crossfire vr4000

[timwebb]

it looks to be connected to the output gate resistors.

 

[Perry Babin]

I would assume that they're connected across the gate drive output and the source legs of the same output FETs.

 

[timwebb]

Both 70v+ 70v+ pins are directly connected across the board. The cathode goes through those smd transistors and goes. Out through another pin to the gate resistor. Each pair of diodes goes to one group output transistors. I will confirm when I get home

 

[timwebb]

I will confirm when I get home.

 

[timwebb]

if the amp have 70v at the output transistor. i would still need a 12v zener right?

 

[Perry Babin]

I don't know definitively what these are used for in this circuit but I think they're used to protect the gates of the FETs. If so, they may have one end connected to the rail but they will never have rail voltage applied across them (unless an output transistor fails).

 

[timwebb]

that looks to be what happened. a few of the output fets were missing when i got the amp.

 

[timwebb]

what u think i should try?

 

[Perry Babin]

See post #21.

Remember, I have no way of knowing if this is right. It may or may not work or could cause more damage.

 

[timwebb]

I drew that area out. The diode run to to the transistors. Then those go to the gate resistors. But the diodes run directly to the other driver card and do the same thing.. I will try what was discussed earlier.

 

[Perry Babin]

I have an amp with a similar board. ZD10A and ZD12A are 1N4737s. ZD9 and ZD11 are 1N4740s. The anodes are directly connected for each pair.

The connections to the main board are color coded to the legs of the diodes in the second photo.

 

[timwebb]

u are the man mr babin!... i been looking all over for another amp with this kinda driver card