Rockford Fosgate Power 650

[RockfordFIx]

Wht do you think perry?

 

[Perry Babin]

Correct me if I'm wrong but I think the 650s all used bipolar transistors in the power supply, not FETs.

 

[seankane]

They used D44VH10 which were a power transistor, 15A-80V-83W and were not bipolar.

They did however also use a couple D45VH7 in the power supply which were bipolar general purpose transistors.

I am not sure why the mix, and these transistors are not FETS like the IRF3205 so I do not believe the IRF3205 would work.

 

[Perry Babin]

The D44VH10 is a bipolar junction transistor. Look at the description at Mouser:

D44VH10 ON Semiconductor | Mouser

 

[seankane]

I stand corrected, the data sheet I used did not specify that.

 

[Perry Babin]

NPN/PNP are BJTs.

N-channel/P-channel are FETs.

 

[seankane]

Right so the IRF3205 will not work in this application.

 

[Perry Babin]

There are some drive circuits that can drive FETs, even though they were intended to drive BJTs. I don't know if that's the case here. I would use the original part number. The supplies in these amps were reliable as designed.

 

[seankane]

How do you determine if an originally designed BJT supply is able to drive FETS?

 

[Perry Babin]

BJTs can be driven by a relatively low amplitude signal since they have a threshold of about 0.6v. FETs require a drive signal with a much greater amplitude. The threshold voltage for an FET is about 3.5v but they are generally driven with a signal that has an amplitude of about 10v (ground to +10v) to ensure that they're fully 'on'.

You can look at the amplitude of the signal to see if it's close to what the FETs need but that's not definitive as to whether they would work. I tried using FETs in an old Orion that used BJTs and even after modifying the drive circuit to get the right signal, they wouldn't work. The amp would work but the 12v primary filter caps would fail after just a few minutes at full power. After removing the drive mods and installing BJTs, the amp worked perfectly and the primary caps didn't overheat.

 

[RockfordFIx]

Hey guys thanks for looking up the data sheets so quick.. I was in digikey looking them up when I got beatup by 4yr & 8yr old boys. Amp repair has been belayed have to go shovel snow.

 

[RockfordFIx]

Here is some pics of finished product. I replaced just about every component.

 

[RockfordFIx]

Here are some pics of before and after repair/upgrades. This was definitely an ongoing project / repair. There was definitely a lot of man hours in this one

 

[chipper]

Wow that's impressive! Nice work man I enjoy checking work like this. Btw where did you come across D40D8 & D41D8 transistors? Need some for a 1st gen Punch 150 & 45

 

[gamblin]

Thats a excellent repair job!!!