajames]

You can see my meter setup on post 43 and 61.

 

[Perry Babin]

What have you changed since the point where you had a constant 12v on pin 15?

Put it back to what you had then.

 

[jrodajames]

Thats what I was attempting to do when I reinstalled c5, I can't account for the change in Voltage.

It is setup in the same manner as it was. Post 95

 

[Perry Babin]

What's preventing you from finding the circuit path from the remote terminal to the switching transistors?

 

[jrodajames]

I traced the remote from the terminal to pin 5 of the LM339M and cannot find where it goes from there.

 

[Perry Babin]

I try to help but I can't do it all.

 

[jrodajames]

I understand and I really appreciate your help. You are very patient.

 

[jrodajames]

I am still looking for the transistors as described in your diagram.

 

[jrodajames]

Just got sidetracked when the voltage values keep changing and I don't understand why.