Autotek MX5000

[caraudioguy2100]

Anyone have a high resolution picture of the power supply driver area?

Some attempted a repair in this and never fixed any of the blown traces

 

[caraudioguy2100]

Ok I put new drivers in this amp and repaired some traces .

The amp will draw excessive current .

Here is what I get for the drive signals on the power supply fets .

Scope set to 10us 5volts/div

These pics are with the fets installed and a current limiter inline with the B+

 

[Perry Babin]

If this is at 10us, the frequency appears to be too high. At 10us, you generally have about 3 complete cycles. Here, you have nearly 8.

 

[caraudioguy2100]

Here is what I get now after some adjustments to the scope .

Do these look ok ?
Scope set to 10us 5 volts div

If so I think I have a shorted transformer .

The amp will draw current for a second when only power and ground are connected .

Then if I hook remote voltage to it it will draw excessive current if I flip the amp over so solder side is facing up the amp idles perfectly fine . But if I face component side up the amp draws excessive current

 

[Perry Babin]

Did you try twisting the transformer to see if it made a difference?

Was the trace aligned with the reference before checking the signal?

Is there something on the bench that's conductive?

 

[caraudioguy2100]

If you twist the transformer makes no difference .

If you let the amp sit for awhile when powering up it will be fine for about 2 mins then out of the blue it will start drawing excessive current. If you flip the amp over it will be fine for 30 secs then start drawing current again .

It’s weird when you hook ground to it then hook b+ up it will draw 60 amps of current for a split second then be fine .

And it’s hit or miss when trying to power the amp up sometimes it’s fine other times it draws current right off the bat .

The reference line was centered when checking for drive signals . From what I can see in the pics it’s not pulling fully back to ground