Quick Question for Amp Techs

[Thumpin6string]

I've got a quick question for you amp techs out there. I've got an A.M.P BH220 head with a bad power amp. Some background. This amp had this happen before and a fellow TBer amp tech was able to fix it, even though it had several shoddy repairs done to it in the past. He told me up front that due to the previous work that there was no telling how long the repair would last and if it failed again, it was a lost cause. About a year after the repair, the board let out the magic smoke again. So, I tried running the preamp into the power amp of another amp and it sounded great just like it always had. My plan is to run it into a Peavey power amp I can get. So, my question is what wires do I need to remove to cut power from the blown amp board? My concern is if I totally remove the board, will the preamp still work? The power amp board is the same as a BH420, so I'm including the manual with schematics in with this thread. Thanks in advance for any help.
A.M.P. BH420 Schematics

 

[agedhorse]

Impossible to say what might happen down the road.

If the power supply is located on the power amp PCB, it can't be removed or disconnected. You may be able to remove the fuses F2 and F3, but it depends on how they are wired within the chassis relative to the low voltage supply.

 

[Thumpin6string]

Impossible to say what might happen down the road.

If the power supply is located on the power amp PCB, it can't be removed or disconnected. You may be able to remove the fuses F2 and F3, but it depends on how they are wired within the chassis relative to the low voltage supply.

Thanks for the reply, Andy. I figured you might respond. The power supply with the large capacitors is on a separate board. If the 2 fuses are specifically for the power amp, that may be the easiest. I'll pull them and see if the preamp still works. That would be great if it is that simple. I really like the preamp on this amp and if this works, I can still use it and keep it out of the landfill.

 

[agedhorse]

There’s no way to know how exactly it’s wired based on the documentation.

 

[Thumpin6string]

There’s no way to know how exactly it’s wired based on the documentation.

I guess I'll wing it and see what happens. It's not like it is going to blow the amp.......again.

 

[Joebone]

Hoping the best for this project. In 1989 I played trombone on a gig with a bassist using AMP equipment - it sounded insane! Many years later, when I started into intentional playing of bass, Thunderfunk was my entry drug to great amps. Moved on for many reasons, including the sense that these amps could sound kind of dry on the gig. Knowing what I now know, it would be hoot to encounter one of these, once again. Good luck!

 

[Thumpin6string]

Hoping the best for this project. In 1989 I played trombone on a gig with a bassist using AMP equipment - it sounded insane! Many years later, when I started into intentional playing of bass, Thunderfunk was my entry drug to great amps. Moved on for many reasons, including the sense that these amps could sound kind of dry on the gig. Knowing what I now know, it would be hoot to encounter one of these, once again. Good luck!

I also have a BH420. It is a great sounding amp. Very Thunderfunkish. Even though the EQ on the 220 is more basic, it sounds amazing. If their factory hadn't been destroyed, I think they could have been one of the top manufacturers.