Hifonics BXI 2010 D

[mike49504]

Wondering if there is a good cross to theese power supply fets The one that are in the amp now are: P75N758

 

[mike49504]

Sorry the part number is P75NF758

 

[Perry Babin]

Is the 8 possibly a letter?

The STP75NF75 may be close. Future has them.

 

[mike49504]

It only appears to be an 8 or an & sign

 

[Perry Babin]

I can't find anything with an 8 suffix.

 

[mike49504]

Neither could I . I Ill try the part you listed as a replacement. Do you want me to take a high res pic and post it before i order parts?

 

[Perry Babin]

If you can take a good quality photo, post it.

Have you tried wiping a bit of heatsink compound on and then off of the transistors to see if it makes it easier to read?

Have you looked at other transistors to see if others were easier to read?

 

[mike49504]

heres a pic of the fet

 

[Perry Babin]

I think the one I listed would be close enough.

 

[mike49504]

Replaced the power supply fets and gate resistors I also checked the drivers all seem to test fine.

But heres my problem 6 out of 12 of the fets the gate signal looks like PIC 1
ANd the other 2 look like the 2nd pic. AMp draws excessive current.

Any ideas on where to start looking?

 

[Perry Babin]

It's strange that they're different but I don't see anything that would cause it to draw excessive current. Did you try removing the rectifiers to see if the excessive current draw was eliminated?

 

[mike49504]

Removed the rectifiers ANd the power supply fets get red hot within 2 secs. Also amp trys pulling 15 amps of current

 

[Perry Babin]

Is it worse without the rectifiers?

Solder bridges between the pads for the rectifiers?

 

[mike49504]

Its the same without the rectifiers and I triple checked no solder bridges

 

[Perry Babin]

It's difficult to tell but when viewing the left gate waveform at full resolution, it appears that the PNP driver transistor may be defective.

 

[mike49504]

Replaced both A1275's and still the same Amp draws 10 amps of current and fets heat up

 

[Perry Babin]

What's the DC resistance between the emitter of the two PNP drivers and ground?

 

[mike49504]

Black probe on ground and red probe on leg 1 of the first 1275:3.75 volts
The other is 4.96 volts.

if i set the meter to ohms from 1 of the 1275's to ground is .463K ohms and the other is.465K ohms

 

[Perry Babin]

What's the resistance from the base terminals of the PNP drivers to ground?

 

[mike49504]

FIRST ONE 3.06 volts to ground
2nd one is 4.06 volts to ground

First 1:1.035K ohms
2nd:0.445K ohms