Mesa mark III R2 volume mod spec. HELP!

[Reeko81]

Does anyone know what really does this volume pot in that point of the circuit?And why i have to connect a wire to r131 and one tho the hole of the removed r130?
What really affect these resistors in the circuit board ?
I tell you because in the schematic there is no trace of a number to identify the r130 and r131 resistors so if you know more you can help me much more than you believe!
I've noticed that only swapping the r130 resistor the volume of r2 channel has increased, but since i made some circuit interruptions with a bad iron (and i believe they are at the bottom of the board) my r2 volume mod doesn't work properly...infact this new pot doesn't control r2 volume and now acts as a master volume for all the channels...and more i've noticed an increased feedback on the lead channel (it's impossible now to crank this channel at high gain level without noisy feedback) and the r2 channel is boosted now!
Is there anyone who can me explain better what really this mod does on the circuit?I can so understand where is now the problem of my circuit disfunction!
Riccardo

 

[Boogiebabies]

It really sounds like you have the pot set up as a resistor only and you are not letting the signal pass. You are stopping it. It is there to taper the amount of signal. If I am wrong, when you turn your R2 master down, you get no signal? When you turn it up, you are overloading the rest of the circuit.

It sounds like it is time to drop a dime an call Mike Bendinelli at Mesa.
Either that, or fix your traces and start over using jumpers. These MK III boards cannot handle a lot of soldering. Most modern PCBs are cheaper to replace the entire board than fix and that was the mentality behind them. If you solder, use flux and get a new tip or an iron that will not be too hot for the job. Tin what you have to and flux where you need to get on and off in a hurry. If you have a carbonized tip and have to wait 15 seconds to desolder, it will burn that board up fast, and if you are adding new components use a heat sink. Otherwise you can over heat your cap or resistor to the point where it is no long in spec or working at all.


Peace !!!

 

[Reeko81]

Well...i don't believe that calling mike B. could be useful, cause i'm italian, and my speech is not great!But i think that i haven't been understood in the previous post...i was telling that my r2 volume mod doesn't work properly, infact now the new pot acts as a master volume for all the three channels...i want to know if there is someone that could me explain better the part of the schematic where this r2 volume mod interact, because in the schematic (the one avalaible from mesa!!!) is hard to find the resistor r130 and r 131 which are involved in this mod. At least i want to know with whom part of the circuit has to interact the new pot installed , and why it has to determine so this volume control for r2 channel...
if someone can answer me properly i can understand what is going wrong with my mark III circuit and i can understand why in this moment my r2 volume pot is acting as a master volume!In fact if i turn it down my amp doesn't sound!
Riccardo

 

[Reeko81]

Well...i don't believe that calling mike B. could be useful, cause i'm italian, and my speech is not great!But i think that i haven't been understood in the previous post...i was telling that my r2 volume mod doesn't work properly, infact now the new pot acts as a master volume for all the three channels...i want to know if there is someone that could me explain better the part of the schematic where this r2 volume mod interact, because in the schematic (the one avalaible from mesa!!!) is hard to find the resistor r130 and r 131 which are involved in this mod. At least i want to know with whom part of the circuit has to interact the new pot installed , and why it has to determine so this volume control for r2 channel...
if someone can answer me properly i can understand what is going wrong with my mark III circuit and i can understand why in this moment my r2 volume pot is acting as a master volume!In fact if i turn it down my amp doesn't sound!
Riccardo

Oh...i forget to tell that my mod was done well the first time...infact after soldering the first time the amp worked with the new volume mod but only for 10 minutes...after that it started buzzing and then it stopped...so the problem is not with a soldering in a bad point, but after i started soldering and soldering again, and then this new volume post started acting as a master volume for all the amp...

 

[RussB]

Sounds to me like you're making a bloody mess out of that amp...put the soldering iron down, and step away from the Mesa! :shock:

There just HAVE to be some good techs out there in Pasta-Land!

 

[Reeko81]

Sounds to me like you're making a bloody mess out of that amp...put the soldering iron down, and step away from the Mesa! :shock:

There just HAVE to be some good techs out there in Pasta-Land!

HEHEHEHEHEHEH! Pasta-Land! You're wrong man...it's quite impossible to find here in Pasta-Land a good tech in Boogie's (apart me....auauauauauauauauauauuaauauau!)