Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Searing on March 31, 2016, 07:24:40 pm

Title: Help with Mesa resistor values!
Post by: Searing on March 31, 2016, 07:24:40 pm

mesa studio .22.  I need to replace two scorched resistors, R131 and R115.  I can't tell what value they are because they are black from fire, and the schem I found is blurry and confusing.  Please help.  Thanks.

Title: Re: Help with Mesa resistor values!
Post by: sluckey on March 31, 2016, 08:03:14 pm

Here's a readable schematic...

     http://el34world.com/charts/Schematics/files/mesa_boogie/boogie_22cal.pdf (http://el34world.com/charts/Schematics/files/mesa_boogie/boogie_22cal.pdf)

Look on page 2.

Title: Re: Help with Mesa resistor values!
Post by: Searing on March 31, 2016, 09:30:18 pm

Ok.  Thanks.  It's a bit different, but I am assuming I need a 56k 3 watt and a 10k 1 watt?

Title: Re: Help with Mesa resistor values!
Post by: sluckey on April 01, 2016, 01:42:18 am

Quote from: Searing on March 31, 2016, 09:30:18 pm

Ok.  Thanks.  It's a bit different, but I am assuming I need a 56k 3 watt and a 10k 1 watt?

That's not what the schematic shows for R131 and R115. You must be looking at R132 and R123???

If you think this is not the correct schematic, post the one you have.

Title: Re: Help with Mesa resistor values!
Post by: Searing on April 01, 2016, 07:17:02 am

It's the caliber series Mesa Boogie .22  Maybe that schem is the right one?  Ok.  I ordered up the correct values, but the one resistor I pulled off was 3 watt, and that schem calls for a 2 watt?  We shall see.  Thanks Sluckey!

Title: Re: Help with Mesa resistor values!
Post by: JB on April 01, 2016, 08:40:43 am

I have the Studio 22, not the later + version.  Think they had issues with the foot switch supply, which is where those resistors are.  Have a look here:

http://www.classictubeamps.com/schematics/Mesa/Mesa%20Boogie%20.22%20caliber%20plus%20schematic.pdf (http://www.classictubeamps.com/schematics/Mesa/Mesa%20Boogie%20.22%20caliber%20plus%20schematic.pdf)

Page 3 has a mod sheet referring to those resistors.

Values changed between the original and + version.

Title: Re: Help with Mesa resistor values!
Post by: Searing on April 01, 2016, 11:02:49 am

Ah, yes.  Thanks JB!  That clears it up for me.