Massive p-1500.1

[mike49504]

Im working on this amp (massive p1500.1) That a guy brought to me. This amp was a do it yourself when brought to me. What im wondering does anyone know if all the outputs are 640's or are some 640's and some 9640's ??

When the outputs are in the amp all 640's it goes into protection with all outputs removed the amp powers up fine.

Any help would greatly be appericated

[Perry Babin]

Do you have a scope?

All outputs are 640s.

Did you check the drivers Q11, 12, 13 and 14?

[mike49504]

I checked the drivers all seem to be ok but it looks like they have been messed with also . I have a scope yes

[mike49504]

Wondering since the drivers were messed with im thinking about replacing them anyway. They are mared 2t and 2 x. I have some 1 a 2 a 1d wondering if any of theese would work or do i need to get the same drivers

[Perry Babin]

With NO outputs in the circuit, you should have square wave pulses with an amplitude of ~10v on the gates of all outputs. You may have to short the positive and negative speaker terminals together to see the pulses that will be at ~0v DC (first image). The other pulses will be referenced to the negative rail (second image). The pulses should be relatively square.

[Perry Babin]

Those transistors (the ones you listed) are rated for slightly less current. There's no point in replacing the other transistors if they're not defective.

[mike49504]

ok im not getting no where near squre waves on outputs . Also i checked the power supply fets and theres mis matched parts in there i believe the correct ones that belong there are p60nf06 wondering whats a good replacement for thoose??

[Perry Babin]

Did you short the speaker terminals?

I think the original power supply FETs were IRFZ44s. If you want something a bit better, the Z48 should be a good sub.

[mike49504]

I shorted the speaker leads together further looking into the amp one on the 4700 uf 80v caps vented so im thinking this may be why its acting the way it is

[Perry Babin]

Check the drive signal on the 2 pins on the corner of the driver board nearest D17. Both should have square wave signals of ~3v amplitude referenced to ground.

For testing without the outputs, you only need a cap large enough to keep the ripple on the rail to less than ~1v. It will have to be able to handle the full rail voltage, of course. If the vented cap still has enough capacitance to remove the ripple, you can continue testing without replacing the cap.