Need help reverting modded Badlander 100 rev 6 to stock

[FlyinBlueDream]

Hey fam,
I bought a modded Badlander that blew the filter caps so I want to revert it to stock and could use a bit of help figuring out what the capacitor values on the gain pot are supposed to be. There was an added capacitor at C32 that must've been too much for the filter caps to handle. The amp could've also been abused a bit and cranked all the way up with IRs. It's amazing the filter caps blew at such a young age...I don't want to deal with it again so I'm reverting it to stock. I will likely get the Mr. Scary Mod and hope that doesn't cause similar problems. No schematics available, obviously, but it's a simple little bit of soldering I can do myself if I can figure out what's supposed to be there. Don't want to bother with a tech. I've already removed the added capacitor and replaced the filter caps, but IDK exactly how it's supposed to be wired up. There's an empty hole in the PCB now...also not sure if the remaining cap is stock. I've seen close up pics of other revisions (5 and 7) that don't have the two holes in the PCB for the caps, unsure if that was added by who modded the amp and exactly what I should do to fix it. The disconnected cap in the pics is the mod that was added. Anybody with a stock rev 6 Badlander 100 that can help?
Thanks!

 

[bandit2013]

The orange cap above the 82.5k resistor has the same numbers on it as the one on the Rev 5 and Rev 7 boards. Not sure what that value is as I believe it is just some sort of part number. Also they are soldered to the two outmost pads. I did not see any other holes as you mentioned. I doubt that was a mod done to the amp as the copper pour in your pictures shows a square cutout around the pad. May be for use with a different capacitor? Are you sure it is damaged (other than the one lead being cut short) ? You can check for continuity between the inner pad and the outer one. If there is no continuity, I would assume it is a different circuit.

 

[incertracing]

I suggest when you bring it back to stock, you do the Mr scary mod if u want more gain. It’s sounds fantastic and it’s safe

 

[FlyinBlueDream]

The orange cap above the 82.5k resistor has the same numbers on it as the one on the Rev 5 and Rev 7 boards. Not sure what that value is as I believe it is just some sort of part number. Also they are soldered to the two outmost pads. I did not see any other holes as you mentioned. I doubt that was a mod done to the amp as the copper pour in your pictures shows a square cutout around the pad. May be for use with a different capacitor? Are you sure it is damaged (other than the one lead being cut short) ? You can check for continuity between the inner pad and the outer one. If there is no continuity, I would assume it is a different circuit.

Thanks for the reply! I should've clarified there's THREE holes for this cap and it's wired up differently in the other PCBs I've seen online. I'll include the best pic I found that I'm using for reference, but it's still difficult to tell what's supposed to go where. It's clear the orange cap is connected differently on mine than the other's I've seen. The value of the orange cap is 1n0k,1 nano farad =/-10%. Thanks for validating it is stock.

The soldering to the two outermost pads is what's throwing me off. Is there a center pad/hole on other PCBs? What's it hooked up to, if anything? Should there be another cap there? Pics online appear to show a single cap at c32.

My meter didn't beep for continuity, but I don't think it would with the cap. These caps didn't fail, it was 2 of the filter caps. I want to get rid of the mod just in case it was contributing to the filter caps failure. The red cap definitely wasn't stock, I could easily tell by the solder and the fact it's not the same brand as the other caps on the PCB. Plus the guy I bought it from said it was modded by a professional amp tech, and that's a very common mod.

Just to clarify, the included pic is NOT my PCB, it is the best pic I found online of what I'm assuming is the stock configuration. I can't tell how many holes/pads are there or how the orange cap is connected to them. You say the outermost holes/pads?

Edit: I just realized you guys are the ones who posted the info and pics I'm using as reference. Thanks for that as well, looks like I'm in the right place.

 

[FlyinBlueDream]

I contacted Mesa customer service and they were very helpful and confirmed it is connected correctly. I'm gonna resolder and clean it up later today. Next I have to replace these diodes that were added during the mod, but I think I got that figured out.

 

[bandit2013]

OK, Let me ask about what transformers you have. Since I have a Rev 5 that uses the smaller 1N4007 didoes, The Rev 7 has much larger amp rated diodes. I assume the one cap on the Rev 6 has its own place on the PCB than the Rev 5 as it was soldered onto the diodes. Here is a picture of that, Rev 5: My first thought was Mesa did an oops. This one is a low SN number, I believe it is below 100.

Now Rev 7 came with different transformers and some mods to the circuits. Still has a few roach wires here and there. Also has a location for the one cap on the board.

There is no point in having diodes soldered over other diodes. The weaker one will still fail since it is in parallel. They have to be removed if you are going to run a 2A or 3A diode vs the 1A.

As for mods to the amp? I am not personally aware of such. If you need to have a mod, best that it is removable like the Mr. Scary mod thing. Hard mods, if the person does not realize what the general circuits are, may not be to any benefit. This preamp is basically a hybrid of a Mark lead drive circuit (in the crunch or VII mode of the Mark VII), but with a Rectifier tone stack driver following it.

My first BAD100 has different transformers than the second one. Perhaps that was part of the changes to the preamp and power sections (assumed). Confirm with Mesa what the diodes should be before making a decision to change them. It should be ok to use a 2A or 3A diode but the lead thickness will be larger and will not fit in the holes of that of the 1N4007. Actually the diodes in the Rev 7 almost look like they are 5A rated. I did not look up the part number on them to confirm.

 

[FlyinBlueDream]

Mesa confirmed the 1N5604 diodes are stock for this amp. Judging by the flux smeared around them, I assumed they were modified. I think they might've been removed and put back. I'm going to clean up and resolder to rule them out, for peace of mind if nothing else. I actually thought that was the issue that blew the filter caps... I will likely send it to a certified Mesa tech if this doesn't fix my issues. Thank you for your help.

 

[bandit2013]

I contacted Mesa customer service and they were very helpful and confirmed it is connected correctly. I'm gonna resolder and clean it up later today. Next I have to replace these diodes that were added during the mod, but I think I got that figured out.

If you look at the image, There are two sets of diodes here. The smaller ones are still on the PCB and the larger ones are soldered over them. That is not the way it is done. The smaller diodes should be removed. However, if that is a Mesa thing, send them the picture and ask if this was done on the Rev 6. To me that does not look right.