Mark III Pull Bright Problem

[Podicle]

Hi guys,
It seems that the pull bright on my Mark III isn't doing anything anymore. I've tried with treble and volume one at different settings with no success (as the strength of the effect depended on these). I just recently had my amp back after a service and I don't really want the 2 hour commute plus 2 week turnaround to take it back to the amp tech. Is there anything easy I can check for? What parts are connected to that switch and how can I tell if they (or the switch) are working properly?

Also, I've been noticing that everyone here seems to run the presence on their Mark IIIs very low (0-2 usually). If I have the presence set any lower than about 4, the amp sounds like it is under a mattress. It's been like that since I've had it (about 10 years), but could this indicate some other problem with the amp? I play blues andf rock (not metal) so could it just be a style thing? It's a 60w red stripe export tranny with reverb and no EQ, C90. I have tried multiple sets of tubes.

Thanks in advance for any help.

 

[Restless Rocks]

The Bright Switch simply closes circuit with a 180pf cap across the volume control. As you know when the volume is set above 6 or 7 the effect is barely noticable. You may have broken the switch and you'll need to replace the pot/switch assembly. http://www.mojotone.com/amp-parts/CTS/CTS-push-pull-1MA-Potentiometer-Volume-Tone

Do make the effort to get a tech if you are not handy with electronics tools.

There is nothing wrong with running your presence at 4, I run mine at 6 as I also play a wide variety of styles and I agree that the sound is less than open when the presence is too low.

 

[Podicle]

Thanks for the reply. I probably will take it back to the tech.
Cheers