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Discussion Forum for Mesa Boogie Products
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PostPosted: Wed Mar 29, 2017 10:58 am 
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Bottle Rocket

Joined: Wed Mar 29, 2017 10:52 am
Posts: 1
Hi all,

I would like to do some retroengineering on an old power amp I've bought time ago and sold after one year... before I started building amps.

The schematic of the Mesa 295 can be found here:
http://www.thetubestore.com/lib/thetube ... ematic.pdf

and the power transformer has the following taps:

Mesa Boogie cod.561180
Lamination: 4 1/2"
Stacking 3"
Primary: 115V BLACK 0V YELLOW 115V BLACK 0V YELLOW
Secondary: 190V RED 0V GN/YEL 190V RED 60V BROWN 0V BROWN 6,3V GREEN 0V GREEN

So B+ is around 500-520 Vdc.

Looking at the datasheet of the TCR508 the phase inverter works at 2,1 mA.
We consider approximately the same for the sum of the two stages after it, so totally 4 mA.

On 22k the voltage drop will be 90V, so the power supply for the PI will be at around 420V.

Has anyone some more informations (voltage at plates/cathodes, OT specs)?


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