The Boogie Board

Discussion Forum for Mesa Boogie Products
It is currently Mon Feb 19, 2018 8:11 pm

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: Mesa Prodigy
PostPosted: Sun Aug 30, 2015 6:10 am 
Offline
Bottle Rocket

Joined: Sun Aug 30, 2015 6:00 am
Posts: 1
Location: UK
Hi

Got hold of my Prodigy four:88 a few weeks ago - my first all valve amp in 25 odd years (last was a Hiwatt DR201)

Playing it through either a Barefaced Super 12T or a Tecamp L810..

I'm liking it a lot, but it seems to get louder throughout a gig - such that I have to keep turning it down.. Is this normal?

Also does anyone know where I can get the FC.PROD footcontroller in the UK or Europe? Noone seems to have any stock..

Regards



Mark


Top
 Profile  
 
 Post subject: Re: Mesa Prodigy
PostPosted: Sun Aug 28, 2016 9:39 am 
Offline
Mark II

Joined: Tue Jan 07, 2014 10:54 pm
Posts: 70
First, it's not an all valve amp - it's 1/2 solid state. The preamp EQ and driver are all transistors...combined with tubes.
We call this a "Hybrid" amplifier.

Second - volume fluctuation
I suspect the 2 MOSFET transistors in the phase inverter driver stage need replacing. OR clean / replace the VOICE switch.

Also, try swapping the preamp tubes, one at a time with a new 12AX7, and retest the amp each time.
Plug a guitar cable between effects send and effects return jacks...and re-test. The jacks have internal switches which can corrode and fail. This will cause fluctuations or it may stop working completely.
Whether or not you use the effects loop - the audio goes thru the effects jack switches. If the switch oxidizes the volume can cut in and out.

Plugging a guitar cable between send and return bypasses the jack switches. This is a good test to see if those switch contacts are failing.

No, you do not work on this amp yourself.
It requires EXPERT skill and professional soldering equipment.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group