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Old 02-11-2013, 09:22 PM   #1
supersize
Registered User
 
Join Date: May 2008
Power Tube replacement

hey everyone

im gonna swap the power tubes in my Marshall Haze 40, but i cant seem to find the points where to put my black and red leads. theres no info on google and im not great at readin schematics. can someone possibly locate these points and tell me where they are?

thanks!

EDIT: i forgot to add the schematic. get it here http://music-electronics-forum.com/t16936/
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Guitars:
FENDER Sugar Rush, Scala-Caster Strat
KRAMER Striker600ST (from 86)

Amps:
MARSHALL Haze 40

Pedals:
Rocktron Banshee 2 Talkbox
Boss MD2
Crybaby
Visual Sound Tremolo
FAB Chorus

Last edited by supersize : 02-11-2013 at 09:27 PM.
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Old 02-12-2013, 12:31 AM   #2
R45VT
Doesn't speak guitar
 
Join Date: Dec 2009
Location: Traffic Town LA
Cool

It looks like an EL34 power amp section. The bias looks normal for Marshall. They have a 3 pin set-up. Common middle and voltage per bank on either side. The test point will be internal to your chassis and must be removed, and hooked up properly.

I am looking at this through my IPhone so I may have missed something but tere does not appear to be a bias adjustment. You can check the bias- set to 39mV- between common( middle) and either outer pole of the test connector.


Free bump.

The test point is normally a little 3 pin deal that is inside the chassis- you have to remove it and the hook up the speaker for a proper load. Amp on, volume at zero, no guitar plugged in.

Have you looked inside your amp yet.


Also be advised there are lethal voltages present in places. Beware the HT voltage.

Your bias points are non-lethal measures in mV DC.
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Last edited by R45VT : 02-12-2013 at 12:34 AM.
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Old 02-13-2013, 12:22 AM   #3
supersize
Registered User
 
Join Date: May 2008
yeah i see the little pots for each valve. i can see where the pins are. i just couldnt locate the test points as theyre not marked on the board itself

grazie mille
__________________
Guitars:
FENDER Sugar Rush, Scala-Caster Strat
KRAMER Striker600ST (from 86)

Amps:
MARSHALL Haze 40

Pedals:
Rocktron Banshee 2 Talkbox
Boss MD2
Crybaby
Visual Sound Tremolo
FAB Chorus
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