Badlander Issue. Need Help.

[incertracing]

So when i purchased my badlander off reverb i not iced that when i move the amp from side to side there was something rolling around inside, i figured it was no big deal as the amp was running fine. Today i took it for my tech to look at JIC and boy is it a good idea i did.
So it turns out there was a resistor that was rolling around. In trying to determine where it came from we discovered that it came from the side of the smaller board above the main board that has the 3 speaker jacks and the xor out etc. There is a burn mark on the area it came out from which probably means it got so hot it melted the solder and came loose. The 2 capacitors in front of the resistors are also going bad. We are going to replace the capacitors with new ones (same brand and spec) and put back the resistor as we tested it and it's not damaged. What i would love you guys help with is determining what those 2 resistors and the capacitors on the end there do in the circuit and if possible could a schematic of the amp be sent to me so we can review it. Pics are below so you can see what im talking about.
Thanks so much.

My tech has a theory. He thinks that the previous owner may have taken for granted that the amp has an internal load and instead of unplugging the speaker cable from the head he did it from the cab and the head did not kick in the internal load as it still has a speaker jack inserted in the speaker out. It's just a theory but it makes sense.

 

[domct203]

Sorry to hear of your issues.

That’s a pretty hefty resistor, so your tech’s theory that it has to do with the power amp seems plausible. The cap related to that resistor looks like it ‘vented’ from the stress.

It looks like whatever that is, it’s laid out in pairs, and there was something definitely not working with that amp so it was not running fine, just not noticeable to someone hearing the amp for the first time.

Which model is that? I’m guessing it’s the 100?

Dom

 

[incertracing]

Sorry to hear of your issues.

That’s a pretty hefty resistor, so your tech’s theory that it has to do with the power amp seems plausible. The cap related to that resistor looks like it ‘vented’ from the stress.

It looks like whatever that is, it’s laid out in pairs, and there was something definitely not working with that amp so it was not running fine, just not noticeable to someone hearing the amp for the first time.

Which model is that? I’m guessing it’s the 100?

Dom

Yeh100w.

 

[incertracing]

Any one know what that section of the board controls? What each resistor and capacitor does in the circuit? Really need some help here, the parts have been replaced/fixed but we looking for some answers before we fire it up. We have searched everywhere for a schematic but we cant find one.

 

[rarebitusa]

Any one know what that section of the board controls? What each resistor and capacitor does in the circuit? Really need some help here, the parts have been replaced/fixed but we looking for some answers before we fire it up. We have searched everywhere for a schematic but we cant find one.

Not the answer you want to hear but since the Badlander is in production a schematic is not likely to be found.

 

[incertracing]

Not the answer you want to hear but since the Badlander is in production a schematic is not likely to be found.

Ok cool, hoping then an engineer type in here with his/her infinite wisdom could probably tell me what those resistors and caps in that section of the of the circuit govern.

 

[tbonesullivan]

Have you tried contacting Mesa customer service? That all is really packed in there though, dang. The resistors for the reactive load are right under (over) that pcb. They should have mounted them outside the chassis IMHO.

 

[bandit2013]

Considering when the Badlander came out, it will still be under factory warranty as it was in 2020 when they were released. I would not make any repairs at this time and go through Mesa customer service and register a claim. I assume the limited warranty is still transferable. Say what you found.

As to what it is?

I do not have infinite wisdom to offer but I am an electrical engineer.
Have no clue what this is used for. However, since I have the other Mesa with the IR cab clone, the same parts are in that amp as well. Different layout but same wire arrangement, white and blue with the large Dale resistors, 8 ohm coil and the pair of capacitors. And the relay.

However, it could be related to the IR Cab Clone circuit as there was something quite similar found inside the Mark VII which was the second amp the Mesa used this tech.

As for the load resistors, they are externally mounted near the front of the amp and not tucked in like they are in the Badlander.

 

[bandit2013]

I see now, I found the same parts in the TC100 but they are not present in the TC50. I believe the parts are used for a means to attenuate the speaker output to a level for the IR Cab Clone. Those high power resistors are also used. The gold anodized ones. I did not find these parts in the JP2C either and that also have the original Cab clone like the TC50 and TC100. Not sure what else it could be.

Then again, no schematic to base this on, just a wild guess and association of the same components on a different amp.

 

[incertracing]

I see now, I found the same parts in the TC100 but they are not present in the TC50. I believe the parts are used for a means to attenuate the speaker output to a level for the IR Cab Clone. Those high power resistors are also used. The gold anodized ones. I did not find these parts in the JP2C either and that also have the original Cab clone like the TC50 and TC100. Not sure what else it could be.

Then again, no schematic to base this on, just a wild guess and association of the same components on a different amp.

Thanks for helping, I will pass this on to my tech.

 

[bandit2013]

If your tech is a Mesa Certified Tech, they would have access to the schematics. This looks to me like a warranty repair. That board should be replaced as it is already compromised.

 

[incertracing]

If your tech is a Mesa Certified Tech, they would have access to the schematics. This looks to me like a warranty repair. That board should be replaced as it is already compromised.

Nah he is not an official Mesa tech. I don not live in the US so it will be a last resort for me to ship the amp to the US to get sorted. My tech is very good and has replaced the components that were damaged but we were trying to confirm his theory correct so we know the issues will not return.

 

[bandit2013]

Still sorry to see this has happened with your new amp, even if it was used.
Your tech's theory may be on the right track. I had thought the same thing. That would explain the overloaded capacitors that vented. That sort of transient usually does not occur unless the amp was moving current through the OT. If it was due to unplugging a hot speaker cable it is possible. However, the if the speaker was unloaded it would not explain the thermal damage caused by the one resistor, I would also assume the other one is compromised. Once you cook the solder to that point that may have some arcing, it may have small fractures that may not be visible. Heat of that magnitude will also lift copper traces off the board. Even if you can get the part installed, there is no guarantee that fixes the issue. I would assume MESA would have an understanding to why this issue occurred. They may request to have the amp shipped to them for analysis if this is something they did not consider or have overlooked in its design. I wonder if that took out the fuse when it happened. It is obvious the damage was done and sold as is. I hope you bought it at a bargain price to cover the cost of repair.

However, that small board on back panel is easier to replace than that of its sibling that also has the IR Cab Clone.

I hope it is not from using the amp with headphones and running it in silent mode. Even if I were to use the cab clone, I will stick with the practice of using the speaker connected to the amp. Sure, it is a novel idea but will add more heat to the internal structure of the amp due to the dissipated power used for that silent mode. The case with the JP2C, it has one really large resistor mounted inside the chassis. The Mark VII makes use of two resistors in series and they are external and sit just behind the front panel.

 

[bandit2013]

Nah he is not an official Mesa tech. I don not live in the US so it will be a last resort for me to ship the amp to the US to get sorted. My tech is very good and has replaced the components that were damaged but we were trying to confirm his theory correct so we know the issues will not return.

I would still inquire with Mesa Customer service. You may be able to get a complete assembled rear board shipped out to replace the damaged one. It may be worth a shot.

 

[incertracing]

I would still inquire with Mesa Customer service. You may be able to get a complete assembled rear board shipped out to replace the damaged one. It may be worth a shot.

I wrote them, waiting on a reply. Wrote you guys first thow lol