Is there amp doctor in the house

Pre Recto days. Boogie modified Fenders, Mark I-IV, Dual Calibers, etc

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nick bell
Bottle Rocket
Posts: 11
Joined: Mon Jan 22, 2018 6:41 pm

Is there amp doctor in the house

Post by nick bell » Mon Jan 22, 2018 9:46 pm

I decided to open my new mark llb up and take a look under the hood, at least 5 filter caps are leaking that would explain why the amp didn't have much volume Well that honeymoon didn't last long Is there anyone out there that help.thanks

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jediguitarist
Mark II
Posts: 127
Joined: Fri Nov 16, 2012 4:55 pm
Location: East Coast, New Jersey

Re: Is there amp doctor in the house

Post by jediguitarist » Mon Jan 22, 2018 10:05 pm

Definitely bring the amp to your tech. Unless of course, you're pretty good with replacing those caps.

93 97 98 PRS CE24
94 98 G&L Legacy
94 G&L ASAT Special
95 G&L S-500
99 Peavy Wolfgang
11 Gibson LP Studio 60

69 Bandmaster Head
88 Quad Pre
91 & 92 Simul 295
92 DC-5
96 Mark IV Maple/Wicker
98 5150 combo
08 Mark IV Wide

nick bell
Bottle Rocket
Posts: 11
Joined: Mon Jan 22, 2018 6:41 pm

Re: Is there amp doctor in the house

Post by nick bell » Mon Jan 22, 2018 10:20 pm

I've done some mods to amps and pedal before the hard part with some amps is getting to the board to desolder the parts.

darkbluemurder
Mark II
Posts: 104
Joined: Fri Jul 28, 2006 5:58 pm
Location: Europe

Re: Is there amp doctor in the house

Post by darkbluemurder » Tue Jan 23, 2018 8:42 am

Don't know about the Mk IIB but with my Mk III the cap job was quite easy. The solder connections were easily accessible on all caps.

You will need 2 220uf/350V caps (4 for a simul class model) and 3 30uf (nowadays 33uf, which is within 10% tolerance and OK) at 500V or more.

Make sure that there is no voltage left in the amp before you replace the caps. After playing, shut the amp off with the power switch but leave the standby in the on position. This will drain the caps through the 330k resistors in parallel to the 220uf caps. I always check with a multimeter.

Good luck,
Stephan

nick bell
Bottle Rocket
Posts: 11
Joined: Mon Jan 22, 2018 6:41 pm

Re: Is there amp doctor in the house

Post by nick bell » Tue Jan 23, 2018 9:43 am

Thanks Stephan I’m glad to hear your project went smooth,it looks like for me to get to the solder pads I’m going to have a little more work.thanks again for your advice.

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