Old school rockford fosgate punch 150

[chipper]

Got this amp here I've had forever I really want to get to fully work. I want to know which parts I need to get this channel working again (Orange & black channel) which is the left side. I believe 2n6487 & 2n6490 are shorted. So was one of the driver transistors. Any help is appreciated. Thanks

 

[Perry Babin]

The 6488 and 6491 are generally used to replace the 87 and 90.

The missing transistor appears to be a D41D8 (if the brown driver is a D40). They are difficult to find. The CENU57 should work. For testing, you can use an MPSA56 or an MPSA92 in place of the D41D8.

 

[chipper]

The 6488 and 6491 are generally used to replace the 87 and 90.

The missing transistor appears to be a D41D8 (if the brown driver is a D40). They are difficult to find. The CENU57 should work. For testing, you can use an MPSA56 or an MPSA92 in place of the D41D8.

What can I use to replace both driver transistors? And do you think there is any further damage on that channel?

 

[Perry Babin]

The CENU07 should be OK to replace the D40D8.

I doubt that there's more damage from the failure of the components you mentioned but it's possible that there are other problems.

 

[chipper]

I ordered a few cenu07 transistors already. What can I use as a replacement for D41D8? Like a good reliable replacement. I saw you mentioned mpsa92 and mpsa56 for testing.

 

[Perry Babin]

Post #2?

 

[chipper]

Are these OG? D40D8 to drive 2N6487. I recently also put in an MPSA56 in place of D41D8 just waiting for the the output transistors to come in the mail.

 

[Perry Babin]

Where did you find those D40s?

 

[chipper]

Ebay the seller is in the US so I took a chance. Do you think these are legit? I also ordered some of these from mousr online parts store. So either way won't lose.

 

[Perry Babin]

The D40 and D41 have been very difficult to find for years. These could be genuine. I wouldn't expect counterfeits to have different date codes (these were made in 1995). I looked at some of the ones I have left and they have the same date codes and have worked well enough.

 

[chipper]

I couldn't find D41 that one is really hard to find and I'm sure if I do find it'll be expensive... But will mpsa56 work with the D40? Also does ON manufacture 2N6488 & 2N6491?

 

[Perry Babin]

Yes. 2N6488G and 2N6491G. Digikey and Mouser should have both.

The CEN-U07 and 57 will work for the drivers.

 

[chipper]

Which way is the transistor suppose to be installed? Part # facing out or back?

 

[chipper]

Or this way? I don't want to install it the wrong way and blow it up. And also can I use one 2N6487 & one 2N6490 to test that channel if it does work? Thanks

 

[Perry Babin]

The text on the face of the transistor faces the transformer in the power supply.

You can use one output of each type. You need to clamp all transistors tightly to the heatsink and insert a 10 amp fuse or a current limiter in the B+ line before applying power.

 

[chipper]

Do these look legit to you? ON semi's. Also there's some DC of set when I installed the driver transistors and a small resistor caught fire! I shut the amp down fast. It happened when I hooked up a 10" sub to see if anything happens I only had the old pair of 2n6487's in. Should I remove them?

 

[chipper]

Reporting back and it works it plays music clear and static free no DC offset I replaced the burnt resistor and it tured out I had MPSA56 installed backward so I installed a fresh new one and put in the new outputs and boom it works now. Thanks perry babin!! One last question will it work bridged still? I'm not going to run this as a subwoofer amp or anything going to put it back in my little amp collection.

 

[Perry Babin]

4 ohm bridged and 2 ohm stereo are the same. The smaller driver will be more likely to fail than the larger one it replaced. If it's abused, it will be more likely to fail. If nothing else, you know that it works and can install the larger driver later if you want to use it.