CAB 2000.1 Protection Flashing

[Perry Babin]

The capacitor terminals are the ones that go to the secondary ground. That's normal.

Do you read a steady 0 ohms across the terminals (inside terminals to the outside terminals) for the rectifiers?

 

[40HRZZ]

I'm not sure what your asking me to check here? Below is resistance across rectifier pads on board with rectifiers out.

Pin 1-3 for each rectifier is steady .7 ohms(DMM Lead Resistance)

Pin 2-3 and 2-1 charges a capacitor in circuit

 

[Perry Babin]

1-3 is reading across the secondary windings.

2-1 and 2-3 are capacitors... charging.

That's normal.

 

[40HRZZ]

hmmm im not sure what would be causing over current then. Nothing gets hot that i can find and the drive wave looks good when FETs are out

 

[Perry Babin]

Could you possibly be triggering the low-voltage protection? What are you using to power the amp? Do you have a limiter inline with the 12v line?

 

[40HRZZ]

My input voltage is 12.65 from a AGM 18AH battery with an inline fuse. All places on board seem to be getting battery potential. I ordered an Astron VS-20ML today to be able to limit current.

 

[Perry Babin]

If the battery is charged and in good condition, voltage shouldn't be a problem.

Is it possible that one of the secondary windings are intermittently shorted when soldered into place normally?

 

[40HRZZ]

What would be the best way to test this? I have less than ohm across the 3 solder points for the secondary winding on the back of the board pictured earlier. I do not have an inductance tester. i did try to manipulate the transformer while powered up and did not get any change.

 

[Perry Babin]

If it will power up with the leads desoldered (and I assume pulled away from the board), Try using a small wire to reconnect the leads (without moving them back to near the board) back to the points where they were originally soldered.

 

[40HRZZ]

Ill try this tomorrow after work. Thanks for all your help so far.

 

[40HRZZ]

I pulled the secondary winding's and wired in jumpers and it does the same in and out of protect. i desoldered the jumpers and the amp does have good drive waves but the green light does not come on and it does not light the protect light either.

 

[Perry Babin]

If the protect LED isn't lighting, how did you determine that it's in protect mode?

 

[40HRZZ]

With thesmall wires attached to board going to lifted secondary windings it flashes in and out protect (LED's are flasimg red then green...)

With the secondary windings lifted the FETS are making a good square waves but no LED comes on ( red nor green are illuminating). I do not believe it is powering completely up when I have the secondary windings lifted.

 

[Perry Babin]

What are you using for a power supply?

Do you have any type of limiter in the B+ line?

 

[40HRZZ]

I am using a 12 volt battery with an inline fuse the battery rests at 12.65 volts. I hooked up another amp today and it functions with no issues. When I first opened this amp up the power input solder wasn't great (maybe got hot or poor from factory) so I refreshed that and I am getting good voltage to pin 2 on all PS FET pads.

 

[Perry Babin]

What happens if you leave the transformer with the jumpers connected but pull the FETs for the other transformer?

 

[40HRZZ]

No change I'm going to try fresh FETs in both banks

 

[40HRZZ]

I put 4 FETs one per bank all batch matched and no change. It is still flashing in and out of protect? I think there is a short somewhere in the positive rail rectifier circuit (this is a hunch) causing a over current.i can't find any short though?

 

[Perry Babin]

Does connecting only 1 of the two jumpers on the transformer make a difference? Try both, alone.

Do you have a lamp with an incandescent lamp (not CFL, not LED)?

 

[40HRZZ]

I have all 4 pulled on the side so I have 4 jumpers I am I doing something incorrect there?