troubleshooting issue after someone plugged in head wrong

[ph0nage]

Hello,

I'm new to this board (and not under the best of circumstances). I let a friend borrow my single rectifier solo 50 recently. He used it well and stuff, but then his friend decided that he wanted to set it up and play it when the original guy was away. Anyways, he hooked up by going Slave Out to the cab input (8 ohms) :roll:

He started play and eventually a crackling sound occurred and then it got quiet. I haven't gotten a chance to pick it up yet, but does anyone know the extent of the damage this would cause?

fuse?
tubes?
transformer?

Any advice would be appreciated. (besides being careful about loaning it out in the future)

thanks

 

[elvis]

Hopefully use and tubes. Maybe transformer. If the tranny is gone, it won't make it any worse to try new tubes.

One of the good things about tube quality sucking is that they are more likely to die before the tranny.

Good luck! Put tape or a cap on your unused outputs.

 

[ph0nage]

that is an excellent idea about tape on the outputs. thanks for the suggestion. I already had some new JJs coming in, so I'll check it out

 

[domct203]

That amp needs to have the screen grid resistors checked. Hopefully it was just a blown tube that took out the fuse, but screen grid resistors are known to fail when a tube fails hard like in this senerio. Hopefully the Output Transformer is OK. Take out all the powertubes (leave the pre's in) and see if the amp fires up with a new fuse. If not, there is more damage than tubes or screen grid resistors. If it fires up without blowing the fuse shut it down, install your new tubes and try again.

I would still have it looked at to make sure that there is not a blown screen grid resistor. Here is a pic of a blown screen grid resistor from my Roadster when I had a new tube fail on me:

It is the black resistor that is circled in red. You can see the burn it left on the PCB next to it. It was a quick and simple fix for my tech.

Don't use tape on those jacks, use these:
http://www.ebay.com/itm/100-1-4-BLA...Parts_Accessories&hash=item45ff277753&vxp=mtr

I use them on every piece of gear I have. Keeps the dust out too!

Dom

 

[MrMarkIII]

Even better: Remove the fuse (and the fuse cap) when you leave the amp in strange neighborhoods.

 

[elvis]

Great idea!!!

They have the same experience as with the fuse (no sound after a few minutes vs. no sound ever), you have a much better experience.

8)

 

[ph0nage]

alright, it turns out the fuse was gone and the power tubes were toast. After some expert troubleshooting from a friend, we took the power tubes out of my other single rec in and got it working again.

I appreciate all the responses. Should I still take a look at the resistors for wear or anything?

 

[domct203]

alright, it turns out the fuse was gone and the power tubes were toast. After some expert troubleshooting from a friend, we took the power tubes out of my other single rec in and got it working again.

I appreciate all the responses. Should I still take a look at the resistors for wear or anything?

I would still check for failed screen grid resistors. I also swapped tubes and a new fuse and thought all was good. It took a couple of weeks for me to notice something wasn't right with my amp, but I thought it was the old powertubes I had put back in. When I installed a new set of powertubes I (always) checked the idle current (bias) and discovered that one tube was not drawing current, and pretty much turned off, this put my output section way out of balance. That made me pull the chassis to investigate & that is when I found the burnt resistor. If you decide to check for yourself DO NOT TOUCH ANYTHING INSIDE THE AMP, Lethal voltages can be stored in the PS caps for days unplugged.

If it were me, I'd bring it to a Mesa Certified Tech, billed to the idiot who broke it.

Dom